Contents of /trunk/mkinitrd-magellan/busybox/libbb/vfork_daemon_rexec.c
Parent Directory | Revision Log
Revision 816 -
(show annotations)
(download)
Fri Apr 24 18:33:46 2009 UTC (15 years, 5 months ago) by niro
File MIME type: text/plain
File size: 8716 byte(s)
Fri Apr 24 18:33:46 2009 UTC (15 years, 5 months ago) by niro
File MIME type: text/plain
File size: 8716 byte(s)
-updated to busybox-1.13.4
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 <paths.h> |
19 | #include "busybox.h" /* uses applet tables */ |
20 | |
21 | /* 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. */ |
23 | pid_t FAST_FUNC spawn(char **argv) |
24 | { |
25 | /* Compiler should not optimize stores here */ |
26 | volatile int failed; |
27 | pid_t pid; |
28 | |
29 | // Ain't it a good place to fflush(NULL)? |
30 | |
31 | /* Be nice to nommu machines. */ |
32 | failed = 0; |
33 | pid = vfork(); |
34 | if (pid < 0) /* error */ |
35 | return pid; |
36 | if (!pid) { /* child */ |
37 | /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */ |
38 | BB_EXECVP(argv[0], argv); |
39 | |
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; |
45 | _exit(111); |
46 | } |
47 | /* parent */ |
48 | /* 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 */ |
53 | 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. */ |
61 | pid_t FAST_FUNC xspawn(char **argv) |
62 | { |
63 | pid_t pid = spawn(argv); |
64 | if (pid < 0) |
65 | bb_simple_perror_msg_and_die(*argv); |
66 | return pid; |
67 | } |
68 | |
69 | pid_t FAST_FUNC safe_waitpid(pid_t pid, int *wstat, int options) |
70 | { |
71 | pid_t r; |
72 | |
73 | do |
74 | r = waitpid(pid, wstat, options); |
75 | while ((r == -1) && (errno == EINTR)); |
76 | return r; |
77 | } |
78 | |
79 | pid_t FAST_FUNC wait_any_nohang(int *wstat) |
80 | { |
81 | return safe_waitpid(-1, wstat, WNOHANG); |
82 | } |
83 | |
84 | // Wait for the specified child PID to exit, returning child's error return. |
85 | int FAST_FUNC wait4pid(pid_t pid) |
86 | { |
87 | int status; |
88 | |
89 | if (pid <= 0) { |
90 | /*errno = ECHILD; -- wrong. */ |
91 | /* we expect errno to be already set from failed [v]fork/exec */ |
92 | return -1; |
93 | } |
94 | if (safe_waitpid(pid, &status, 0) == -1) |
95 | return -1; |
96 | if (WIFEXITED(status)) |
97 | return WEXITSTATUS(status); |
98 | if (WIFSIGNALED(status)) |
99 | return WTERMSIG(status) + 1000; |
100 | return 0; |
101 | } |
102 | |
103 | #if ENABLE_FEATURE_PREFER_APPLETS |
104 | void FAST_FUNC save_nofork_data(struct nofork_save_area *save) |
105 | { |
106 | memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp)); |
107 | save->applet_name = applet_name; |
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 | |
114 | void FAST_FUNC restore_nofork_data(struct nofork_save_area *save) |
115 | { |
116 | memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp)); |
117 | applet_name = save->applet_name; |
118 | xfunc_error_retval = save->xfunc_error_retval; |
119 | option_mask32 = save->option_mask32; |
120 | die_sleep = save->die_sleep; |
121 | } |
122 | |
123 | int FAST_FUNC run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **argv) |
124 | { |
125 | int rc, argc; |
126 | |
127 | applet_name = APPLET_NAME(applet_no); |
128 | |
129 | xfunc_error_retval = EXIT_FAILURE; |
130 | |
131 | /* Special flag for xfunc_die(). If xfunc will "die" |
