Allow the use of posix_spawn() instead of vfork/execlp()

Backport of #7041

Co-authored-by: elahav <elahav@users.noreply.github.com>

include/SDL_config.h.cmake

@@ -262,6 +262,8 @@
 #cmakedefine HAVE_XINPUT_GAMEPAD_EX @HAVE_XINPUT_GAMEPAD_EX@
 #cmakedefine HAVE_XINPUT_STATE_EX @HAVE_XINPUT_STATE_EX@
 
+#cmakedefine USE_POSIX_SPAWN @USE_POSIX_SPAWN@
+
 /* SDL internal assertion support */
 #if @SDL_DEFAULT_ASSERT_LEVEL_CONFIGURED@
 #cmakedefine SDL_DEFAULT_ASSERT_LEVEL @SDL_DEFAULT_ASSERT_LEVEL@

src/misc/unix/SDL_sysurl.c

@@ -32,6 +32,18 @@ int SDL_SYS_OpenURL(const char *url)
 {
     const pid_t pid1 = fork();
     if (pid1 == 0) { /* child process */
+#ifdef USE_POSIX_SPAWN
+        pid_t pid2;
+        const char *args[] = { "xdg-open", url, NULL };
+        /* Clear LD_PRELOAD so Chrome opens correctly when this application is launched by Steam */
+        unsetenv("LD_PRELOAD");
+        if (posix_spawnp(&pid2, args[0], NULL, NULL, (char **)args, environ) == 0) {
+            /* Child process doesn't wait for possibly-blocking grandchild. */
+            _exit(EXIT_SUCCESS);
+        } else {
+            _exit(EXIT_FAILURE);
+        }
+#else
         pid_t pid2;
         /* Clear LD_PRELOAD so Chrome opens correctly when this application is launched by Steam */
         unsetenv("LD_PRELOAD");
@@ -46,6 +58,7 @@ int SDL_SYS_OpenURL(const char *url)
             /* Child process doesn't wait for possibly-blocking grandchild. */
             _exit(EXIT_SUCCESS);
         }
+#endif /* USE_POSIX_SPAWN */
     } else if (pid1 < 0) {
         return SDL_SetError("fork() failed: %s", strerror(errno));
     } else {