*: introduce and use xfork()

function                                             old     new   delta
xfork                                                  -      20     +20
msh_main                                            1377    1380      +3
mod_process                                          455     446      -9
forkexit_or_rexec                                     30      17     -13
expand_variables                                    1434    1421     -13
open_transformer                                      91      76     -15
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/4 up/down: 23/-50)            Total: -27 bytes

archival/libunarchive/open_transformer.c

@@ -20,14 +20,7 @@ int FAST_FUNC open_transformer(int src_fd,
 
 	xpiped_pair(fd_pipe);
 
-#if BB_MMU
+	pid = BB_MMU ? xfork() : xvfork();
-	pid = fork();
-	if (pid == -1)
-		bb_perror_msg_and_die("can't fork");
-#else
-	pid = xvfork();
-#endif
-
 	if (pid == 0) {
 		/* child process */
 		close(fd_pipe.rd); /* We don't want to read from the parent */

include/libbb.h

@@ -719,6 +719,9 @@ int bb_execvp(const char *file, char *const argv[]) FAST_FUNC;
 #define BB_EXECLP(prog,cmd,...) execlp(prog,cmd, __VA_ARGS__)
 #endif
 
+#if BB_MMU
+pid_t xfork(void) FAST_FUNC;
+#endif
 pid_t xvfork(void) FAST_FUNC;
 
 /* NOMMU friendy fork+exec */

libbb/vfork_daemon_rexec.c

@@ -238,9 +238,7 @@ void FAST_FUNC forkexit_or_rexec(char **argv)
 void FAST_FUNC forkexit_or_rexec(void)
 {
 	pid_t pid;
-	pid = fork();
+	pid = xfork();
-	if (pid < 0) /* wtf? */
-		bb_perror_msg_and_die("fork");
 	if (pid) /* parent */
 		exit(EXIT_SUCCESS);
 	/* child */

libbb/xvfork.c

@@ -16,3 +16,13 @@ pid_t FAST_FUNC xvfork(void)
 		bb_perror_msg_and_die("vfork");
 	return pid;
 }
+
+#if BB_MMU
+pid_t FAST_FUNC xfork(void)
+{
+	pid_t pid = fork();
+	if (pid < 0)
+		bb_perror_msg_and_die("vfork" + 1);
+	return pid;
+}
+#endif

networking/inetd.c

@@ -1303,7 +1303,7 @@ int inetd_main(int argc ATTRIBUTE_UNUSED, char **argv)
 					pid = vfork();
 
 				if (pid < 0) { /* fork error */
-					bb_perror_msg("fork");
+					bb_perror_msg(BB_MMU ? "vfork" + 1 : "vfork");
 					sleep(1);
 					restore_sigmask(&omask);
 					maybe_close(accepted_fd);

shell/hush.c

@@ -1902,7 +1902,7 @@ static int run_pipe(struct pipe *pi)
 #endif
 		if (child->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_progs++;
 #if ENABLE_HUSH_JOB
@@ -3096,11 +3096,7 @@ static FILE *generate_stream_from_list(struct pipe *head)
  * huge=`cat TESTFILE` # will block here forever
  * echo OK
  */
-	pid = BB_MMU ? fork() : xvfork();
+	pid = BB_MMU ? xfork() : xvfork();
-#if BB_MMU
-	if (pid < 0)
-		bb_perror_msg_and_die("fork");
-#endif
 	if (pid == 0) { /* child */
 		if (ENABLE_HUSH_JOB)
 			die_sleep = 0; /* let nofork's xfuncs die */

util-linux/mount.c

@@ -890,6 +890,7 @@ get_mountport(struct pmap *pm_mnt,
 }
 
 #if BB_MMU
+/* Unlike bb_daemonize(), parent does NOT exit here, but returns 0 */
 static int daemonize(void)
 {
 	int fd;