start-stop-daemon: do not lose error messages with -b

function                                             old     new   delta
start_stop_daemon_main                              1186    1206     +20
bb_daemonize_or_rexec                                196     212     +16
bb_banner                                             47      46      -1
packed_usage                                       34656   34645     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 36/-12)             Total: 24 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 41 insertions, 36 deletions

diff --git a/debianutils/start_stop_daemon.c b/debianutils/start_stop_daemon.c
index 04ba8baa7..00fa0a82c 100644
--- a/debianutils/start_stop_daemon.c
+++ b/debianutils/start_stop_daemon.c
@@ -71,7 +71,7 @@ Options which are valid for --start only:
                                 done after the chroot if the -r|--chroot option is set.
                                 When not specified, start-stop-daemon will change directory to the
                                 root directory before starting the process.
-                                ^^^^ Seems to be false, no default "/" chdir is done.
+                                ^^^^ Gentoo does not have the default chdir("/"). Debian does.
         Tested -S with 1.21.22:
         "start-stop-daemon -S -x /bin/pwd" is the minimum needed to run pwd.
         "start-stop-daemon -S -a /bin/pwd -n pwd" works too.
@@ -111,7 +111,6 @@ Misc options:
 //config:       -o|--oknodo ignored since we exit with 0 anyway
 //config:       -v|--verbose
 //config:       -N|--nicelevel N
-//config:       -O|--output FILE
 
 //applet:IF_START_STOP_DAEMON(APPLET_ODDNAME(start-stop-daemon, start_stop_daemon, BB_DIR_SBIN, BB_SUID_DROP, start_stop_daemon))
 /* not NOEXEC: uses bb_common_bufsiz1 */
@@ -136,6 +135,7 @@ Misc options:
 //usage:     "\n        -x EXECUTABLE   Program to run"
 //usage:     "\n        -a NAME         Zeroth argument"
 //usage:     "\n        -b              Background"
+//usage:     "\n        -O FILE         Append stdout and stderr to FILE"
 //usage:        IF_FEATURE_START_STOP_DAEMON_FANCY(
 //usage:     "\n        -N N            Change nice level"
 //usage:        )
@@ -150,7 +150,6 @@ Misc options:
 //usage:     "\n        -o              Exit with status 0 if nothing is done"
 //usage:     "\n        -v              Verbose"
 //usage:     "\n        -q              Quiet"
-//usage:     "\n        -O FILE         Append stdout and stderr to FILE"
 //usage:        )
 
 /* Override ENABLE_FEATURE_PIDFILE */
@@ -178,20 +177,20 @@ enum {
         OPT_d          = (1 << 11), // -d
         OPT_x          = (1 << 12), // -x
         OPT_p          = (1 << 13), // -p
-        OPT_OKNODO     = (1 << 14) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
-        OPT_VERBOSE    = (1 << 15) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
-        OPT_NICELEVEL  = (1 << 16) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
-        OPT_OUTPUT     = (1 << 17) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -O
+        OPT_OUTPUT     = (1 << 14), // -O
+        OPT_OKNODO     = (1 << 15) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
+        OPT_VERBOSE    = (1 << 16) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
+        OPT_NICELEVEL  = (1 << 17) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
 };
 #define QUIET (option_mask32 & OPT_QUIET)
 #define TEST  (option_mask32 & OPT_TEST)
 
 struct globals {
         struct pid_list *found_procs;
-        char *userspec;
-        char *cmdname;
-        char *execname;
-        char *pidfile;
+        const char *userspec;
+        const char *cmdname;
+        const char *execname;
+        const char *pidfile;
         char *execname_cmpbuf;
         unsigned execname_sizeof;
         int user_id;
@@ -361,7 +360,7 @@ static void do_procinit(void)
 
 static int do_stop(void)
 {
-        char *what;
+        const char *what;
         struct pid_list *p;
         int killed = 0;
 
@@ -408,7 +407,7 @@ static int do_stop(void)
         }
  ret:
         if (ENABLE_FEATURE_CLEAN_UP)
-                free(what);
+                free((char *)what);
         return killed;
 }
 
@@ -449,22 +448,22 @@ int start_stop_daemon_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
 {
         unsigned opt;
-        char *signame;
-        char *startas = NULL;
+        const char *signame;
+        const char *startas = NULL;
         char *chuid;
-        char *chdir;
+        const char *chdir;
+        const char *output = NULL;
 #if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
-//      char *retry_arg = NULL;
+//      const char *retry_arg = NULL;
 //      int retries = -1;
-        char *opt_N;
-        char *output;
+        const char *opt_N;
 #endif
 
