*
* Modified for uClibc by Erik Andersen <andersee@debian.org>
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+#include "busybox.h" /* uses applet tables */
+#include "NUM_APPLETS.h"
-#include <paths.h>
-#include "busybox.h" /* for struct bb_applet */
+#define NOFORK_SUPPORT ((NUM_APPLETS > 1) && (ENABLE_FEATURE_PREFER_APPLETS || ENABLE_FEATURE_SH_NOFORK))
+#define NOEXEC_SUPPORT ((NUM_APPLETS > 1) && (ENABLE_FEATURE_PREFER_APPLETS || ENABLE_FEATURE_SH_STANDALONE))
+
+#if defined(__linux__) && (NUM_APPLETS > 1)
+# include <sys/prctl.h>
+# ifndef PR_SET_NAME
+# define PR_SET_NAME 15
+# endif
+# ifndef PR_GET_NAME
+# define PR_GET_NAME 16
+# endif
+void FAST_FUNC set_task_comm(const char *comm)
+{
+ /* okay if too long (truncates) */
+ prctl(PR_SET_NAME, (long)comm, 0, 0, 0);
+}
+#endif
+
+/*
+ * NOFORK/NOEXEC support
+ */
+#if NOFORK_SUPPORT
+static jmp_buf die_jmp;
+static void jump(void)
+{
+ /* Special case. We arrive here if NOFORK applet
+ * calls xfunc, which then decides to die.
+ * We don't die, but instead jump back to caller.
+ * NOFORK applets still cannot carelessly call xfuncs:
+ * p = xmalloc(10);
+ * q = xmalloc(10); // BUG! if this dies, we leak p!
+ */
+ /* | 0x100 allows to pass zero exitcode (longjmp can't pass 0).
+ * This works because exitcodes are bytes,
+ * run_nofork_applet() ensures that by "& 0xff"
+ */
+ longjmp(die_jmp, xfunc_error_retval | 0x100);
+}
+
+struct nofork_save_area {
+ jmp_buf die_jmp;
+ void (*die_func)(void);
+ const char *applet_name;
+ uint32_t option_mask32;
+ smallint logmode;
+ uint8_t xfunc_error_retval;
+};
+static void save_nofork_data(struct nofork_save_area *save)
+{
+ memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
+ save->die_func = die_func;
+ save->applet_name = applet_name;
+ save->option_mask32 = option_mask32;
+ save->logmode = logmode;
+ save->xfunc_error_retval = xfunc_error_retval;
+}
+static void restore_nofork_data(struct nofork_save_area *save)
+{
+ memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
+ die_func = save->die_func;
+ applet_name = save->applet_name;
+ option_mask32 = save->option_mask32;
+ logmode = save->logmode;
+ xfunc_error_retval = save->xfunc_error_retval;
+}
+
+int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
+{
+ int rc, argc;
+ struct nofork_save_area old;
+
+ save_nofork_data(&old);
+
+ logmode = LOGMODE_STDIO;
+ xfunc_error_retval = EXIT_FAILURE;
+ /* In case getopt() was already called:
+ * reset the libc getopt() function, which keeps internal state.
+ * (getopt32() does it itself, but getopt() doesn't (and can't))
+ */
+ GETOPT_RESET();
+
+ argc = string_array_len(argv);
+
+ /* If xfunc "dies" in NOFORK applet, die_func longjmp's here instead */
+ die_func = jump;
+ 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]));
+ applet_name = tmp_argv[0];
+ /* Finally we can call NOFORK applet's main() */
+ rc = applet_main[applet_no](argc, tmp_argv);
+ /* Important for shells: `which CMD` was failing */
+ fflush_all();
+ } else {
+ /* xfunc died in NOFORK applet */
+ }
+
+ /* Restoring some globals */
+ restore_nofork_data(&old);
+ /* Other globals can be simply reset to defaults */
+ GETOPT_RESET();
+
+ return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
+}
+#endif
+
+#if NOEXEC_SUPPORT
+void FAST_FUNC run_noexec_applet_and_exit(int a, const char *name, char **argv)
+{
+ /* reset some state and run without execing */
+ /* msg_eol = "\n"; - no caller needs this reinited yet */
+ logmode = LOGMODE_STDIO;
+ xfunc_error_retval = EXIT_FAILURE;
+ die_func = NULL;
+ GETOPT_RESET();
+
+//TODO: think pidof, pgrep, pkill!
+//set_task_comm() makes our pidof find NOEXECs (e.g. "yes >/dev/null"),
+//but one from procps-ng-3.3.10 needs more!
+//Rewrite /proc/PID/cmdline? (need to save argv0 and length at init for this to work!)
+ set_task_comm(name);
+ /* applet_name is set by this function: */
+ run_applet_no_and_exit(a, name, argv);
+}
+#endif
+
+/*
+ * Higher-level code, hiding optional NOFORK/NOEXEC trickery.
+ */
/* 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)
+pid_t FAST_FUNC spawn(char **argv)
{
/* Compiler should not optimize stores here */
volatile int failed;
pid_t pid;
-// Ain't it a good place to fflush(NULL)?
+ fflush_all();
/* Be nice to nommu machines. */
failed = 0;
* (but don't run atexit() stuff, which would screw up parent.)
*/
failed = errno;
+ /* mount, for example, does not want the message */
+ /*bb_perror_msg("can't execute '%s'", argv[0]);*/
_exit(111);
}
/* parent */
* Interested party can wait on pid and learn exit code.
