/*
    * Copyright (C) 2020-2021 Jo-Philipp Wich <jo@mein.io>
    *
    * Permission to use, copy, modify, and/or distribute this software for any
    * purpose with or without fee is hereby granted, provided that the above
    * copyright notice and this permission notice appear in all copies.
    *
    * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  /**
   * # Filesystem Access
   *
   * The `fs` module provides functions for interacting with the file system.
   *
   * Functions can be individually imported and directly accessed using the
   * {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#named_import named import}
   * syntax:
   *
   *   ```
   *   import { readlink, popen } from 'fs';
   *
   *   let dest = readlink('/sys/class/net/eth0');
   *   let proc = popen('ps ww');
   *   ```
   *
   * Alternatively, the module namespace can be imported
   * using a wildcard import statement:
   *
   *   ```
   *   import * as fs from 'fs';
   *
   *   let dest = fs.readlink('/sys/class/net/eth0');
   *   let proc = fs.popen('ps ww');
   *   ```
   *
   * Additionally, the filesystem module namespace may also be imported by invoking
   * the `ucode` interpreter with the `-lfs` switch.
   *
   * @module fs
   */
  
  #include <stdio.h>
  #include <errno.h>
  #include <string.h>
  #include <dirent.h>
  #include <unistd.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <sys/file.h>
  #include <grp.h>
  #include <pwd.h>
  #include <glob.h>
  #include <fnmatch.h>
  #include <limits.h>
  #include <fcntl.h>
  
  #if defined(__linux__)
  #define HAS_IOCTL
  #endif
  
  #ifdef HAS_IOCTL
  #include <sys/ioctl.h>
  
  #define IOC_DIR_NONE    (_IOC_NONE)
  #define IOC_DIR_READ    (_IOC_READ)
  #define IOC_DIR_WRITE   (_IOC_WRITE)
  #define IOC_DIR_RW              (_IOC_READ | _IOC_WRITE)
  
  #endif
  
  #include "ucode/module.h"
  #include "ucode/platform.h"
  
  #define err_return(err) do { \
          uc_vm_registry_set(vm, "fs.last_error", ucv_int64_new(err)); \
          return NULL; \
  } while(0)
  
  static int
  get_fd(uc_vm_t *vm, uc_value_t *val)
  {
          uc_value_t *fn;
          int64_t n;
  
          fn = ucv_property_get(val, "fileno");
          errno = 0;
  
          if (ucv_is_callable(fn)) {
                  uc_vm_stack_push(vm, ucv_get(val));
                  uc_vm_stack_push(vm, ucv_get(fn));
  
                  if (uc_vm_call(vm, true, 0) != EXCEPTION_NONE)
                         return -1;
 
                 val = uc_vm_stack_pop(vm);
                 n = ucv_int64_get(val);
                 ucv_put(val);
         }
         else {
                 n = ucv_int64_get(val);
         }
 
         if (errno || n < 0 || n > (int64_t)INT_MAX)
                 return -1;
 
         return (int)n;
 }
 
 
 /**
  * Query error information.
  *
  * Returns a string containing a description of the last occurred error or
  * `null` if there is no error information.
  *
  * @function module:fs#error
  *
  *
  * @returns {?string}
  *
  * @example
  * // Trigger file system error
  * unlink('/path/does/not/exist');
  *
  * // Print error (should yield "No such file or directory")
  * print(error(), "\n");
  */
 static uc_value_t *
 uc_fs_error(uc_vm_t *vm, size_t nargs)
 {
         int last_error = ucv_int64_get(uc_vm_registry_get(vm, "fs.last_error"));
 
         if (last_error == 0)
                 return NULL;
 
         uc_vm_registry_set(vm, "fs.last_error", ucv_int64_new(0));
 
         return ucv_string_new(strerror(last_error));
 }
 
 static uc_value_t *
 uc_fs_read_common(uc_vm_t *vm, size_t nargs, const char *type)
 {
         uc_value_t *limit = uc_fn_arg(0);
         uc_value_t *rv = NULL;
         char buf[128], *p = NULL, *tmp;
         size_t rlen, len = 0;
         const char *lstr;
         int64_t lsize;
         ssize_t llen;
 
         FILE **fp = uc_fn_this(type);
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         if (ucv_type(limit) == UC_STRING) {
                 lstr = ucv_string_get(limit);
                 llen = ucv_string_length(limit);
 
                 if (llen == 4 && !strcmp(lstr, "line")) {
                         llen = getline(&p, &rlen, *fp);
 
                         if (llen == -1) {
                                 free(p);
                                 err_return(errno);
                         }
 
                         len = (size_t)llen;
                 }
                 else if (llen == 3 && !strcmp(lstr, "all")) {
                         while (true) {
                                 rlen = fread(buf, 1, sizeof(buf), *fp);
 
                                 tmp = realloc(p, len + rlen);
 
                                 if (!tmp) {
                                         free(p);
                                         err_return(ENOMEM);
                                 }
 
                                 memcpy(tmp + len, buf, rlen);
 
                                 p = tmp;
                                 len += rlen;
 
                                 if (rlen == 0)
                                         break;
                         }
                 }
                 else if (llen == 1) {
                         llen = getdelim(&p, &rlen, *lstr, *fp);
 
                         if (llen == -1) {
                                 free(p);
                                 err_return(errno);
                         }
 
                         len = (size_t)llen;
                 }
                 else {
                         return NULL;
                 }
         }
         else if (ucv_type(limit) == UC_INTEGER) {
                 lsize = ucv_int64_get(limit);
 
                 if (lsize <= 0)
                         return NULL;
 
                 p = calloc(1, lsize);
 
                 if (!p)
                         err_return(ENOMEM);
 
                 len = fread(p, 1, lsize, *fp);
 
                 if (ferror(*fp)) {
                         free(p);
                         err_return(errno);
                 }
         }
         else {
                 err_return(EINVAL);
         }
 
         rv = ucv_string_new_length(p, len);
         free(p);
 
         return rv;
 }
 
 static uc_value_t *
 uc_fs_write_common(uc_vm_t *vm, size_t nargs, const char *type)
 {
         uc_value_t *data = uc_fn_arg(0);
         size_t len, wsize;
         char *str;
 
         FILE **fp = uc_fn_this(type);
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         if (ucv_type(data) == UC_STRING) {
                 len = ucv_string_length(data);
                 wsize = fwrite(ucv_string_get(data), 1, len, *fp);
         }
         else {
                 str = ucv_to_jsonstring(vm, data);
                 len = str ? strlen(str) : 0;
                 wsize = fwrite(str, 1, len, *fp);
                 free(str);
         }
 
         if (wsize < len && ferror(*fp))
                 err_return(errno);
 
         return ucv_int64_new(wsize);
 }
 
 static uc_value_t *
 uc_fs_flush_common(uc_vm_t *vm, size_t nargs, const char *type)
 {
         FILE **fp = uc_fn_this(type);
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         if (fflush(*fp) != EOF)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 static uc_value_t *
 uc_fs_fileno_common(uc_vm_t *vm, size_t nargs, const char *type)
 {
         int fd;
 
         FILE **fp = uc_fn_this(type);
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         fd = fileno(*fp);
 
         if (fd == -1)
                 err_return(errno);
 
         return ucv_int64_new(fd);
 }
 
 
 /**
  * Represents a handle for interacting with a program launched by `popen()`.
  *
  * @class module:fs.proc
  * @hideconstructor
  *
  * @borrows module:fs#error as module:fs.proc#error
  *
  * @see {@link module:fs#popen|popen()}
  *
  * @example
  *
  * const handle = popen(…);
  *
  * handle.read(…);
  * handle.write(…);
  * handle.flush();
  *
  * handle.fileno();
  *
  * handle.close();
  *
  * handle.error();
  */
 
 /**
  * Closes the program handle and awaits program termination.
  *
  * Upon calling `close()` on the handle, the program's input or output stream
  * (depending on the open mode) is closed. Afterwards, the function awaits the
  * termination of the underlying program and returns its exit code.
  *
  * - When the program was terminated by a signal, the return value will be the
  *   negative signal number, e.g. `-9` for SIGKILL.
  *
  * - When the program terminated normally, the return value will be the positive
  *   exit code of the program.
  *
  * Returns a negative signal number if the program was terminated by a signal.
  *
  * Returns a positive exit code if the program terminated normally.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.proc#close
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_pclose(uc_vm_t *vm, size_t nargs)
 {
         FILE **fp = uc_fn_this("fs.proc");
         int rc;
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         rc = pclose(*fp);
         *fp = NULL;
 
         if (rc == -1)
                 err_return(errno);
 
         if (WIFEXITED(rc))
                 return ucv_int64_new(WEXITSTATUS(rc));
 
         if (WIFSIGNALED(rc))
                 return ucv_int64_new(-WTERMSIG(rc));
 
         return ucv_int64_new(0);
 }
 
 /**
  * Reads a chunk of data from the program handle.
  *
  * The length argument may be either a positive number of bytes to read, in
  * which case the read call returns up to that many bytes, or a string to
  * specify a dynamic read size.
  *
  *  - If length is a number, the method will read the specified number of bytes
  *    from the handle. Reading stops after the given amount of bytes or after
  *    encountering EOF, whatever comes first.
  *
  *  - If length is the string "line", the method will read an entire line,
  *    terminated by "\n" (a newline), from the handle. Reading stops at the next
  *    newline or when encountering EOF. The returned data will contain the
  *    terminating newline character if one was read.
  *
  *  - If length is the string "all", the method will read from the handle until
  *    encountering EOF and return the complete contents.
  *
  *  - If length is a single character string, the method will read from the
  *    handle until encountering the specified character or upon encountering
  *    EOF. The returned data will contain the terminating character if one was
  *    read.
  *
  * Returns a string containing the read data.
  *
  * Returns an empty string on EOF.
  *
  * Returns `null` if a read error occurred.
  *
  * @function module:fs.proc#read
  *
  * @param {number|string} length
  * The length of data to read. Can be a number, the string "line", the string
  * "all", or a single character string.
  *
  * @returns {?string}
  *
  * @example
  * const fp = popen("command", "r");
  *
  * // Example 1: Read 10 bytes from the handle
  * const chunk = fp.read(10);
  *
  * // Example 2: Read the handle line by line
  * for (let line = fp.read("line"); length(line); line = fp.read("line"))
  *   print(line);
  *
  * // Example 3: Read the complete contents from the handle
  * const content = fp.read("all");
  *
  * // Example 4: Read until encountering the character ':'
  * const field = fp.read(":");
  */
 static uc_value_t *
 uc_fs_pread(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_read_common(vm, nargs, "fs.proc");
 }
 
