*: introduce and use xfork() and xvfork()

function                                             old     new   delta
launch_helper                                        170     169      -1
setup_heredoc                                        312     302     -10
handle_dir_common                                    367     354     -13
expand_vars_to_list                                 2456    2443     -13
open_transformer                                      89      74     -15
data_extract_to_command                              439     423     -16
do_ipaddr                                           1406    1389     -17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/7 up/down: 0/-85)             Total: -85 bytes

Signed-off-by: Pascal Bellard <pascal.bellard@ads-lu.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

archival/libunarchive/data_extract_to_command.c

@@ -82,11 +82,8 @@ void FAST_FUNC data_extract_to_command(archive_handle_t *archive_handle)
 		memset(tar_env, 0, sizeof(tar_env));
 
 		xpipe(p);
-		pid = BB_MMU ? fork() : vfork();
-		switch (pid) {
-		case -1:
-			bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
-		case 0:
+		pid = BB_MMU ? xfork() : xvfork();
+		if (pid == 0) {
 			/* Child */
 			/* str2env(tar_env, TAR_FILETYPE, "f"); - parent should do it once */
 			oct2env(tar_env, TAR_MODE, file_header->mode);

archival/libunarchive/open_transformer.c

@@ -19,19 +19,9 @@ void FAST_FUNC open_transformer(int fd,
 	int pid;
 
 	xpiped_pair(fd_pipe);
-
-#if BB_MMU
-	pid = fork();
-	if (pid == -1)
-		bb_perror_msg_and_die("vfork" + 1);
-#else
-	pid = vfork();
-	if (pid == -1)
-		bb_perror_msg_and_die("vfork");
-#endif
-
+	pid = BB_MMU ? xfork() : xvfork();
 	if (pid == 0) {
-		/* child process */
+		/* Child */
 		close(fd_pipe.rd); /* we don't want to read from the parent */
 		// FIXME: error check?
 #if BB_MMU

archival/tar.c

@@ -514,9 +514,7 @@ static void NOINLINE vfork_compressor(int tar_fd, int gzip)
 	(void) &zip_exec;
 # endif
 
-	gzipPid = vfork();
-	if (gzipPid < 0)
-		bb_perror_msg_and_die("vfork");
+	gzipPid = xvfork();
 
 	if (gzipPid == 0) {
 		/* child */

debianutils/start_stop_daemon.c

@@ -409,9 +409,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
 		/* DAEMON_DEVNULL_STDIO is superfluous -
 		 * it's always done by bb_daemonize() */
 #else
-		pid_t pid = vfork();
-		if (pid < 0) /* error */
-			bb_perror_msg_and_die("vfork");
+		pid_t pid = xvfork();
 		if (pid != 0) {
 			/* parent */
 			/* why _exit? the child may have changed the stack,

e2fsprogs/old_e2fsprogs/fsck.c

@@ -612,7 +612,7 @@ static int execute(const char *type, const char *device, const char *mntpt,
 	if (noexecute)
 		pid = -1;
 	else if ((pid = fork()) < 0) {
-		perror("fork");
+		perror("vfork"+1);
 		return errno;
 	} else if (pid == 0) {
 		if (!interactive)

include/libbb.h

@@ -841,6 +841,19 @@ int bb_execvp(const char *file, char *const argv[]) FAST_FUNC;
 #endif
 int BB_EXECVP_or_die(char **argv) NORETURN FAST_FUNC;
 
+/* xvfork() can't be a _function_, return after vfork mangles stack
+ * in the parent. It must be a macro. */
+#define xvfork() \
+({ \
+	pid_t bb__xvfork_pid = vfork(); \
+	if (bb__xvfork_pid < 0) \
+		bb_perror_msg_and_die("vfork"); \
+	bb__xvfork_pid; \
+})
+#if BB_MMU
+pid_t xfork(void) FAST_FUNC;
+#endif
+
 /* NOMMU friendy fork+exec: */
 pid_t spawn(char **argv) FAST_FUNC;
 pid_t xspawn(char **argv) FAST_FUNC;
@@ -886,7 +899,7 @@ int run_nofork_applet_prime(struct nofork_save_area *old, int applet_no, char **
  * Both of the above will redirect fd 0,1,2 to /dev/null and drop ctty
  * (will do setsid()).
  *
- * fork_or_rexec(argv) = bare-bones "fork" on MMU,
+ * fork_or_rexec(argv) = bare-bones fork on MMU,
  *      "vfork + re-exec ourself" on NOMMU. No fd redirection, no setsid().
  *      On MMU ignores argv.
  *
@@ -902,19 +915,19 @@ enum {
 	DAEMON_ONLY_SANITIZE = 8, /* internal use */
 };
 #if BB_MMU
-  pid_t fork_or_rexec(void) FAST_FUNC;
   enum { re_execed = 0 };
-# define fork_or_rexec(argv)                fork_or_rexec()
+# define fork_or_rexec(argv)                xfork()
 # define bb_daemonize_or_rexec(flags, argv) bb_daemonize_or_rexec(flags)
 # define bb_daemonize(flags)                bb_daemonize_or_rexec(flags, bogus)
 #else
+  extern bool re_execed;
   void re_exec(char **argv) NORETURN FAST_FUNC;
   pid_t fork_or_rexec(char **argv) FAST_FUNC;
-  extern bool re_execed;
   int  BUG_fork_is_unavailable_on_nommu(void) FAST_FUNC;
   int  BUG_daemon_is_unavailable_on_nommu(void) FAST_FUNC;
   void BUG_bb_daemonize_is_unavailable_on_nommu(void) FAST_FUNC;
 # define fork()          BUG_fork_is_unavailable_on_nommu()
+# define xfork()         BUG_fork_is_unavailable_on_nommu()
 # define daemon(a,b)     BUG_daemon_is_unavailable_on_nommu()
 # define bb_daemonize(a) BUG_bb_daemonize_is_unavailable_on_nommu()
 #endif