* If 111 - then it (most probably) failed to exec */
if (failed) {
+ safe_waitpid(pid, NULL, 0); /* prevent zombie */
errno = failed;
return -1;
}
}
/* Die with an error message if we can't spawn a child process. */
-pid_t xspawn(char **argv)
+pid_t FAST_FUNC xspawn(char **argv)
{
pid_t pid = spawn(argv);
if (pid < 0)
- bb_perror_msg_and_die("%s", *argv);
+ bb_simple_perror_msg_and_die(*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 spawn_and_wait(char **argv)
+int FAST_FUNC spawn_and_wait(char **argv)
{
-#if ENABLE_FEATURE_PREFER_APPLETS
int rc;
- const struct bb_applet *a = find_applet_by_name(argv[0]);
+#if ENABLE_FEATURE_PREFER_APPLETS && (NUM_APPLETS > 1)
+ int a = find_applet_by_name(argv[0]);
- if (a && (a->nofork
-#if BB_MMU
- || a->noexec /* NOEXEC trick needs fork() */
-#endif
- )) {
- int argc = 1;
- char **pp = argv;
- while (*++pp)
- argc++;
-#if BB_MMU
- if (a->nofork)
-#endif
- {
- int old_sleep = die_sleep;
- int old_x = xfunc_error_retval;
- uint32_t old_m = option_mask32;
-
- 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;
-
- rc = setjmp(die_jmp);
- if (!rc) {
- const struct bb_applet *old_a = current_applet;
- current_applet = a;
- applet_name = a->name;
-// what else should we save/restore?
-// TODO: what if applet will mangle argv vector?
-// xargs needs argv untouched because it frees argv[i]!
-// shouldn't we pass a copy?
- rc = a->main(argc, argv);
- current_applet = old_a;
- applet_name = old_a->name;
- } else {
- /* xfunc died in NOFORK applet */
- if (rc == -111)
- rc = 0;
- }
-
- die_sleep = old_sleep;
- xfunc_error_retval = old_x;
- option_mask32 = old_m;
- return rc;
+ if (a >= 0) {
+ if (APPLET_IS_NOFORK(a))
+ return run_nofork_applet(a, argv);
+# if BB_MMU /* NOEXEC needs fork(), thus this is done only on MMU machines: */
+ if (APPLET_IS_NOEXEC(a)) {
+ fflush_all();
+ rc = fork();
+ if (rc) /* parent or error */
+ return wait4pid(rc);
+
+ /* child */
+ run_noexec_applet_and_exit(a, argv[0], 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(argc, argv);
-#endif
+# endif
}
-#endif /* FEATURE_PREFER_APPLETS */
+#endif
rc = spawn(argv);
return wait4pid(rc);
}
-
#if !BB_MMU
-void forkexit_or_rexec(char **argv)
+void FAST_FUNC re_exec(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 */
+ * "we have (already) 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);
+ execv(bb_busybox_exec_path, argv);
+ bb_perror_msg_and_die("can't execute '%s'", bb_busybox_exec_path);
}
-#else
-/* Dance around (void)...*/
-#undef forkexit_or_rexec
-void forkexit_or_rexec(void)
+
+pid_t FAST_FUNC fork_or_rexec(char **argv)
{
pid_t pid;
- pid = fork();
- if (pid < 0) /* wtf? */
- bb_perror_msg_and_die("fork");
+ /* Maybe we are already re-execed and come here again? */
+ if (re_execed)
+ return 0;
+
+ /* fflush_all(); ? - so far all callers had no buffered output to flush */
+
+ pid = xvfork();
if (pid) /* parent */
- exit(0);
- /* child */
+ return pid;
+ /* child - re-exec ourself */
+ re_exec(argv);
}
-#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)
+void FAST_FUNC 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);
+ fd = open(bb_dev_null, O_RDWR);
+ if (fd < 0) {
+ /* NB: we can be called as bb_sanitize_stdio() from init
+ * or mdev, and there /dev/null may legitimately not (yet) exist!
+ * Do not use xopen above, but obtain _ANY_ open descriptor,
+ * even bogus one as below. */
+ fd = xopen("/", O_RDONLY); /* don't believe this can fail */
}
- while ((unsigned)fd < 2)
- fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
+ if (flags & DAEMON_DEVNULL_STDIO) {
+ xdup2(fd, 0);
+ xdup2(fd, 1);
+ xdup2(fd, 2);
+ } else {
+ /* have 0,1,2 open at least to /dev/null */
+ while ((unsigned)fd < 2)
+ fd = dup(fd);
+ }
if (!(flags & DAEMON_ONLY_SANITIZE)) {
- forkexit_or_rexec(argv);
- /* if daemonizing, make sure we detach from stdio */
+
+ /* fflush_all(); - add it in fork_or_rexec() if necessary */
+
+ if (fork_or_rexec(argv))
+ _exit(EXIT_SUCCESS); /* parent */
+ /* if daemonizing, detach from stdio & ctty */
setsid();
dup2(fd, 0);
dup2(fd, 1);
dup2(fd, 2);
+// if (flags & DAEMON_DOUBLE_FORK) {
+// /* On Linux, session leader can acquire ctty
+// * unknowingly, by opening a tty.
+// * Prevent this: stop being a session leader.
+// */
+// if (fork_or_rexec(argv))
+// _exit(EXIT_SUCCESS); /* parent */
+// }
}
- if (fd > 2)
+ while (fd > 2) {
close(fd--);
- if (flags & DAEMON_CLOSE_EXTRA_FDS)
- while (fd > 2)
- close(fd--); /* close everything after fd#2 */
+ if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
+ return;
+ /* else close everything after fd#2 */
+ }
}
-void bb_sanitize_stdio(void)
+void FAST_FUNC bb_sanitize_stdio(void)
{
bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
}
projects / oweals / busybox.git / blobdiff