libudev: add library to access udev information

1 files changed, 583 insertions, 0 deletions

diff --git a/udev/lib/libudev.c b/udev/lib/libudev.c
new file mode 100644
index 0000000000..098ca8f602
--- /dev/null
+++ b/udev/lib/libudev.c
@@ -0,0 +1,583 @@
+/*
+ * libudev - interface to udev device information
+ *
+ * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/stat.h>
+
+#include "libudev.h"
+#include "libudev-private.h"
+#include "../udev.h"
+
+void udev_log(struct udev *udev,
+	      int priority, const char *file, int line, const char *fn,
+	      const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	udev->log_fn(udev, priority, file, line, fn, format, args);
+	va_end(args);
+}
+
+static void log_stderr(struct udev *udev,
+		       int priority, const char *file, int line, const char *fn,
+		       const char *format, va_list args)
+{
+	static int log = -1;
+
+	if (log == -1) {
+		if (getenv("LIBUDEV_DEBUG") != NULL)
+			log = 1;
+		else
+			log = 0;
+	}
+
+	if (log == 1) {
+		fprintf(stderr, "libudev: %s: ", fn);
+		vfprintf(stderr, format, args);
+	}
+}
+
+/* glue to udev logging, needed until udev logging code is "fixed" */
+#ifdef USE_LOG
+void log_message(int priority, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	log_stderr(NULL, priority, NULL, 0, "", format, args);
+	va_end(args);
+}
+#endif
+
+static ssize_t get_subsystem(struct udev *udev, const char *devpath, char *subsystem, size_t size)
+{
+	char path[PATH_SIZE];
+	ssize_t len;
+	const char *pos;
+
+	strlcpy(path, udev_get_sys_path(udev), sizeof(path));
+	strlcat(path, devpath, sizeof(path));
+	strlcat(path, "/subsystem", sizeof(path));
+	len = readlink(path, path, sizeof(path));
+	if (len < 0 || len >= (ssize_t) sizeof(path))
+		return -1;
+	path[len] = '\0';
+	pos = strrchr(path, '/');
+	if (pos == NULL)
+		return -1;
+	pos = &pos[1];
+	return strlcpy(subsystem, pos, size);
+}
+
+/**
+ * udev_new:
+ *
+ * Create udev library context.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the ressources of the udev library context.
+ *
+ * Returns: a new udev library context
+ **/
+struct udev *udev_new(void)
+{
+	struct udev *udev;
+
+	udev = malloc(sizeof(struct udev));
+	if (udev == NULL)
+		return NULL;
+	memset(udev, 0x00, (sizeof(struct udev)));
+	udev->refcount = 1;
+	udev->log_fn = log_stderr;
+	udev_config_init();
+	sysfs_init();
+	log_info(udev, "context %p created\n", udev);
+	return udev;
+}
+
+/**
+ * udev_ref:
+ * @udev: udev library context
+ *
+ * Take a reference of the udev library context.
+ *
+ * Returns: the passed udev library context
+ **/
+struct udev *udev_ref(struct udev *udev)
+{
+	udev->refcount++;
+	return udev;
+}
+
+/**
+ * udev_unref:
+ * @udev: udev library context
+ *
+ * Drop a reference of the udev library context. If the refcount
+ * reaches zero, the ressources of the context will be released.
+ *
+ **/
+void udev_unref(struct udev *udev)
+{
+	udev->refcount--;
+	if (udev->refcount > 0)
+		return;
+	sysfs_cleanup();
+	log_info(udev, "context %p released\n", udev);
+	free(udev);
+}
+
+/**
+ * udev_set_log_fn:
+ * @udev: udev library context
+ * @log_fn: function to be called for logging messages
+ *
+ * The built-in logging, which writes to stderr if the
+ * LIBUDEV_DEBUG environment variable is set, can be
+ * overridden by a custom function, to plug log messages
+ * into the users logging functionality.
+ *
+ **/
+void udev_set_log_fn(struct udev *udev,
+		     void (*log_fn)(struct udev *udev,
+				    int priority, const char *file, int line, const char *fn,
+				    const char *format, va_list args))
+{
+	udev->log_fn = log_fn;
+	log_info(udev, "custom logging function %p registered\n", udev);
+}
+
+/**
+ * udev_get_sys_path:
+ * @udev: udev library context
+ *
+ * Retrieve the sysfs mount point. The default is "/sys". For
+ * testing purposes, it can be overridden with the environment
+ * variable SYSFS_PATH.