 /**
  * Writes a chunk of data to the program handle.
  *
  * In case the given data is not a string, it is converted to a string before
  * being written to the program's stdin. String values are written as-is,
  * integer and double values are written in decimal notation, boolean values are
  * written as `true` or `false` while arrays and objects are converted to their
  * JSON representation before being written. The `null` value is represented by
  * an empty string so `proc.write(null)` would be a no-op. Resource values are
  * written in the form `<type address>`, e.g. `<fs.file 0x7f60f0981760>`.
  *
  * If resource, array or object values contain a `tostring()` function in their
  * prototypes, then this function is invoked to obtain an alternative string
  * representation of the value.
  *
  * Returns the number of bytes written.
  *
  * Returns `null` if a write error occurred.
  *
  * @function module:fs.proc#write
  *
  * @param {*} data
  * The data to be written.
  *
  * @returns {?number}
  *
  * @example
  * const fp = popen("command", "w");
  *
  * fp.write("Hello world!\n");
  */
 static uc_value_t *
 uc_fs_pwrite(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_write_common(vm, nargs, "fs.proc");
 }
 
 /**
  * Forces a write of all buffered data to the underlying handle.
  *
  * Returns `true` if the data was successfully flushed.
  *
  * Returns `null` on error.
  *
  * @function module:fs.proc#flush
  *
  * @returns {?boolean}
  *
  */
 static uc_value_t *
 uc_fs_pflush(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_flush_common(vm, nargs, "fs.proc");
 }
 
 /**
  * Obtains the number of the handle's underlying file descriptor.
  *
  * Returns the descriptor number.
  *
  * Returns `null` on error.
  *
  * @function module:fs.proc#fileno
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_pfileno(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_fileno_common(vm, nargs, "fs.proc");
 }
 
 /**
  * Starts a process and returns a handle representing the executed process.
  *
  * The handle will be connected to the process stdin or stdout, depending on the
  * value of the mode argument.
  *
  * The mode argument may be either "r" to open the process for reading (connect
  * to its stdin) or "w" to open the process for writing (connect to its stdout).
  *
  * The mode character "r" or "w" may be optionally followed by "e" to apply the
  * FD_CLOEXEC flag onto the open descriptor.
  *
  * Returns a process handle referring to the executed process.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#popen
  *
  * @param {string} command
  * The command to be executed.
  *
  * @param {string} [mode="r"]
  * The open mode of the process handle.
  *
  * @returns {?module:fs.proc}
  *
  * @example
  * // Open a process
  * const process = popen('command', 'r');
  */
 static uc_value_t *
 uc_fs_popen(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *comm = uc_fn_arg(0);
         uc_value_t *mode = uc_fn_arg(1);
         FILE *fp;
 
         if (ucv_type(comm) != UC_STRING)
                 err_return(EINVAL);
 
         fp = popen(ucv_string_get(comm),
                 ucv_type(mode) == UC_STRING ? ucv_string_get(mode) : "r");
 
         if (!fp)
                 err_return(errno);
 
         return ucv_resource_create(vm, "fs.proc", fp);
 }
 
 
 /**
  * Represents a handle for interacting with a file opened by one of the file
  * open functions.
  *
  * @class module:fs.file
  * @hideconstructor
  *
  * @borrows module:fs#error as module:fs.file#error
  *
  * @see {@link module:fs#open|open()}
  * @see {@link module:fs#fdopen|fdopen()}
  * @see {@link module:fs#mkstemp|mkstemp()}
  * @see {@link module:fs#pipe|pipe()}
  *
  * @example
  *
  * const handle = open(…);
  *
  * handle.read(…);
  * handle.write(…);
  * handle.flush();
  *
  * handle.seek(…);
  * handle.tell();
  *
  * handle.isatty();
  * handle.fileno();
  *
  * handle.close();
  *
  * handle.error();
  */
 
 /**
  * Closes the file handle.
  *
  * Upon calling `close()` on the handle, buffered data is flushed and the
  * underlying file descriptor is closed.
  *
  * Returns `true` if the handle was properly closed.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.file#close
  *
  * @returns {?boolean}
  */
 static uc_value_t *
 uc_fs_close(uc_vm_t *vm, size_t nargs)
 {
         FILE **fp = uc_fn_this("fs.file");
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         fclose(*fp);
         *fp = NULL;
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Reads a chunk of data from the file handle.
  *
  * The length argument may be either a positive number of bytes to read, in
  * which case the read call returns up to that many bytes, or a string to
  * specify a dynamic read size.
  *
  *  - If length is a number, the method will read the specified number of bytes
  *    from the handle. Reading stops after the given amount of bytes or after
  *    encountering EOF, whatever comes first.
  *
  *  - If length is the string "line", the method will read an entire line,
  *    terminated by "\n" (a newline), from the handle. Reading stops at the next
  *    newline or when encountering EOF. The returned data will contain the
  *    terminating newline character if one was read.
  *
  *  - If length is the string "all", the method will read from the handle until
  *    encountering EOF and return the complete contents.
  *
  *  - If length is a single character string, the method will read from the
  *    handle until encountering the specified character or upon encountering
  *    EOF. The returned data will contain the terminating character if one was
  *    read.
  *
  * Returns a string containing the read data.
  *
  * Returns an empty string on EOF.
  *
  * Returns `null` if a read error occurred.
  *
  * @function module:fs.file#read
  *
  * @param {number|string} length
  * The length of data to read. Can be a number, the string "line", the string
  * "all", or a single character string.
  *
  * @returns {?string}
  *
  * @example
  * const fp = open("file.txt", "r");
  *
  * // Example 1: Read 10 bytes from the handle
  * const chunk = fp.read(10);
  *
  * // Example 2: Read the handle line by line
  * for (let line = fp.read("line"); length(line); line = fp.read("line"))
  *   print(line);
  *
  * // Example 3: Read the complete contents from the handle
  * const content = fp.read("all");
  *
  * // Example 4: Read until encountering the character ':'
  * const field = fp.read(":");
  */
 static uc_value_t *
 uc_fs_read(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_read_common(vm, nargs, "fs.file");
 }
 
 /**
  * Writes a chunk of data to the file handle.
  *
  * In case the given data is not a string, it is converted to a string before
  * being written into the file. String values are written as-is, integer and
  * double values are written in decimal notation, boolean values are written as
  * `true` or `false` while arrays and objects are converted to their JSON
  * representation before being written. The `null` value is represented by an
  * empty string so `file.write(null)` would be a no-op. Resource values are
  * written in the form `<type address>`, e.g. `<fs.file 0x7f60f0981760>`.
  *
  * If resource, array or object values contain a `tostring()` function in their
  * prototypes, then this function is invoked to obtain an alternative string
  * representation of the value.
  *
  * Returns the number of bytes written.
  *
  * Returns `null` if a write error occurred.
  *
  * @function module:fs.file#write
  *
  * @param {*} data
  * The data to be written.
  *
  * @returns {?number}
  *
  * @example
  * const fp = open("file.txt", "w");
  *
  * fp.write("Hello world!\n");
  */
 static uc_value_t *
 uc_fs_write(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_write_common(vm, nargs, "fs.file");
 }
 
 /**
  * Set file read position.
  *
  * Set the read position of the open file handle to the given offset and
  * position.
  *
  * Returns `true` if the read position was set.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.file#seek
  *
  * @param {number} [offset=0]
  * The offset in bytes.
  *
  * @param {number} [position=0]
  * The position of the offset.
  *
  * | Position | Description                                                                                  |
  * |----------|----------------------------------------------------------------------------------------------|
  * | `0`      | The given offset is relative to the start of the file. This is the default value if omitted. |
  * | `1`      | The given offset is relative to the current read position.                                   |
  * | `2`      | The given offset is relative to the end of the file.                                         |
  *
  * @returns {?boolean}
  *
  * @example
  * const fp = open("file.txt", "r");
  *
  * print(fp.read(100), "\n");  // read 100 bytes...
  * fp.seek(0, 0);              // ... and reset position to start of file
  * print(fp.read(100), "\n");  // ... read same 100 bytes again
  *
  * fp.seek(10, 1);  // skip 10 bytes forward, relative to current offset ...
  * fp.tell();       // ... position is at 110 now
  *
  * fp.seek(-10, 2);            // set position to ten bytes before EOF ...
  * print(fp.read(100), "\n");  // ... reads 10 bytes at most
  */
 static uc_value_t *
 uc_fs_seek(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *ofs = uc_fn_arg(0);
         uc_value_t *how = uc_fn_arg(1);
         int whence, res;
         off_t offset;
 
