Annotation of /trunk/mkinitrd-magellan/busybox/libbb/vfork_daemon_rexec.c
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Revision 984 -
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Sun May 30 11:32:42 2010 UTC (14 years ago) by niro
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File size: 8742 byte(s)
Sun May 30 11:32:42 2010 UTC (14 years ago) by niro
File MIME type: text/plain
File size: 8742 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
1 | niro | 532 | /* vi: set sw=4 ts=4: */ |
2 | /* | ||
3 | * Rexec program for system have fork() as vfork() with foreground option | ||
4 | * | ||
5 | * Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru> | ||
6 | * Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu> | ||
7 | * | ||
8 | * daemon() portion taken from uClibc: | ||
9 | * | ||
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 | * | ||
15 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. | ||
16 | */ | ||
17 | |||
18 | niro | 816 | #include "busybox.h" /* uses applet tables */ |
19 | niro | 532 | |
20 | niro | 816 | /* This does a fork/exec in one call, using vfork(). Returns PID of new child, |
21 | * -1 for failure. Runs argv[0], searching path if that has no / in it. */ | ||
22 | pid_t FAST_FUNC spawn(char **argv) | ||
23 | niro | 532 | { |
24 | niro | 816 | /* Compiler should not optimize stores here */ |
25 | volatile int failed; | ||
26 | pid_t pid; | ||
27 | niro | 532 | |
28 | niro | 984 | fflush_all(); |
29 | niro | 532 | |
30 | niro | 816 | /* Be nice to nommu machines. */ |
31 | failed = 0; | ||
32 | pid = vfork(); | ||
33 | if (pid < 0) /* error */ | ||
34 | return pid; | ||
35 | if (!pid) { /* child */ | ||
36 | /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */ | ||
37 | BB_EXECVP(argv[0], argv); | ||
38 | niro | 532 | |
39 | niro | 816 | /* We are (maybe) sharing a stack with blocked parent, |
40 | * let parent know we failed and then exit to unblock parent | ||
41 | * (but don't run atexit() stuff, which would screw up parent.) | ||
42 | */ | ||
43 | failed = errno; | ||
44 | niro | 984 | /* mount, for example, does not want the message */ |
45 | /*bb_perror_msg("can't execute '%s'", argv[0]);*/ | ||
46 | niro | 816 | _exit(111); |
47 | niro | 532 | } |
48 | niro | 816 | /* parent */ |
49 | /* Unfortunately, this is not reliable: according to standards | ||
50 | * vfork() can be equivalent to fork() and we won't see value | ||
51 | * of 'failed'. | ||
52 | * Interested party can wait on pid and learn exit code. | ||
53 | * If 111 - then it (most probably) failed to exec */ | ||
54 | if (failed) { | ||
55 | errno = failed; | ||
56 | return -1; | ||
57 | } | ||
58 | return pid; | ||
59 | } | ||
60 | niro | 532 | |
61 | niro | 816 | /* Die with an error message if we can't spawn a child process. */ |
62 | pid_t FAST_FUNC xspawn(char **argv) | ||
63 | { | ||
64 | pid_t pid = spawn(argv); | ||
65 | if (pid < 0) | ||
66 | bb_simple_perror_msg_and_die(*argv); | ||
67 | return pid; | ||
68 | } | ||
69 | |||
70 | pid_t FAST_FUNC safe_waitpid(pid_t pid, int *wstat, int options) | ||
71 | { | ||
72 | pid_t r; | ||
73 | |||
74 | do | ||
75 | r = waitpid(pid, wstat, options); | ||
76 | while ((r == -1) && (errno == EINTR)); | ||
77 | return r; | ||
78 | } | ||
79 | |||
80 | pid_t FAST_FUNC wait_any_nohang(int *wstat) | ||
81 | { | ||
82 | return safe_waitpid(-1, wstat, WNOHANG); | ||
83 | } | ||
84 | |||
85 | // Wait for the specified child PID to exit, returning child's error return. | ||
86 | int FAST_FUNC wait4pid(pid_t pid) | ||
87 | { | ||
88 | int status; | ||
89 | |||
90 | if (pid <= 0) { | ||
91 | /*errno = ECHILD; -- wrong. */ | ||
92 | /* we expect errno to be already set from failed [v]fork/exec */ | ||
93 | return -1; | ||
94 | niro | 532 | } |
95 | niro | 816 | if (safe_waitpid(pid, &status, 0) == -1) |
96 | return -1; | ||
97 | if (WIFEXITED(status)) | ||
98 | return WEXITSTATUS(status); | ||
99 | if (WIFSIGNALED(status)) | ||
100 | return WTERMSIG(status) + 1000; | ||
101 | return 0; | ||
102 | } | ||
103 | |||
104 | #if ENABLE_FEATURE_PREFER_APPLETS | ||
105 | void FAST_FUNC save_nofork_data(struct nofork_save_area *save) | ||
106 | { | ||
