*: 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>

21 files changed, 56 insertions, 95 deletions

diff --git a/archival/libunarchive/data_extract_to_command.c b/archival/libunarchive/data_extract_to_command.c
index eb09439bc..95f5bc864 100644
--- a/archival/libunarchive/data_extract_to_command.c
+++ b/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);
diff --git a/archival/libunarchive/open_transformer.c b/archival/libunarchive/open_transformer.c
index 47c13e6f4..cba049f1f 100644
--- a/archival/libunarchive/open_transformer.c
+++ b/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
diff --git a/archival/tar.c b/archival/tar.c
index f49fb129e..9dd74536e 100644
--- a/archival/tar.c
+++ b/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 */
diff --git a/debianutils/start_stop_daemon.c b/debianutils/start_stop_daemon.c
index 3ded758bf..665f38fbd 100644
--- a/debianutils/start_stop_daemon.c
+++ b/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,
diff --git a/e2fsprogs/old_e2fsprogs/fsck.c b/e2fsprogs/old_e2fsprogs/fsck.c
index dc029b65a..2a66d728a 100644
--- a/e2fsprogs/old_e2fsprogs/fsck.c
+++ b/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)
diff --git a/include/libbb.h b/include/libbb.h
index 4b6699f2f..e2a8322b8 100644
--- a/include/libbb.h
+++ b/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
diff --git a/init/bootchartd.c b/init/bootchartd.c
index 42b98c827..b3e08af92 100644
--- a/init/bootchartd.c
+++ b/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);
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index 8102ea2dc..5c2c529c9 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/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 -
diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
index f021493b1..7069a7c8e 100644
--- a/libbb/xfuncs_printf.c
+++ b/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
diff --git a/mailutils/mail.c b/mailutils/mail.c
index 5eb99e13d..bcd358302 100644
--- a/mailutils/mail.c
+++ b/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
diff --git a/miscutils/conspy.c b/miscutils/conspy.c
index 3f341ce18..509a0f271 100644
--- a/miscutils/conspy.c
+++ b/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");
diff --git a/miscutils/crontab.c b/miscutils/crontab.c
index 5557bc491..b8a5abc64 100644
--- a/miscutils/crontab.c
+++ b/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 */
diff --git a/miscutils/time.c b/miscutils/time.c
index 5cfbcef8e..9facc3657 100644
--- a/miscutils/time.c
+++ b/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);
diff --git a/miscutils/timeout.c b/miscutils/timeout.c
index f6e655acc..48b8d8fc0 100644
--- a/miscutils/timeout.c
+++ b/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();
diff --git a/networking/ftpd.c b/networking/ftpd.c
index c63b9319e..e8cae0a36 100644
--- a/networking/ftpd.c
+++ b/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
diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 1bab2c5cb..69c56e879 100644
--- a/networking/ifupdown.c
+++ b/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);
diff --git a/networking/inetd.c b/networking/inetd.c
index 2b0e0069e..7030062b6 100644
--- a/networking/inetd.c
+++ b/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);
diff --git a/networking/nc.c b/networking/nc.c
index 5fd8bd759..0dacaf117 100644
--- a/networking/nc.c
+++ b/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);
diff --git a/scripts/basic/docproc.c b/scripts/basic/docproc.c
index ef5181226..50ef37157 100644
--- a/scripts/basic/docproc.c
+++ b/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"));
diff --git a/shell/hush.c b/shell/hush.c
index 29ff3c442..831443e2e 100644
--- a/shell/hush.c
+++ b/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
diff --git a/util-linux/script.c b/util-linux/script.c
index d9a62fbfe..c23117cf3 100644
--- a/util-linux/script.c
+++ b/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 */