[gnome-software/mwleeds/honor-g-messages-debug: 1/2] Honor G_MESSAGES_DEBUG env var

[Phaedrus Leeds <mwleeds src gnome org>]

commit 4c633a14d5468a2989c6a66884288cd8cb630ef6
Author: Phaedrus Leeds <mwleeds endlessos org>
Date:   Wed Feb 17 11:46:48 2021 -0800

    Honor G_MESSAGES_DEBUG env var
    
    Instead of requiring the --verbose command line argument, also respect
    the G_MESSAGES_DEBUG environment variable, as is standard for GLib-based
    applications.

 lib/gs-debug.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)
---
diff --git a/lib/gs-debug.c b/lib/gs-debug.c
index af278495b..c269f6bb6 100644
--- a/lib/gs-debug.c
+++ b/lib/gs-debug.c
@@ -30,15 +30,22 @@ gs_log_writer_console (GLogLevelFlags log_level,
                       gpointer user_data)
 {
        GsDebug *debug = GS_DEBUG (user_data);
+       const gchar *domains = NULL;
+       const gchar *gs_debug = NULL;
        const gchar *log_domain = NULL;
        const gchar *log_message = NULL;
        g_autofree gchar *tmp = NULL;
        g_autoptr(GMutexLocker) locker = NULL;
        g_autoptr(GString) domain = NULL;
 
-       /* enabled */
-       if (g_getenv ("GS_DEBUG") == NULL &&
-           log_level == G_LOG_LEVEL_DEBUG)
+       domains = g_getenv ("G_MESSAGES_DEBUG");
+       gs_debug = g_getenv ("GS_DEBUG");
+
+       /* check enabled, fast path without parsing fields */
+       if ((log_level == G_LOG_LEVEL_DEBUG ||
+            log_level == G_LOG_LEVEL_INFO) &&
+           gs_debug == NULL &&
+           (domains == NULL || *domains == '\0'))
                return G_LOG_WRITER_HANDLED;
 
        /* get data from arguments */
@@ -53,6 +60,15 @@ gs_log_writer_console (GLogLevelFlags log_level,
                }
        }
 
+       /* check enabled, slower path */
+       if ((log_level == G_LOG_LEVEL_DEBUG ||
+            log_level == G_LOG_LEVEL_INFO) &&
+           gs_debug == NULL &&
+           domains != NULL &&
+           g_strcmp0 (domains, "all") != 0 &&
+           (log_domain == NULL || !strstr (domains, log_domain)))
+               return G_LOG_WRITER_HANDLED;
+
        /* this is really verbose */
        if ((g_strcmp0 (log_domain, "dconf") == 0 ||
             g_strcmp0 (log_domain, "GLib-GIO") == 0 ||