global: use dev_null_fd instead of opening /dev/null

src/lib-program-client/program-client-local.c

@@ -52,40 +52,26 @@ void exec_child(const char *bin_path, const char *const *args, const char *const
 
 	/* Setup stdin/stdout */
 
-	if (in_fd < 0) {
-		in_fd = open("/dev/null", O_RDONLY);
-
-		if (in_fd == -1)
-			i_fatal("open(/dev/null) failed: %m");
-	}
-	if (out_fd < 0) {
-		out_fd = open("/dev/null", O_WRONLY);
-
-		if (out_fd == -1)
-			i_fatal("open(/dev/null) failed: %m");
-	}
+	if (in_fd < 0)
+		in_fd = dev_null_fd;
+	if (out_fd < 0)
+		out_fd = dev_null_fd;
 
 	if (in_fd != STDIN_FILENO && dup2(in_fd, STDIN_FILENO) < 0)
 		i_fatal("dup2(stdin) failed: %m");
 	if (out_fd != STDOUT_FILENO && dup2(out_fd, STDOUT_FILENO) < 0)
 		i_fatal("dup2(stdout) failed: %m");
 
-	if (in_fd != STDIN_FILENO && close(in_fd) < 0)
+	if (in_fd != STDIN_FILENO && in_fd != dev_null_fd && close(in_fd) < 0)
 		i_error("close(in_fd) failed: %m");
-	if (out_fd != STDOUT_FILENO && (out_fd != in_fd) && close(out_fd) < 0)
+	if (out_fd != STDOUT_FILENO && out_fd != dev_null_fd &&
+	    (out_fd != in_fd) && close(out_fd) < 0)
 		i_error("close(out_fd) failed: %m");
 
 	/* Drop stderr if requested */
 	if (drop_stderr) {
-		int err_fd = open("/dev/null", O_WRONLY);
-		if (err_fd == -1)
-			i_fatal("open(/dev/null) failed: %m");
-		if (err_fd != STDERR_FILENO) {
-			if (dup2(err_fd, STDERR_FILENO) < 0)
-				i_fatal("dup2(stderr) failed: %m");
-			if (close(err_fd) < 0)
-				i_error("close(err_fd) failed: %m");
-		}
+		if (dup2(dev_null_fd, STDERR_FILENO) < 0)
+			i_fatal("dup2(stderr) failed: %m");
 	}
 
 	/* Setup extra fds */

src/lib/module-dir.c

@@ -149,25 +149,20 @@ static void *quiet_dlopen(const char *path, int flags)
 	return dlopen(path, flags);
 #else
 	void *handle;
-	int fd, fd_null;
+	int fd;
 
 	/* OpenBSD likes to print all "undefined symbol" errors to stderr.
 	   Hide them by sending them to /dev/null. */
-	fd_null = open("/dev/null", O_WRONLY);
-	if (fd_null == -1)
-		i_fatal("open(/dev/null) failed: %m");
 	fd = dup(STDERR_FILENO);
 	if (fd == -1)
 		i_fatal("dup() failed: %m");
-	if (dup2(fd_null, STDERR_FILENO) < 0)
+	if (dup2(dev_null_fd, STDERR_FILENO) < 0)
 		i_fatal("dup2() failed: %m");
 	handle = dlopen(path, flags);
 	if (dup2(fd, STDERR_FILENO) < 0)
 		i_fatal("dup2() failed: %m");
 	if (close(fd) < 0)
 		i_error("close() failed: %m");
-	if (close(fd_null) < 0)
-		i_error("close() failed: %m");
 	return handle;
 #endif
 }

src/master/common.h

@@ -9,7 +9,7 @@ extern uid_t master_uid;
 extern gid_t master_gid;
 extern bool core_dumps_disabled;
 extern const char *ssl_manual_key_password;
-extern int null_fd, global_master_dead_pipe_fd[2];
+extern int global_master_dead_pipe_fd[2];
 extern struct service_list *services;
 extern bool startup_finished;
 

src/master/main.c

@@ -43,7 +43,7 @@ uid_t master_uid;
 gid_t master_gid;
 bool core_dumps_disabled;
 const char *ssl_manual_key_password;
-int null_fd, global_master_dead_pipe_fd[2];
+int global_master_dead_pipe_fd[2];
 struct service_list *services;
 bool startup_finished = FALSE;
 
@@ -826,12 +826,6 @@ int main(int argc, char *argv[])
 		i_fatal("Unknown argument: --%s", argv[optind]);
 	}
 
-	null_fd = open("/dev/null", O_WRONLY);
-	if (null_fd == -1)
-		i_fatal("Can't open /dev/null: %m");
-	fd_close_on_exec(null_fd, TRUE);
-	i_assert(null_fd > STDERR_FILENO);
-
 	if (pipe(global_master_dead_pipe_fd) < 0)
 		i_fatal("pipe() failed: %m");
 	fd_close_on_exec(global_master_dead_pipe_fd[0], TRUE);
@@ -843,10 +837,10 @@ int main(int argc, char *argv[])
 			t_askpass("Give the password for SSL keys: ");
 	}
 
-	if (dup2(null_fd, STDIN_FILENO) < 0)
-		i_fatal("dup2(null_fd) failed: %m");
-	if (!foreground && dup2(null_fd, STDOUT_FILENO) < 0)
-		i_fatal("dup2(null_fd) failed: %m");
+	if (dup2(dev_null_fd, STDIN_FILENO) < 0)
+		i_fatal("dup2(dev_null_fd) failed: %m");
+	if (!foreground && dup2(dev_null_fd, STDOUT_FILENO) < 0)
+		i_fatal("dup2(dev_null_fd) failed: %m");
 
 	pidfile_path =
 		i_strconcat(set->base_dir, "/"MASTER_PID_FILE_NAME, NULL);

src/master/service-process.c

@@ -122,7 +122,7 @@ service_dup_fds(struct service *service)
 	case SERVICE_TYPE_LOG:
 	case SERVICE_TYPE_ANVIL:
 	case SERVICE_TYPE_CONFIG:
-		dup2_append(&dups, null_fd, MASTER_ANVIL_FD);
+		dup2_append(&dups, dev_null_fd, MASTER_ANVIL_FD);
 		break;
 	case SERVICE_TYPE_UNKNOWN:
 	case SERVICE_TYPE_LOGIN: