From 55c5cfab46c27586050e5b417b7b5ec9a748ac39 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Thu, 9 May 2019 19:14:58 +0200
Subject: [PATCH] main: add -c,--check-config

When this option is used, we exit after loading the
configuration. Either with an error message and a non-zero exit
code (bad config), or no messages and a zero exit code (good config).
---
 doc/f00bar.1.scd |  5 +++++
 main.c           | 18 ++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/doc/f00bar.1.scd b/doc/f00bar.1.scd
index 6116021..d8f8751 100644
--- a/doc/f00bar.1.scd
+++ b/doc/f00bar.1.scd
@@ -8,6 +8,11 @@ f00bar - modular status panel for X11 and Wayland
 
 # OPTIONS
 
+*-c, --check-config*
+	Verify the configuration and then quit. If no errors are detected,
+	nothing is printed and the exit code is 0. If there are errors,
+	these are printed on stdout and the exit code is non-zero.
+
 *-v, --version*
 	Show the version number and quit
 
diff --git a/main.c b/main.c
index 50d9804..d7a3c83 100644
--- a/main.c
+++ b/main.c
@@ -124,7 +124,8 @@ print_usage(const char *prog_name)
     printf("Usage: %s [OPTION]...\n", prog_name);
     printf("\n");
     printf("Options:\n");
-    printf("  -v,--version               print f00sel version and quit\n");
+    printf("  -c,--check-config          verify configuration then quit\n"
+           "  -v,--version               print f00sel version and quit\n");
 }
 
 int
@@ -133,17 +134,24 @@ main(int argc, char *const *argv)
     setlocale(LC_ALL, "");
 
     static const struct option longopts[] = {
+        {"check-config",     no_argument,       0, 'c'},
         {"version",          no_argument,       0, 'v'},
         {"help",             no_argument,       0, 'h'},
         {NULL,               no_argument,       0, 0},
     };
 
+    bool verify_config = false;
+
     while (true) {
-        int c = getopt_long(argc, argv, ":vh", longopts, NULL);
+        int c = getopt_long(argc, argv, ":cvh", longopts, NULL);
         if (c == -1)
             break;
 
         switch (c) {
+        case 'c':
+            verify_config = true;
+            break;
+
         case 'v':
             printf("f00bar version %s\n", F00BAR_VERSION);
             return EXIT_SUCCESS;
@@ -194,6 +202,12 @@ main(int argc, char *const *argv)
         return 1;
     }
 
+    if (verify_config) {
+        bar->destroy(bar);
+        close(abort_fd);
+        return 0;
+    }
+
     bar->abort_fd = abort_fd;
 
     thrd_t bar_thread;