         INIT_G();
 
         opt = GETOPT32(argv, "^"
-                "KSbqtma:n:s:u:c:d:x:p:"
-                IF_FEATURE_START_STOP_DAEMON_FANCY("ovN:O:R:")
+                "KSbqtma:n:s:u:c:d:x:p:O:"
+                IF_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:")
                         "\0"
                         "K:S:K--S:S--K"
                         /* -K or -S is required; they are mutually exclusive */
@@ -479,9 +478,8 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
                         IF_FEATURE_START_STOP_DAEMON_FANCY(":q-v") /* -q turns off -v */
                         ,
                 LONGOPTS
-                &startas, &cmdname, &signame, &userspec, &chuid, &chdir, &execname, &pidfile
+                &startas, &cmdname, &signame, &userspec, &chuid, &chdir, &execname, &pidfile, &output
                 IF_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
-                IF_FEATURE_START_STOP_DAEMON_FANCY(,&output)
                 /* We accept and ignore -R <param> / --retry <param> */
                 IF_FEATURE_START_STOP_DAEMON_FANCY(,NULL)
         );
@@ -519,7 +517,7 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
                 }
                 if (!startas) /* -a is not given: use -x EXECUTABLE or argv[0] */
                         startas = execname;
-                *--argv = startas;
+                *--argv = (char *)startas;
         }
         if (execname) {
                 G.execname_sizeof = strlen(execname) + 1;
@@ -578,8 +576,11 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
                 }
                 /* Child */
                 setsid(); /* detach from controlling tty */
-                /* Redirect stdio to /dev/null, close extra FDs */
-                bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS);
+                /* Redirect stdin to /dev/null, close extra FDs */
+                /* Testcase: "start-stop-daemon -Sb -d /does/not/exist usleep 1" should not eat error message */
+                bb_daemon_helper(DAEMON_DEVNULL_STDIN + DAEMON_CLOSE_EXTRA_FDS);
+                if (!output)
+                        output = bb_dev_null; /* redirect output just before execv */
                 /* On Linux, session leader can acquire ctty
                  * unknowingly, by opening a tty.
                  * Prevent this: stop being a session leader.
@@ -618,14 +619,12 @@ int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
         if (opt & OPT_d) {
                 xchdir(chdir);
         }
-#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
-        if (opt & OPT_OUTPUT) {
+        if (output) {
                 int outfd = xopen(output, O_WRONLY | O_CREAT | O_APPEND);
                 xmove_fd(outfd, STDOUT_FILENO);
                 xdup2(STDOUT_FILENO, STDERR_FILENO);
                 /* on execv error, the message goes to -O file. This is intended */
         }
-#endif
         /* Try:
          * strace -oLOG start-stop-daemon -S -x /bin/usleep -a qwerty 500000
          * should exec "/bin/usleep", but argv[0] should be "qwerty":
diff --git a/include/libbb.h b/include/libbb.h
index 0883fb565..ef5d04713 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1309,10 +1309,12 @@ void _exit_FAILURE(void) NORETURN FAST_FUNC;
  */
 enum {
         DAEMON_CHDIR_ROOT      = 1 << 0,
-        DAEMON_DEVNULL_STDIO   = 1 << 1,
-        DAEMON_CLOSE_EXTRA_FDS = 1 << 2,
-        DAEMON_ONLY_SANITIZE   = 1 << 3, /* internal use */
-        //DAEMON_DOUBLE_FORK     = 1 << 4, /* double fork to avoid controlling tty */
+        DAEMON_DEVNULL_STDIN   = 1 << 1,
+        DAEMON_DEVNULL_OUTERR  = 2 << 1,
+        DAEMON_DEVNULL_STDIO   = 3 << 1,
+        DAEMON_CLOSE_EXTRA_FDS = 1 << 3,
+        DAEMON_ONLY_SANITIZE   = 1 << 4, /* internal use */
+        //DAEMON_DOUBLE_FORK     = 1 << 5, /* double fork to avoid controlling tty */
 };
 #if BB_MMU
   enum { re_execed = 0 };
@@ -1335,6 +1337,7 @@ enum {
 # define bb_daemonize(a) BUG_bb_daemonize_is_unavailable_on_nommu()
 #endif
 void bb_daemonize_or_rexec(int flags, char **argv) FAST_FUNC;
+/* Unlike bb_daemonize_or_rexec, these two helpers do not setsid: */
 void bb_sanitize_stdio(void) FAST_FUNC;
 #define bb_daemon_helper(arg) bb_daemonize_or_rexec((arg) | DAEMON_ONLY_SANITIZE, NULL)
 /* Clear dangerous stuff, set PATH. Return 1 if was run by different user. */
diff --git a/libbb/vfork_daemon_rexec.c b/libbb/vfork_daemon_rexec.c
index a570ddbf2..2055c4b71 100644
--- a/libbb/vfork_daemon_rexec.c
+++ b/libbb/vfork_daemon_rexec.c
@@ -296,9 +296,12 @@ void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
         }
 
         if (flags & DAEMON_DEVNULL_STDIO) {
-                xdup2(fd, 0);
-                xdup2(fd, 1);
-                xdup2(fd, 2);
+                if (flags & DAEMON_DEVNULL_STDIN)
+                        xdup2(fd, 0);
+                if (flags & DAEMON_DEVNULL_OUTERR) {
+                        xdup2(fd, 1);
+                        xdup2(fd, 2);
+                }
         } else {
                 /* have 0,1,2 open at least to /dev/null */
                 while ((unsigned)fd < 2)