| /* vi: set sw=4 ts=4: */ |
| /* |
| * Rexec program for system have fork() as vfork() with foreground option |
| * |
| * Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru> |
| * Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu> |
| * |
| * daemon() portion taken from uClibc: |
| * |
| * Copyright (c) 1991, 1993 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Modified for uClibc by Erik Andersen <andersee@debian.org> |
| * |
| * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
| */ |
| |
| #include <paths.h> |
| #include "busybox.h" /* for struct bb_applet */ |
| |
| /* This does a fork/exec in one call, using vfork(). Returns PID of new child, |
| * -1 for failure. Runs argv[0], searching path if that has no / in it. */ |
| pid_t spawn(char **argv) |
| { |
| /* Compiler should not optimize stores here */ |
| volatile int failed; |
| pid_t pid; |
| |
| // Ain't it a good place to fflush(NULL)? |
| |
| /* Be nice to nommu machines. */ |
| failed = 0; |
| pid = vfork(); |
| if (pid < 0) /* error */ |
| return pid; |
| if (!pid) { /* child */ |
| /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */ |
| BB_EXECVP(argv[0], argv); |
| |
| /* We are (maybe) sharing a stack with blocked parent, |
| * let parent know we failed and then exit to unblock parent |
| * (but don't run atexit() stuff, which would screw up parent.) |
| */ |
| failed = errno; |
| _exit(111); |
| } |
| /* parent */ |
| /* Unfortunately, this is not reliable: according to standards |
| * vfork() can be equivalent to fork() and we won't see value |
| * of 'failed'. |
| * Interested party can wait on pid and learn exit code. |
| * If 111 - then it (most probably) failed to exec */ |
| if (failed) { |
| errno = failed; |
| return -1; |
| } |
| return pid; |
| } |
| |
| /* Die with an error message if we can't spawn a child process. */ |
| pid_t xspawn(char **argv) |
| { |
| pid_t pid = spawn(argv); |
| if (pid < 0) |
| bb_perror_msg_and_die("%s", *argv); |
| return pid; |
| } |
| |
| // Wait for the specified child PID to exit, returning child's error return. |
| int wait4pid(int pid) |
| { |
| int status; |
| |
| if (pid <= 0) { |
| /*errno = ECHILD; -- wrong. */ |
| /* we expect errno to be already set from failed [v]fork/exec */ |
| return -1; |
| } |
| if (waitpid(pid, &status, 0) == -1) |
| return -1; |
| if (WIFEXITED(status)) |
| return WEXITSTATUS(status); |
| if (WIFSIGNALED(status)) |
| return WTERMSIG(status) + 1000; |
| return 0; |
| } |
| |
| int wait_nohang(int *wstat) |
| { |
| return waitpid(-1, wstat, WNOHANG); |
| } |
| |
| int wait_pid(int *wstat, int pid) |
| { |
| int r; |
| |
| do |
| r = waitpid(pid, wstat, 0); |
| while ((r == -1) && (errno == EINTR)); |
| return r; |
| } |
| |
| int run_nofork_applet(const struct bb_applet *a, char **argv) |
| { |
| int rc, argc; |
| |
| /* Save some shared globals */ |
| const struct bb_applet *old_a = current_applet; |
| int old_x = xfunc_error_retval; |
| uint32_t old_m = option_mask32; |
| int old_sleep = die_sleep; |
| |
| current_applet = a; |
| applet_name = a->name; |
| xfunc_error_retval = EXIT_FAILURE; |
| /*option_mask32 = 0; - not needed */ |
| /* special flag for xfunc_die(). If xfunc will "die" |
| * in NOFORK applet, xfunc_die() sees negative |
| * die_sleep and longjmp here instead. */ |
