1 /* Guts of POSIX spawn interface. Generic POSIX.1 version.
2 Copyright (C) 2000-2006, 2008-2014 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 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
93
94 /* Native Windows API. */
95 int
__spawni(pid_t * pid,const char * file,const posix_spawn_file_actions_t * file_actions,const posix_spawnattr_t * attrp,char * const argv[],char * const envp[],int use_path)96 __spawni (pid_t *pid, const char *file,
97 const posix_spawn_file_actions_t *file_actions,
98 const posix_spawnattr_t *attrp, char *const argv[],
99 char *const envp[], int use_path)
100 {
101 /* Not yet implemented. */
102 return ENOSYS;
103 }
104
105 #else
106
107
108 /* The file is accessible but it is not an executable file. Invoke
109 the shell to interpret it as a script. */
110 static void
111 internal_function
script_execute(const char * file,char * const argv[],char * const envp[])112 script_execute (const char *file, char *const argv[], char *const envp[])
113 {
114 /* Count the arguments. */
115 int argc = 0;
116 while (argv[argc++])
117 ;
118
119 /* Construct an argument list for the shell. */
120 {
121 char **new_argv = (char **) alloca ((argc + 1) * sizeof (char *));
122 new_argv[0] = (char *) _PATH_BSHELL;
123 new_argv[1] = (char *) file;
124 while (argc > 1)
125 {
126 new_argv[argc] = argv[argc - 1];
127 --argc;
128 }
129
130 /* Execute the shell. */
131 execve (new_argv[0], new_argv, envp);
132 }
133 }
134
135
136 /* Spawn a new process executing PATH with the attributes describes in *ATTRP.
137 Before running the process perform the actions described in FILE-ACTIONS. */
138 int
__spawni(pid_t * pid,const char * file,const posix_spawn_file_actions_t * file_actions,const posix_spawnattr_t * attrp,char * const argv[],char * const envp[],int use_path)139 __spawni (pid_t *pid, const char *file,
140 const posix_spawn_file_actions_t *file_actions,
141 const posix_spawnattr_t *attrp, char *const argv[],
142 char *const envp[], int use_path)
143 {
144 pid_t new_pid;
145 char *path, *p, *name;
146 size_t len;
147 size_t pathlen;
148
149 /* Do this once. */
150 short int flags = attrp == NULL ? 0 : attrp->_flags;
151
152 /* Avoid gcc warning
153 "variable 'flags' might be clobbered by 'longjmp' or 'vfork'" */
154 (void) &flags;
155
156 /* Generate the new process. */
157 #if HAVE_VFORK
158 if ((flags & POSIX_SPAWN_USEVFORK) != 0
159 /* If no major work is done, allow using vfork. Note that we
160 might perform the path searching. But this would be done by
161 a call to execvp(), too, and such a call must be OK according
162 to POSIX. */
163 || ((flags & (POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSIGDEF
164 | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER
165 | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS)) == 0
166 && file_actions == NULL))
167 new_pid = vfork ();
168 else
169 #endif
170 new_pid = fork ();
171
172 if (new_pid != 0)
173 {
174 if (new_pid < 0)
175 return errno;
176
177 /* The call was successful. Store the PID if necessary. */
178 if (pid != NULL)
179 *pid = new_pid;
180
181 return 0;
182 }
183
184 /* Set signal mask. */
185 if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
186 && sigprocmask (SIG_SETMASK, &attrp->_ss, NULL) != 0)
187 _exit (SPAWN_ERROR);
188
189 /* Set signal default action. */
190 if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
191 {
192 /* We have to iterate over all signals. This could possibly be
193 done better but it requires system specific solutions since
194 the sigset_t data type can be very different on different
195 architectures. */
196 int sig;
197 struct sigaction sa;
198
199 memset (&sa, '\0', sizeof (sa));
200 sa.sa_handler = SIG_DFL;
201
202 for (sig = 1; sig <= NSIG; ++sig)
203 if (sigismember (&attrp->_sd, sig) != 0
204 && sigaction (sig, &sa, NULL) != 0)
205 _exit (SPAWN_ERROR);
206
207 }
208
209 #if (_LIBC ? defined _POSIX_PRIORITY_SCHEDULING : HAVE_SCHED_SETPARAM && HAVE_SCHED_SETSCHEDULER)
210 /* Set the scheduling algorithm and parameters. */
211 if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
212 == POSIX_SPAWN_SETSCHEDPARAM)
213 {