132 | * in NOFORK applet, xfunc_die() sees negative |
133 | * die_sleep and longjmp here instead. */ |
134 | die_sleep = -1; |
135 | |
136 | /* In case getopt() or getopt32() was already called: |
137 | * reset the libc getopt() function, which keeps internal state. |
138 | * |
139 | * BSD-derived getopt() functions require that optind be set to 1 in |
140 | * order to reset getopt() state. This used to be generally accepted |
141 | * way of resetting getopt(). However, glibc's getopt() |
142 | * has additional getopt() state beyond optind, and requires that |
143 | * optind be set to zero to reset its state. So the unfortunate state of |
144 | * affairs is that BSD-derived versions of getopt() misbehave if |
145 | * optind is set to 0 in order to reset getopt(), and glibc's getopt() |
146 | * will core dump if optind is set 1 in order to reset getopt(). |
147 | * |
148 | * More modern versions of BSD require that optreset be set to 1 in |
149 | * order to reset getopt(). Sigh. Standards, anyone? |
150 | */ |
151 | #ifdef __GLIBC__ |
152 | optind = 0; |
153 | #else /* BSD style */ |
154 | optind = 1; |
155 | /* optreset = 1; */ |
156 | #endif |
157 | /* optarg = NULL; opterr = 1; optopt = 63; - do we need this too? */ |
158 | /* (values above are what they initialized to in glibc and uclibc) */ |
159 | /* option_mask32 = 0; - not needed, no applet depends on it being 0 */ |
160 | |
161 | argc = 1; |
162 | while (argv[argc]) |
163 | argc++; |
164 | |
165 | rc = setjmp(die_jmp); |
166 | if (!rc) { |
167 | /* Some callers (xargs) |
168 | * need argv untouched because they free argv[i]! */ |
169 | char *tmp_argv[argc+1]; |
170 | memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0])); |
171 | /* Finally we can call NOFORK applet's main() */ |
172 | rc = applet_main[applet_no](argc, tmp_argv); |
173 | |
174 | /* The whole reason behind nofork_save_area is that <applet>_main |
175 | * may exit non-locally! For example, in hush Ctrl-Z tries |
176 | * (modulo bugs) to dynamically create a child (backgrounded task) |
177 | * if it detects that Ctrl-Z was pressed when a NOFORK was running. |
178 | * Testcase: interactive "rm -i". |
179 | * Don't fool yourself into thinking "and <applet>_main() returns |
180 | * quickly here" and removing "useless" nofork_save_area code. */ |
181 | |
182 | } else { /* xfunc died in NOFORK applet */ |
183 | /* in case they meant to return 0... */ |
184 | if (rc == -2222) |
185 | rc = 0; |
186 | } |
187 | |
188 | /* Restoring some globals */ |
189 | restore_nofork_data(old); |
190 | |
191 | /* Other globals can be simply reset to defaults */ |
192 | #ifdef __GLIBC__ |
193 | optind = 0; |
194 | #else /* BSD style */ |
195 | optind = 1; |
196 | #endif |
197 | |
198 | return rc & 0xff; /* don't confuse people with "exitcodes" >255 */ |
199 | } |
200 | |
201 | int FAST_FUNC run_nofork_applet(int applet_no, char **argv) |
202 | { |
203 | struct nofork_save_area old; |
204 | |
205 | /* Saving globals */ |
206 | save_nofork_data(&old); |
207 | return run_nofork_applet_prime(&old, applet_no, argv); |
208 | } |
209 | #endif /* FEATURE_PREFER_APPLETS */ |
210 | |
211 | int FAST_FUNC spawn_and_wait(char **argv) |
212 | { |
213 | int rc; |
214 | #if ENABLE_FEATURE_PREFER_APPLETS |
215 | int a = find_applet_by_name(argv[0]); |
216 | |