         FILE **fp = uc_fn_this("fs.file");
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         if (!ofs)
                 offset = 0;
         else if (ucv_type(ofs) != UC_INTEGER)
                 err_return(EINVAL);
         else
                 offset = (off_t)ucv_int64_get(ofs);
 
         if (!how)
                 whence = 0;
         else if (ucv_type(how) != UC_INTEGER)
                 err_return(EINVAL);
         else
                 whence = (int)ucv_int64_get(how);
 
         res = fseeko(*fp, offset, whence);
 
         if (res < 0)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Truncate file to a given size
  *
  * Returns `true` if the file was successfully truncated.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.file#truncate
  *
  * @param {number} [offset=0]
  * The offset in bytes.
  *
  * @returns {?boolean}
  */
 static uc_value_t *
 uc_fs_truncate(uc_vm_t *vm, size_t nargs)
 {
         FILE *fp = uc_fn_thisval("fs.file");
         uc_value_t *ofs = uc_fn_arg(0);
         off_t offset;
 
         if (!fp)
                 err_return(EBADF);
 
         if (!ofs)
                 offset = 0;
         else if (ucv_type(ofs) != UC_INTEGER)
                 err_return(EINVAL);
         else
                 offset = (off_t)ucv_int64_get(ofs);
 
         if (ftruncate(fileno(fp), offset) < 0)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Locks or unlocks a file.
  *
  * The mode argument specifies lock/unlock operation flags.
  *
  * | Flag    | Description                  |
  * |---------|------------------------------|
  * | "s"     | shared lock                  |
  * | "x"     | exclusive lock               |
  * | "n"     | don't block when locking     |
  * | "u"     | unlock                       |
  *
  * Returns `true` if the file was successfully locked/unlocked.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.file#lock
  *
  * @param {string} [op]
  * The lock operation flags
  *
  * @returns {?boolean}
  */
 static uc_value_t *
 uc_fs_lock(uc_vm_t *vm, size_t nargs)
 {
         FILE *fp = uc_fn_thisval("fs.file");
         uc_value_t *mode = uc_fn_arg(0);
         int i, op = 0;
         char *m;
 
         if (!fp)
                 err_return(EBADF);
 
         if (ucv_type(mode) != UC_STRING)
                 err_return(EINVAL);
 
         m = ucv_string_get(mode);
         for (i = 0; m[i]; i++) {
                 switch (m[i]) {
                 case 's': op |= LOCK_SH; break;
                 case 'x': op |= LOCK_EX; break;
                 case 'n': op |= LOCK_NB; break;
                 case 'u': op |= LOCK_UN; break;
                 default: err_return(EINVAL);
                 }
         }
 
         if (flock(fileno(fp), op) < 0)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Obtain current read position.
  *
  * Obtains the current, absolute read position of the open file.
  *
  * Returns an integer containing the current read offset in bytes.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.file#tell
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_tell(uc_vm_t *vm, size_t nargs)
 {
         off_t offset;
 
         FILE **fp = uc_fn_this("fs.file");
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         offset = ftello(*fp);
 
         if (offset < 0)
                 err_return(errno);
 
         return ucv_int64_new(offset);
 }
 
 /**
  * Check for TTY.
  *
  * Checks whether the open file handle refers to a TTY (terminal) device.
  *
  * Returns `true` if the handle refers to a terminal.
  *
  * Returns `false` if the handle refers to another kind of file.
  *
  * Returns `null` on error.
  *
  * @function module:fs.file#isatty
  *
  * @returns {?boolean}
  *
  */
 static uc_value_t *
 uc_fs_isatty(uc_vm_t *vm, size_t nargs)
 {
         FILE **fp = uc_fn_this("fs.file");
         int fd;
 
         if (!fp || !*fp)
                 err_return(EBADF);
 
         fd = fileno(*fp);
 
         if (fd == -1)
                 err_return(errno);
 
         return ucv_boolean_new(isatty(fd) == 1);
 }
 
 /**
  * Forces a write of all buffered data to the underlying handle.
  *
  * Returns `true` if the data was successfully flushed.
  *
  * Returns `null` on error.
  *
  * @function module:fs.file#flush
  *
  * @returns {?boolean}
  *
  */
 static uc_value_t *
 uc_fs_flush(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_flush_common(vm, nargs, "fs.file");
 }
 
 /**
  * Obtains the number of the handle's underlying file descriptor.
  *
  * Returns the descriptor number.
  *
  * Returns `null` on error.
  *
  * @function module:fs.file#fileno
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_fileno(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_fileno_common(vm, nargs, "fs.file");
 }
 
 #ifdef HAS_IOCTL
 
 /**
  * Performs an ioctl operation on the file.
  *
  * The direction parameter specifies who is reading and writing,
  * from the user's point of view. It can be one of the following values:
  *
  * | Direction      | Description                                                                       |
  * |----------------|-----------------------------------------------------------------------------------|
  * | IOC_DIR_NONE   | neither userspace nor kernel is writing, ioctl is executed without passing data.  |
  * | IOC_DIR_WRITE  | userspace is writing and kernel is reading.                                       |
  * | IOC_DIR_READ   | kernel is writing and userspace is reading.                                       |
  * | IOC_DIR_RW     | userspace is writing and kernel is writing back into the data structure.          |
  *
  * Returns the result of the ioctl operation; for `IOC_DIR_READ` and
  * `IOC_DIR_RW` this is a string containing the data, otherwise a number as
  * return code.
  *
  * In case of an error, null is returned and error details are available via
  * {@link module:fs#error|error()}.
  *
  * @function module:fs.file#ioctl
  *
  * @param {number} direction
  * The direction of the ioctl operation. Use constants IOC_DIR_*.
  *
  * @param {number} type
  * The ioctl type (see https://www.kernel.org/doc/html/latest/userspace-api/ioctl/ioctl-number.html)
  *
  * @param {number} num
  * The ioctl sequence number.
  *
  * @param {number|string} [value]
  * The value to pass to the ioctl system call. For `IOC_DIR_NONE`, this argument
  * is ignored. With `IOC_DIR_READ`, the value should be a positive integer
  * specifying the number of bytes to expect from the kernel. For the other
  * directions, `IOC_DIR_WRITE` and `IOC_DIR_RW`, that value parameter must be a
  * string, serving as buffer for the data to send.
  *
  * @returns {?number|?string}
  */
 static uc_value_t *
 uc_fs_ioctl(uc_vm_t *vm, size_t nargs)
 {
         FILE *fp = uc_fn_thisval("fs.file");
         uc_value_t *direction = uc_fn_arg(0);
         uc_value_t *type = uc_fn_arg(1);
         uc_value_t *num = uc_fn_arg(2);
         uc_value_t *value = uc_fn_arg(3);
         uc_value_t *mem = NULL;
         char *buf = NULL;
         unsigned long req = 0;
         unsigned int dir, ty, nr;
         size_t sz = 0;
         int fd, ret;
 
         if (!fp)
                 err_return(EBADF);
 
         fd = fileno(fp);
         if (fd == -1)
                 err_return(EBADF);
 
         if (ucv_type(direction) != UC_INTEGER || ucv_type(type) != UC_INTEGER ||
             ucv_type(num) != UC_INTEGER)
                 err_return(EINVAL);
 
         dir = ucv_uint64_get(direction);
         ty = ucv_uint64_get(type);
         nr = ucv_uint64_get(num);
 
         switch (dir) {
         case IOC_DIR_NONE:
                 break;
 
         case IOC_DIR_WRITE:
                 if (ucv_type(value) != UC_STRING)
                         err_return(EINVAL);
 
                 sz = ucv_string_length(value);
                 buf = ucv_string_get(value);
                 break;
 
         case IOC_DIR_READ:
                 if (ucv_type(value) != UC_INTEGER)
                         err_return(EINVAL);
 
                 sz = ucv_to_unsigned(value);
 
                 if (errno != 0)
                         err_return(errno);
 
                 mem = xalloc(sizeof(uc_string_t) + sz + 1);
                 mem->type = UC_STRING;
                 mem->refcount = 1;
                 buf = ucv_string_get(mem);
                 ((uc_string_t *)mem)->length = sz;
                 break;
 
         case IOC_DIR_RW:
                 if (ucv_type(value) != UC_STRING)
                         err_return(EINVAL);
 
                 sz = ucv_string_length(value);
                 mem = ucv_string_new_length(ucv_string_get(value), sz);
                 buf = ucv_string_get(mem);
                 break;
 
         default:
                 err_return(EINVAL);
         }
 
         req = _IOC(dir, ty, nr, sz);
         ret = ioctl(fd, req, buf);
 
         if (ret < 0) {
                 ucv_put(mem);
                 err_return(errno);
         }
 
         return mem ? mem : ucv_uint64_new(ret);
 }
 
 #endif
 
 /**
  * Opens a file.
  *
  * The mode argument specifies the way the file is opened, it may
  * start with one of the following values:
  *
  * | Mode    | Description                                                                                                   |
  * |---------|---------------------------------------------------------------------------------------------------------------|
  * | "r"     | Opens a file for reading. The file must exist.                                                                 |
  * | "w"     | Opens a file for writing. If the file exists, it is truncated. If the file does not exist, it is created.     |
  * | "a"     | Opens a file for appending. Data is written at the end of the file. If the file does not exist, it is created. |
  * | "r+"    | Opens a file for both reading and writing. The file must exist.                                              |
  * | "w+"    | Opens a file for both reading and writing. If the file exists, it is truncated. If the file does not exist, it is created. |
  * | "a+"    | Opens a file for both reading and appending. Data can be read and written at the end of the file. If the file does not exist, it is created. |
  *
  * Additionally, the following flag characters may be appended to
  * the mode value:
  *
  * | Flag    | Description                                                                                                   |
  * |---------|---------------------------------------------------------------------------------------------------------------|
  * | "x"     | Opens a file for exclusive creation. If the file exists, the `open` call fails.                             |
  * | "e"     | Opens a file with the `O_CLOEXEC` flag set, ensuring that the file descriptor is closed on `exec` calls.      |
  *
  * If the mode is one of `"w…"` or `"a…"`, the permission argument
  * controls the filesystem permissions bits used when creating
  * the file.
  *
  * Returns a file handle object associated with the opened file.
  *
  * @function module:fs#open
  *
  * @param {string} path
  * The path to the file.
  *
  * @param {string} [mode="r"]
  * The file opening mode.
  *
  * @param {number} [perm=0o666]
  * The file creation permissions (for modes `w…` and `a…`)
  *
  * @returns {?module:fs.file}
  *
  * @example
  * // Open a file in read-only mode
  * const fileHandle = open('file.txt', 'r');
  */
 static uc_value_t *
 uc_fs_open(uc_vm_t *vm, size_t nargs)
 {
         int open_mode, open_flags, fd, i;
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *mode = uc_fn_arg(1);
         uc_value_t *perm = uc_fn_arg(2);
         mode_t open_perm = 0666;
         FILE *fp;
         char *m;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         m = (ucv_type(mode) == UC_STRING) ? ucv_string_get(mode) : "r";
 
