platform: setter/getter of /proc/sys and /sys options

src/platform/nm-fake-platform.c

@@ -29,6 +29,7 @@
 #define debug(format, ...) nm_log_dbg (LOGD_PLATFORM, format, __VA_ARGS__)
 
 typedef struct {
+	GHashTable *options;
 	GArray *links;
 	GArray *ip4_addresses;
 	GArray *ip6_addresses;
@@ -50,6 +51,24 @@ nm_fake_platform_setup (void)
 
 /******************************************************************/
 
+static gboolean
+sysctl_set (NMPlatform *platform, const char *path, const char *value)
+{
+	NMFakePlatformPrivate *priv = NM_FAKE_PLATFORM_GET_PRIVATE (platform);
+
+	g_hash_table_insert (priv->options, g_strdup (path), g_strdup (value));
+
+	return TRUE;
+}
+
+static char *
+sysctl_get (NMPlatform *platform, const char *path)
+{
+	NMFakePlatformPrivate *priv = NM_FAKE_PLATFORM_GET_PRIVATE (platform);
+
+	return g_strdup (g_hash_table_lookup (priv->options, path));
+}
+
 static void
 link_init (NMPlatformLink *device, int ifindex, int type, const char *name)
 {
@@ -735,6 +754,7 @@ nm_fake_platform_init (NMFakePlatform *fake_platform)
 {
 	NMFakePlatformPrivate *priv = NM_FAKE_PLATFORM_GET_PRIVATE (fake_platform);
 
+	priv->options = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);
 	priv->links = g_array_new (TRUE, TRUE, sizeof (NMPlatformLink));
 	priv->ip4_addresses = g_array_new (TRUE, TRUE, sizeof (NMPlatformIP4Address));
 	priv->ip6_addresses = g_array_new (TRUE, TRUE, sizeof (NMPlatformIP6Address));
@@ -764,6 +784,7 @@ nm_fake_platform_finalize (GObject *object)
 {
 	NMFakePlatformPrivate *priv = NM_FAKE_PLATFORM_GET_PRIVATE (object);
 
+	g_hash_table_unref (priv->options);
 	g_array_unref (priv->links);
 	g_array_unref (priv->ip4_addresses);
 	g_array_unref (priv->ip6_addresses);
@@ -786,6 +807,9 @@ nm_fake_platform_class_init (NMFakePlatformClass *klass)
 
 	platform_class->setup = setup;
 
+	platform_class->sysctl_set = sysctl_set;
+	platform_class->sysctl_get = sysctl_get;
+
 	platform_class->link_get_all = link_get_all;
 	platform_class->link_add = link_add;
 	platform_class->link_delete = link_delete;

src/platform/nm-linux-platform.c

@@ -22,6 +22,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <sys/socket.h>
+#include <fcntl.h>
 #include <netinet/icmp6.h>
 #include <netinet/in.h>
 #include <linux/if_arp.h>
@@ -725,6 +726,70 @@ event_notification (struct nl_msg *msg, gpointer user_data)
 
 /******************************************************************/
 
+static gboolean
+sysctl_set (NMPlatform *platform, const char *path, const char *value)
+{
+	int fd, len, nwrote, tries;
+	char *actual;
+
+	g_return_val_if_fail (path != NULL, FALSE);
+	g_return_val_if_fail (value != NULL, FALSE);
+
+	fd = open (path, O_WRONLY | O_TRUNC);
+	if (fd == -1) {
+		error ("sysctl: failed to open '%s': (%d) %s",
+				path, errno, strerror (errno));
+		return FALSE;
+	}
+
+	debug ("sysctl: setting '%s' to '%s'", path, value);
+
+	/* Most sysfs and sysctl options don't care about a trailing LF, while some
+	 * (like infiniband) do.  So always add the LF.  Also, neither sysfs nor
+	 * sysctl support partial writes so the LF must be added to the string we're
+	 * about to write.
+	 */
+	actual = g_strdup_printf ("%s\n", value);
+
+	/* Try to write the entire value three times if a partial write occurs */
+	len = strlen (actual);
+	for (tries = 0, nwrote = 0; tries < 3 && nwrote != len; tries++) {
+		errno = 0;
+		nwrote = write (fd, actual, len);
+		if (nwrote == -1) {
+			if (errno == EINTR) {
+				error ("sysctl: interrupted, will try again");
+				continue;
+			}
+			break;
+		}
+	}
+	if (nwrote != len && errno != EEXIST) {
+		error ("sysctl: failed to set '%s' to '%s': (%d) %s",
+		             path, value, errno, strerror (errno));
+	}
+
+	g_free (actual);
+	close (fd);
+	return (nwrote == len);
+}
+
+static char *
+sysctl_get (NMPlatform *platform, const char *path)
+{
+	GError *error = NULL;
+	char *contents;
+
+	if (!g_file_get_contents (path, &contents, NULL, &error)) {
+		error ("error reading %s: %s", path, error->message);
+		return NULL;
+	}
+
+	return g_strstrip (contents);
+}
+
+/******************************************************************/
+
 static GArray *
 link_get_all (NMPlatform *platform)
 {
@@ -1450,6 +1515,9 @@ nm_linux_platform_class_init (NMLinuxPlatformClass *klass)
 