217 | if (a >= 0 && (APPLET_IS_NOFORK(a) |
218 | #if BB_MMU |
219 | || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */ |
220 | #endif |
221 | )) { |
222 | #if BB_MMU |
223 | if (APPLET_IS_NOFORK(a)) |
224 | #endif |
225 | { |
226 | return run_nofork_applet(a, argv); |
227 | } |
228 | #if BB_MMU |
229 | /* MMU only */ |
230 | /* a->noexec is true */ |
231 | rc = fork(); |
232 | if (rc) /* parent or error */ |
233 | return wait4pid(rc); |
234 | /* child */ |
235 | xfunc_error_retval = EXIT_FAILURE; |
236 | run_applet_no_and_exit(a, argv); |
237 | #endif |
238 | } |
239 | #endif /* FEATURE_PREFER_APPLETS */ |
240 | rc = spawn(argv); |
241 | return wait4pid(rc); |
242 | } |
243 | |
244 | #if !BB_MMU |
245 | void FAST_FUNC re_exec(char **argv) |
246 | { |
247 | /* high-order bit of first char in argv[0] is a hidden |
248 | * "we have (already) re-execed, don't do it again" flag */ |
249 | argv[0][0] |= 0x80; |
250 | execv(bb_busybox_exec_path, argv); |
251 | bb_perror_msg_and_die("exec %s", bb_busybox_exec_path); |
252 | } |
253 | |
254 | void FAST_FUNC forkexit_or_rexec(char **argv) |
255 | { |
256 | pid_t pid; |
257 | /* Maybe we are already re-execed and come here again? */ |
258 | if (re_execed) |
259 | return; |
260 | |
261 | pid = vfork(); |
262 | if (pid < 0) /* wtf? */ |
263 | bb_perror_msg_and_die("vfork"); |
264 | if (pid) /* parent */ |
265 | exit(EXIT_SUCCESS); |
266 | /* child - re-exec ourself */ |
267 | re_exec(argv); |
268 | } |
269 | #else |
270 | /* Dance around (void)...*/ |
271 | #undef forkexit_or_rexec |
272 | void FAST_FUNC forkexit_or_rexec(void) |
273 | { |
274 | pid_t pid; |
275 | pid = fork(); |
276 | if (pid < 0) /* wtf? */ |
277 | bb_perror_msg_and_die("fork"); |
278 | if (pid) /* parent */ |
279 | exit(EXIT_SUCCESS); |
280 | /* child */ |
281 | } |
282 | #define forkexit_or_rexec(argv) forkexit_or_rexec() |
283 | #endif |
284 | |
285 | /* Due to a #define in libbb.h on MMU systems we actually have 1 argument - |
286 | * char **argv "vanishes" */ |
287 | void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv) |
288 | { |
289 | int fd; |
290 | |
291 | if (flags & DAEMON_CHDIR_ROOT) |
292 | xchdir("/"); |
293 | |
294 | if (flags & DAEMON_DEVNULL_STDIO) { |
295 | close(0); |
296 | close(1); |
297 | close(2); |
298 | } |
299 | |
300 | fd = open(bb_dev_null, O_RDWR); |
301 | if (fd < 0) { |
302 | /* NB: we can be called as bb_sanitize_stdio() from init |
303 | * or mdev, and there /dev/null may legitimately not (yet) exist! |
304 | * Do not use xopen above, but obtain _ANY_ open descriptor, |
305 | * even bogus one as below. */ |
306 | fd = xopen("/", O_RDONLY); /* don't believe this can fail */ |
307 | } |
308 | |
309 | while ((unsigned)fd < 2) |
310 | fd = dup(fd); /* have 0,1,2 open at least to /dev/null */ |
311 | |
312 | if (!(flags & DAEMON_ONLY_SANITIZE)) { |
313 | forkexit_or_rexec(argv); |
314 | /* if daemonizing, make sure we detach from stdio & ctty */ |
315 | setsid(); |
316 | dup2(fd, 0); |
317 | dup2(fd, 1); |
318 | dup2(fd, 2); |
319 | } |
320 | while (fd > 2) { |
321 | close(fd--); |
322 | if (!(flags & DAEMON_CLOSE_EXTRA_FDS)) |
323 | return; |
324 | /* else close everything after fd#2 */ |
325 | } |
326 | } |
327 | |
328 | void FAST_FUNC bb_sanitize_stdio(void) |
329 | { |
330 | bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL); |
331 | } |