         switch (*m) {
         case 'r':
                 open_mode = O_RDONLY;
                 open_flags = 0;
                 break;
 
         case 'w':
                 open_mode = O_WRONLY;
                 open_flags = O_CREAT | O_TRUNC;
                 break;
 
         case 'a':
                 open_mode = O_WRONLY;
                 open_flags = O_CREAT | O_APPEND;
                 break;
 
         default:
                 err_return(EINVAL);
         }
 
         for (i = 1; m[i]; i++) {
                 switch (m[i]) {
                 case '+': open_mode = O_RDWR;      break;
                 case 'x': open_flags |= O_EXCL;    break;
                 case 'e': open_flags |= O_CLOEXEC; break;
                 }
         }
 
         if (perm) {
                 if (ucv_type(perm) != UC_INTEGER)
                         err_return(EINVAL);
 
                 open_perm = ucv_int64_get(perm);
         }
 
 #ifdef O_LARGEFILE
         open_flags |= open_mode | O_LARGEFILE;
 #else
         open_flags |= open_mode;
 #endif
 
         fd = open(ucv_string_get(path), open_flags, open_perm);
 
         if (fd < 0)
                 return NULL;
 
         fp = fdopen(fd, m);
 
         if (!fp) {
                 i = errno;
                 close(fd);
                 err_return(i);
         }
 
         return ucv_resource_create(vm, "fs.file", fp);
 }
 
 /**
  * Associates a file descriptor number with a file handle object.
  *
  * The mode argument controls how the file handle object is opened
  * and must match the open mode of the underlying descriptor.
  *
  * It may be set to one of the following values:
  *
  * | Mode    | Description                                                                                                  |
  * |---------|--------------------------------------------------------------------------------------------------------------|
  * | "r"     | Opens a file stream for reading. The file descriptor must be valid and opened in read mode.                  |
  * | "w"     | Opens a file stream for writing. The file descriptor must be valid and opened in write mode.                 |
  * | "a"     | Opens a file stream for appending. The file descriptor must be valid and opened in write mode.               |
  * | "r+"    | Opens a file stream for both reading and writing. The file descriptor must be valid and opened in read/write mode. |
  * | "w+"    | Opens a file stream for both reading and writing. The file descriptor must be valid and opened in read/write mode. |
  * | "a+"    | Opens a file stream for both reading and appending. The file descriptor must be valid and opened in read/write mode. |
  *
  * Returns the file handle object associated with the file descriptor.
  *
  * @function module:fs#fdopen
  *
  * @param {number} fd
  * The file descriptor.
  *
  * @param {string} [mode="r"]
  * The open mode.
  *
  * @returns {Object}
  *
  * @example
  * // Associate file descriptors of stdin and stdout with handles
  * const stdinHandle = fdopen(0, 'r');
  * const stdoutHandle = fdopen(1, 'w');
  */
 static uc_value_t *
 uc_fs_fdopen(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *fdno = uc_fn_arg(0);
         uc_value_t *mode = uc_fn_arg(1);
         int64_t n;
         FILE *fp;
 
         if (ucv_type(fdno) != UC_INTEGER)
                 err_return(EINVAL);
 
         n = ucv_int64_get(fdno);
 
         if (n < 0 || n > INT_MAX)
                 err_return(EBADF);
 
         fp = fdopen((int)n,
                 ucv_type(mode) == UC_STRING ? ucv_string_get(mode) : "r");
 
         if (!fp)
                 err_return(errno);
 
         return ucv_resource_create(vm, "fs.file", fp);
 }
 
 /**
  * Duplicates a file descriptor.
  *
  * This function duplicates the file descriptor `oldfd` to `newfd`. If `newfd`
  * was previously open, it is silently closed before being reused.
  *
  * Returns `true` on success.
  * Returns `null` on error.
  *
  * @function module:fs#dup2
  *
  * @param {number} oldfd
  * The file descriptor to duplicate.
  *
  * @param {number} newfd
  * The file descriptor number to duplicate to.
  *
  * @returns {?boolean}
  *
  * @example
  * // Redirect stderr to a log file
  * const logfile = open('/tmp/error.log', 'w');
  * dup2(logfile.fileno(), 2);
  * logfile.close();
  */
 static uc_value_t *
 uc_fs_dup2(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *oldfd_arg = uc_fn_arg(0);
         uc_value_t *newfd_arg = uc_fn_arg(1);
         int oldfd, newfd;
 
         oldfd = get_fd(vm, oldfd_arg);
 
         if (oldfd == -1)
                 err_return(errno ? errno : EBADF);
 
         newfd = get_fd(vm, newfd_arg);
 
         if (newfd == -1)
                 err_return(errno ? errno : EBADF);
 
         if (dup2(oldfd, newfd) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 
 /**
  * Represents a handle for interacting with a directory opened by `opendir()`.
  *
  * @class module:fs.dir
  * @hideconstructor
  *
  * @borrows module:fs#error as module:fs.dir#error
  *
  * @see {@link module:fs#opendir|opendir()}
  *
  * @example
  *
  * const handle = opendir(…);
  *
  * handle.read();
  *
  * handle.tell();
  * handle.seek(…);
  *
  * handle.close();
  *
  * handle.error();
  */
 
 /**
  * Obtains the number of the handle's underlying file descriptor.
  *
  * Returns the descriptor number.
  *
  * Returns `null` on error.
  *
  * @function module:fs.dir#fileno
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_dfileno(uc_vm_t *vm, size_t nargs)
 {
         DIR *dp = uc_fn_thisval("fs.dir");
         int fd;
 
         if (!dp)
                 err_return(EBADF);
 
         fd = dirfd(dp);
 
         if (fd == -1)
                 err_return(errno);
 
         return ucv_int64_new(fd);
 }
 
 /**
  * Read the next entry from the open directory.
  *
  * Returns a string containing the entry name.
  *
  * Returns `null` if there are no more entries to read.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.dir#read
  *
  * @returns {?string}
  */
 static uc_value_t *
 uc_fs_readdir(uc_vm_t *vm, size_t nargs)
 {
         DIR **dp = uc_fn_this("fs.dir");
         struct dirent *e;
 
         if (!dp || !*dp)
                 err_return(EINVAL);
 
         errno = 0;
         e = readdir(*dp);
 
         if (!e)
                 err_return(errno);
 
         return ucv_string_new(e->d_name);
 }
 
 /**
  * Obtain current read position.
  *
  * Returns the current read position in the open directory handle which can be
  * passed back to the `seek()` function to return to this position. This is
  * mainly useful to read an open directory handle (or specific items) multiple
  * times.
  *
  * Returns an integer referring to the current position.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.dir#tell
  *
  * @returns {?number}
  */
 static uc_value_t *
 uc_fs_telldir(uc_vm_t *vm, size_t nargs)
 {
         DIR **dp = uc_fn_this("fs.dir");
         long position;
 
         if (!dp || !*dp)
                 err_return(EBADF);
 
         position = telldir(*dp);
 
         if (position == -1)
                 err_return(errno);
 
         return ucv_int64_new((int64_t)position);
 }
 
 /**
  * Set read position.
  *
  * Sets the read position within the open directory handle to the given offset
  * value. The offset value should be obtained by a previous call to `tell()` as
  * the specific integer values are implementation defined.
  *
  * Returns `true` if the read position was set.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.dir#seek
  *
  * @param {number} offset
  * Position value obtained by `tell()`.
  *
  * @returns {?boolean}
  *
  * @example
  *
  * const handle = opendir("/tmp");
  * const begin = handle.tell();
  *
  * print(handle.read(), "\n");
  *
  * handle.seek(begin);
  *
  * print(handle.read(), "\n");  // prints the first entry again
  */
 static uc_value_t *
 uc_fs_seekdir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *ofs = uc_fn_arg(0);
         DIR **dp = uc_fn_this("fs.dir");
         long position;
 
         if (ucv_type(ofs) != UC_INTEGER)
                 err_return(EINVAL);
 
         if (!dp || !*dp)
                 err_return(EBADF);
 
         position = (long)ucv_int64_get(ofs);
 
         seekdir(*dp, position);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Closes the directory handle.
  *
  * Closes the underlying file descriptor referring to the opened directory.
  *
  * Returns `true` if the handle was properly closed.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs.dir#close
  *
  * @returns {?boolean}
  */
 static uc_value_t *
 uc_fs_closedir(uc_vm_t *vm, size_t nargs)
 {
         DIR **dp = uc_fn_this("fs.dir");
 
         if (!dp || !*dp)
                 err_return(EBADF);
 
         closedir(*dp);
         *dp = NULL;
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Opens a directory and returns a directory handle associated with the open
  * directory descriptor.
  *
  * Returns a director handle referring to the open directory.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#opendir
  *
  * @param {string} path
  * The path to the directory.
  *
  * @returns {?module:fs.dir}
  *
  * @example
  * // Open a directory
  * const directory = opendir('path/to/directory');
  */
 static uc_value_t *
 uc_fs_opendir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         DIR *dp;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         dp = opendir(ucv_string_get(path));
 
         if (!dp)
                 err_return(errno);
 
