X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=libbb%2Fvfork_daemon_rexec.c;h=c0bea0ed21b3eb7bcc806432627e3c25fbb28b86;hb=a94eeb0b4222de7f05594c93ffdd84faea5b8e2d;hp=487ecb0e4ffeb4b03e45bb01efe644b5765b04e5;hpb=39194f030918b87eeb3e11e94cfa05f575fb47b4;p=oweals%2Fbusybox.git

diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 487ecb0e4..c0bea0ed2 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -14,76 +14,45 @@
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
-
 #include "busybox.h" /* uses applet tables */
 #include "NUM_APPLETS.h"
 
-/* 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;
-}
+#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)
+# 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)
 {
-	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);
 }
 
@@ -123,14 +92,13 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 
 	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;
@@ -143,6 +111,8 @@ 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 */
 	}
@@ -154,7 +124,82 @@ int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
 
 	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.
+ */
+
+/* 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;
+}
+
+/* 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)
 {
@@ -173,20 +218,11 @@ 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 /* FEATURE_PREFER_APPLETS */
+#endif
 	rc = spawn(argv);
 	return wait4pid(rc);
 }
@@ -207,6 +243,9 @@ 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;
@@ -243,8 +282,11 @@ 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);
@@ -256,7 +298,7 @@ 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) {