Contents of /trunk/mkinitrd-magellan/busybox/libbb/vfork_daemon_rexec.c
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Sun May 30 11:32:42 2010 UTC (14 years, 4 months ago) by niro
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Sun May 30 11:32:42 2010 UTC (14 years, 4 months 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 | /* 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 | #include "busybox.h" /* uses applet tables */ |
19 | |
20 | /* 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 | { |
24 | /* Compiler should not optimize stores here */ |
25 | volatile int failed; |
26 | pid_t pid; |
27 | |
28 | fflush_all(); |
29 | |
30 | /* 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 | |
39 | /* 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 | /* mount, for example, does not want the message */ |
45 | /*bb_perror_msg("can't execute '%s'", argv[0]);*/ |
46 | _exit(111); |
47 | } |
48 | /* 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 | |
61 | /* 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 | } |
95 | 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 | pid_t FAST_FUNC fork_or_rexec(char **argv) |
256 | { |
257 | pid_t pid; |
258 | /* Maybe we are already re-execed and come here again? */ |
259 | if (re_execed) |
260 | return 0; |
261 | pid = vfork(); |
262 | if (pid < 0) /* wtf? */ |
263 | bb_perror_msg_and_die("vfork"); |
264 | if (pid) /* parent */ |
265 | return pid; |
266 | /* child - re-exec ourself */ |
267 | re_exec(argv); |
268 | } |
269 | #else |
270 | /* Dance around (void)...*/ |
271 | #undef fork_or_rexec |
272 | pid_t FAST_FUNC fork_or_rexec(void) |
273 | { |
274 | pid_t pid; |
275 | pid = fork(); |
276 | if (pid < 0) /* wtf? */ |
277 | bb_perror_msg_and_die("fork"); |
278 | return pid; |
279 | } |
280 | #define fork_or_rexec(argv) fork_or_rexec() |
281 | #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 | } |
297 | |
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 | if (fork_or_rexec(argv)) |
312 | exit(EXIT_SUCCESS); /* parent */ |
313 | /* 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 | } |
326 | |
327 | void FAST_FUNC bb_sanitize_stdio(void) |
328 | { |
329 | bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL); |
330 | } |