roken_detach_prep() should return fd

kadmin/kadmind.c

@@ -123,7 +123,7 @@ main(int argc, char **argv)
     }
 
     if (detach_from_console > 0 && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
 
     ret = krb5_init_context(&context);
     if (ret)

kcm/main.c

@@ -87,7 +87,7 @@ main(int argc, char **argv)
     signal(SIGPIPE, SIG_IGN);
 #endif
     if (detach_from_console && !launchd_flag && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
     rk_pidfile(NULL);
 
     if (launchd_flag) {

kdc/config.c

@@ -189,7 +189,7 @@ configure(krb5_context context, int argc, char **argv, int *optidx)
 							   "detach", NULL);
 
     if (detach_from_console && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
 
     {
 	char **files;

kpasswd/kpasswdd.c

@@ -798,7 +798,7 @@ main(int argc, char **argv)
     }
 
     if (detach_from_console > 0 && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
 
     if (config_file == NULL) {
 	aret = asprintf(&config_file, "%s/kdc.conf", hdb_db_dir(context));

lib/kadm5/ipropd_master.c

@@ -1152,7 +1152,7 @@ main(int argc, char **argv)
     }
 
     if (detach_from_console && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
     rk_pidfile(NULL);
 
     ret = krb5_init_context(&context);

lib/kadm5/ipropd_slave.c

@@ -719,7 +719,7 @@ main(int argc, char **argv)
     }
 
     if (detach_from_console && daemon_child == -1)
-        roken_detach_prep(argc, argv, "--daemon-child");
+        daemon_child = roken_detach_prep(argc, argv, "--daemon-child");
     rk_pidfile(NULL);
 
     ret = krb5_init_context(&context);

lib/roken/detach.c

@@ -44,54 +44,57 @@
 
 static int pipefds[2] = {-1, -1};
 
-ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
+ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
 roken_detach_prep(int argc, char **argv, char *special_arg)
 {
-    pid_t child;
-    char buf[1];
     ssize_t bytes;
+    size_t i;
+    pid_t child;
+    char **new_argv;
+    char buf[1];
+    char *fildes;
     int status;
 
     pipefds[0] = -1;
     pipefds[1] = -1;
 
 #ifdef WIN32
-    if (_pipe(pipefds, 4, O_BINARY) == -1)
+    if (_pipe(pipefds, 4, _O_NOINHERIT | O_BINARY) == -1)
         err(1, "failed to setup to detach daemon (_pipe failed)");
 #else
     if (pipe(pipefds) == -1)
         err(1, "failed to setup to detach daemon (pipe failed)");
 #endif
 
+    new_argv = calloc(argc + 3, sizeof(*new_argv));
+    if (new_argv == NULL)
+        err(1, "Out of memory");
+
+#ifdef WIN32
+    pipefds[1] = _dup(pipefds[1]); /* The new fd will be inherited */
+    if (pipefds[1] == -1)
+        err(1, "Out of memory");
+#else
+    fcntl(pipefds[1], F_SETFD, fcntl(pipefds[1], F_GETFD & ~(O_CLOEXEC)));
+#endif
+
+    if (asprintf(&fildes, "%d", pipefds[1]) == -1 ||
+        fildes == NULL)
+        err(1, "failed to setup to detach daemon (_dup failed)");
+
+    new_argv[0] = argv[0];
+    new_argv[1] = special_arg;
+    new_argv[2] = fildes;
+    for (i = 1; argv[i] != NULL; i++)
+        new_argv[i + 2] = argv[i];
+    new_argv[argc + 2] = NULL;
+
 #ifndef WIN32
     fflush(stdout);
     child = fork();
 #else
     {
         intptr_t child_handle;
-	int write_side;
-        size_t i;
-	char *fildes;
-        char **new_argv;
-
-        new_argv = calloc(argc + 2, sizeof(*new_argv));
-        if (new_argv == NULL)
-            err(1, "Out of memory");
-
-	write_side = _dup(pipefds[1]); /* The new fd will be inherited */
-	if (write_side == -1)
-            err(1, "Out of memory");
-
-	if (asprintf(&fildes, "%d", write_side) == -1 ||
-	    fildes == NULL)
-            err(1, "failed to setup to detach daemon (_dup failed)");
-
-        new_argv[0] = argv[0];
-        new_argv[1] = special_arg;
-        new_argv[2] = fildes;
-        for (i = 1; argv[i] != NULL; i++)
-            new_argv[i + 1] = argv[i];
-	new_argv[argc + 2] = NULL;
 