         return ucv_resource_create(vm, "fs.dir", dp);
 }
 
 /**
  * Reads the target path of a symbolic link.
  *
  * Returns a string containing the target path.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#readlink
  *
  * @param {string} path
  * The path to the symbolic link.
  *
  * @returns {?string}
  *
  * @example
  * // Read the value of a symbolic link
  * const targetPath = readlink('symbolicLink');
  */
 static uc_value_t *
 uc_fs_readlink(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *res;
         ssize_t buflen = 0, rv;
         char *buf = NULL, *tmp;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         do {
                 buflen += 128;
                 tmp = realloc(buf, buflen);
 
                 if (!tmp) {
                         free(buf);
                         err_return(ENOMEM);
                 }
 
                 buf = tmp;
                 rv = readlink(ucv_string_get(path), buf, buflen);
 
                 if (rv == -1) {
                         free(buf);
                         err_return(errno);
                 }
 
                 if (rv < buflen)
                         break;
         }
         while (true);
 
         res = ucv_string_new_length(buf, rv);
 
         free(buf);
 
         return res;
 }
 
 /**
  * @typedef {Object} module:fs.FileStatResult
  * @property {Object} dev - The device information.
  * @property {number} dev.major - The major device number.
  * @property {number} dev.minor - The minor device number.
  * @property {Object} perm - The file permissions.
  * @property {boolean} perm.setuid - Whether the setuid bit is set.
  * @property {boolean} perm.setgid - Whether the setgid bit is set.
  * @property {boolean} perm.sticky - Whether the sticky bit is set.
  * @property {boolean} perm.user_read - Whether the file is readable by the owner.
  * @property {boolean} perm.user_write - Whether the file is writable by the owner.
  * @property {boolean} perm.user_exec - Whether the file is executable by the owner.
  * @property {boolean} perm.group_read - Whether the file is readable by the group.
  * @property {boolean} perm.group_write - Whether the file is writable by the group.
  * @property {boolean} perm.group_exec - Whether the file is executable by the group.
  * @property {boolean} perm.other_read - Whether the file is readable by others.
  * @property {boolean} perm.other_write - Whether the file is writable by others.
  * @property {boolean} perm.other_exec - Whether the file is executable by others.
  * @property {number} inode - The inode number.
  * @property {number} mode - The file mode.
  * @property {number} nlink - The number of hard links.
  * @property {number} uid - The user ID of the owner.
  * @property {number} gid - The group ID of the owner.
  * @property {number} size - The file size in bytes.
  * @property {number} blksize - The block size for file system I/O.
  * @property {number} blocks - The number of 512-byte blocks allocated for the file.
  * @property {number} atime - The timestamp when the file was last accessed.
  * @property {number} mtime - The timestamp when the file was last modified.
  * @property {number} ctime - The timestamp when the file status was last changed.
  * @property {string} type - The type of the file ("directory", "file", etc.).
  */
 
 static uc_value_t *
 uc_fs_stat_common(uc_vm_t *vm, size_t nargs, bool use_lstat)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *res, *o;
         struct stat st;
         int rv;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         rv = (use_lstat ? lstat : stat)(ucv_string_get(path), &st);
 
         if (rv == -1)
                 err_return(errno);
 
         res = ucv_object_new(vm);
 
         if (!res)
                 err_return(ENOMEM);
 
         o = ucv_object_new(vm);
 
         if (o) {
                 ucv_object_add(o, "major", ucv_int64_new(major(st.st_dev)));
                 ucv_object_add(o, "minor", ucv_int64_new(minor(st.st_dev)));
 
                 ucv_object_add(res, "dev", o);
         }
 
         o = ucv_object_new(vm);
 
         if (o) {
                 ucv_object_add(o, "setuid", ucv_boolean_new(st.st_mode & S_ISUID));
                 ucv_object_add(o, "setgid", ucv_boolean_new(st.st_mode & S_ISGID));
                 ucv_object_add(o, "sticky", ucv_boolean_new(st.st_mode & S_ISVTX));
 
                 ucv_object_add(o, "user_read", ucv_boolean_new(st.st_mode & S_IRUSR));
                 ucv_object_add(o, "user_write", ucv_boolean_new(st.st_mode & S_IWUSR));
                 ucv_object_add(o, "user_exec", ucv_boolean_new(st.st_mode & S_IXUSR));
 
                 ucv_object_add(o, "group_read", ucv_boolean_new(st.st_mode & S_IRGRP));
                 ucv_object_add(o, "group_write", ucv_boolean_new(st.st_mode & S_IWGRP));
                 ucv_object_add(o, "group_exec", ucv_boolean_new(st.st_mode & S_IXGRP));
 
                 ucv_object_add(o, "other_read", ucv_boolean_new(st.st_mode & S_IROTH));
                 ucv_object_add(o, "other_write", ucv_boolean_new(st.st_mode & S_IWOTH));
                 ucv_object_add(o, "other_exec", ucv_boolean_new(st.st_mode & S_IXOTH));
 
                 ucv_object_add(res, "perm", o);
         }
 
         ucv_object_add(res, "inode", ucv_int64_new((int64_t)st.st_ino));
         ucv_object_add(res, "mode", ucv_int64_new((int64_t)st.st_mode & ~S_IFMT));
         ucv_object_add(res, "nlink", ucv_int64_new((int64_t)st.st_nlink));
         ucv_object_add(res, "uid", ucv_int64_new((int64_t)st.st_uid));
         ucv_object_add(res, "gid", ucv_int64_new((int64_t)st.st_gid));
         ucv_object_add(res, "size", ucv_int64_new((int64_t)st.st_size));
         ucv_object_add(res, "blksize", ucv_int64_new((int64_t)st.st_blksize));
         ucv_object_add(res, "blocks", ucv_int64_new((int64_t)st.st_blocks));
         ucv_object_add(res, "atime", ucv_int64_new((int64_t)st.st_atime));
         ucv_object_add(res, "mtime", ucv_int64_new((int64_t)st.st_mtime));
         ucv_object_add(res, "ctime", ucv_int64_new((int64_t)st.st_ctime));
 
         if (S_ISREG(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("file"));
         else if (S_ISDIR(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("directory"));
         else if (S_ISCHR(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("char"));
         else if (S_ISBLK(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("block"));
         else if (S_ISFIFO(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("fifo"));
         else if (S_ISLNK(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("link"));
         else if (S_ISSOCK(st.st_mode))
                 ucv_object_add(res, "type", ucv_string_new("socket"));
         else
                 ucv_object_add(res, "type", ucv_string_new("unknown"));
 
         return res;
 }
 
 /**
  * Retrieves information about a file or directory.
  *
  * Returns an object containing information about the file or directory.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions.
  *
  * @function module:fs#stat
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @returns {?module:fs.FileStatResult}
  *
  * @example
  * // Get information about a file
  * const fileInfo = stat('path/to/file');
  */
 static uc_value_t *
 uc_fs_stat(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_stat_common(vm, nargs, false);
 }
 
 /**
  * Retrieves information about a file or directory, without following symbolic
  * links.
  *
  * Returns an object containing information about the file or directory.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions.
  *
  * @function module:fs#lstat
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @returns {?module:fs.FileStatResult}
  *
  * @example
  * // Get information about a directory
  * const dirInfo = lstat('path/to/directory');
  */
 static uc_value_t *
 uc_fs_lstat(uc_vm_t *vm, size_t nargs)
 {
         return uc_fs_stat_common(vm, nargs, true);
 }
 
 /**
  * Creates a new directory.
  *
  * Returns `true` if the directory was successfully created.
  *
  * Returns `null` if an error occurred, e.g. due to inexistent path.
  *
  * @function module:fs#mkdir
  *
  * @param {string} path
  * The path to the new directory.
  *
  * @returns {?boolean}
  *
  * @example
  * // Create a directory
  * mkdir('path/to/new-directory');
  */
 static uc_value_t *
 uc_fs_mkdir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *mode = uc_fn_arg(1);
 
         if (ucv_type(path) != UC_STRING ||
             (mode && ucv_type(mode) != UC_INTEGER))
                 err_return(EINVAL);
 
         if (mkdir(ucv_string_get(path), (mode_t)(mode ? ucv_int64_get(mode) : 0777)) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Removes the specified directory.
  *
  * Returns `true` if the directory was successfully removed.
  *
  * Returns `null` if an error occurred, e.g. due to inexistent path.
  *
  * @function module:fs#rmdir
  *
  * @param {string} path
  * The path to the directory to be removed.
  *
  * @returns {?boolean}
  *
  * @example
  * // Remove a directory
  * rmdir('path/to/directory');
  */
 static uc_value_t *
 uc_fs_rmdir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (rmdir(ucv_string_get(path)) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Creates a new symbolic link.
  *
  * Returns `true` if the symlink was successfully created.
  *
  * Returns `null` if an error occurred, e.g. due to inexistent path.
  *
  * @function module:fs#symlink
  *
  * @param {string} target
  * The target of the symbolic link.
  *
  * @param {string} path
  * The path of the symbolic link.
  *
  * @returns {?boolean}
  *
  * @example
  * // Create a symbolic link
  * symlink('target', 'path/to/symlink');
  */
 static uc_value_t *
 uc_fs_symlink(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *dest = uc_fn_arg(0);
         uc_value_t *path = uc_fn_arg(1);
 
         if (ucv_type(dest) != UC_STRING ||
             ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (symlink(ucv_string_get(dest), ucv_string_get(path)) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Removes the specified file or symbolic link.
  *
  * Returns `true` if the unlink operation was successful.
  *
  * Returns `null` if an error occurred, e.g. due to inexistent path.
  *
  * @function module:fs#unlink
  *
  * @param {string} path
  * The path to the file or symbolic link.
  *
  * @returns {?boolean}
  *
  * @example
  * // Remove a file
  * unlink('path/to/file');
  */
 static uc_value_t *
 uc_fs_unlink(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (unlink(ucv_string_get(path)) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Retrieves the current working directory.
  *
  * Returns a string containing the current working directory path.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#getcwd
  *
  * @returns {?string}
  *
  * @example
  * // Get the current working directory
  * const cwd = getcwd();
  */
 static uc_value_t *
 uc_fs_getcwd(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *res;
         char *buf = NULL, *tmp;
         size_t buflen = 0;
 