+ *
+ * Returns: the sys mount point
+ **/
+const char *udev_get_sys_path(struct udev *udev)
+{
+	return sysfs_path;
+}
+
+/**
+ * udev_get_dev_path:
+ * @udev: udev library context
+ *
+ * Retrieve the device directory path. The default value is "/dev",
+ * the actual value may be overridden in the udev configuration
+ * file.
+ *
+ * Returns: the device directory path
+ **/
+const char *udev_get_dev_path(struct udev *udev)
+{
+	return udev_root;
+}
+
+static struct udev_device *device_init(struct udev *udev)
+{
+	struct udev_device *udev_device;
+
+	udev_device = malloc(sizeof(struct udev_device));
+	if (udev_device == NULL)
+		return NULL;
+	memset(udev_device, 0x00, sizeof(struct udev_device));
+	udev_device->refcount = 1;
+	udev_device->udev = udev;
+	return udev_device;
+}
+
+/**
+ * udev_device_new_from_devpath:
+ * @udev: udev library context
+ * @devpath: sys device path
+ *
+ * Create new udev device, and fill in information from the sysfs
+ * device and the udev database entry. The devpath must not contain
+ * the sysfs mount path, and must contain a leading '/'.
+ *
+ * The initial refcount is 1, and needs to be decremented to
+ * release the ressources of the udev device.
+ *
+ * Returns: a new udev device, or #NULL, if it does not exist
+ **/
+struct udev_device *udev_device_new_from_devpath(struct udev *udev, const char *devpath)
+{
+	char path[PATH_SIZE];
+	struct stat statbuf;
+	struct udev_device *udev_device;
+	int err;
+
+	strlcpy(path, udev_get_sys_path(udev), sizeof(path));
+	strlcat(path, devpath, sizeof(path));
+	if (stat(path, &statbuf) != 0)
+		return NULL;
+	if (!S_ISDIR(statbuf.st_mode))
+		return NULL;
+
+	udev_device = device_init(udev);
+	if (udev_device == NULL)
+		return NULL;
+
+	udev_device->udevice = udev_device_init(NULL);
+	if (udev_device->udevice == NULL) {
+		free(udev_device);
+		return NULL;
+	}
+	log_info(udev, "device %p created\n", udev_device);
+
+	strlcpy(path, devpath, sizeof(path));
+	sysfs_resolve_link(path, sizeof(path));
+
+	err = udev_db_get_device(udev_device->udevice, path);
+	if (err >= 0)
+		log_info(udev, "device %p filled with udev database data\n", udev_device);
+	log_info(udev, "device %p filled with %s data\n", udev_device, udev_device_get_devpath(udev_device));
+	return udev_device;
+}
+
+/**
+ * udev_device_get_udev:
+ *
+ * Retrieve the udev library context the device was created with.
+ *
+ * Returns: the udev library context
+ **/
+struct udev *udev_device_get_udev(struct udev_device *udev_device)
+{
+	return udev_device->udev;
+}
+
+/**
+ * udev_device_ref:
+ * @udev_device: udev device
+ *
+ * Take a reference of a udev device.
+ *
+ * Returns: the passed udev device
+ **/
+struct udev_device *udev_device_ref(struct udev_device *udev_device)
+{
+	udev_device->refcount++;
+	return udev_device;
+}
+
+/**
+ * udev_device_unref:
+ * @udev_device: udev device
+ *
+ * Drop a reference of a udev device. If the refcount reaches zero,
+ * the ressources of the device will be released.
+ *
+ **/
+void udev_device_unref(struct udev_device *udev_device)
+{
+	udev_device->refcount--;
+	if (udev_device->refcount > 0)
+		return;
+	udev_device_cleanup(udev_device->udevice);
+	free(udev_device);
+}
+
+/**
+ * udev_device_get_devpath:
+ * @udev_device: udev device
+ *
+ * Retrieve the sys path of the udev device. The path does not contain
+ * the sys mount point.
+ *
+ * Returns: the sys path of the udev device
+ **/
+const char *udev_device_get_devpath(struct udev_device *udev_device)
+{
+	return udev_device->udevice->dev->devpath;
+}
+
+/**
+ * udev_device_get_devname:
+ * @udev_device: udev device
+ *
+ * Retrieve the device node file name belonging to the udev device.