init/bootchartd.c

@@ -427,9 +427,7 @@ int bootchartd_main(int argc UNUSED_PARAM, char **argv)
 	}
 
 	if (cmd == CMD_START && argv[2]) { /* "start PROG ARGS" */
-		pid_t pid = vfork();
-		if (pid < 0)
-			bb_perror_msg_and_die("vfork");
+		pid_t pid = xvfork();
 		if (pid == 0) { /* child */
 			argv += 2;
 			execvp(argv[0], argv);

libbb/vfork_daemon_rexec.c

@@ -224,26 +224,12 @@ pid_t FAST_FUNC fork_or_rexec(char **argv)
 	/* Maybe we are already re-execed and come here again? */
 	if (re_execed)
 		return 0;
-	pid = vfork();
-	if (pid < 0) /* wtf? */
-		bb_perror_msg_and_die("vfork");
+	pid = xvfork();
 	if (pid) /* parent */
 		return pid;
 	/* child - re-exec ourself */
 	re_exec(argv);
 }
-#else
-/* Dance around (void)...*/
-#undef fork_or_rexec
-pid_t FAST_FUNC fork_or_rexec(void)
-{
-	pid_t pid;
-	pid = fork();
-	if (pid < 0) /* wtf? */
-		bb_perror_msg_and_die("fork");
-	return pid;
-}
-#define fork_or_rexec(argv) fork_or_rexec()
 #endif
 
 /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -

libbb/xfuncs_printf.c

@@ -589,3 +589,14 @@ void FAST_FUNC generate_uuid(uint8_t *buf)
 	/* variant = 10x */
 	buf[4 + 2 + 2] = (buf[4 + 2 + 2] & 0x3f) | 0x80;
 }
+
+#if BB_MMU
+pid_t FAST_FUNC xfork(void)
+{
+	pid_t pid;
+	pid = fork();
+	if (pid < 0) /* wtf? */
+		bb_perror_msg_and_die("vfork"+1);
+	return pid;
+}
+#endif

mailutils/mail.c

@@ -54,9 +54,7 @@ void FAST_FUNC launch_helper(const char **argv)
 		+ (1 << SIGALRM)
 		, signal_handler);
 
-	G.helper_pid = vfork();
-	if (G.helper_pid < 0)
-		bb_perror_msg_and_die("vfork");
+	G.helper_pid = xvfork();
 
 	i = (!G.helper_pid) * 2; // for parent:0, for child:2
 	close(pipes[i + 1]); // 1 or 3 - closing one write end

miscutils/conspy.c

@@ -309,10 +309,7 @@ static void create_cdev_if_doesnt_exist(const char* name, dev_t dev)
 
 static NOINLINE void start_shell_in_child(const char* tty_name)
 {
-	int pid = vfork();
-	if (pid < 0) {
-		bb_perror_msg_and_die("vfork");
-	}
+	int pid = xvfork();
 	if (pid == 0) {
 		struct termios termchild;
 		char *shell = getenv("SHELL");

miscutils/crontab.c

@@ -20,10 +20,8 @@
 static void edit_file(const struct passwd *pas, const char *file)
 {
 	const char *ptr;
-	int pid = vfork();
+	int pid = xvfork();
 
-	if (pid < 0) /* failure */
-		bb_perror_msg_and_die("vfork");
 	if (pid) { /* parent */
 		wait4pid(pid);
 		return;
@@ -51,9 +49,7 @@ static int open_as_user(const struct passwd *pas, const char *file)
 	pid_t pid;
 	char c;
 