         do {
                 buflen += 128;
                 tmp = realloc(buf, buflen);
 
                 if (!tmp) {
                         free(buf);
                         err_return(ENOMEM);
                 }
 
                 buf = tmp;
 
                 if (getcwd(buf, buflen) != NULL)
                         break;
 
                 if (errno == ERANGE)
                         continue;
 
                 free(buf);
                 err_return(errno);
         }
         while (true);
 
         res = ucv_string_new(buf);
 
         free(buf);
 
         return res;
 }
 
 /**
  * Changes the current working directory to the specified path.
  *
  * Returns `true` if the permission change was successful.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions or
  * invalid arguments.
  *
  * @function module:fs#chdir
  *
  * @param {string} path
  * The path to the new working directory.
  *
  * @returns {?boolean}
  *
  * @example
  * // Change the current working directory
  * chdir('new-directory');
  */
 static uc_value_t *
 uc_fs_chdir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
 
         if (ucv_type(path) == UC_STRING) {
                 if (chdir(ucv_string_get(path)) == -1)
                         err_return(errno);
         }
         else {
                 int fd = get_fd(vm, path);
 
                 if (fd < 0)
                         err_return(EINVAL);
 
                 if (fchdir(fd) == -1)
                         err_return(errno);
         }
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Changes the permission mode bits of a file or directory.
  *
  * Returns `true` if the permission change was successful.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions or
  * invalid arguments.
  *
  * @function module:fs#chmod
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @param {number} mode
  * The new mode (permissions).
  *
  * @returns {?boolean}
  *
  * @example
  * // Change the mode of a file
  * chmod('path/to/file', 0o644);
  */
 static uc_value_t *
 uc_fs_chmod(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *mode = uc_fn_arg(1);
 
         if (ucv_type(path) != UC_STRING ||
             ucv_type(mode) != UC_INTEGER)
                 err_return(EINVAL);
 
         if (chmod(ucv_string_get(path), (mode_t)ucv_int64_get(mode)) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 static bool
 uc_fs_resolve_user(uc_value_t *v, uid_t *uid)
 {
         struct passwd *pw = NULL;
         int64_t n;
         char *s;
 
         *uid = (uid_t)-1;
 
         switch (ucv_type(v)) {
         case UC_INTEGER:
                 n = ucv_int64_get(v);
 
                 if (n < -1) {
                         errno = ERANGE;
 
                         return false;
                 }
 
                 *uid = (uid_t)n;
 
                 return true;
 
         case UC_STRING:
                 s = ucv_string_get(v);
                 pw = getpwnam(s);
 
                 if (!pw) {
                         errno = ENOENT;
 
                         return false;
                 }
 
                 *uid = pw->pw_uid;
 
                 return true;
 
         case UC_NULL:
                 return true;
 
         default:
                 errno = EINVAL;
 
                 return false;
         }
 }
 
 static bool
 uc_fs_resolve_group(uc_value_t *v, gid_t *gid)
 {
         struct group *gr = NULL;
         int64_t n;
         char *s;
 
         *gid = (gid_t)-1;
 
         switch (ucv_type(v)) {
         case UC_INTEGER:
                 n = ucv_int64_get(v);
 
                 if (n < -1) {
                         errno = ERANGE;
 
                         return false;
                 }
 
                 *gid = (gid_t)n;
 
                 return true;
 
         case UC_STRING:
                 s = ucv_string_get(v);
                 gr = getgrnam(s);
 
                 if (!gr) {
                         errno = ENOENT;
 
                         return false;
                 }
 
                 *gid = gr->gr_gid;
 
                 return true;
 
         case UC_NULL:
                 return true;
 
         default:
                 errno = EINVAL;
 
                 return false;
         }
 }
 
 /**
  * Changes the owner and group of a file or directory.
  *
  * The user and group may be specified either as uid or gid number respectively,
  * or as a string containing the user or group name, in which case it is
  * resolved to the proper uid/gid first.
  *
  * If either the user or group parameter is omitted or given as `-1`,
  * it is not changed.
  *
  * Returns `true` if the ownership change was successful.
  *
  * Returns `null` if an error occurred or if a user/group name cannot be
  * resolved to a uid/gid value.
  *
  * @function module:fs#chown
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @param {number|string} [uid=-1]
  * The new owner's user ID. When given as number, it is used as-is, when given
  * as string, the user name is resolved to the corresponding uid first.
  *
  * @param {number|string} [gid=-1]
  * The new group's ID. When given as number, it is used as-is, when given as
  * string, the group name is resolved to the corresponding gid first.
  *
  * @returns {?boolean}
  *
  * @example
  * // Change the owner of a file
  * chown('path/to/file', 1000);
  *
  * // Change the group of a directory
  * chown('/htdocs/', null, 'www-data');
  */
 static uc_value_t *
 uc_fs_chown(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *user = uc_fn_arg(1);
         uc_value_t *group = uc_fn_arg(2);
         uid_t uid;
         gid_t gid;
 
         if (ucv_type(path) != UC_STRING)
             err_return(EINVAL);
 
         if (!uc_fs_resolve_user(user, &uid) ||
             !uc_fs_resolve_group(group, &gid))
                 err_return(errno);
 
         if (chown(ucv_string_get(path), uid, gid) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Renames or moves a file or directory.
  *
  * Returns `true` if the rename operation was successful.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#rename
  *
  * @param {string} oldPath
  * The current path of the file or directory.
  *
  * @param {string} newPath
  * The new path of the file or directory.
  *
  * @returns {?boolean}
  *
  * @example
  * // Rename a file
  * rename('old-name.txt', 'new-name.txt');
  */
 static uc_value_t *
 uc_fs_rename(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *oldpath = uc_fn_arg(0);
         uc_value_t *newpath = uc_fn_arg(1);
 
         if (ucv_type(oldpath) != UC_STRING ||
             ucv_type(newpath) != UC_STRING)
                 err_return(EINVAL);
 
         if (rename(ucv_string_get(oldpath), ucv_string_get(newpath)))
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 static uc_value_t *
 uc_fs_glob(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *pat, *arr;
         glob_t gl = { 0 };
         size_t i;
 
         for (i = 0; i < nargs; i++) {
                 pat = uc_fn_arg(i);
 
                 if (ucv_type(pat) != UC_STRING) {
                         globfree(&gl);
                         err_return(EINVAL);
                 }
 
                 glob(ucv_string_get(pat), i ? GLOB_APPEND : 0, NULL, &gl);
         }
 
         arr = ucv_array_new(vm);
 
         for (i = 0; i < gl.gl_pathc; i++)
                 ucv_array_push(arr, ucv_string_new(gl.gl_pathv[i]));
 
         globfree(&gl);
 
         return arr;
 }
 
 /**
  * Retrieves the directory name of a path.
  *
  * Returns the directory name component of the specified path.
  *
  * Returns `null` if the path argument is not a string.
  *
  * @function module:fs#dirname
  *
  * @param {string} path
  * The path to extract the directory name from.
  *
  * @returns {?string}
  *
  * @example
  * // Get the directory name of a path
  * const directoryName = dirname('/path/to/file.txt');
  */
 static uc_value_t *
 uc_fs_dirname(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         size_t i;
         char *s;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         i = ucv_string_length(path);
         s = ucv_string_get(path);
 
         if (i == 0)
                 return ucv_string_new(".");
 
         for (i--; s[i] == '/'; i--)
                 if (i == 0)
                         return ucv_string_new("/");
 
         for (; s[i] != '/'; i--)
                 if (i == 0)
                         return ucv_string_new(".");
 
         for (; s[i] == '/'; i--)
                 if (i == 0)
                         return ucv_string_new("/");
 
         return ucv_string_new_length(s, i + 1);
 }
 
 /**
  * Retrieves the base name of a path.
  *
  * Returns the base name component of the specified path.
  *
  * Returns `null` if the path argument is not a string.
  *
  * @function module:fs#basename
  *
  * @param {string} path
  * The path to extract the base name from.
  *
  * @returns {?string}
  *
  * @example
  * // Get the base name of a path
  * const baseName = basename('/path/to/file.txt');
  */
 static uc_value_t *
 uc_fs_basename(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         size_t i, len, skip;
         char *s;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         len = ucv_string_length(path);
         s = ucv_string_get(path);
 
         if (len == 0)
                 return ucv_string_new(".");
 
         for (i = len - 1, skip = 0; i > 0 && s[i] == '/'; i--, skip++)
                 ;
 
         for (; i > 0 && s[i - 1] != '/'; i--)
                 ;
 
         return ucv_string_new_length(s + i, len - i - skip);
 }
 
 static int
 uc_fs_lsdir_sort_fn(const void *k1, const void *k2)
 {
         uc_value_t * const *v1 = k1;
         uc_value_t * const *v2 = k2;
 
         return strcmp(ucv_string_get(*v1), ucv_string_get(*v2));
 }
 
 /**
  * Lists the content of a directory.
  *
  * Returns a sorted array of the names of files and directories in the specified
  * directory.
  *
  * Returns `null` if an error occurred, e.g. if the specified directory cannot
  * be opened.
  *
  * @function module:fs#lsdir
  *
  * @param {string} path
  * The path to the directory.
  *
  * @returns {?string[]}
  *
  * @example
  * // List the content of a directory
  * const fileList = lsdir('/path/to/directory');
  */
 static uc_value_t *
 uc_fs_lsdir(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *pat = uc_fn_arg(1);
         uc_value_t *res = NULL;
         uc_regexp_t *reg;
         struct dirent *e;
         DIR *d;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         switch (ucv_type(pat)) {
         case UC_NULL:
         case UC_STRING:
         case UC_REGEXP:
                 break;
 
         default:
                 err_return(EINVAL);
         }
 
         d = opendir(ucv_string_get(path));
 
         if (!d)
                 err_return(errno);
 
         res = ucv_array_new(vm);
 
         while ((e = readdir(d)) != NULL) {
                 if (!strcmp(e->d_name, ".") || !strcmp(e->d_name, ".."))
                         continue;
 
                 if (ucv_type(pat) == UC_REGEXP) {
                         reg = (uc_regexp_t *)pat;
 
