Changeset 1765 in MondoRescue for branches/2.2.5/mindi-busybox/libbb/vfork_daemon_rexec.c

Timestamp:

Nov 4, 2007, 3:16:40 AM (16 years ago)

Author:

Bruno Cornec

Message:

Update to busybox 1.7.2

File:

• branches/2.2.5/mindi-busybox/libbb/vfork_daemon_rexec.c (modified) (1 diff)

branches/2.2.5/mindi-busybox/libbb/vfork_daemon_rexec.c

@@ -16 +16 @@
  */
 
-#include <unistd.h>
-#include <stdio.h>
-#include <fcntl.h>
 #include <paths.h>
-#include "libbb.h"
-
-
-#ifdef BB_NOMMU
-void vfork_daemon_rexec(int nochdir, int noclose,
-        int argc, char **argv, char *foreground_opt)
+#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;
+}
+
+#if ENABLE_FEATURE_PREFER_APPLETS
+void save_nofork_data(struct nofork_save_area *save)
+{
+    memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
+    save->current_applet = current_applet;
+    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));
+    current_applet = save->current_applet;
+    xfunc_error_retval = save->xfunc_error_retval;
+    option_mask32 = save->option_mask32;
+    die_sleep = save->die_sleep;
+
+    applet_name = current_applet->name;
+}
+
+int run_nofork_applet_prime(struct nofork_save_area *old, const struct bb_applet *a, char **argv)
+{
+    int rc, argc;
+
+    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 == -2222)
+            rc = 0;
+    }
+
+    /* Restoring globals */
+    restore_nofork_data(old);
+    return rc;
+}
+
+int run_nofork_applet(const struct bb_applet *a, char **argv)
+{
+    struct nofork_save_area old;
+
+    /* Saving globals */
+    save_nofork_data(&old);
+    return run_nofork_applet_prime(&old, a, argv);
+}
+#endif /* FEATURE_PREFER_APPLETS */
+
+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 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");
+    if (pid) /* parent */
+        exit(0);
+    /* 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(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;
-    char **vfork_args;
-    int a = 0;
-
-    setsid();
-
-    if (!nochdir)
-        chdir("/");
-
-    if (!noclose && (fd = open(bb_dev_null, O_RDWR, 0)) != -1) {
-        dup2(fd, STDIN_FILENO);
-        dup2(fd, STDOUT_FILENO);
-        dup2(fd, STDERR_FILENO);
-        if (fd > 2)
-            close(fd);
-    }
-
-    vfork_args = xcalloc(sizeof(char *), argc + 3);
-    vfork_args[a++] = "/bin/busybox";
-    while(*argv) {
-        vfork_args[a++] = *argv;
-        argv++;
-    }
-    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 */
-        bb_perror_msg_and_die("vfork");
-    default: /* parent */
-        exit(0);
-    }
-}
-#endif /* BB_NOMMU */
+
+    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);
+}