 	_flushall();
 	child_handle = spawnvp(_P_NOWAIT, argv[0], new_argv);
@@ -120,10 +123,15 @@ roken_detach_prep(int argc, char **argv, char *special_arg)
         (void) dup2(fd, STDIN_FILENO);
         if (fd > STDERR_FILENO)
             (void) close(fd);
-        return;
+        if (getenv("ROKEN_DETACH_USE_EXEC")) {
+            (void) execvp(argv[0], new_argv);
+            err(1, "failed to self-re-exec");
+        }
+        return pipefds[1];
     }
 #endif
 
+    /* Parent */
     (void) close(pipefds[1]);
     pipefds[1] = -1;
     do {
@@ -149,6 +157,8 @@ roken_detach_prep(int argc, char **argv, char *special_arg)
                  "daemon child preparation failed (child exited)");
     }
     _exit(0);
+    /* NOTREACHED */
+    return -1;
 }
 
 #ifdef WIN32

lib/roken/roken.h.in

@@ -836,7 +836,7 @@ ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL roken_vconcat (char *, size_t, va_list);
 ROKEN_LIB_FUNCTION size_t ROKEN_LIB_CALL
     roken_vmconcat (char **, size_t, va_list);
 
-ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL roken_detach_prep(int, char **, char *);
+ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL roken_detach_prep(int, char **, char *);
 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL roken_detach_finish(const char *, int);
 
 ROKEN_LIB_FUNCTION ssize_t ROKEN_LIB_CALL

lib/roken/test-detach.c

@@ -53,11 +53,13 @@ int main(int argc, char **argv)
     char *ends;
     long n;
     int fd = -1;
+    pid_t parent = getpid();
+    pid_t child;
 
-    if (argc > 1) {
+    if (argc == 2 && strcmp(argv[1], "--reexec"))
-	if (argc != 3)
+        errx(1, "Usage: test-detach [--reexec] [--daemon-child FD]");
-	    errx(1, "Usage: test-detach [--daemon-child fd]");
+    if (argc == 3 || argc == 4) {
-	fprintf(stderr, "Child started (argv[1] = %s, argv[2] = %s)!\n", argv[1], argv[2]);
+        parent = getppid();
         errno = 0;
         n = strtol(argv[2], &ends, 10);
         fd = n;
@@ -66,11 +68,19 @@ int main(int argc, char **argv)
         if (n < 0 || ends == NULL || *ends != '\0' || n != fd)
 	    errx(1, "Usage: test-detach [--daemon-child fd]");
     } else {
-	fprintf(stderr, "Parent started as %ld\n", (long)getpid());
+        if (argc == 2)
-	roken_detach_prep(argc, argv, "--daemon-child");
+            /* Make sure we re-exec on the child-side of fork() (not WIN32) */
+            putenv("ROKEN_DETACH_USE_EXEC=1");
+	fd = roken_detach_prep(argc, argv, "--daemon-child");
+        if (fd == -1)
+            errx(1, "bad");
     }
-    fprintf(stderr, "Now should be the child: %ld\n", (long)getpid());
+    if (parent == getpid())
+        errx(1, "detach prep failed");
+    child = getpid();
     roken_detach_finish(NULL, fd);
+    if (child != getpid())
+        errx(1, "detach finish failed");
     /*
      * These printfs will not appear: stderr will have been replaced
      * with /dev/null.