107 | memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp)); | ||
108 | save->applet_name = applet_name; | ||
109 | save->xfunc_error_retval = xfunc_error_retval; | ||
110 | save->option_mask32 = option_mask32; | ||
111 | save->die_sleep = die_sleep; | ||
112 | save->saved = 1; | ||
113 | } | ||
114 | |||
115 | void FAST_FUNC restore_nofork_data(struct nofork_save_area *save) | ||
116 | { | ||
117 | memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp)); | ||
118 | applet_name = save->applet_name; | ||
119 | xfunc_error_retval = save->xfunc_error_retval; | ||
120 | option_mask32 = save->option_mask32; | ||
121 | die_sleep = save->die_sleep; | ||
122 | } | ||
123 | |||
124 | int FAST_FUNC run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **argv) | ||
125 | { | ||
126 | int rc, argc; | ||
127 | |||
128 | applet_name = APPLET_NAME(applet_no); | ||
129 | |||
130 | xfunc_error_retval = EXIT_FAILURE; | ||
131 | |||
132 | /* Special flag for xfunc_die(). If xfunc will "die" | ||
133 | * in NOFORK applet, xfunc_die() sees negative | ||
134 | * die_sleep and longjmp here instead. */ | ||
135 | die_sleep = -1; | ||
136 | |||
137 | /* In case getopt() or getopt32() was already called: | ||
138 | * reset the libc getopt() function, which keeps internal state. | ||
139 | * | ||
140 | * BSD-derived getopt() functions require that optind be set to 1 in | ||
141 | * order to reset getopt() state. This used to be generally accepted | ||
142 | * way of resetting getopt(). However, glibc's getopt() | ||
143 | * has additional getopt() state beyond optind, and requires that | ||
144 | * optind be set to zero to reset its state. So the unfortunate state of | ||
145 | * affairs is that BSD-derived versions of getopt() misbehave if | ||
146 | * optind is set to 0 in order to reset getopt(), and glibc's getopt() | ||
147 | * will core dump if optind is set 1 in order to reset getopt(). | ||
148 | * | ||
149 | * More modern versions of BSD require that optreset be set to 1 in | ||
150 | * order to reset getopt(). Sigh. Standards, anyone? | ||
151 | */ | ||
152 | #ifdef __GLIBC__ | ||
153 | optind = 0; | ||
154 | #else /* BSD style */ | ||
155 | optind = 1; | ||
156 | /* optreset = 1; */ | ||
157 | #endif | ||
158 | /* optarg = NULL; opterr = 1; optopt = 63; - do we need this too? */ | ||
159 | /* (values above are what they initialized to in glibc and uclibc) */ | ||
160 | /* option_mask32 = 0; - not needed, no applet depends on it being 0 */ | ||
161 | |||
162 | argc = 1; | ||
163 | while (argv[argc]) | ||
164 | argc++; | ||
165 | |||
166 | rc = setjmp(die_jmp); | ||
167 | if (!rc) { | ||
168 | /* Some callers (xargs) | ||
169 | * need argv untouched because they free argv[i]! */ | ||
170 | char *tmp_argv[argc+1]; | ||
171 | memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0])); | ||
172 | /* Finally we can call NOFORK applet's main() */ | ||
173 | rc = applet_main[applet_no](argc, tmp_argv); | ||
174 | |||
175 | /* The whole reason behind nofork_save_area is that <applet>_main | ||
176 | * may exit non-locally! For example, in hush Ctrl-Z tries | ||
177 | * (modulo bugs) to dynamically create a child (backgrounded task) | ||
178 | * if it detects that Ctrl-Z was pressed when a NOFORK was running. | ||
179 | * Testcase: interactive "rm -i". | ||
180 | * Don't fool yourself into thinking "and <applet>_main() returns | ||
181 | * quickly here" and removing "useless" nofork_save_area code. */ | ||
182 | |||
183 | } else { /* xfunc died in NOFORK applet */ | ||
184 | /* in case they meant to return 0... */ | ||
185 | if (rc == -2222) | ||
186 | rc = 0; | ||
187 | } | ||
188 | |||
189 | /* Restoring some globals */ | ||
190 | restore_nofork_data(old); | ||
191 | |||
192 | /* Other globals can be simply reset to defaults */ | ||
193 | #ifdef __GLIBC__ | ||
194 | optind = 0; | ||
195 | #else /* BSD style */ | ||
196 | optind = 1; | ||
197 | #endif | ||
198 | |||
199 | return rc & 0xff; /* don't confuse people with "exitcodes" >255 */ | ||
200 | } | ||
201 | |||
202 | int FAST_FUNC run_nofork_applet(int applet_no, char **argv) | ||
203 | { | ||
204 | struct nofork_save_area old; | ||
205 | |||
206 | /* Saving globals */ | ||