214 if (sched_setparam (0, &attrp->_sp) == -1)
215 _exit (SPAWN_ERROR);
216 }
217 else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
218 {
219 if (sched_setscheduler (0, attrp->_policy,
220 (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
221 ? &attrp->_sp : NULL) == -1)
222 _exit (SPAWN_ERROR);
223 }
224 #endif
225
226 /* Set the process group ID. */
227 if ((flags & POSIX_SPAWN_SETPGROUP) != 0
228 && setpgid (0, attrp->_pgrp) != 0)
229 _exit (SPAWN_ERROR);
230
231 /* Set the effective user and group IDs. */
232 if ((flags & POSIX_SPAWN_RESETIDS) != 0
233 && (local_seteuid (getuid ()) != 0
234 || local_setegid (getgid ()) != 0))
235 _exit (SPAWN_ERROR);
236
237 /* Execute the file actions. */
238 if (file_actions != NULL)
239 {
240 int cnt;
241
242 for (cnt = 0; cnt < file_actions->_used; ++cnt)
243 {
244 struct __spawn_action *action = &file_actions->_actions[cnt];
245
246 switch (action->tag)
247 {
248 case spawn_do_close:
249 if (close_not_cancel (action->action.close_action.fd) != 0)
250 /* Signal the error. */
251 _exit (SPAWN_ERROR);
252 break;
253
254 case spawn_do_open:
255 {
256 int new_fd = open_not_cancel (action->action.open_action.path,
257 action->action.open_action.oflag
258 | O_LARGEFILE,
259 action->action.open_action.mode);
260
261 if (new_fd == -1)
262 /* The 'open' call failed. */
263 _exit (SPAWN_ERROR);
264
265 /* Make sure the desired file descriptor is used. */
266 if (new_fd != action->action.open_action.fd)
267 {
268 if (dup2 (new_fd, action->action.open_action.fd)
269 != action->action.open_action.fd)
270 /* The 'dup2' call failed. */
271 _exit (SPAWN_ERROR);
272
273 if (close_not_cancel (new_fd) != 0)
274 /* The 'close' call failed. */
275 _exit (SPAWN_ERROR);
276 }
277 }
278 break;
279
280 case spawn_do_dup2:
281 if (dup2 (action->action.dup2_action.fd,
282 action->action.dup2_action.newfd)
283 != action->action.dup2_action.newfd)
284 /* The 'dup2' call failed. */
285 _exit (SPAWN_ERROR);
286 break;
287 }
288 }
289 }
290
291 if (! use_path || strchr (file, '/') != NULL)
292 {
293 /* The FILE parameter is actually a path. */
294 execve (file, argv, envp);
295
296 if (errno == ENOEXEC)
297 script_execute (file, argv, envp);
298
299 /* Oh, oh. 'execve' returns. This is bad. */
300 _exit (SPAWN_ERROR);
301 }
302
303 /* We have to search for FILE on the path. */
304 path = getenv ("PATH");
305 if (path == NULL)
306 {
307 #if HAVE_CONFSTR
308 /* There is no 'PATH' in the environment.
309 The default search path is the current directory
310 followed by the path 'confstr' returns for '_CS_PATH'. */
311 len = confstr (_CS_PATH, (char *) NULL, 0);
312 path = (char *) alloca (1 + len);
313 path[0] = ':';
314 (void) confstr (_CS_PATH, path + 1, len);
315 #else
316 /* Pretend that the PATH contains only the current directory. */
317 path = "";
318 #endif
319 }
320
321 len = strlen (file) + 1;
322 pathlen = strlen (path);
323 name = alloca (pathlen + len + 1);
324 /* Copy the file name at the top. */
325 name = (char *) memcpy (name + pathlen + 1, file, len);
326 /* And add the slash. */
327 *--name = '/';
328
329 p = path;
330 do
331 {
332 char *startp;
333
334 path = p;
335 p = strchrnul (path, ':');
336
337 if (p == path)
338 /* Two adjacent colons, or a colon at the beginning or the end
339 of 'PATH' means to search the current directory. */
340 startp = name + 1;
341 else
342 startp = (char *) memcpy (name - (p - path), path, p - path);
343
344 /* Try to execute this name. If it works, execv will not return. */
345 execve (startp, argv, envp);
346
347 if (errno == ENOEXEC)
348 script_execute (startp, argv, envp);
349
350 switch (errno)
351 {
352 case EACCES:
353 case ENOENT:
354 case ESTALE:
355 case ENOTDIR:
356 /* Those errors indicate the file is missing or not executable
357 by us, in which case we want to just try the next path
358 directory. */
359 break;
360
361 default:
362 /* Some other error means we found an executable file, but
363 something went wrong executing it; return the error to our
364 caller. */
365 _exit (SPAWN_ERROR);
366 }
367 }
368 while (*p++ != '\0');
369
370 /* Return with an error. */
371 _exit (SPAWN_ERROR);
372 }
373
374 #endif
375