exec_always: fix leaks

 - child would leak in the workspace_record_pid path
 - removing malloc lets us get rid of That Comment nobody seems
to remember what it was about
 - we would leak pipe fds on first fork failling
 - we didn't return an error if second fork failed
 - the final executed process still had both pipe fds
(would show up in /proc/23560/fd in launched programs)
 - we would write twice to the pipe if execl failed for some reason
(e.g. if /bin/sh doesn't exist?!)

1 files changed, 13 insertions, 14 deletions

diff --git a/sway/commands/exec_always.c b/sway/commands/exec_always.c
index 682d195e..1c99de97 100644
--- a/sway/commands/exec_always.c
+++ b/sway/commands/exec_always.c
@@ -42,43 +42,42 @@ struct cmd_results *cmd_exec_always(int argc, char **argv) {
                 wlr_log(L_ERROR, "Unable to create pipe for fork");
         }
 
-        pid_t pid;
-        pid_t *child = malloc(sizeof(pid_t)); // malloc'd so that Linux can avoid copying the process space
-        if (!child) {
-                return cmd_results_new(CMD_FAILURE, "exec_always", "Unable to allocate child pid");
-        }
+        pid_t pid, child;
         // Fork process
         if ((pid = fork()) == 0) {
                 // Fork child process again
                 setsid();
-                if ((*child = fork()) == 0) {
+                close(fd[0]);
+                if ((child = fork()) == 0) {
+                        close(fd[1]);
                         execl("/bin/sh", "/bin/sh", "-c", cmd, (void *)NULL);
-                        // Not reached
+                        _exit(0);
                 }
-                close(fd[0]);
                 ssize_t s = 0;
                 while ((size_t)s < sizeof(pid_t)) {
-                        s += write(fd[1], ((uint8_t *)child) + s, sizeof(pid_t) - s);
+                        s += write(fd[1], ((uint8_t *)&child) + s, sizeof(pid_t) - s);
                 }
                 close(fd[1]);
                 _exit(0); // Close child process
         } else if (pid < 0) {
-                free(child);
+                close(fd[0]);
+                close(fd[1]);
                 return cmd_results_new(CMD_FAILURE, "exec_always", "fork() failed");
         }
         close(fd[1]); // close write
         ssize_t s = 0;
         while ((size_t)s < sizeof(pid_t)) {
-                s += read(fd[0], ((uint8_t *)child) + s, sizeof(pid_t) - s);
+                s += read(fd[0], ((uint8_t *)&child) + s, sizeof(pid_t) - s);
         }
         close(fd[0]);
         // cleanup child process
         waitpid(pid, NULL, 0);
-        if (*child > 0) {
-                wlr_log(L_DEBUG, "Child process created with pid %d", *child);
+        if (child > 0) {
+                wlr_log(L_DEBUG, "Child process created with pid %d", child);
                 // TODO: add PID to active workspace
         } else {
-                free(child);
+                return cmd_results_new(CMD_FAILURE, "exec_always",
+                        "Second fork() failed");
         }
 
         return cmd_results_new(CMD_SUCCESS, NULL, NULL);