+/* vi: set sw=4 ts=4: */
/*
* Rexec program for system have fork() as vfork() with foreground option
*
*
* Modified for uClibc by Erik Andersen <andersee@debian.org>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-#include <unistd.h>
-#include <stdio.h>
-#include <fcntl.h>
#include <paths.h>
-#include "libbb.h"
+#include "busybox.h" /* uses applet tables */
+
+/* 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;
+}
-#if defined(__uClinux__)
-void vfork_daemon_rexec(int nochdir, int noclose,
- int argc, char **argv, char *foreground_opt)
+/* Die with an error message if we can't spawn a child process. */
+pid_t xspawn(char **argv)
{
- int fd;
- char **vfork_args;
- int a = 0;
+ pid_t pid = spawn(argv);
+ if (pid < 0)
+ bb_simple_perror_msg_and_die(*argv);
+ return pid;
+}
+
+int safe_waitpid(int pid, int *wstat, int options)
+{
+ int r;
+
+ do
+ r = waitpid(pid, wstat, options);
+ while ((r == -1) && (errno == EINTR));
+ return r;
+}
+
+int wait_any_nohang(int *wstat)
+{
+ return safe_waitpid(-1, wstat, WNOHANG);
+}
+
+// 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 (safe_waitpid(pid, &status, 0) == -1)
+ return -1;
+ if (WIFEXITED(status))
+ return WEXITSTATUS(status);
+ if (WIFSIGNALED(status))
+ return WTERMSIG(status) + 1000;
+ return 0;
+}
+
+#if ENABLE_FEATURE_PREFER_APPLETS
+void save_nofork_data(struct nofork_save_area *save)
+{
+ memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
+ save->applet_name = applet_name;
+ save->xfunc_error_retval = xfunc_error_retval;
+ save->option_mask32 = option_mask32;
+ save->die_sleep = die_sleep;
+ save->saved = 1;
+}
+
+void restore_nofork_data(struct nofork_save_area *save)
+{
+ memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
+ applet_name = save->applet_name;
+ xfunc_error_retval = save->xfunc_error_retval;
+ option_mask32 = save->option_mask32;
+ die_sleep = save->die_sleep;
+}
+
+int run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **argv)
+{
+ int rc, argc;
+
+ applet_name = APPLET_NAME(applet_no);
+ xfunc_error_retval = EXIT_FAILURE;
+
+ /* 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;
- setsid();
+ /* option_mask32 = 0; - not needed */
- if (!nochdir)
- chdir("/");
+ argc = 1;
+ while (argv[argc])
+ argc++;
- if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
- dup2(fd, STDIN_FILENO);
- dup2(fd, STDOUT_FILENO);
- dup2(fd, STDERR_FILENO);
- if (fd > 2)
- close(fd);
+ 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 = applet_main[applet_no](argc, tmp_argv);
+
+ /* The whole reason behind nofork_save_area is that <applet>_main
+ * may exit non-locally! For example, in hush Ctrl-Z tries
+ * (modulo bugs) to dynamically create a child (backgrounded task)
+ * if it detects that Ctrl-Z was pressed when a NOFORK was running.
+ * Testcase: interactive "rm -i".
+ * Don't fool yourself into thinking "and <applet>_main() returns
+ * quickly here" and removing "useless" nofork_save_area code. */
+
+ } else { /* xfunc died in NOFORK applet */
+ /* in case they meant to return 0... */
+ if (rc == -2222)
+ rc = 0;
}
- vfork_args = xcalloc(sizeof(char *), argc + 3);
- vfork_args[a++] = "/bin/busybox";
- while(*argv) {
- vfork_args[a++] = *argv;
- argv++;
+ /* Restoring globals */
+ restore_nofork_data(old);
+ return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
+}
+
+int run_nofork_applet(int applet_no, char **argv)
+{
+ struct nofork_save_area old;
+
+ /* Saving globals */
+ save_nofork_data(&old);
+ return run_nofork_applet_prime(&old, applet_no, argv);
+}
+#endif /* FEATURE_PREFER_APPLETS */
+
+int spawn_and_wait(char **argv)
+{
+ int rc;
+#if ENABLE_FEATURE_PREFER_APPLETS
+ int a = find_applet_by_name(argv[0]);
+
+ if (a >= 0 && (APPLET_IS_NOFORK(a)
+#if BB_MMU
+ || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
+#endif
+ )) {
+#if BB_MMU
+ if (APPLET_IS_NOFORK(a))
+#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;
+ run_applet_no_and_exit(a, argv);
+#endif
}
- vfork_args[a] = foreground_opt;
- switch (vfork()) {
- case 0: /* child */
- /* Make certain we are not a session leader, or else we
- * might reacquire a controlling terminal */
- if (vfork())
- _exit(0);
- execv(vfork_args[0], vfork_args);
- bb_perror_msg_and_die("execv %s", vfork_args[0]);
- case -1: /* error */
+#endif /* FEATURE_PREFER_APPLETS */
+ rc = spawn(argv);
+ return wait4pid(rc);
+}
+
+#if !BB_MMU
+void re_exec(char **argv)
+{
+ /* high-order bit of first char in argv[0] is a hidden
+ * "we have (already) re-execed, don't do it again" flag */
+ argv[0][0] |= 0x80;
+ execv(bb_busybox_exec_path, argv);
+ bb_perror_msg_and_die("exec %s", bb_busybox_exec_path);
+}
+
+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");
- default: /* parent */
- exit(0);
+ if (pid) /* parent */
+ exit(EXIT_SUCCESS);
+ /* child - re-exec ourself */
+ re_exec(argv);
+}
+#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(EXIT_SUCCESS);
+ /* 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;
+
+ if (flags & DAEMON_CHDIR_ROOT)
+ xchdir("/");
+
+ if (flags & DAEMON_DEVNULL_STDIO) {
+ close(0);
+ close(1);
+ close(2);
}
+
+ fd = xopen(bb_dev_null, O_RDWR);
+
+ 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 & ctty */
+ setsid();
+ dup2(fd, 0);
+ dup2(fd, 1);
+ dup2(fd, 2);
+ }
+ while (fd > 2) {
+ close(fd--);
+ if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
+ return;
+ /* else close everything after fd#2 */
+ }
+}
+
+void bb_sanitize_stdio(void)
+{
+ bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
}
-#endif /* uClinux */
projects / oweals / busybox.git / blobdiff