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196 lines
4.5 KiB
C
196 lines
4.5 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Rexec program for system have fork() as vfork() with foreground option
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*
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* Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru>
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* Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu>
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*
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* daemon() portion taken from uClibc:
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*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Modified for uClibc by Erik Andersen <andersee@debian.org>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <paths.h>
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#include "libbb.h"
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/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
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* -1 for failure. Runs argv[0], searching path if that has no / in it. */
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pid_t spawn(char **argv)
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{
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/* Compiler should not optimize stores here */
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volatile int failed;
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pid_t pid;
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// Be nice to nommu machines.
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failed = 0;
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pid = vfork();
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if (pid < 0) /* error */
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return pid;
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if (!pid) { /* child */
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/* Don't use BB_EXECVP tricks here! */
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execvp(argv[0], argv);
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/* We are (maybe) sharing a stack with blocked parent,
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* let parent know we failed and then exit to unblock parent
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* (but don't run atexit() stuff, which would screw up parent.)
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*/
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failed = errno;
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_exit(111);
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}
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/* parent */
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/* Unfortunately, this is not reliable: according to standards
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* vfork() can be equivalent to fork() and we won't see value
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* of 'failed'.
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* Interested party can wait on pid and learn exit code.
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* If 111 - then it (most probably) failed to exec */
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if (failed) {
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errno = failed;
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return -1;
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}
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return pid;
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}
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/* Die with an error message if we can't spawn a child process. */
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pid_t xspawn(char **argv)
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{
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pid_t pid = spawn(argv);
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if (pid < 0) bb_perror_msg_and_die("%s", *argv);
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return pid;
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}
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#if 0 //ndef BB_NOMMU
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// Die with an error message if we can't daemonize.
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void xdaemon(int nochdir, int noclose)
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{
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if (daemon(nochdir, noclose))
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bb_perror_msg_and_die("daemon");
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}
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#endif
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#if 0 // def BB_NOMMU
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void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
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{
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int fd;
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/* Maybe we are already re-execed and come here again? */
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if (re_execed)
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return;
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setsid();
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if (!nochdir)
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xchdir("/");
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if (!noclose) {
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/* if "/dev/null" doesn't exist, bail out! */
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fd = xopen(bb_dev_null, O_RDWR);
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dup2(fd, STDIN_FILENO);
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dup2(fd, STDOUT_FILENO);
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dup2(fd, STDERR_FILENO);
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while (fd > 2)
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close(fd--);
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}
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switch (vfork()) {
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case 0: /* child */
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/* Make certain we are not a session leader, or else we
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* might reacquire a controlling terminal */
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if (vfork())
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_exit(0);
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/* High-order bit of first char in argv[0] is a hidden
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* "we have (alrealy) re-execed, don't do it again" flag */
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argv[0][0] |= 0x80;
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execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
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bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
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case -1: /* error */
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bb_perror_msg_and_die("vfork");
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default: /* parent */
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exit(0);
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}
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}
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#endif /* BB_NOMMU */
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#ifdef BB_NOMMU
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void forkexit_or_rexec(char **argv)
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{
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pid_t pid;
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/* Maybe we are already re-execed and come here again? */
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if (re_execed)
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return;
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pid = vfork();
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if (pid < 0) /* wtf? */
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bb_perror_msg_and_die("vfork");
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if (pid) /* parent */
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exit(0);
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/* child - re-exec ourself */
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/* high-order bit of first char in argv[0] is a hidden
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* "we have (alrealy) re-execed, don't do it again" flag */
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argv[0][0] |= 0x80;
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execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
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bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
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}
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#else
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/* Dance around (void)...*/
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#undef forkexit_or_rexec
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void forkexit_or_rexec(void)
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{
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pid_t pid;
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pid = fork();
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if (pid < 0) /* wtf? */
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bb_perror_msg_and_die("fork");
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if (pid) /* parent */
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exit(0);
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/* child */
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}
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#define forkexit_or_rexec(argv) forkexit_or_rexec()
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#endif
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/* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
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* char **argv "vanishes" */
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void bb_daemonize_or_rexec(int flags, char **argv)
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{
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int fd;
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fd = xopen(bb_dev_null, O_RDWR);
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if (flags & DAEMON_CHDIR_ROOT)
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xchdir("/");
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if (flags & DAEMON_DEVNULL_STDIO) {
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close(0);
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close(1);
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close(2);
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}
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while ((unsigned)fd < 2)
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fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
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if (!(flags & DAEMON_ONLY_SANITIZE)) {
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forkexit_or_rexec(argv);
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/* if daemonizing, make sure we detach from stdio */
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setsid();
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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}
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if (fd > 2)
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close(fd--);
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if (flags & DAEMON_CLOSE_EXTRA_FDS)
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while (fd > 2)
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close(fd--); /* close everything after fd#2 */
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}
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void bb_sanitize_stdio(void)
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{
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bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
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}
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