blob: ea7b475eb0bad2f29fbb0cd69c335225b7f79e65 [file] [log] [blame]
Bernhard Reutner-Fischer0a8812b2006-05-19 13:12:21 +00001/* vi: set sw=4 ts=4: */
Eric Andersen35e643b2003-07-28 07:40:39 +00002/*
Eric Andersenaff114c2004-04-14 17:51:38 +00003 * Rexec program for system have fork() as vfork() with foreground option
Russ Dilla1fece22003-12-15 21:57:44 +00004 *
5 * Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru>
6 * Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu>
7 *
Eric Andersenaff114c2004-04-14 17:51:38 +00008 * daemon() portion taken from uClibc:
Russ Dilla1fece22003-12-15 21:57:44 +00009 *
10 * Copyright (c) 1991, 1993
11 * The Regents of the University of California. All rights reserved.
12 *
13 * Modified for uClibc by Erik Andersen <andersee@debian.org>
14 *
Bernhard Reutner-Fischer0a8812b2006-05-19 13:12:21 +000015 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
Eric Andersen35e643b2003-07-28 07:40:39 +000016 */
17
Russ Dilla1fece22003-12-15 21:57:44 +000018#include <paths.h>
Denis Vlasenko335b63d2007-04-10 21:38:30 +000019#include "busybox.h" /* for struct bb_applet */
Eric Andersen35e643b2003-07-28 07:40:39 +000020
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000021/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
22 * -1 for failure. Runs argv[0], searching path if that has no / in it. */
23pid_t spawn(char **argv)
24{
25 /* Compiler should not optimize stores here */
26 volatile int failed;
27 pid_t pid;
28
Denis Vlasenko7e754f12007-04-09 13:04:50 +000029// Ain't it a good place to fflush(NULL)?
30
31 /* Be nice to nommu machines. */
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000032 failed = 0;
33 pid = vfork();
34 if (pid < 0) /* error */
35 return pid;
36 if (!pid) { /* child */
Denis Vlasenko7e754f12007-04-09 13:04:50 +000037 /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
38 BB_EXECVP(argv[0], argv);
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000039
40 /* We are (maybe) sharing a stack with blocked parent,
41 * let parent know we failed and then exit to unblock parent
42 * (but don't run atexit() stuff, which would screw up parent.)
43 */
44 failed = errno;
Denis Vlasenkoafa70232007-03-26 17:25:33 +000045 _exit(111);
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000046 }
47 /* parent */
Denis Vlasenkoafa70232007-03-26 17:25:33 +000048 /* Unfortunately, this is not reliable: according to standards
49 * vfork() can be equivalent to fork() and we won't see value
50 * of 'failed'.
51 * Interested party can wait on pid and learn exit code.
52 * If 111 - then it (most probably) failed to exec */
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000053 if (failed) {
54 errno = failed;
55 return -1;
56 }
57 return pid;
58}
59
60/* Die with an error message if we can't spawn a child process. */
61pid_t xspawn(char **argv)
62{
63 pid_t pid = spawn(argv);
Denis Vlasenko53d445a2007-04-09 13:21:33 +000064 if (pid < 0)
65 bb_perror_msg_and_die("%s", *argv);
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000066 return pid;
67}
68
Denis Vlasenko53d445a2007-04-09 13:21:33 +000069// Wait for the specified child PID to exit, returning child's error return.
