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Sources/rpcd/exec.c

  1 /*
  2  * rpcd - UBUS RPC server
  3  *
  4  *   Copyright (C) 2013-2014 Jo-Philipp Wich <jow@openwrt.org>
  5  *
  6  * Permission to use, copy, modify, and/or distribute this software for any
  7  * purpose with or without fee is hereby granted, provided that the above
  8  * copyright notice and this permission notice appear in all copies.
  9  *
 10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 17  */
 18 
 19 #include <fcntl.h>
 20 #include <errno.h>
 21 #include <unistd.h>
 22 #include <stdlib.h>
 23 #include <string.h>
 24 #include <limits.h>
 25 #include <dirent.h>
 26 #include <sys/stat.h>
 27 #include <sys/wait.h>
 28 
 29 #include <rpcd/exec.h>
 30 
 31 static int
 32 rpc_errno_status(void)
 33 {
 34         switch (errno)
 35         {
 36         case EACCES:
 37                 return UBUS_STATUS_PERMISSION_DENIED;
 38 
 39         case ENOTDIR:
 40                 return UBUS_STATUS_INVALID_ARGUMENT;
 41 
 42         case ENOENT:
 43                 return UBUS_STATUS_NOT_FOUND;
 44 
 45         case EINVAL:
 46                 return UBUS_STATUS_INVALID_ARGUMENT;
 47 
 48         default:
 49                 return UBUS_STATUS_UNKNOWN_ERROR;
 50         }
 51 }
 52 
 53 const char *
 54 rpc_exec_lookup(const char *cmd)
 55 {
 56         struct stat s;
 57         int plen = 0, clen = strlen(cmd) + 1;
 58         char *search, *p;
 59         static char path[PATH_MAX];
 60 
 61         if (!stat(cmd, &s) && S_ISREG(s.st_mode))
 62                 return cmd;
 63 
 64         search = getenv("PATH");
 65 
 66         if (!search)
 67                 search = "/bin:/usr/bin:/sbin:/usr/sbin";
 68 
 69         p = search;
 70 
 71         do
 72         {
 73                 if (*p != ':' && *p != '\0')
 74                         continue;
 75 
 76                 plen = p - search;
 77 
 78                 if ((plen + clen) >= sizeof(path))
 79                         continue;
 80 
 81                 strncpy(path, search, plen);
 82                 sprintf(path + plen, "/%s", cmd);
 83 
 84                 if (!stat(path, &s) && S_ISREG(s.st_mode))
 85                         return path;
 86 
 87                 search = p + 1;
 88         }
 89         while (*p++);
 90 
 91         return NULL;
 92 }
 93 
 94 
 95 static void
 96 rpc_ustream_to_blobmsg(struct blob_buf *blob, struct ustream *s,
 97                        const char *name)
 98 {
 99         int len;
100         char *rbuf, *wbuf;
101 
102         if ((len = ustream_pending_data(s, false)) > 0)
103         {
104                 wbuf = blobmsg_alloc_string_buffer(blob, name, len + 1);
105 
106                 if (!wbuf)
107                         return;
108 
109                 ustream_for_each_read_buffer(s, rbuf, len)
110                 {
111                         memcpy(wbuf, rbuf, len);
112                         wbuf += len;
113                 }
114 
115                 *wbuf = 0;
116                 blobmsg_add_string_buffer(blob);
117         }
118 }
119 
120 static void
121 rpc_exec_reply(struct rpc_exec_context *c, int rv)
122 {
123         uloop_timeout_cancel(&c->timeout);
124         uloop_process_delete(&c->process);
125 
126         if (rv == UBUS_STATUS_OK)
127         {
128                 if (!c->stdout_cb && !c->stderr_cb && !c->finish_cb)
129                 {
130                         blobmsg_add_u32(&c->blob, "code", WEXITSTATUS(c->stat));
131                         rpc_ustream_to_blobmsg(&c->blob, &c->opipe.stream, "stdout");
132                         rpc_ustream_to_blobmsg(&c->blob, &c->epipe.stream, "stderr");
133                 }
134         }
135 
136         if (c->finish_cb)
