X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=libudev%2Flibudev-monitor.c;h=31dd66827c674ee24d870b6e760ee5adbb1c40f1;hb=50579295272b744208519037c6931d1e6569e6f0;hp=c97f6faa653350489cdc5b907f26b53371a1b949;hpb=b4155660f2b60006816de5966d2b1859dc57ff6a;p=elogind.git

diff --git a/libudev/libudev-monitor.c b/libudev/libudev-monitor.c
index c97f6faa6..31dd66827 100644
--- a/libudev/libudev-monitor.c
+++ b/libudev/libudev-monitor.c
@@ -37,7 +37,7 @@
 /**
  * udev_monitor:
  *
- * Opaque object handling one event source.
+ * Opaque object handling an event source.
  */
 struct udev_monitor {
 	struct udev *udev;
@@ -50,6 +50,7 @@ struct udev_monitor {
 	socklen_t addrlen;
 	struct udev_list_node filter_subsystem_list;
 	struct udev_list_node filter_tag_list;
+	bool bound;
 };
 
 enum udev_monitor_netlink_group {
@@ -101,7 +102,12 @@ static struct udev_monitor *udev_monitor_new(struct udev *udev)
  * @udev: udev library context
  * @socket_path: unix socket path
  *
- * Create new udev monitor and connect to a specified socket. The
+ * This function should not be used in any new application. The
+ * kernel's netlink socket multiplexes messages to all interested
+ * clients. Creating custom sockets from udev to applications
+ * should be avoided.
+ *
+ * Create a new udev monitor and connect to a specified socket. The
  * path to a socket either points to an existing socket file, or if
  * the socket path starts with a '@' character, an abstract namespace
  * socket will be used.
@@ -116,7 +122,7 @@ static struct udev_monitor *udev_monitor_new(struct udev *udev)
  *
  * Returns: a new udev monitor, or #NULL, in case of an error
  **/
-struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
+UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char *socket_path)
 {
 	struct udev_monitor *udev_monitor;
 	struct stat statbuf;
@@ -144,7 +150,7 @@ struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char
 		util_strscpy(&udev_monitor->sun.sun_path[1], sizeof(udev_monitor->sun.sun_path)-1, socket_path);
 		udev_monitor->addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(socket_path)+1;
 	}
-	udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+	udev_monitor->sock = socket(AF_LOCAL, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
 	if (udev_monitor->sock == -1) {
 		err(udev, "error getting socket: %m\n");
 		free(udev_monitor);
@@ -155,32 +161,7 @@ struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char
 	return udev_monitor;
 }
 
-/**
- * udev_monitor_new_from_netlink:
- * @udev: udev library context
- * @name: name of event source
- *
- * Create new udev monitor and connect to a specified event
- * source. Valid sources identifiers are "udev" and "kernel".
- *
- * Applications should usually not connect directly to the
- * "kernel" events, because the devices might not be useable
- * at that time, before udev has configured them, and created
- * device nodes.
- *
- * Accessing devices at the same time as udev, might result
- * in unpredictable behavior.
- *
- * The "udev" events are sent out after udev has finished its
- * event processing, all rules have been processed, and needed
- * device nodes are created.
- *
- * The initial refcount is 1, and needs to be decremented to
- * release the resources of the udev monitor.
- *
- * Returns: a new udev monitor, or #NULL, in case of an error
- **/
-struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
+struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
 {
 	struct udev_monitor *udev_monitor;
 	unsigned int group;
@@ -201,11 +182,16 @@ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char
 	if (udev_monitor == NULL)
 		return NULL;
 
-	udev_monitor->sock = socket(PF_NETLINK, SOCK_DGRAM|SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT);
-	if (udev_monitor->sock == -1) {
-		err(udev, "error getting socket: %m\n");
-		free(udev_monitor);
-		return NULL;
+	if (fd < 0) {
+		udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
+		if (udev_monitor->sock == -1) {
+			err(udev, "error getting socket: %m\n");
+			free(udev_monitor);
+			return NULL;
+		}
+	} else {
+		udev_monitor->bound = true;
+		udev_monitor->sock = fd;
 	}
 
 	udev_monitor->snl.nl_family = AF_NETLINK;
@@ -219,6 +205,33 @@ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char
 	return udev_monitor;
 }
 
+/**
+ * udev_monitor_new_from_netlink:
+ * @udev: udev library context
+ * @name: name of event source
+ *
+ * Create new udev monitor and connect to a specified event
+ * source. Valid sources identifiers are "udev" and "kernel".
+ *
+ * Applications should usually not connect directly to the
+ * "kernel" events, because the devices might not be useable
+ * at that time, before udev has configured them, and created
+ * device nodes. Accessing devices at the same time as udev,
+ * might result in unpredictable behavior. The "udev" events
+ * are sent out after udev has finished its event processing,
+ * all rules have been processed, and needed device nodes are
+ * created.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the resources of the udev monitor.
+ *
+ * Returns: a new udev monitor, or #NULL, in case of an error
+ **/
+UDEV_EXPORT struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
+{
+	return udev_monitor_new_from_netlink_fd(udev, name, -1);
+}
+
 static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
 			    unsigned short code, unsigned int data)
 {
@@ -246,11 +259,12 @@ static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
  * udev_monitor_filter_update:
  * @udev_monitor: monitor
  *
- * Update the installed filter. This might only be needed, if the filter was removed or changed.
+ * Update the installed socket filter. This is only needed,
+ * if the filter was removed or changed.
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
+UDEV_EXPORT int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
 {
 	struct sock_filter ins[512];
 	struct sock_fprog filter;
@@ -362,18 +376,26 @@ int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
+UDEV_EXPORT int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
 {
-	int err;
+	int err = 0;
 	const int on = 1;
 
