core: add configuration main.debug and interpret environment variable NM_DEBUG

Interpret the configuration option main.debug and the
environment variable NM_DEBUG as a comma separated list
of debugging options (parsed with g_parse_debug_string()).

Currently only the option "RLIMIT_CORE" is supported, to set
the core dump size to unlimited.

Signed-off-by: Thomas Haller <thaller@redhat.com>

man/NetworkManager.conf.xml

@@ -207,6 +207,20 @@ Copyright (C) 2010 - 2013 Red Hat, Inc.
 	modify resolv.conf.</para>
 	</listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><varname>debug</varname></term>
+        <listitem><para>Comma separated list of options to aid
+        debugging. This value will be combined with the environment
+        variable <literal>NM_DEBUG</literal>. Currently the following
+        values are supported:</para>
+        <para>
+          <literal>RLIMIT_CORE</literal>: set ulimit -c unlimited
+          to write out core dumps.
+        </para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
   </refsect1>
 

src/config/nm-config.c

@@ -51,6 +51,8 @@ typedef struct {
 	char *log_level;
 	char *log_domains;
 
+	char *debug;
+
 	char *connectivity_uri;
 	gint connectivity_interval;
 	char *connectivity_response;
@@ -131,6 +133,14 @@ nm_config_get_log_domains (NMConfig *config)
 	return NM_CONFIG_GET_PRIVATE (config)->log_domains;
 }
 
+const char *
+nm_config_get_debug (NMConfig *config)
+{
+	g_return_val_if_fail (config != NULL, NULL);
+
+	return NM_CONFIG_GET_PRIVATE (config)->debug;
+}
+
 const char *
 nm_config_get_connectivity_uri (NMConfig *config)
 {
@@ -519,6 +529,8 @@ nm_config_new (GError **error)
 	priv->log_level = g_key_file_get_value (priv->keyfile, "logging", "level", NULL);
 	priv->log_domains = g_key_file_get_value (priv->keyfile, "logging", "domains", NULL);
 
+	priv->debug = g_key_file_get_value (priv->keyfile, "main", "debug", NULL);
+
 	if (cli_connectivity_uri && cli_connectivity_uri[0])
 		g_key_file_set_value (priv->keyfile, "connectivity", "uri", cli_connectivity_uri);
 	priv->connectivity_uri = g_key_file_get_value (priv->keyfile, "connectivity", "uri", NULL);
@@ -562,6 +574,7 @@ finalize (GObject *gobject)
 	g_free (priv->dns_mode);
 	g_free (priv->log_level);
 	g_free (priv->log_domains);
+	g_free (priv->debug);
 	g_free (priv->connectivity_uri);
 	g_free (priv->connectivity_response);
 	g_strfreev (priv->no_auto_default);

src/config/nm-config.h

@@ -56,6 +56,7 @@ const char *nm_config_get_dhcp_client (NMConfig *config);
 const char *nm_config_get_dns_mode (NMConfig *config);
 const char *nm_config_get_log_level (NMConfig *config);
 const char *nm_config_get_log_domains (NMConfig *config);
+const char *nm_config_get_debug (NMConfig *config);
 const char *nm_config_get_connectivity_uri (NMConfig *config);
 const guint nm_config_get_connectivity_interval (NMConfig *config);
 const char *nm_config_get_connectivity_response (NMConfig *config);

src/main.c

@@ -37,6 +37,7 @@
 #include <glib/gi18n.h>
 #include <gmodule.h>
 #include <string.h>
+#include <sys/resource.h>
 
 #include "libgsystem.h"
 #include "NetworkManager.h"
@@ -293,6 +294,37 @@ parse_state_file (const char *filename,
 	return TRUE;
 }
 
+static void
+_init_nm_debug (const char *debug)
+{
+	const guint D_RLIMIT_CORE = 1;
+	GDebugKey keys[] = {
+		{ "RLIMIT_CORE", D_RLIMIT_CORE },
+	};
+	guint flags = 0;
+	const char *env = getenv ("NM_DEBUG");
+
+	if (env && strcasecmp (env, "help") != 0) {
+		/* g_parse_debug_string() prints options to stderr if the variable
+		 * is set to "help". Don't allow that. */
+		flags = g_parse_debug_string (env,  keys, G_N_ELEMENTS (keys));
+	}
+
+	if (debug && strcasecmp (debug, "help") != 0)
+		flags |= g_parse_debug_string (debug,  keys, G_N_ELEMENTS (keys));
+
+	if (flags & D_RLIMIT_CORE) {
+		/* only enable this, if explicitly requested, because it might
+		 * expose sensitive data. */
+
+		struct rlimit limit = {
+			.rlim_cur = RLIM_INFINITY,
+			.rlim_max = RLIM_INFINITY,
+		};
+		setrlimit (RLIMIT_CORE, &limit);
+	}
+}
+
 /*
  * main
  *
@@ -516,6 +548,8 @@ main (int argc, char *argv[])
 			wrote_pidfile = TRUE;
 	}
 
+	_init_nm_debug (nm_config_get_debug (config));
+
 	/* Set up unix signal handling - before creating threads, but after daemonizing! */
 	if (!setup_signals ())
 		exit (1);