Mercurial > hg > octave-kai > gnulib-hg

comparison lib/spawni.c @ 10505:bb42f3fdba16

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
New module 'posix_spawn-internal'.
author Bruno Haible <bruno@clisp.org>
date Sun, 28 Sep 2008 13:30:49 +0200
parents
children f65529c86553
comparison
equal deleted inserted replaced
10504:21e72b03bb51 10505:bb42f3fdba16
1 /* Guts of POSIX spawn interface. Generic POSIX.1 version.
2 Copyright (C) 2000-2005, 2006, 2008 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include <spawn.h>
22 #include "spawn_int.h"
23
24 #include <alloca.h>
25 #include <errno.h>
26
27 #include <fcntl.h>
28 #ifndef O_LARGEFILE
29 # define O_LARGEFILE 0
30 #endif
31
32 #if _LIBC || HAVE_PATHS_H
33 # include <paths.h>
34 #else
35 # define _PATH_BSHELL "/bin/sh"
36 #endif
37
38 #include <signal.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42
43 #if _LIBC
44 # include <not-cancel.h>
45 #else
46 # define close_not_cancel close
47 # define open_not_cancel open
48 #endif
49
50 #if _LIBC
51 # include <local-setxid.h>
52 #else
53 # if !HAVE_SETEUID
54 # define seteuid(id) setresuid (-1, id, -1)
55 # endif
56 # if !HAVE_SETEGID
57 # define setegid(id) setresgid (-1, id, -1)
58 # endif
59 # define local_seteuid(id) seteuid (id)
60 # define local_setegid(id) setegid (id)
61 #endif
62
63 #if _LIBC
64 # define alloca __alloca
65 # define execve __execve
66 # define dup2 __dup2
67 # define fork __fork
68 # define getgid __getgid
69 # define getuid __getuid
70 # define sched_setparam __sched_setparam
71 # define sched_setscheduler __sched_setscheduler
72 # define setpgid __setpgid
73 # define sigaction __sigaction
74 # define sigismember __sigismember
75 # define sigprocmask __sigprocmask
76 # define strchrnul __strchrnul
77 # define vfork __vfork
78 #else
79 # undef internal_function
80 # define internal_function /* empty */
81 #endif
82
83
84 /* The Unix standard contains a long explanation of the way to signal
85 an error after the fork() was successful. Since no new wait status
86 was wanted there is no way to signal an error using one of the
87 available methods. The committee chose to signal an error by a
88 normal program exit with the exit code 127. */
89 #define SPAWN_ERROR 127
90
91
92 /* The file is accessible but it is not an executable file. Invoke
93 the shell to interpret it as a script. */
94 static void
95 internal_function
96 script_execute (const char *file, char *const argv[], char *const envp[])
97 {
98 /* Count the arguments. */
99 int argc = 0;
100 while (argv[argc++])
101 ;
102
103 /* Construct an argument list for the shell. */
104 {
105 char **new_argv = (char **) alloca ((argc + 1) * sizeof (char *));
106 new_argv[0] = (char *) _PATH_BSHELL;
107 new_argv[1] = (char *) file;
108 while (argc > 1)
109 {
110 new_argv[argc] = argv[argc - 1];
111 --argc;
112 }
113
114 /* Execute the shell. */
115 execve (new_argv[0], new_argv, envp);
116 }
117 }
118
119
120 /* Spawn a new process executing PATH with the attributes describes in *ATTRP.
121 Before running the process perform the actions described in FILE-ACTIONS. */
122 int
123 __spawni (pid_t *pid, const char *file,
124 const posix_spawn_file_actions_t *file_actions,
125 const posix_spawnattr_t *attrp, char *const argv[],
126 char *const envp[], int use_path)
127 {
128 pid_t new_pid;
129 char *path, *p, *name;
130 size_t len;
131 size_t pathlen;
132
133 /* Do this once. */
134 short int flags = attrp == NULL ? 0 : attrp->_flags;
135
136 /* Generate the new process. */
137 #if HAVE_VFORK
138 if ((flags & POSIX_SPAWN_USEVFORK) != 0
139 /* If no major work is done, allow using vfork. Note that we
140 might perform the path searching. But this would be done by
141 a call to execvp(), too, and such a call must be OK according
142 to POSIX. */
143 || ((flags & (POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSIGDEF
144 | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER
145 | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS)) == 0
146 && file_actions == NULL))
147 new_pid = vfork ();
148 else
149 #endif
150 new_pid = fork ();
151
152 if (new_pid != 0)
153 {
154 if (new_pid < 0)
155 return errno;
156
157 /* The call was successful. Store the PID if necessary. */
158 if (pid != NULL)
159 *pid = new_pid;
160
161 return 0;
162 }
163
164 /* Set signal mask. */
165 if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
166 && sigprocmask (SIG_SETMASK, &attrp->_ss, NULL) != 0)
167 _exit (SPAWN_ERROR);
168
169 /* Set signal default action. */
170 if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
171 {
172 /* We have to iterate over all signals. This could possibly be
173 done better but it requires system specific solutions since
