[gnome-software: 3/8] gs-plugin-loader: Disable job timeouts if running under gdb

[Milan Crha <mcrha src gnome org>]

commit 87a2ad54507bd9315548a11bb8b7b96266b0e22b
Author: Philip Withnall <pwithnall endlessos org>
Date:   Mon Dec 6 13:44:58 2021 +0000

    gs-plugin-loader: Disable job timeouts if running under gdb
    
    They’re very disruptive to debugging sessions.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>

 lib/gs-plugin-loader.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
---
diff --git a/lib/gs-plugin-loader.c b/lib/gs-plugin-loader.c
index ef8ccac82..786a9db9a 100644
--- a/lib/gs-plugin-loader.c
+++ b/lib/gs-plugin-loader.c
@@ -3768,11 +3768,61 @@ gs_plugin_loader_process_in_thread_pool_cb (gpointer data,
        g_object_unref (task);
 }
 
+/* This needs to err on the side of being fast, rather than perfectly accurate.
+ * False positives (saying the program is running under gdb when it isn’t) are
+ * not OK. False negatives (saying the program is not running under gdb when it
+ * is) are OK. */
+static gboolean
+is_running_under_gdb (void)
+{
+       g_autofree gchar *status = NULL;
+       gsize status_len = 0;
+       const gchar *tracer_pid, *end;
+
+       /* Look for a line of the form:
+        * ```
+        * TracerPid:   748899
+        * ```
+        * or
+        * ```
+        * TracerPid:   0
+        * ```
+        * in `/proc/self/status`. If it’s 0, the process is not being traced. */
+       if (!g_file_get_contents ("/proc/self/status", &status, &status_len, NULL))
+               return FALSE;
+
+       tracer_pid = g_strstr_len (status, status_len, "TracerPid:");
+       if (tracer_pid == NULL)
+               return FALSE;
+
+       end = status + status_len;
+
+       /* Find the number. */
+       for (tracer_pid += strlen ("TracerPid:");
+            tracer_pid < end &&
+            g_ascii_isspace (*tracer_pid);
+            tracer_pid++);
+
+       if (tracer_pid >= end)
+               return FALSE;
+
+       return (*tracer_pid != '0');
+}
+
 static gboolean
 gs_plugin_loader_job_timeout_cb (gpointer user_data)
 {
        GsPluginLoaderHelper *helper = (GsPluginLoaderHelper *) user_data;
 
+       /* Don’t impose timeouts if running under gdb. */
+       if (is_running_under_gdb ()) {
+               g_debug ("Not cancelling job %s even though it took longer "
+                        "than %u seconds, as running under gdb",
+                        helper->function_name,
+                        gs_plugin_job_get_timeout (helper->plugin_job));
+               return G_SOURCE_REMOVE;
+       }
+
        /* call the cancellable */
        g_debug ("cancelling job %s as it took longer than %u seconds",
                 helper->function_name,