foot/footclient: use a custom exit code when foot/footclient fail to run

Normally, foot and footclient uses the exit code from the client
application (i.e. the shell).

However, foot (or footclient) itself may fail to run; if run outside
of a Wayland session, or no fonts are installed, or the client
application/shell cannot be found (“foot lsdjfldsjf”) etc.

Up until now, there has been no way to differentiate these kind of
failures from the client application exiting with code 1.

This patch changes foot’s failure exit code to -27/229, and
footclient’s to -28/228. Note that footclient will exit with foot’s
-27/229 if footclient ran successfully, but the foot server failed to
instantiate a new window.

Closes #466.

CHANGELOG.md

@@ -51,6 +51,12 @@
 * Point values in `line-height`, `letter-spacing`,
   `horizontal-letter-offset` and `vertical-letter-offset` are now
   rounded, not truncated, when translated to pixel values.
+* Foot’s exit code is now -27/229 when foot itself failed to launch
+  (due to invalid command line options, client application/shell not
+  found etc). Footclient’s exit code is -28/228 when it itself fails
+  to launch (e.g. bad command line option) and -27/229 when the foot
+  server failed to instantiate a new window
+  (https://codeberg.org/dnkl/foot/issues/466).
 
 
 ### Deprecated

client.c

@@ -69,7 +69,10 @@ print_usage(const char *prog_name)
 int
 main(int argc, char *const *argv)
 {
-    int ret = EXIT_FAILURE;
+    /* Custom exit code, to enable users to differentiate between foot
+     * itself failing, and the client application failiing */
+    static const int foot_exit_failure = -28;
+    int ret = foot_exit_failure;
 
     const char *const prog_name = argv[0];
 
@@ -135,7 +138,7 @@ main(int argc, char *const *argv)
             struct stat st;
             if (stat(optarg, &st) < 0 || !(st.st_mode & S_IFDIR)) {
                 fprintf(stderr, "error: %s: not a directory\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             custom_cwd = optarg;
             break;
@@ -144,7 +147,7 @@ main(int argc, char *const *argv)
         case 'w':
             if (sscanf(optarg, "%ux%u", &width, &height) != 2 || width == 0 || height == 0) {
                 fprintf(stderr, "error: invalid window-size-pixels: %s\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             size_type = 0; // CONF_SIZE_PX
             break;
@@ -152,7 +155,7 @@ main(int argc, char *const *argv)
         case 'W':
             if (sscanf(optarg, "%ux%u", &width, &height) != 2 || width == 0 || height == 0) {
                 fprintf(stderr, "error: invalid window-size-chars: %s\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             size_type = 1; // CONF_SIZE_CELLS
             break;
@@ -187,7 +190,7 @@ main(int argc, char *const *argv)
                     "-d,--log-level: %s: argument must be one of %s\n",
                     optarg,
                     log_level_string_hint());
-                return EXIT_FAILURE;
+                return ret;
             }
             log_level = lvl;
             break;
@@ -202,7 +205,7 @@ main(int argc, char *const *argv)
                 log_colorize = LOG_COLORIZE_ALWAYS;
             else {
                 fprintf(stderr, "%s: argument must be one of 'never', 'always' or 'auto'\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             break;
 
@@ -215,7 +218,7 @@ main(int argc, char *const *argv)
             return EXIT_SUCCESS;
 
         case '?':
-            return EXIT_FAILURE;
+            return ret;
         }
     }
 
@@ -373,6 +376,8 @@ main(int argc, char *const *argv)
     int exit_code;
     ssize_t rcvd = recv(fd, &exit_code, sizeof(exit_code), 0);
 
+    LOG_INFO("exit-code=%d", exit_code);
+
     if (rcvd == -1 && errno == EINTR)
         xassert(aborted);
     else if (rcvd != sizeof(exit_code))

main.c

@@ -151,7 +151,10 @@ print_pid(const char *pid_file, bool *unlink_at_exit)
 int
 main(int argc, char *const *argv)
 {
-    int ret = EXIT_FAILURE;
+    /* Custom exit code, to enable users to differentiate between foot
+     * itself failing, and the client application failiing */
+    static const int foot_exit_failure = -27;
+    int ret = foot_exit_failure;
 
     /* Startup notifications; we don't support it, but must ensure we
      * don't pass this on to programs launched by us */
@@ -242,7 +245,7 @@ main(int argc, char *const *argv)
             struct stat st;
             if (stat(optarg, &st) < 0 || !(st.st_mode & S_IFDIR)) {
                 fprintf(stderr, "error: %s: not a directory\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             custom_cwd = optarg;
             break;
@@ -274,7 +277,7 @@ main(int argc, char *const *argv)
             unsigned width, height;
             if (sscanf(optarg, "%ux%u", &width, &height) != 2 || width == 0 || height == 0) {
                 fprintf(stderr, "error: invalid window-size-pixels: %s\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
 
             conf_size_type = CONF_SIZE_PX;
@@ -287,7 +290,7 @@ main(int argc, char *const *argv)
             unsigned width, height;
             if (sscanf(optarg, "%ux%u", &width, &height) != 2 || width == 0 || height == 0) {
                 fprintf(stderr, "error: invalid window-size-chars: %s\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
 
             conf_size_type = CONF_SIZE_CELLS;
@@ -332,7 +335,7 @@ main(int argc, char *const *argv)
                     "-d,--log-level: %s: argument must be one of %s\n",
                     optarg,
                     log_level_string_hint());
-                return EXIT_FAILURE;
+                return ret;
             }
             log_level = lvl;
             break;
@@ -347,7 +350,7 @@ main(int argc, char *const *argv)
                 log_colorize = LOG_COLORIZE_ALWAYS;
             else {
                 fprintf(stderr, "%s: argument must be one of 'never', 'always' or 'auto'\n", optarg);
-                return EXIT_FAILURE;
+                return ret;
             }
             break;
 
@@ -364,7 +367,7 @@ main(int argc, char *const *argv)
             return EXIT_SUCCESS;
 
         case '?':
-            return EXIT_FAILURE;
+            return ret;
         }
     }
 
@@ -464,7 +467,7 @@ main(int argc, char *const *argv)
     struct renderer *renderer = NULL;
     struct terminal *term = NULL;
     struct server *server = NULL;
-    struct shutdown_context shutdown_ctx = {.term = &term, .exit_code = EXIT_FAILURE};
+    struct shutdown_context shutdown_ctx = {.term = &term, .exit_code = foot_exit_failure};
 
     const char *cwd = custom_cwd;
     char *_cwd = NULL;
@@ -533,7 +536,8 @@ main(int argc, char *const *argv)
             break;
     }
 
-    ret = aborted || tll_length(wayl->terms) == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+    if (aborted || tll_length(wayl->terms) == 0)
+        ret = EXIT_SUCCESS;
 
 out:
     free(_cwd);

server.c

@@ -312,7 +312,7 @@ fdm_client(struct fdm *fdm, int fd, int events, void *data)
 
     if (instance->terminal == NULL) {
         LOG_ERR("failed to instantiate new terminal");
-        client_send_exit_code(client, -1);
+        client_send_exit_code(client, -27);
         instance_destroy(instance, -1);
         goto shutdown;
     }
@@ -497,7 +497,7 @@ server_destroy(struct server *server)
             tll_length(server->clients));
 
     tll_foreach(server->clients, it) {
-        client_send_exit_code(it->item, 1);
+        client_send_exit_code(it->item, -27);
         client_destroy(it->item);
     }