174 the sigset_t data type can be very different on different
175 architectures. */
176 int sig;
177 struct sigaction sa;
178
179 memset (&sa, '\0', sizeof (sa));
180 sa.sa_handler = SIG_DFL;
181
182 for (sig = 1; sig <= NSIG; ++sig)
183 if (sigismember (&attrp->_sd, sig) != 0
184 && sigaction (sig, &sa, NULL) != 0)
185 _exit (SPAWN_ERROR);
186
187 }
188
189 #if (_LIBC ? defined _POSIX_PRIORITY_SCHEDULING : HAVE_SCHED_SETPARAM && HAVE_SCHED_SETSCHEDULER)
190 /* Set the scheduling algorithm and parameters. */
191 if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
192 == POSIX_SPAWN_SETSCHEDPARAM)
193 {
194 if (sched_setparam (0, &attrp->_sp) == -1)
195 _exit (SPAWN_ERROR);
196 }
197 else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
198 {
199 if (sched_setscheduler (0, attrp->_policy,
200 (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
201 ? &attrp->_sp : NULL) == -1)
202 _exit (SPAWN_ERROR);
203 }
204 #endif
205
206 /* Set the process group ID. */
207 if ((flags & POSIX_SPAWN_SETPGROUP) != 0
208 && setpgid (0, attrp->_pgrp) != 0)
209 _exit (SPAWN_ERROR);
210
211 /* Set the effective user and group IDs. */
212 if ((flags & POSIX_SPAWN_RESETIDS) != 0
213 && (local_seteuid (getuid ()) != 0
214 || local_setegid (getgid ()) != 0))
215 _exit (SPAWN_ERROR);
216
217 /* Execute the file actions. */
218 if (file_actions != NULL)
219 {
220 int cnt;
221
222 for (cnt = 0; cnt < file_actions->_used; ++cnt)
223 {
224 struct __spawn_action *action = &file_actions->_actions[cnt];
225
226 switch (action->tag)
227 {
228 case spawn_do_close:
229 if (close_not_cancel (action->action.close_action.fd) != 0)
230 /* Signal the error. */
231 _exit (SPAWN_ERROR);
232 break;
233
234 case spawn_do_open:
235 {
236 int new_fd = open_not_cancel (action->action.open_action.path,
237 action->action.open_action.oflag
238 | O_LARGEFILE,
239 action->action.open_action.mode);
240
241 if (new_fd == -1)
242 /* The `open' call failed. */
243 _exit (SPAWN_ERROR);
244
245 /* Make sure the desired file descriptor is used. */
246 if (new_fd != action->action.open_action.fd)
247 {
248 if (dup2 (new_fd, action->action.open_action.fd)
249 != action->action.open_action.fd)
250 /* The `dup2' call failed. */
251 _exit (SPAWN_ERROR);
252
253 if (close_not_cancel (new_fd) != 0)
254 /* The `close' call failed. */
255 _exit (SPAWN_ERROR);
256 }
257 }
258 break;
259
260 case spawn_do_dup2:
261 if (dup2 (action->action.dup2_action.fd,
262 action->action.dup2_action.newfd)
263 != action->action.dup2_action.newfd)
264 /* The `dup2' call failed. */
265 _exit (SPAWN_ERROR);
266 break;
267 }
268 }
269 }
270
271 if (! use_path || strchr (file, '/') != NULL)
272 {
273 /* The FILE parameter is actually a path. */
274 execve (file, argv, envp);
275
276 if (errno == ENOEXEC)
277 script_execute (file, argv, envp);
278
279 /* Oh, oh. `execve' returns. This is bad. */
280 _exit (SPAWN_ERROR);
281 }
282
283 /* We have to search for FILE on the path. */
284 path = getenv ("PATH");
285 if (path == NULL)
286 {
287 #if HAVE_CONFSTR
288 /* There is no `PATH' in the environment.
289 The default search path is the current directory
290 followed by the path `confstr' returns for `_CS_PATH'. */
291 len = confstr (_CS_PATH, (char *) NULL, 0);
292 path = (char *) alloca (1 + len);
293 path[0] = ':';
294 (void) confstr (_CS_PATH, path + 1, len);
295 #else
296 /* Pretend that the PATH contains only the current directory. */
297 path = "";
298 #endif
299 }
300
301 len = strlen (file) + 1;
302 pathlen = strlen (path);
303 name = alloca (pathlen + len + 1);
304 /* Copy the file name at the top. */
305 name = (char *) memcpy (name + pathlen + 1, file, len);
306 /* And add the slash. */
307 *--name = '/';
308
309 p = path;
310 do
311 {
312 char *startp;
313
314 path = p;
315 p = strchrnul (path, ':');
316
317 if (p == path)
318 /* Two adjacent colons, or a colon at the beginning or the end
319 of `PATH' means to search the current directory. */
320 startp = name + 1;
321 else
322 startp = (char *) memcpy (name - (p - path), path, p - path);
323
324 /* Try to execute this name. If it works, execv will not return. */
325 execve (startp, argv, envp);
326
327 if (errno == ENOEXEC)
328 script_execute (startp, argv, envp);
329
330 switch (errno)
331 {
332 case EACCES:
333 case ENOENT:
334 case ESTALE:
335 case ENOTDIR:
336 /* Those errors indicate the file is missing or not executable
337 by us, in which case we want to just try the next path
338 directory. */
339 break;
340
341 default:
342 /* Some other error means we found an executable file, but
343 something went wrong executing it; return the error to our
344 caller. */
345 _exit (SPAWN_ERROR);
346 }
347 }
348 while (*p++ != '\0');
349
350 /* Return with an error. */
351 _exit (SPAWN_ERROR);
352 }