Merge branch 'busybox' into merge

1 files changed, 118 insertions, 73 deletions

diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 4b3ed5a3b..eca2fabf5 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -14,78 +14,46 @@
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+#include <sys/prctl.h>
+#ifndef PR_SET_NAME
+#define PR_SET_NAME 15
+#endif
+#ifndef PR_GET_NAME
+#define PR_GET_NAME 16
+#endif
 
 #include "busybox.h" /* uses applet tables */
 #include "NUM_APPLETS.h"
 
-#if !ENABLE_PLATFORM_MINGW32
-/* 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 FAST_FUNC spawn(char **argv)
-{
-        /* Compiler should not optimize stores here */
-        volatile int failed;
-        pid_t pid;
-
-        fflush_all();
-
-        /* 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;
-                /* mount, for example, does not want the message */
-                /*bb_perror_msg("can't execute '%s'", argv[0]);*/
-                _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) {
-                safe_waitpid(pid, NULL, 0); /* prevent zombie */
-                errno = failed;
-                return -1;
-        }
-        return pid;
-}
-#endif
+#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))
 
-/* Die with an error message if we can't spawn a child process. */
-pid_t FAST_FUNC xspawn(char **argv)
+#if defined(__linux__) && (NUM_APPLETS > 1)
+void FAST_FUNC set_task_comm(const char *comm)
 {
-        pid_t pid = spawn(argv);
-        if (pid < 0)
-                bb_simple_perror_msg_and_die(*argv);
-        return pid;
+        /* okay if too long (truncates) */
+        prctl(PR_SET_NAME, (long)comm, 0, 0, 0);
 }
+#endif
 
-#if ENABLE_FEATURE_PREFER_APPLETS \
- || ENABLE_FEATURE_SH_NOFORK
+/*
+ * 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 jump instead back to caller.
+         * 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" */
+         * run_nofork_applet() ensures that by "& 0xff"
+         */
         longjmp(die_jmp, xfunc_error_retval | 0x100);
 }
 
@@ -94,6 +62,7 @@ struct nofork_save_area {
         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)
@@ -102,6 +71,7 @@ static void save_nofork_data(struct nofork_save_area *save)
         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)
@@ -110,6 +80,7 @@ static void restore_nofork_data(struct nofork_save_area *save)
         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;
 }
 
@@ -120,16 +91,15 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 
         save_nofork_data(&old);
 
+        logmode = LOGMODE_STDIO;
         xfunc_error_retval = EXIT_FAILURE;
-
-        /* In case getopt() or getopt32() was already called:
+        /* 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 = 1;
-        while (argv[argc])
-                argc++;
+        argc = string_array_len(argv);
 
         /* If xfunc "dies" in NOFORK applet, die_func longjmp's here instead */
         die_func = jump;
@@ -142,19 +112,97 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
                 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 /* FEATURE_PREFER_APPLETS || FEATURE_SH_NOFORK */
+#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.
+ */
+
+#if !ENABLE_PLATFORM_MINGW32
+/* 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 FAST_FUNC spawn(char **argv)
+{
+        /* Compiler should not optimize stores here */
+        volatile int failed;
+        pid_t pid;
+
+        fflush_all();
+
+        /* 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;
+                /* mount, for example, does not want the message */
+                /*bb_perror_msg("can't execute '%s'", argv[0]);*/
+                _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) {
+                safe_waitpid(pid, NULL, 0); /* prevent zombie */
+                errno = failed;
+                return -1;
+        }
+        return pid;
+}
+#endif
+
+/* Die with an error message if we can't spawn a child process. */
+pid_t FAST_FUNC xspawn(char **argv)
+{
+        pid_t pid = spawn(argv);
+        if (pid < 0)
+                bb_simple_perror_msg_and_die(*argv);
+        return pid;
+}
 
 int FAST_FUNC spawn_and_wait(char **argv)
 {
@@ -174,21 +222,12 @@ int FAST_FUNC spawn_and_wait(char **argv)
                                 return wait4pid(rc);
 
                         /* child */
-                        /* reset some state and run without execing */
-
-                        /* msg_eol = "\n"; - no caller needs this reinited yet */
-                        logmode = LOGMODE_STDIO;
-                        /* die_func = NULL; - needed if the caller is a shell,
-                         * init, or a NOFORK applet. But none of those call us
-                         * as of yet (and that should probably always stay true).
-                         */
-                        /* xfunc_error_retval and applet_name are init by: */
-                        run_applet_no_and_exit(a, argv[0], argv);
+                        run_noexec_applet_and_exit(a, argv[0], argv);
                 }
 #  endif
 # endif
         }
-#endif /* FEATURE_PREFER_APPLETS */
+#endif
         rc = spawn(argv);
         return wait4pid(rc);
 }
@@ -209,6 +248,9 @@ pid_t FAST_FUNC fork_or_rexec(char **argv)
         /* 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 */
                 return pid;
@@ -245,8 +287,11 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
                 fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
 
         if (!(flags & DAEMON_ONLY_SANITIZE)) {
+
+                /* fflush_all(); - add it in fork_or_rexec() if necessary */
+
                 if (fork_or_rexec(argv))
-                        exit(EXIT_SUCCESS); /* parent */
+                        _exit(EXIT_SUCCESS); /* parent */
                 /* if daemonizing, detach from stdio & ctty */
                 setsid();
                 dup2(fd, 0);
@@ -258,7 +303,7 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
                          * Prevent this: stop being a session leader.
                          */
                         if (fork_or_rexec(argv))
-                                exit(EXIT_SUCCESS); /* parent */
+                                _exit(EXIT_SUCCESS); /* parent */
                 }
         }
         while (fd > 2) {