                         if (regexec(&reg->regexp, e->d_name, 0, NULL, 0) == REG_NOMATCH)
                                 continue;
                 }
                 else if (ucv_type(pat) == UC_STRING) {
                         if (fnmatch(ucv_string_get(pat), e->d_name, 0) == FNM_NOMATCH)
                                 continue;
                 }
 
                 ucv_array_push(res, ucv_string_new(e->d_name));
         }
 
         closedir(d);
 
         ucv_array_sort(res, uc_fs_lsdir_sort_fn);
 
         return res;
 }
 
 /**
  * Creates a unique, ephemeral temporary file.
  *
  * Creates a new temporary file, opens it in read and write mode, unlinks it and
  * returns a file handle object referring to the yet open but deleted file.
  *
  * Upon closing the handle, the associated file will automatically vanish from
  * the system.
  *
  * The optional path template argument may be used to override the path and name
  * chosen for the temporary file. If the path template contains no path element,
  * `/tmp/` is prepended, if it does not end with `XXXXXX`, then  * `.XXXXXX` is
  * appended to it. The `XXXXXX` sequence is replaced with a random value
  * ensuring uniqueness of the temporary file name.
  *
  * Returns a file handle object referring to the ephemeral file on success.
  *
  * Returns `null` if an error occurred, e.g. on insufficient permissions or
  * inaccessible directory.
  *
  * @function module:fs#mkstemp
  *
  * @param {string} [template="/tmp/XXXXXX"]
  * The path template to use when forming the temporary file name.
  *
  * @returns {?module:fs.file}
  *
  * @example
  * // Create a unique temporary file in the current working directory
  * const tempFile = mkstemp('./data-XXXXXX');
  */
 static uc_value_t *
 uc_fs_mkstemp(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *template = uc_fn_arg(0);
         bool ends_with_template = false;
         char *path, *t;
         FILE *fp;
         size_t l;
         int fd;
 
         if (template && ucv_type(template) != UC_STRING)
                 err_return(EINVAL);
 
         t = ucv_string_get(template);
         l = ucv_string_length(template);
 
         ends_with_template = (l >= 6 && strcmp(&t[l - 6], "XXXXXX") == 0);
 
         if (t && strchr(t, '/')) {
                 if (ends_with_template)
                         xasprintf(&path, "%s", t);
                 else
                         xasprintf(&path, "%s.XXXXXX", t);
         }
         else if (t) {
                 if (ends_with_template)
                         xasprintf(&path, "/tmp/%s", t);
                 else
                         xasprintf(&path, "/tmp/%s.XXXXXX", t);
         }
         else {
                 xasprintf(&path, "/tmp/XXXXXX");
         }
 
         do {
                 fd = mkstemp(path);
         }
         while (fd == -1 && errno == EINTR);
 
         if (fd == -1) {
                 free(path);
                 err_return(errno);
         }
 
         unlink(path);
         free(path);
 
         fp = fdopen(fd, "r+");
 
         if (!fp) {
                 close(fd);
                 err_return(errno);
         }
 
         return ucv_resource_create(vm, "fs.file", fp);
 }
 
 /**
  * Creates a unique temporary directory based on the given template.
  *
  * If the template argument is given and contains a relative path, the created
  * directory will be placed relative to the current working directory.
  *
  * If the template argument is given and contains an absolute path, the created
  * directory will be placed relative to the given directory.
  *
  * If the template argument is given but does not contain a directory separator,
  * the directory will be placed in `/tmp/`.
  *
  * If no template argument is given, the default `/tmp/XXXXXX` is used.
  *
  * The template argument must end with six consecutive X characters (`XXXXXX`),
  * which will be replaced with a random string to create the unique directory name.
  * If the template does not end with `XXXXXX`, it will be automatically appended.
  *
  * Returns a string containing the path of the created directory on success.
  *
  * Returns `null` if an error occurred, e.g. on insufficient permissions or
  * inaccessible directory.
  *
  * @function module:fs#mkdtemp
  *
  * @param {string} [template="/tmp/XXXXXX"]
  * The path template to use when forming the temporary directory name.
  *
  * @returns {?string}
  *
  * @example
  * // Create a unique temporary directory in the current working directory
  * const tempDir = mkdtemp('./data-XXXXXX');
  */
 static uc_value_t *
 uc_fs_mkdtemp(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *template = uc_fn_arg(0);
         bool ends_with_template = false;
         char *path, *t, *result;
         uc_value_t *rv;
         size_t l;
 
         if (template && ucv_type(template) != UC_STRING)
                 err_return(EINVAL);
 
         t = ucv_string_get(template);
         l = ucv_string_length(template);
 
         ends_with_template = (l >= 6 && strcmp(&t[l - 6], "XXXXXX") == 0);
 
         if (t && strchr(t, '/')) {
                 if (ends_with_template)
                         xasprintf(&path, "%s", t);
                 else
                         xasprintf(&path, "%s.XXXXXX", t);
         }
         else if (t) {
                 if (ends_with_template)
                         xasprintf(&path, "/tmp/%s", t);
                 else
                         xasprintf(&path, "/tmp/%s.XXXXXX", t);
         }
         else {
                 xasprintf(&path, "/tmp/XXXXXX");
         }
 
         result = mkdtemp(path);
 
         if (!result) {
                 free(path);
                 err_return(errno);
         }
 
         rv = ucv_string_new(result);
         free(path);
 
         return rv;
 }
 
 /**
  * Checks the accessibility of a file or directory.
  *
  * The optional modes argument specifies the access modes which should be
  * checked. A file is only considered accessible if all access modes specified
  * in the modes argument are possible.
  *
  * The following modes are recognized:
  *
  * | Mode | Description                           |
  * |------|---------------------------------------|
  * | "r"  | Tests whether the file is readable.   |
  * | "w"  | Tests whether the file is writable.   |
  * | "x"  | Tests whether the file is executable. |
  * | "f"  | Tests whether the file exists.        |
  *
  * Returns `true` if the given path is accessible or `false` when it is not.
  *
  * Returns `null` if an error occurred, e.g. due to inaccessible intermediate
  * path components, invalid path arguments etc.
  *
  * @function module:fs#access
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @param {number} [mode="f"]
  * Optional access mode.
  *
  * @returns {?boolean}
  *
  * @example
  * // Check file read and write accessibility
  * const isAccessible = access('path/to/file', 'rw');
  *
  * // Check execute permissions
  * const mayExecute = access('/usr/bin/example', 'x');
  */
 static uc_value_t *
 uc_fs_access(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *test = uc_fn_arg(1);
         int mode = F_OK;
         char *p;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (test && ucv_type(test) != UC_STRING)
                 err_return(EINVAL);
 
         for (p = ucv_string_get(test); p && *p; p++) {
                 switch (*p) {
                 case 'r':
                         mode |= R_OK;
                         break;
 
                 case 'w':
                         mode |= W_OK;
                         break;
 
                 case 'x':
                         mode |= X_OK;
                         break;
 
                 case 'f':
                         mode |= F_OK;
                         break;
 
                 default:
                         err_return(EINVAL);
                 }
         }
 
         if (access(ucv_string_get(path), mode) == -1)
                 err_return(errno);
 
         return ucv_boolean_new(true);
 }
 
 /**
  * Reads the content of a file, optionally limited to the given amount of bytes.
  *
  * Returns a string containing the file contents.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions.
  *
  * @function module:fs#readfile
  *
  * @param {string} path
  * The path to the file.
  *
  * @param {number} [limit]
  * Number of bytes to limit the result to. When omitted, the entire content is
  * returned.
  *
  * @returns {?string}
  *
  * @example
  * // Read first 100 bytes of content
  * const content = readfile('path/to/file', 100);
  *
  * // Read entire file content
  * const content = readfile('path/to/file');
  */
 static uc_value_t *
 uc_fs_readfile(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *size = uc_fn_arg(1);
         uc_value_t *res = NULL;
         uc_stringbuf_t *buf;
         ssize_t limit = -1;
         size_t rlen, blen;
         FILE *fp;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (size) {
                 if (ucv_type(size) != UC_INTEGER)
                         err_return(EINVAL);
 
                 limit = ucv_int64_get(size);
         }
 
         fp = fopen(ucv_string_get(path), "r");
 
         if (!fp)
                 err_return(errno);
 
         buf = ucv_stringbuf_new();
 
         if (limit > -1 && limit < BUFSIZ)
                 setvbuf(fp, NULL, _IONBF, 0);
 
         while (limit != 0) {
                 blen = 1024;
 
                 if (limit > 0 && blen > (size_t)limit)
                         blen = (size_t)limit;
 
                 printbuf_memset(buf, printbuf_length(buf) + blen - 1, 0, 1);
 
                 buf->bpos -= blen;
                 rlen = fread(buf->buf + buf->bpos, 1, blen, fp);
                 buf->bpos += rlen;
 
                 if (rlen < blen)
                         break;
 
                 if (limit > 0)
                         limit -= rlen;
         }
 
         if (ferror(fp)) {
                 fclose(fp);
                 printbuf_free(buf);
                 err_return(errno);
         }
 
         fclose(fp);
 