-	pid = vfork();
-	if (pid < 0) /* ERROR */
-		bb_perror_msg_and_die("vfork");
+	pid = xvfork();
 	if (pid) { /* PARENT */
 		if (wait4pid(pid) == 0) {
 			/* exitcode 0: child says it can read */

miscutils/time.c

@@ -372,9 +372,7 @@ static void run_command(char *const *cmd, resource_t *resp)
 	void (*quit_signal)(int);
 
 	resp->elapsed_ms = monotonic_ms();
-	pid = vfork();
-	if (pid < 0)
-		bb_perror_msg_and_die("vfork");
+	pid = xvfork();
 	if (pid == 0) {
 		/* Child */
 		BB_EXECVP_or_die((char**)cmd);

miscutils/timeout.c

@@ -71,9 +71,7 @@ int timeout_main(int argc UNUSED_PARAM, char **argv)
 	sv1 = argv[optind];
 	sv2 = argv[optind + 1];
 #endif
-	pid = vfork();
-	if (pid < 0)
-		bb_perror_msg_and_die("vfork");
+	pid = xvfork();
 	if (pid == 0) {
 		/* Child: spawn grandchild and exit */
 		parent = getppid();

networking/ftpd.c

@@ -632,10 +632,7 @@ popen_ls(const char *opt)
 	xpiped_pair(outfd);
 
 	/*fflush_all(); - so far we dont use stdio on output */
-	pid = BB_MMU ? fork() : vfork();
-	if (pid < 0)
-		bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
-
+	pid = BB_MMU ? xfork() : xvfork();
 	if (pid == 0) {
 		/* child */
 #if !BB_MMU

networking/ifupdown.c

@@ -1041,12 +1041,10 @@ static int popen2(FILE **in, FILE **out, char *command, char *param)
 	xpiped_pair(outfd);
 
 	fflush_all();
-	pid = vfork();
+	pid = xvfork();
 
-	switch (pid) {
-	case -1:  /* failure */
-		bb_perror_msg_and_die("vfork");
-	case 0:  /* child */
+	if (pid == 0) {
+		/* Child */
 		/* NB: close _first_, then move fds! */
 		close(infd.wr);
 		close(outfd.rd);

networking/inetd.c

@@ -1271,7 +1271,7 @@ int inetd_main(int argc UNUSED_PARAM, char **argv)
 					pid = vfork();
 
 				if (pid < 0) { /* fork error */
-					bb_perror_msg("fork");
+					bb_perror_msg("vfork"+1);
 					sleep(1);
 					restore_sigmask(&omask);
 					maybe_close(accepted_fd);

networking/nc.c

@@ -216,10 +216,8 @@ int nc_main(int argc, char **argv)
 	if (execparam) {
 		pid_t pid;
 		/* With more than one -l, repeatedly act as server */
-		if (do_listen > 1 && (pid = vfork()) != 0) {
-			/* parent or error */
-			if (pid < 0)
-				bb_perror_msg_and_die("vfork");
+		if (do_listen > 1 && (pid = xvfork()) != 0) {
+			/* parent */
 			/* prevent zombies */
 			signal(SIGCHLD, SIG_IGN);
 			close(cfd);

scripts/basic/docproc.c

@@ -86,7 +86,7 @@ void exec_kernel_doc(char **svec)
 	fflush(stdout);
 	switch(pid=fork()) {
 		case -1:
-			perror("fork");
+			perror("vfork"+1);
 			exit(1);
 		case  0:
 			rflen  = strlen(getenv("SRCTREE"));

shell/hush.c

@@ -3208,15 +3208,11 @@ static void setup_heredoc(struct redir_struct *redir)
 #if !BB_MMU
 	to_free = NULL;
 #endif
-	pid = vfork();
-	if (pid < 0)
-		bb_perror_msg_and_die("vfork");
+	pid = xvfork();
 	if (pid == 0) {
 		/* child */
 		disable_restore_tty_pgrp_on_exit();
-		pid = BB_MMU ? fork() : vfork();
-		if (pid < 0)
-			bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
+		pid = BB_MMU ? xfork() : xvfork();
 		if (pid != 0)
 			_exit(0);
 		/* grandchild */
@@ -4450,7 +4446,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
 		argv_expanded = NULL;
 		if (command->pid < 0) { /* [v]fork failed */
 			/* Clearly indicate, was it fork or vfork */
-			bb_perror_msg(BB_MMU ? "fork" : "vfork");
+			bb_perror_msg(BB_MMU ? "vfork"+1 : "vfork");
 		} else {
 			pi->alive_cmds++;
 #if ENABLE_HUSH_JOB
@@ -5586,10 +5582,7 @@ static FILE *generate_stream_from_string(const char *s, pid_t *pid_p)
 # endif
 
 	xpipe(channel);
-	pid = BB_MMU ? fork() : vfork();
-	if (pid < 0)
-		bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
-
+	pid = BB_MMU ? xfork() : xvfork();
 	if (pid == 0) { /* child */
 		disable_restore_tty_pgrp_on_exit();
 		/* Process substitution is not considered to be usual

util-linux/script.c

@@ -88,10 +88,7 @@ int script_main(int argc UNUSED_PARAM, char **argv)
 
 	/* TODO: SIGWINCH? pass window size changes down to slave? */
 
-	child_pid = vfork();
-	if (child_pid < 0) {
-		bb_perror_msg_and_die("vfork");
-	}
+	child_pid = xvfork();
 
 	if (child_pid) {
 		/* parent */