 	platform_class->setup = setup;
 
+	platform_class->sysctl_set = sysctl_set;
+	platform_class->sysctl_get = sysctl_get;
+
 	platform_class->link_get_all = link_get_all;
 	platform_class->link_add = link_add;
 	platform_class->link_delete = link_delete;

src/platform/nm-platform.c

@@ -23,6 +23,7 @@
 #include <unistd.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
+#include <string.h>
 
 #include "nm-platform.h"
 #include "nm-logging.h"
@@ -175,6 +176,54 @@ reset_error (void)
 
 /******************************************************************/
 
+/**
+ * nm_platform_sysctl_set:
+ * @path: Absolute option path
+ * @value: Value to write
+ *
+ * This function is intended to be used for writing values to sysctl-style
+ * virtual runtime configuration files. This includes not only /proc/sys
+ * but also for example /sys/class.
+ *
+ * Returns: %TRUE on success.
+ */
+gboolean
+nm_platform_sysctl_set (const char *path, const char *value)
+{
+	reset_error ();
+
+	g_return_val_if_fail (path, FALSE);
+	g_return_val_if_fail (value, FALSE);
+	g_return_val_if_fail (klass->sysctl_set, FALSE);
+
+	/* Don't write outside known locations */
+	g_assert (g_str_has_prefix (path, "/proc/sys")
+			|| g_str_has_prefix (path, "/sys"));
+	/* Don't write to suspicious locations */
+	g_assert (!strstr (path, ".."));
+
+	return klass->sysctl_set (platform, path, value);
+}
+
+/**
+ * nm_platform_sysctl_get:
+ * @path: Absolute path to sysctl
+ *
+ * Returns: (transfer full): Contents of the virtual sysctl file.
+ */
+char *
+nm_platform_sysctl_get (const char *path)
+{
+	reset_error ();
+
+	g_return_val_if_fail (path, NULL);
+	g_return_val_if_fail (klass->sysctl_get, NULL);
+
+	return klass->sysctl_get (platform, path);
+}
+
+/******************************************************************/
+
 /**
  * nm_platform_link_get_all:
  *

src/platform/nm-platform.h

@@ -125,6 +125,9 @@ typedef struct {
 
 	gboolean (*setup) (NMPlatform *);
 
+	gboolean (*sysctl_set) (NMPlatform *, const char *path, const char *value);
+	char * (*sysctl_get) (NMPlatform *, const char *path);
+
 	GArray *(*link_get_all) (NMPlatform *);
 	gboolean (*link_add) (NMPlatform *, const char *name, NMLinkType type);
 	gboolean (*link_delete) (NMPlatform *, int ifindex);
@@ -224,6 +227,9 @@ void nm_platform_free (void);
 int nm_platform_get_error (void);
 const char *nm_platform_get_error_msg (void);
 
+gboolean nm_platform_sysctl_set (const char *path, const char *value);
+char *nm_platform_sysctl_get (const char *path);
+
 GArray *nm_platform_link_get_all (void);
 gboolean nm_platform_dummy_add (const char *name);
 gboolean nm_platform_bridge_add (const char *name);