137                 rv = c->finish_cb(&c->blob, c->stat, c->priv);
138 
139         if (rv == UBUS_STATUS_OK)
140                 ubus_send_reply(c->context, &c->request, c->blob.head);
141 
142         ubus_complete_deferred_request(c->context, &c->request, rv);
143 
144         blob_buf_free(&c->blob);
145 
146         ustream_free(&c->opipe.stream);
147         ustream_free(&c->epipe.stream);
148 
149         close(c->opipe.fd.fd);
150         close(c->epipe.fd.fd);
151 
152         if (c->priv)
153                 free(c->priv);
154 
155         free(c);
156 }
157 
158 static void
159 rpc_exec_timeout_cb(struct uloop_timeout *t)
160 {
161         struct rpc_exec_context *c =
162                 container_of(t, struct rpc_exec_context, timeout);
163 
164         kill(c->process.pid, SIGKILL);
165         rpc_exec_reply(c, UBUS_STATUS_TIMEOUT);
166 }
167 
168 static void
169 rpc_exec_process_cb(struct uloop_process *p, int stat)
170 {
171         struct rpc_exec_context *c =
172                 container_of(p, struct rpc_exec_context, process);
173 
174         c->stat = stat;
175 
176         ustream_poll(&c->opipe.stream);
177         ustream_poll(&c->epipe.stream);
178 
179         close(c->opipe.fd.fd);
180         close(c->epipe.fd.fd);
181 
182         ustream_poll(&c->opipe.stream);
183         ustream_poll(&c->epipe.stream);
184 }
185 
186 static void
187 rpc_exec_ipipe_write_cb(struct ustream *s, int bytes)
188 {
189         struct rpc_exec_context *c =
190                 container_of(s, struct rpc_exec_context, ipipe.stream);
191 
192         if (c->stdin_cb(s, c->priv) <= 0)
193         {
194                 ustream_free(&c->ipipe.stream);
195                 close(c->ipipe.fd.fd);
196         }
197 }
198 
199 static void
200 rpc_exec_opipe_read_cb(struct ustream *s, int bytes)
201 {
202         int len, rv;
203         char *buf;
204         struct rpc_exec_context *c =
205                 container_of(s, struct rpc_exec_context, opipe.stream);
206 
207         if (c->stdout_cb)
208         {
209                 do {
210                         buf = ustream_get_read_buf(s, &len);
211 
212                         if (!buf || !len)
213                                 break;
214 
215                         rv = c->stdout_cb(&c->blob, buf, len, c->priv);
216 
217                         if (rv <= 0)
218                                 break;
219 
220                         ustream_consume(s, rv);
221                 } while(1);
222         }
223         else if (ustream_read_buf_full(s))
224         {
225                 rpc_exec_reply(c, UBUS_STATUS_NOT_SUPPORTED);
226         }
227 }
228 
229 static void
230 rpc_exec_epipe_read_cb(struct ustream *s, int bytes)
231 {
232         int len, rv;
233         char *buf;
234         struct rpc_exec_context *c =
235                 container_of(s, struct rpc_exec_context, epipe.stream);
236 
237         if (c->stderr_cb)
238         {
239                 do {
240                         buf = ustream_get_read_buf(s, &len);
241 
242                         if (!buf || !len)
243                                 break;
244 
245                         rv = c->stderr_cb(&c->blob, buf, len, c->priv);
246 
247                         if (rv <= 0)
248                                 break;
249 
250                         ustream_consume(s, rv);
251                 } while(1);
252         }
253         else if (ustream_read_buf_full(s))
254         {
255                 rpc_exec_reply(c, UBUS_STATUS_NOT_SUPPORTED);
256         }
257 }
258 
259 static void
260 rpc_exec_opipe_state_cb(struct ustream *s)
261 {
262         struct rpc_exec_context *c =
263                 container_of(s, struct rpc_exec_context, opipe.stream);