70int wait4pid(int pid)
71{
72 int status;
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +000073
Denis Vlasenko53d445a2007-04-09 13:21:33 +000074 if (pid <= 0) {
Denis Vlasenkocd7001f2007-04-09 21:32:30 +000075 /*errno = ECHILD; -- wrong. */
76 /* we expect errno to be already set from failed [v]fork/exec */
Denis Vlasenko53d445a2007-04-09 13:21:33 +000077 return -1;
78 }
79 if (waitpid(pid, &status, 0) == -1)
80 return -1;
81 if (WIFEXITED(status))
82 return WEXITSTATUS(status);
83 if (WIFSIGNALED(status))
Denis Vlasenkocd7001f2007-04-09 21:32:30 +000084 return WTERMSIG(status) + 1000;
Denis Vlasenko53d445a2007-04-09 13:21:33 +000085 return 0;
86}
87
88int wait_nohang(int *wstat)
89{
90 return waitpid(-1, wstat, WNOHANG);
91}
92
93int wait_pid(int *wstat, int pid)
94{
95 int r;
96
97 do
98 r = waitpid(pid, wstat, 0);
99 while ((r == -1) && (errno == EINTR));
100 return r;
101}
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000102
Denis Vlasenko96f67dc2007-05-17 13:02:41 +0000103#if ENABLE_FEATURE_PREFER_APPLETS
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000104void save_nofork_data(struct nofork_save_area *save)
105{
Denis Vlasenkob0550012007-05-24 12:18:16 +0000106 memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000107 save->current_applet = current_applet;
108 save->xfunc_error_retval = xfunc_error_retval;
109 save->option_mask32 = option_mask32;
110 save->die_sleep = die_sleep;
111 save->saved = 1;
112}
113
114void restore_nofork_data(struct nofork_save_area *save)
115{
Denis Vlasenkob0550012007-05-24 12:18:16 +0000116 memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000117 current_applet = save->current_applet;
118 xfunc_error_retval = save->xfunc_error_retval;
119 option_mask32 = save->option_mask32;
120 die_sleep = save->die_sleep;
121
122 applet_name = current_applet->name;
123}
124
125int run_nofork_applet_prime(struct nofork_save_area *old, const struct bb_applet *a, char **argv)
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000126{
127 int rc, argc;
128
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000129 current_applet = a;
130 applet_name = a->name;
131 xfunc_error_retval = EXIT_FAILURE;
132 /*option_mask32 = 0; - not needed */
133 /* special flag for xfunc_die(). If xfunc will "die"
134 * in NOFORK applet, xfunc_die() sees negative
135 * die_sleep and longjmp here instead. */
136 die_sleep = -1;
137
138 argc = 1;
139 while (argv[argc])
140 argc++;
141
142 rc = setjmp(die_jmp);
143 if (!rc) {
144 /* Some callers (xargs)
145 * need argv untouched because they free argv[i]! */
146 char *tmp_argv[argc+1];
147 memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
148 /* Finally we can call NOFORK applet's main() */
149 rc = a->main(argc, tmp_argv);
150 } else { /* xfunc died in NOFORK applet */
151 /* in case they meant to return 0... */
Denis Vlasenkob0550012007-05-24 12:18:16 +0000152 if (rc == -2222)
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000153 rc = 0;
154 }
155
156 /* Restoring globals */
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000157 restore_nofork_data(old);
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000158 return rc;
159}
160
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000161int run_nofork_applet(const struct bb_applet *a, char **argv)
162{
163 struct nofork_save_area old;
Denis Vlasenkob0550012007-05-24 12:18:16 +0000164
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000165 /* Saving globals */
166 save_nofork_data(&old);
167 return run_nofork_applet_prime(&old, a, argv);
168}
Denis Vlasenko96f67dc2007-05-17 13:02:41 +0000169#endif /* FEATURE_PREFER_APPLETS */
Denis Vlasenko18e19f22007-04-28 16:43:18 +0000170
Denis Vlasenkocd7001f2007-04-09 21:32:30 +0000171int spawn_and_wait(char **argv)
172{
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000173 int rc;
Denis Vlasenkod571c082007-04-11 07:26:56 +0000174#if ENABLE_FEATURE_PREFER_APPLETS
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000175 const struct bb_applet *a = find_applet_by_name(argv[0]);
Denis Vlasenko335b63d2007-04-10 21:38:30 +0000176
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000177 if (a && (a->nofork