 	if (udev_monitor->sun.sun_family != 0) {
-		err = bind(udev_monitor->sock,
-			   (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
+		if (!udev_monitor->bound) {
+			err = bind(udev_monitor->sock,
+				   (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
+			if (err == 0)
+				udev_monitor->bound = true;
+		}
 	} else if (udev_monitor->snl.nl_family != 0) {
 		udev_monitor_filter_update(udev_monitor);
-		err = bind(udev_monitor->sock,
-			   (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
+		if (!udev_monitor->bound) {
+			err = bind(udev_monitor->sock,
+				   (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
+			if (err == 0)
+				udev_monitor->bound = true;
+		}
 		if (err == 0) {
 			struct sockaddr_nl snl;
 			socklen_t addrlen;
@@ -411,7 +433,7 @@ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
  *
  * Returns: 0 on success, otherwise -1 on error.
  */
-int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
+UDEV_EXPORT int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
 {
 	if (udev_monitor == NULL)
 		return -1;
@@ -435,7 +457,7 @@ int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
  *
  * Returns: the passed udev monitor
  **/
-struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
+UDEV_EXPORT struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
 {
 	if (udev_monitor == NULL)
 		return NULL;
@@ -452,7 +474,7 @@ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
  * will be released.
  *
  **/
-void udev_monitor_unref(struct udev_monitor *udev_monitor)
+UDEV_EXPORT void udev_monitor_unref(struct udev_monitor *udev_monitor)
 {
 	if (udev_monitor == NULL)
 		return;
@@ -475,7 +497,7 @@ void udev_monitor_unref(struct udev_monitor *udev_monitor)
  *
  * Returns: the udev library context
  **/
-struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
+UDEV_EXPORT struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
 {
 	if (udev_monitor == NULL)
 		return NULL;
@@ -490,7 +512,7 @@ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
  *
  * Returns: the socket file descriptor
  **/
-int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
+UDEV_EXPORT int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
 {
 	if (udev_monitor == NULL)
 		return -1;
@@ -542,16 +564,14 @@ tag:
  * Receive data from the udev monitor socket, allocate a new udev
  * device, fill in the received data, and return the device.
  *
- * Only socket connections with uid=0 are accepted. The caller
- * needs to make sure that there is data to read from the socket.
- * The call will block until the socket becomes readable.
+ * Only socket connections with uid=0 are accepted.
  *
  * The initial refcount is 1, and needs to be decremented to
  * release the resources of the udev device.
  *
  * Returns: a new udev device, or #NULL, in case of an error
  **/
-struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
+UDEV_EXPORT struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
 {
 	struct udev_device *udev_device;
 	struct msghdr smsg;
@@ -797,21 +817,21 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor,
  * @subsystem: the subsystem value to match the incoming devices against
  * @devtype: the devtype value to match the incoming devices against
  *
- * This filer is efficiently executed inside the kernel, and libudev subscribers
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
  * will usually not be woken up for devices which do not match.
  *
  * The filter must be installed before the monitor is switched to listening mode.
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
+UDEV_EXPORT int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
 {
 	if (udev_monitor == NULL)
 		return -EINVAL;
 	if (subsystem == NULL)
 		return -EINVAL;
 	if (udev_list_entry_add(udev_monitor->udev,
-				&udev_monitor->filter_subsystem_list, subsystem, devtype, 0, 0) == NULL)
+				&udev_monitor->filter_subsystem_list, subsystem, devtype, 0) == NULL)
 		return -ENOMEM;
 	return 0;
 }
@@ -821,21 +841,21 @@ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_mo
  * @udev_monitor: the monitor
  * @tag: the name of a tag
  *
- * This filer is efficiently executed inside the kernel, and libudev subscribers
+ * This filter is efficiently executed inside the kernel, and libudev subscribers
  * will usually not be woken up for devices which do not match.
  *
  * The filter must be installed before the monitor is switched to listening mode.
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
+UDEV_EXPORT int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
 {
 	if (udev_monitor == NULL)
 		return -EINVAL;
 	if (tag == NULL)
 		return -EINVAL;
 	if (udev_list_entry_add(udev_monitor->udev,
-				&udev_monitor->filter_tag_list, tag, NULL, 0, 0) == NULL)
+				&udev_monitor->filter_tag_list, tag, NULL, 0) == NULL)
 		return -ENOMEM;
 	return 0;
 }
@@ -848,7 +868,7 @@ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const c
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
+UDEV_EXPORT int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
 {
 	static struct sock_fprog filter = { 0, NULL };