207 | save_nofork_data(&old); | ||
208 | return run_nofork_applet_prime(&old, applet_no, argv); | ||
209 | } | ||
210 | #endif /* FEATURE_PREFER_APPLETS */ | ||
211 | |||
212 | int FAST_FUNC spawn_and_wait(char **argv) | ||
213 | { | ||
214 | int rc; | ||
215 | #if ENABLE_FEATURE_PREFER_APPLETS | ||
216 | int a = find_applet_by_name(argv[0]); | ||
217 | |||
218 | if (a >= 0 && (APPLET_IS_NOFORK(a) | ||
219 | #if BB_MMU | ||
220 | || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */ | ||
221 | #endif | ||
222 | )) { | ||
223 | #if BB_MMU | ||
224 | if (APPLET_IS_NOFORK(a)) | ||
225 | #endif | ||
226 | { | ||
227 | return run_nofork_applet(a, argv); | ||
228 | } | ||
229 | #if BB_MMU | ||
230 | /* MMU only */ | ||
231 | /* a->noexec is true */ | ||
232 | rc = fork(); | ||
233 | if (rc) /* parent or error */ | ||
234 | return wait4pid(rc); | ||
235 | /* child */ | ||
236 | xfunc_error_retval = EXIT_FAILURE; | ||
237 | run_applet_no_and_exit(a, argv); | ||
238 | #endif | ||
239 | } | ||
240 | #endif /* FEATURE_PREFER_APPLETS */ | ||
241 | rc = spawn(argv); | ||
242 | return wait4pid(rc); | ||
243 | } | ||
244 | |||
245 | #if !BB_MMU | ||
246 | void FAST_FUNC re_exec(char **argv) | ||
247 | { | ||
248 | /* high-order bit of first char in argv[0] is a hidden | ||
249 | * "we have (already) re-execed, don't do it again" flag */ | ||
250 | argv[0][0] |= 0x80; | ||
251 | execv(bb_busybox_exec_path, argv); | ||
252 | bb_perror_msg_and_die("exec %s", bb_busybox_exec_path); | ||
253 | } | ||
254 | |||
255 | niro | 984 | pid_t FAST_FUNC fork_or_rexec(char **argv) |
256 | niro | 816 | { |
257 | pid_t pid; | ||
258 | /* Maybe we are already re-execed and come here again? */ | ||
259 | if (re_execed) | ||
260 | niro | 984 | return 0; |
261 | niro | 816 | pid = vfork(); |
262 | if (pid < 0) /* wtf? */ | ||
263 | niro | 532 | bb_perror_msg_and_die("vfork"); |
264 | niro | 816 | if (pid) /* parent */ |
265 | niro | 984 | return pid; |
266 | niro | 816 | /* child - re-exec ourself */ |
267 | re_exec(argv); | ||
268 | } | ||
269 | #else | ||
270 | /* Dance around (void)...*/ | ||
271 | niro | 984 | #undef fork_or_rexec |
272 | pid_t FAST_FUNC fork_or_rexec(void) | ||
273 | niro | 816 | { |
274 | pid_t pid; | ||
275 | pid = fork(); | ||
276 | if (pid < 0) /* wtf? */ | ||
277 | bb_perror_msg_and_die("fork"); | ||
278 | niro | 984 | return pid; |
279 | niro | 816 | } |
280 | niro | 984 | #define fork_or_rexec(argv) fork_or_rexec() |
281 | niro | 816 | #endif |
282 | |||
283 | /* Due to a #define in libbb.h on MMU systems we actually have 1 argument - | ||
284 | * char **argv "vanishes" */ | ||
285 | void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv) | ||
286 | { | ||
287 | int fd; | ||
288 | |||
289 | if (flags & DAEMON_CHDIR_ROOT) | ||
290 | xchdir("/"); | ||
291 | |||
292 | if (flags & DAEMON_DEVNULL_STDIO) { | ||
293 | close(0); | ||
294 | close(1); | ||
295 | close(2); | ||
296 | niro | 532 | } |
297 | niro | 816 | |
298 | fd = open(bb_dev_null, O_RDWR); | ||
299 | if (fd < 0) { | ||
300 | /* NB: we can be called as bb_sanitize_stdio() from init | ||
301 | * or mdev, and there /dev/null may legitimately not (yet) exist! | ||
302 | * Do not use xopen above, but obtain _ANY_ open descriptor, | ||
303 | * even bogus one as below. */ | ||
304 | fd = xopen("/", O_RDONLY); /* don't believe this can fail */ | ||
305 | } | ||
306 | |||
307 | while ((unsigned)fd < 2) | ||
308 | fd = dup(fd); /* have 0,1,2 open at least to /dev/null */ | ||
309 | |||
310 | if (!(flags & DAEMON_ONLY_SANITIZE)) { | ||
311 | niro | 984 | if (fork_or_rexec(argv)) |
312 | exit(EXIT_SUCCESS); /* parent */ | ||
313 | niro | 816 | /* if daemonizing, make sure we detach from stdio & ctty */ |
314 | setsid(); | ||
315 | dup2(fd, 0); | ||
316 | dup2(fd, 1); | ||
317 | dup2(fd, 2); | ||
318 | } | ||
319 | while (fd > 2) { | ||
320 | close(fd--); | ||
321 | if (!(flags & DAEMON_CLOSE_EXTRA_FDS)) | ||
322 | return; | ||
323 | /* else close everything after fd#2 */ | ||
324 | } | ||
325 | niro | 532 | } |
326 | niro | 816 | |
327 | void FAST_FUNC bb_sanitize_stdio(void) | ||
328 | { | ||
329 | bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL); | ||
330 | } |