Denis Vlasenko473dae02007-04-11 07:04:23 +0000178#if BB_MMU
179 || a->noexec /* NOEXEC trick needs fork() */
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000180#endif
181 )) {
Denis Vlasenko473dae02007-04-11 07:04:23 +0000182#if BB_MMU
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000183 if (a->nofork)
184#endif
185 {
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000186 return run_nofork_applet(a, argv);
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000187 }
Denis Vlasenko473dae02007-04-11 07:04:23 +0000188#if BB_MMU
189 /* MMU only */
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000190 /* a->noexec is true */
191 rc = fork();
Denis Vlasenko473dae02007-04-11 07:04:23 +0000192 if (rc) /* parent or error */
193 return wait4pid(rc);
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000194 /* child */
Denis Vlasenkof1a71412007-04-10 23:32:37 +0000195 xfunc_error_retval = EXIT_FAILURE;
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000196 current_applet = a;
Denis Vlasenkof5294e12007-04-14 10:09:57 +0000197 run_current_applet_and_exit(argv);
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000198#endif
Denis Vlasenkocd7001f2007-04-09 21:32:30 +0000199 }
Denis Vlasenko473dae02007-04-11 07:04:23 +0000200#endif /* FEATURE_PREFER_APPLETS */
Denis Vlasenkocd7001f2007-04-09 21:32:30 +0000201 rc = spawn(argv);
Denis Vlasenkocd7001f2007-04-09 21:32:30 +0000202 return wait4pid(rc);
Eric Andersen35e643b2003-07-28 07:40:39 +0000203}
Denis Vlasenkoc6758a02007-04-10 21:40:19 +0000204
Denis Vlasenko473dae02007-04-11 07:04:23 +0000205#if !BB_MMU
Denis Vlasenko53091ec2007-03-26 13:35:09 +0000206void forkexit_or_rexec(char **argv)
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000207{
208 pid_t pid;
209 /* Maybe we are already re-execed and come here again? */
210 if (re_execed)
211 return;
212
213 pid = vfork();
214 if (pid < 0) /* wtf? */
215 bb_perror_msg_and_die("vfork");
216 if (pid) /* parent */
217 exit(0);
218 /* child - re-exec ourself */
219 /* high-order bit of first char in argv[0] is a hidden
220 * "we have (alrealy) re-execed, don't do it again" flag */
221 argv[0][0] |= 0x80;
Denis Vlasenkobdbbb7e2007-06-08 15:02:55 +0000222 execv(bb_busybox_exec_path, argv);
223 bb_perror_msg_and_die("exec %s", bb_busybox_exec_path);
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000224}
225#else
Denis Vlasenko53091ec2007-03-26 13:35:09 +0000226/* Dance around (void)...*/
227#undef forkexit_or_rexec
228void forkexit_or_rexec(void)
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000229{
230 pid_t pid;
231 pid = fork();
232 if (pid < 0) /* wtf? */
233 bb_perror_msg_and_die("fork");
234 if (pid) /* parent */
235 exit(0);
236 /* child */
237}
Denis Vlasenko53091ec2007-03-26 13:35:09 +0000238#define forkexit_or_rexec(argv) forkexit_or_rexec()
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000239#endif
240
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000241/* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
242 * char **argv "vanishes" */
243void bb_daemonize_or_rexec(int flags, char **argv)
244{
245 int fd;
246
247 fd = xopen(bb_dev_null, O_RDWR);
248
249 if (flags & DAEMON_CHDIR_ROOT)
250 xchdir("/");
251
252 if (flags & DAEMON_DEVNULL_STDIO) {
253 close(0);
254 close(1);
255 close(2);
256 }
257
258 while ((unsigned)fd < 2)
259 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
260
261 if (!(flags & DAEMON_ONLY_SANITIZE)) {
Denis Vlasenko53091ec2007-03-26 13:35:09 +0000262 forkexit_or_rexec(argv);
Denis Vlasenkod8540f72007-06-14 07:53:06 +0000263 /* if daemonizing, make sure we detach from stdio & ctty */
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000264 setsid();
265 dup2(fd, 0);
266 dup2(fd, 1);
267 dup2(fd, 2);
268 }
Denis Vlasenkod8540f72007-06-14 07:53:06 +0000269 while (fd > 2) {
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000270 close(fd--);
Denis Vlasenkod8540f72007-06-14 07:53:06 +0000271 if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
272 return;
273 /* else close everything after fd#2 */
274 }
Denis Vlasenkobb7fcb42007-03-26 13:20:04 +0000275}
276
277void bb_sanitize_stdio(void)
278{
279 bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
280}