264 
265         if (c->opipe.stream.eof && c->epipe.stream.eof)
266                 rpc_exec_reply(c, UBUS_STATUS_OK);
267 }
268 
269 static void
270 rpc_exec_epipe_state_cb(struct ustream *s)
271 {
272         struct rpc_exec_context *c =
273                 container_of(s, struct rpc_exec_context, epipe.stream);
274 
275         if (c->opipe.stream.eof && c->epipe.stream.eof)
276                 rpc_exec_reply(c, UBUS_STATUS_OK);
277 }
278 
279 int
280 rpc_exec(const char **args, rpc_exec_write_cb_t in,
281          rpc_exec_read_cb_t out, rpc_exec_read_cb_t err,
282          rpc_exec_done_cb_t end, void *priv, struct ubus_context *ctx,
283          struct ubus_request_data *req)
284 {
285         pid_t pid;
286 
287         int ipipe[2];
288         int opipe[2];
289         int epipe[2];
290 
291         const char *cmd;
292         struct rpc_exec_context *c;
293 
294         cmd = rpc_exec_lookup(args[0]);
295 
296         if (!cmd)
297                 return UBUS_STATUS_NOT_FOUND;
298 
299         c = malloc(sizeof(*c));
300 
301         if (!c)
302                 return UBUS_STATUS_UNKNOWN_ERROR;
303 
304         if (pipe(ipipe))
305                 goto fail_ipipe;
306 
307         if (pipe(opipe))
308                 goto fail_opipe;
309 
310         if (pipe(epipe))
311                 goto fail_epipe;
312 
313         switch ((pid = fork()))
314         {
315         case -1:
316                 goto fail_fork;
317 
318         case 0:
319                 uloop_done();
320 
321                 dup2(ipipe[0], 0);
322                 dup2(opipe[1], 1);
323                 dup2(epipe[1], 2);
324 
325                 close(ipipe[0]);
326                 close(ipipe[1]);
327                 close(opipe[0]);
328                 close(opipe[1]);
329                 close(epipe[0]);
330                 close(epipe[1]);
331 
332                 if (execv(cmd, (char * const *)args))
333                         return rpc_errno_status();
334 
335         default:
336                 memset(c, 0, sizeof(*c));
337                 blob_buf_init(&c->blob, 0);
338 
339                 c->stdin_cb  = in;
340                 c->stdout_cb = out;
341                 c->stderr_cb = err;
342                 c->finish_cb = end;
343                 c->priv      = priv;
344 
345                 ustream_declare_read(c->opipe, opipe[0], opipe);
346                 ustream_declare_read(c->epipe, epipe[0], epipe);
347 
348                 c->process.pid = pid;
349                 c->process.cb = rpc_exec_process_cb;
350                 uloop_process_add(&c->process);
351 
352                 c->timeout.cb = rpc_exec_timeout_cb;
353                 uloop_timeout_set(&c->timeout, rpc_exec_timeout);
354 
355                 if (c->stdin_cb)
356                 {
357                         ustream_declare_write(c->ipipe, ipipe[1], ipipe);
358                         rpc_exec_ipipe_write_cb(&c->ipipe.stream, 0);
359                 }
360                 else
361                 {
362                         close(ipipe[1]);
363                 }
364 
365                 close(ipipe[0]);
366                 close(opipe[1]);
367                 close(epipe[1]);
368 
369                 c->context = ctx;
370                 ubus_defer_request(ctx, req, &c->request);
371         }
372 
373         return UBUS_STATUS_OK;
374 
375 fail_fork:
376         close(epipe[0]);
377         close(epipe[1]);
378 
379 fail_epipe:
380         close(opipe[0]);
381         close(opipe[1]);
382 
383 fail_opipe:
384         close(ipipe[0]);
385         close(ipipe[1]);
386 
387 fail_ipipe:
388         free(c);
389         return rpc_errno_status();
390 }
391 

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