         /* add sentinel null byte but don't count it towards the string length */
         printbuf_memappend_fast(buf, "\0", 1);
         res = ucv_stringbuf_finish(buf);
         ((uc_string_t *)res)->length--;
 
         return res;
 }
 
 /**
  * Writes the given data to a file, optionally truncated to the given amount
  * of bytes.
  *
  * In case the given data is not a string, it is converted to a string before
  * being written into the file. String values are written as-is, integer and
  * double values are written in decimal notation, boolean values are written as
  * `true` or `false` while arrays and objects are converted to their JSON
  * representation before being written into the file. The `null` value is
  * represented by an empty string so `writefile(…, null)` would write an empty
  * file. Resource values are written in the form `<type address>`, e.g.
  * `<fs.file 0x7f60f0981760>`.
  *
  * If resource, array or object values contain a `tostring()` function in their
  * prototypes, then this function is invoked to obtain an alternative string
  * representation of the value.
  *
  * If a file already exists at the given path, it is truncated. If no file
  * exists, it is created with default permissions 0o666 masked by the currently
  * effective umask.
  *
  * Returns the number of bytes written.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions.
  *
  * @function module:fs#writefile
  *
  * @param {string} path
  * The path to the file.
  *
  * @param {*} data
  * The data to be written.
  *
  * @param {number} [limit]
  * Truncates the amount of data to be written to the specified amount of bytes.
  * When omitted, the entire content is written.
  *
  * @returns {?number}
  *
  * @example
  * // Write string to a file
  * const bytesWritten = writefile('path/to/file', 'Hello, World!');
  *
  * // Write object as JSON to a file and limit to 1024 bytes at most
  * const obj = { foo: "Hello world", bar: true, baz: 123 };
  * const bytesWritten = writefile('debug.txt', obj, 1024);
  */
 static uc_value_t *
 uc_fs_writefile(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0);
         uc_value_t *data = uc_fn_arg(1);
         uc_value_t *size = uc_fn_arg(2);
         uc_stringbuf_t *buf = NULL;
         ssize_t limit = -1;
         size_t wlen = 0;
         int err = 0;
         FILE *fp;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         if (size) {
                 if (ucv_type(size) != UC_INTEGER)
                         err_return(EINVAL);
 
                 limit = ucv_int64_get(size);
         }
 
         fp = fopen(ucv_string_get(path), "w");
 
         if (!fp)
                 err_return(errno);
 
         if (data && ucv_type(data) != UC_STRING) {
                 buf = xprintbuf_new();
                 ucv_to_stringbuf_formatted(vm, buf, data, 0, '\0', 0);
 
                 if (limit < 0 || limit > printbuf_length(buf))
                         limit = printbuf_length(buf);
 
                 wlen = fwrite(buf->buf, 1, limit, fp);
 
                 if (wlen < (size_t)limit)
                         err = errno;
 
                 printbuf_free(buf);
         }
         else if (data) {
                 if (limit < 0 || (size_t)limit > ucv_string_length(data))
                         limit = ucv_string_length(data);
 
                 wlen = fwrite(ucv_string_get(data), 1, limit, fp);
 
                 if (wlen < (size_t)limit)
                         err = errno;
         }
 
         fclose(fp);
 
         if (err)
                 err_return(err);
 
         return ucv_uint64_new(wlen);
 }
 
 /**
  * Resolves the absolute path of a file or directory.
  *
  * Returns a string containing the resolved path.
  *
  * Returns `null` if an error occurred, e.g. due to insufficient permissions.
  *
  * @function module:fs#realpath
  *
  * @param {string} path
  * The path to the file or directory.
  *
  * @returns {?string}
  *
  * @example
  * // Resolve the absolute path of a file
  * const absolutePath = realpath('path/to/file', 'utf8');
  */
 static uc_value_t *
 uc_fs_realpath(uc_vm_t *vm, size_t nargs)
 {
         uc_value_t *path = uc_fn_arg(0), *rv;
         char *resolved;
 
         if (ucv_type(path) != UC_STRING)
                 err_return(EINVAL);
 
         resolved = realpath(ucv_string_get(path), NULL);
 
         if (!resolved)
                 err_return(errno);
 
         rv = ucv_string_new(resolved);
 
         free(resolved);
 
         return rv;
 }
 
 /**
  * Creates a pipe and returns file handle objects associated with the read- and
  * write end of the pipe respectively.
  *
  * Returns a two element array containing both a file handle object open in read
  * mode referring to the read end of the pipe and a file handle object open in
  * write mode referring to the write end of the pipe.
  *
  * Returns `null` if an error occurred.
  *
  * @function module:fs#pipe
  *
  * @returns {?module:fs.file[]}
  *
  * @example
  * // Create a pipe
  * const pipeHandles = pipe();
  * pipeHandles[1].write("Hello world\n");
  * print(pipeHandles[0].read("line"));
  */
 static uc_value_t *
 uc_fs_pipe(uc_vm_t *vm, size_t nargs)
 {
         int pfds[2], err;
         FILE *rfp, *wfp;
         uc_value_t *rv;
 
         if (pipe(pfds) == -1)
                 err_return(errno);
 
         rfp = fdopen(pfds[0], "r");
 
         if (!rfp) {
                 err = errno;
                 close(pfds[0]);
                 close(pfds[1]);
                 err_return(err);
         }
 
         wfp = fdopen(pfds[1], "w");
 
         if (!wfp) {
                 err = errno;
                 fclose(rfp);
                 close(pfds[1]);
                 err_return(err);
         }
 
         rv = ucv_array_new_length(vm, 2);
 
         ucv_array_push(rv, ucv_resource_create(vm, "fs.file", rfp));
         ucv_array_push(rv, ucv_resource_create(vm, "fs.file", wfp));
 
         return rv;
 }
 
 
 static const uc_function_list_t proc_fns[] = {
         { "read",               uc_fs_pread },
         { "write",              uc_fs_pwrite },
         { "close",              uc_fs_pclose },
         { "flush",              uc_fs_pflush },
         { "fileno",             uc_fs_pfileno },
         { "error",              uc_fs_error },
 };
 
 static const uc_function_list_t file_fns[] = {
         { "read",               uc_fs_read },
         { "write",              uc_fs_write },
         { "seek",               uc_fs_seek },
         { "tell",               uc_fs_tell },
         { "close",              uc_fs_close },
         { "flush",              uc_fs_flush },
         { "fileno",             uc_fs_fileno },
         { "error",              uc_fs_error },
         { "isatty",             uc_fs_isatty },
         { "truncate",   uc_fs_truncate },
         { "lock",               uc_fs_lock },
 #if defined(__linux__)
         { "ioctl",              uc_fs_ioctl },
 #endif
 };
 
 static const uc_function_list_t dir_fns[] = {
         { "fileno",             uc_fs_dfileno },
         { "read",               uc_fs_readdir },
         { "seek",               uc_fs_seekdir },
         { "tell",               uc_fs_telldir },
         { "close",              uc_fs_closedir },
         { "error",              uc_fs_error },
 };
 
 static const uc_function_list_t global_fns[] = {
         { "error",              uc_fs_error },
         { "open",               uc_fs_open },
         { "fdopen",             uc_fs_fdopen },
         { "dup2",               uc_fs_dup2 },
         { "opendir",    uc_fs_opendir },
         { "popen",              uc_fs_popen },
         { "readlink",   uc_fs_readlink },
         { "stat",               uc_fs_stat },
         { "lstat",              uc_fs_lstat },
         { "mkdir",              uc_fs_mkdir },
         { "rmdir",              uc_fs_rmdir },
         { "symlink",    uc_fs_symlink },
         { "unlink",             uc_fs_unlink },
         { "getcwd",             uc_fs_getcwd },
         { "chdir",              uc_fs_chdir },
         { "chmod",              uc_fs_chmod },
         { "chown",              uc_fs_chown },
         { "rename",             uc_fs_rename },
         { "glob",               uc_fs_glob },
         { "dirname",    uc_fs_dirname },
         { "basename",   uc_fs_basename },
         { "lsdir",              uc_fs_lsdir },
         { "mkstemp",    uc_fs_mkstemp },
         { "mkdtemp",    uc_fs_mkdtemp },
         { "access",             uc_fs_access },
         { "readfile",   uc_fs_readfile },
         { "writefile",  uc_fs_writefile },
         { "realpath",   uc_fs_realpath },
         { "pipe",               uc_fs_pipe },
 };
 
 
 static void close_proc(void *ud)
 {
         FILE *fp = ud;
 
         if (fp)
                 pclose(fp);
 }
 
 static void close_file(void *ud)
 {
         FILE *fp = ud;
         int n;
 
         n = fp ? fileno(fp) : -1;
 
         if (n > 2)
                 fclose(fp);
 }
 
 static void close_dir(void *ud)
 {
         DIR *dp = ud;
 
         if (dp)
                 closedir(dp);
 }
 
 void uc_module_init(uc_vm_t *vm, uc_value_t *scope)
 {
         uc_function_list_register(scope, global_fns);
 
         uc_type_declare(vm, "fs.proc", proc_fns, close_proc);
         uc_type_declare(vm, "fs.dir", dir_fns, close_dir);
 
         uc_resource_type_t *file_type = uc_type_declare(vm, "fs.file", file_fns, close_file);
 
         ucv_object_add(scope, "stdin", uc_resource_new(file_type, stdin));
         ucv_object_add(scope, "stdout", uc_resource_new(file_type, stdout));
         ucv_object_add(scope, "stderr", uc_resource_new(file_type, stderr));
 
 #ifdef HAS_IOCTL
 #define ADD_CONST(x) ucv_object_add(scope, #x, ucv_int64_new(x))
         ADD_CONST(IOC_DIR_NONE);
         ADD_CONST(IOC_DIR_READ);
         ADD_CONST(IOC_DIR_WRITE);
         ADD_CONST(IOC_DIR_RW);
 #endif
 }
 

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