+ * The path does not contain the device directory, and does not contain
+ * a leading '/'.
+ *
+ * Returns: the device node file name of the udev device, or #NULL if no device node exists
+ **/
+const char *udev_device_get_devname(struct udev_device *udev_device)
+{
+	if (udev_device->udevice->name[0] == '\0')
+		return NULL;
+	return udev_device->udevice->name;
+}
+
+/**
+ * udev_device_get_subsystem:
+ * @udev_device: udev device
+ *
+ * Retrieve the subsystem string of the udev device. The string does not
+ * contain any "/".
+ *
+ * Returns: the subsystem name of the udev device, or #NULL if it can not be determined
+ **/
+const char *udev_device_get_subsystem(struct udev_device *udev_device)
+{
+	struct sysfs_device *dev = udev_device->udevice->dev;
+	if (dev->subsystem[0] != '\0')
+		return dev->subsystem;
+	if (get_subsystem(udev_device->udev, dev->devpath,
+			  dev->subsystem, sizeof(dev->subsystem)) < 2)
+		return NULL;
+	return dev->subsystem;
+}
+
+/**
+ * udev_device_get_devlinks:
+ * @udev_device: udev device
+ * @cb: function to be called for every device link found
+ * @data: data to be passed to the function
+ *
+ * Retrieve the device links pointing to the device file of the
+ * udev device. For every device link, the passed function will be
+ * called with the device link string. If the function returns 1,
+ * remaning device links will be ignored. The device link path
+ * does not contain the device directory, and does not contain
+ * a leading '/'.
+ *
+ * Returns: the number of device links passed to the caller, or a negative value on error
+ **/
+int udev_device_get_devlinks(struct udev_device *udev_device,
+			      int (*cb)(struct udev_device *udev_device, const char *value, void *data),
+			      void *data)
+{
+	struct name_entry *name_loop;
+	int count = 0;
+
+	list_for_each_entry(name_loop, &udev_device->udevice->symlink_list, node) {
+		count++;
+		if (cb(udev_device, name_loop->name, data) != 0)
+			break;
+	}
+	return count;
+}
+
+/**
+ * udev_device_get_properties:
+ * @udev_device: udev device
+ * @cb: function to be called for every property found
+ * @data: data to be passed to the function
+ *
+ * Retrieve the property key/value pairs belonging to the
+ * udev device. For every key/value pair, the passed function will be
+ * called. If the function returns 1, remaning properties will be
+ * ignored.
+ *
+ * Returns: the number of properties passed to the caller, or a negative value on error
+ **/
+int udev_device_get_properties(struct udev_device *udev_device,
+				int (*cb)(struct udev_device *udev_device, const char *key, const char *value, void *data),
+				void *data)
+{
+	struct name_entry *name_loop;
+	int count = 0;
+
+	list_for_each_entry(name_loop, &udev_device->udevice->env_list, node) {
+		char name[PATH_SIZE];
+		char *val;
+
+		strncpy(name, name_loop->name, PATH_SIZE);
+		name[PATH_SIZE-1] = '\0';
+		val = strchr(name, '=');
+		if (val == NULL)
+			continue;
+		val[0] = '\0';
+		val = &val[1];
+		if (cb(udev_device, name, val, data) != 0)
+			break;
+	}
+	return count;
+}
+
+static int devices_scan_subsystem(struct udev *udev,
+				  const char *basedir, const char *subsystem, const char *subdir,
+				  struct list_head *device_list)
+{
+	char path[PATH_SIZE];
+	DIR *dir;
+	struct dirent *dent;
+	size_t len;
+
+	len = strlcpy(path, udev_get_sys_path(udev), sizeof(path));
+	strlcat(path, basedir, sizeof(path));
+	strlcat(path, "/", sizeof(path));
+	strlcat(path, subsystem, sizeof(path));
+	if (subdir != NULL)
+		strlcat(path, subdir, sizeof(path));
+	dir = opendir(path);
+	if (dir == NULL)
+		return -1;
+	for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
+		char devpath[PATH_SIZE];
+
+		if (dent->d_name[0] == '.')
