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

[Phaedrus Leeds <mwleeds src gnome org>]

commit 0e752fd9c781b2129aaeec5d1fef4ec6bdfd8f21
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, 17 insertions(+), 5 deletions(-)
---
diff --git a/lib/gs-debug.c b/lib/gs-debug.c
index af278495b..a9ce19865 100644
--- a/lib/gs-debug.c
+++ b/lib/gs-debug.c
@@ -30,17 +30,14 @@ 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)
-               return G_LOG_WRITER_HANDLED;
-
        /* get data from arguments */
        for (gsize i = 0; i < n_fields; i++) {
                if (g_strcmp0 (fields[i].key, "MESSAGE") == 0) {
@@ -53,6 +50,21 @@ gs_log_writer_console (GLogLevelFlags log_level,
                }
        }
 
+       domains = g_getenv ("G_MESSAGES_DEBUG");
+       gs_debug = g_getenv ("GS_DEBUG");
+
+       /* enabled */
+       if ((log_level == G_LOG_LEVEL_DEBUG ||
+            log_level == G_LOG_LEVEL_INFO) &&
+           gs_debug == NULL) {
+               if (domains == NULL || *domains == '\0')
+                       return G_LOG_WRITER_HANDLED;
+
+               if (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 ||