libudev: allow to get list of all available sysfs attrs for a device

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>

diff --git a/libudev/exported_symbols b/libudev/exported_symbols
index 2e6a9b7dc0a4da5dac4c01849b603a2bfcead49a..500e981586b44f1be257683343b3f7fa150e8dcf 100644 (file)
--- a/libudev/exported_symbols
+++ b/libudev/exported_symbols
@@ -32,6 +32,7 @@ udev_device_get_is_initialized
 udev_device_get_devlinks_list_entry
 udev_device_get_properties_list_entry
 udev_device_get_tags_list_entry
+udev_device_get_sysattr_list_entry
 udev_device_get_property_value
 udev_device_get_action
 udev_device_get_driver

diff --git a/libudev/libudev-device.c b/libudev/libudev-device.c
index 16bee19dff4cca9463aab0b24e44fd593d1d12e0..af0bc2e5a3e457a49e827dcd7b586963e6b93c14 100644 (file)
--- a/libudev/libudev-device.c
+++ b/libudev/libudev-device.c
@@ -61,6 +61,7 @@ struct udev_device {
        struct udev_list_node devlinks_list;
        struct udev_list_node properties_list;
        struct udev_list_node sysattr_list;
+       struct udev_list_node available_sysattr_list;
        struct udev_list_node tags_list;
        unsigned long long int seqnum;
        unsigned long long int usec_initialized;
@@ -83,6 +84,7 @@ struct udev_device {
        bool db_loaded;
        bool uevent_loaded;
        bool is_initialized;
+       bool sysattrs_cached;
 };
 
 struct udev_list_entry *udev_device_add_property(struct udev_device *udev_device, const char *key, const char *value)
@@ -361,6 +363,7 @@ struct udev_device *udev_device_new(struct udev *udev)
        udev_list_init(&udev_device->devlinks_list);
        udev_list_init(&udev_device->properties_list);
        udev_list_init(&udev_device->sysattr_list);
+       udev_list_init(&udev_device->available_sysattr_list);
        udev_list_init(&udev_device->tags_list);
        udev_device->event_timeout = -1;
        udev_device->watch_handle = -1;
@@ -785,6 +788,7 @@ void udev_device_unref(struct udev_device *udev_device)
        udev_list_cleanup_entries(udev_device->udev, &udev_device->devlinks_list);
        udev_list_cleanup_entries(udev_device->udev, &udev_device->properties_list);
        udev_list_cleanup_entries(udev_device->udev, &udev_device->sysattr_list);
+       udev_list_cleanup_entries(udev_device->udev, &udev_device->available_sysattr_list);
        udev_list_cleanup_entries(udev_device->udev, &udev_device->tags_list);
        free(udev_device->action);
        free(udev_device->driver);
@@ -1235,6 +1239,83 @@ out:
        return val;
 }
 
+static int udev_device_cache_sysattrs(struct udev_device *udev_device)
+{
+       struct dirent *entry;
+       DIR *dir;
+       int num = 0;
+
+       if (udev_device == NULL)
+               return -1;
+       /* caching already done? */
+       if (udev_device->sysattrs_cached)
+               return 0;
+
+       dir = opendir(udev_device_get_syspath(udev_device));
+       if (!dir) {
+               dbg(udev_device->udev, "sysfs dir '%s' can not be opened\n",
+                               udev_device_get_syspath(udev_device));
+               return -1;
+       }
+
+       while (NULL != (entry = readdir(dir))) {
+               char path[UTIL_PATH_SIZE];
+               struct stat statbuf;
+
+               /* only handle symlinks and regular files */
+               if (DT_LNK != entry->d_type && DT_REG != entry->d_type)
+                       continue;
+
+               util_strscpyl(path, sizeof(path), udev_device_get_syspath(udev_device),
+                               "/", entry->d_name, NULL);
+               if (0 != lstat(path, &statbuf))
+                       continue;
+
+               if (0 == (statbuf.st_mode & S_IRUSR))
+                       continue;
+
+               if (DT_LNK == entry->d_type) {
+                       if (strcmp(entry->d_name, "driver") != 0 &&
+                               strcmp(entry->d_name, "subsystem") != 0 &&
+                               strcmp(entry->d_name, "module") != 0)
+                               continue;
+               }
+               udev_list_entry_add(udev_device->udev,
+                               &udev_device->available_sysattr_list, entry->d_name,
+                               DT_LNK == entry->d_type ? "s" : "r", 0, 0);
+               ++num;
+       }
+
+       dbg(udev_device->udev, "found %d sysattrs for '%s'\n", num,
+                       udev_device_get_syspath(udev_device));
+       udev_device->sysattrs_cached = true;
+
+       return num;
+}
+
+/**
+ * udev_device_get_sysattr_list_entry:
+ * @udev_device: udev device
+ *
+ * Retrieve the list of available sysattrs, with value being empty;
+ * This is to be able to read all available sysfs attributes for a particular
+ * device without the necessity to access sysfs from outside libudev.
+ *
+ * Returns: the first entry of the property list
+ **/
+struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device)
+{
+       /* perform initial caching of sysattr list */
+       if (!udev_device->sysattrs_cached) {
+               int ret;
+               ret = udev_device_cache_sysattrs(udev_device);
+               if (0 > ret)
+                       return NULL;
+       }
+
+       return udev_list_get_entry(&udev_device->available_sysattr_list);
+}
+
 int udev_device_set_syspath(struct udev_device *udev_device, const char *syspath)
 {
        const char *pos;

diff --git a/libudev/libudev.h b/libudev/libudev.h
index 0abd7c8b0e3dfbc22b26cb9ec59c65fd95fdf2de..892530b77384af94fba7d7029acde468b0903bfc 100644 (file)
--- a/libudev/libudev.h
+++ b/libudev/libudev.h
@@ -92,6 +92,7 @@ int udev_device_get_is_initialized(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_devlinks_list_entry(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_properties_list_entry(struct udev_device *udev_device);
 struct udev_list_entry *udev_device_get_tags_list_entry(struct udev_device *udev_device);
+struct udev_list_entry *udev_device_get_sysattr_list_entry(struct udev_device *udev_device);
 const char *udev_device_get_property_value(struct udev_device *udev_device, const char *key);
 const char *udev_device_get_driver(struct udev_device *udev_device);
 dev_t udev_device_get_devnum(struct udev_device *udev_device);