+			continue;
+		strlcpy(devpath, &path[len], sizeof(devpath));
+		strlcat(devpath, "/", sizeof(devpath));
+		strlcat(devpath, dent->d_name, sizeof(devpath));
+		sysfs_resolve_link(devpath, sizeof(devpath));
+		name_list_add(device_list, devpath, 1);
+	}
+	closedir(dir);
+	return 0;
+}
+
+static int devices_scan_subsystems(struct udev *udev,
+				   const char *basedir, const char *subsystem, const char *subdir,
+				   struct list_head *device_list)
+{
+	char path[PATH_SIZE];
+	DIR *dir;
+	struct dirent *dent;
+
+	if (subsystem != NULL)
+		return devices_scan_subsystem(udev, basedir, subsystem, subdir, device_list);
+
+	strlcpy(path, udev_get_sys_path(udev), sizeof(path));
+	strlcat(path, basedir, sizeof(path));
+	dir = opendir(path);
+	if (dir == NULL)
+		return -1;
+	for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
+		if (dent->d_name[0] == '.')
+			continue;
+		devices_scan_subsystem(udev, basedir, dent->d_name, subdir, device_list);
+	}
+	closedir(dir);
+	return 0;
+}
+
+static int devices_delay(struct udev *udev, const char *devpath)
+{
+	static const char *delay_device_list[] = {
+		"/block/md",
+		"/block/dm-",
+		NULL
+	};
+	int i;
+
+	for (i = 0; delay_device_list[i] != NULL; i++) {
+		if (strstr(devpath, delay_device_list[i]) != NULL) {
+			log_info(udev, "delaying: %s\n", devpath);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+static int devices_call(struct udev *udev, const char *devpath,
+			int (*cb)(struct udev *udev,
+				  const char *devpath, const char *subsystem, const char *name,
+				  void *data),
+			void *data,
+			int *cb_rc)
+{
+	char subsystem[NAME_SIZE];
+	const char *name;
+
+	name = strrchr(devpath, '/');
+	if (name == NULL)
+		return -1;
+	name++;
+
+	if (get_subsystem(udev, devpath, subsystem, sizeof(subsystem)) < 2)
+		return -1;
+	*cb_rc = cb(udev, devpath, subsystem, name, data);
+	return 0;
+}
+
+/**
+ * udev_devices_enumerate:
+ * @udev_device: udev device
+ * @cb: function to be called for every property found
+ * @data: data to be passed to the function
+ *
+ * Retrieve the property key/value pairs belonging to the
+ * udev device. For every key/value pair, the passed function will be
+ * called. If the function returns 1, remaning properties will be
+ * ignored.
+ *
+ * Returns: the number of properties passed to the caller, or a negative value on error
+ **/
+int udev_devices_enumerate(struct udev *udev, const char *subsystem,
+			   int (*cb)(struct udev *udev,
+				     const char *devpath, const char *subsystem, const char *name, void *data),
+			   void *data)
+{
+	char base[PATH_SIZE];
+	struct stat statbuf;
+	struct list_head device_list;
+	struct name_entry *loop_device;
+	struct name_entry *tmp_device;
+	int cb_rc = 0;
+	int count = 0;
+
+	INIT_LIST_HEAD(&device_list);
+
+	/* if we have /sys/subsystem/, forget all the old stuff */
+	strlcpy(base, sysfs_path, sizeof(base));
+	strlcat(base, "/subsystem", sizeof(base));
+	if (stat(base, &statbuf) == 0) {
+		devices_scan_subsystems(udev, "/subsystem", subsystem, "/devices", &device_list);
+	} else {
+		devices_scan_subsystems(udev, "/bus", subsystem, "/devices", &device_list);
+		devices_scan_subsystems(udev, "/class", subsystem, NULL, &device_list);
+	}
+
+	list_for_each_entry_safe(loop_device, tmp_device, &device_list, node) {
+		if (devices_delay(udev, loop_device->name))
+			continue;
+		if (cb_rc == 0)
+			if (devices_call(udev, loop_device->name, cb, data, &cb_rc) == 0)
+				count++;
+		list_del(&loop_device->node);
+		free(loop_device);
+	}
+
+	/* handle remaining delayed devices */
+	list_for_each_entry_safe(loop_device, tmp_device, &device_list, node) {
+		if (cb_rc == 0)
+			if (devices_call(udev, loop_device->name, cb, data, &cb_rc) == 0)
+				count++;
+		list_del(&loop_device->node);
+		free(loop_device);
+	}
+
+	return count;
+}