| die_sleep = -1; |
| |
| argc = 1; |
| while (argv[argc]) |
| argc++; |
| |
| rc = setjmp(die_jmp); |
| if (!rc) { |
| /* Some callers (xargs) |
| * need argv untouched because they free argv[i]! */ |
| char *tmp_argv[argc+1]; |
| memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0])); |
| /* Finally we can call NOFORK applet's main() */ |
| rc = a->main(argc, tmp_argv); |
| } else { /* xfunc died in NOFORK applet */ |
| /* in case they meant to return 0... */ |
| if (rc == -111) |
| rc = 0; |
| } |
| |
| /* Restoring globals */ |
| current_applet = old_a; |
| applet_name = old_a->name; |
| xfunc_error_retval = old_x; |
| option_mask32 = old_m; |
| die_sleep = old_sleep; |
| return rc; |
| } |
| |
| int spawn_and_wait(char **argv) |
| { |
| int rc; |
| #if ENABLE_FEATURE_PREFER_APPLETS |
| const struct bb_applet *a = find_applet_by_name(argv[0]); |
| |
| if (a && (a->nofork |
| #if BB_MMU |
| || a->noexec /* NOEXEC trick needs fork() */ |
| #endif |
| )) { |
| #if BB_MMU |
| if (a->nofork) |
| #endif |
| { |
| return run_nofork_applet(a, argv); |
| } |
| #if BB_MMU |
| /* MMU only */ |
| /* a->noexec is true */ |
| rc = fork(); |
| if (rc) /* parent or error */ |
| return wait4pid(rc); |
| /* child */ |
| xfunc_error_retval = EXIT_FAILURE; |
| current_applet = a; |
| run_current_applet_and_exit(argv); |
| #endif |
| } |
| #endif /* FEATURE_PREFER_APPLETS */ |
| rc = spawn(argv); |
| return wait4pid(rc); |
| } |
| |
| |
| #if !BB_MMU |
| void forkexit_or_rexec(char **argv) |
| { |
| pid_t pid; |
| /* Maybe we are already re-execed and come here again? */ |
| if (re_execed) |
| return; |
| |
| pid = vfork(); |
| if (pid < 0) /* wtf? */ |
| bb_perror_msg_and_die("vfork"); |
| if (pid) /* parent */ |
| exit(0); |
| /* child - re-exec ourself */ |
| /* high-order bit of first char in argv[0] is a hidden |
| * "we have (alrealy) re-execed, don't do it again" flag */ |
| argv[0][0] |= 0x80; |
| execv(CONFIG_BUSYBOX_EXEC_PATH, argv); |
| bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH); |
| } |
| #else |
| /* Dance around (void)...*/ |
| #undef forkexit_or_rexec |
| void forkexit_or_rexec(void) |
| { |
| pid_t pid; |
| pid = fork(); |
| if (pid < 0) /* wtf? */ |
| bb_perror_msg_and_die("fork"); |
| if (pid) /* parent */ |
| exit(0); |
| /* child */ |
| } |
| #define forkexit_or_rexec(argv) forkexit_or_rexec() |
| #endif |
| |
| /* Due to a #define in libbb.h on MMU systems we actually have 1 argument - |
| * char **argv "vanishes" */ |
| void bb_daemonize_or_rexec(int flags, char **argv) |
| { |
| int fd; |
| |
| fd = xopen(bb_dev_null, O_RDWR); |
| |
| if (flags & DAEMON_CHDIR_ROOT) |
| xchdir("/"); |
| |
| if (flags & DAEMON_DEVNULL_STDIO) { |
| close(0); |
| close(1); |
| close(2); |
| } |
| |
| while ((unsigned)fd < 2) |
| fd = dup(fd); /* have 0,1,2 open at least to /dev/null */ |
| |
| if (!(flags & DAEMON_ONLY_SANITIZE)) { |
| forkexit_or_rexec(argv); |
| /* if daemonizing, make sure we detach from stdio */ |
| setsid(); |
| dup2(fd, 0); |
| dup2(fd, 1); |
| dup2(fd, 2); |
| } |
| if (fd > 2) |
| close(fd--); |
| if (flags & DAEMON_CLOSE_EXTRA_FDS) |
| while (fd > 2) |
| close(fd--); /* close everything after fd#2 */ |
| } |
| |
| void bb_sanitize_stdio(void) |
| { |
| bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL); |
| } |