1 /* Guts of POSIX spawn interface. Generic POSIX.1 version. 2 Copyright (C) 2000-2006, 2008-2012 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 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 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 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
