1 files changed, 225 insertions, 0 deletions
diff --git a/libblkid/src/cache.c b/libblkid/src/cache.c
new file mode 100644
index 0000000..c199b91
--- /dev/null
+++ b/libblkid/src/cache.c
@@ -0,0 +1,225 @@
+/*
+ * cache.c - allocation/initialization/free routines for cache
+ *
+ * Copyright (C) 2001 Andreas Dilger
+ * Copyright (C) 2003 Theodore Ts'o
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ * %End-Header%
+ */
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#include "blkidP.h"
+#include "env.h"
+
+/**
+ * SECTION:cache
+ * @title: Cache
+ * @short_description: basic routines to work with libblkid cache
+ *
+ * Block device information is normally kept in a cache file blkid.tab and is
+ * verified to still be valid before being returned to the user (if the user has
+ * read permission on the raw block device, otherwise not).  The cache file also
+ * allows unprivileged users (normally anyone other than root, or those not in the
+ * "disk" group) to locate devices by label/id.  The standard location of the
+ * cache file can be overridden by the environment variable BLKID_FILE.
+ *
+ * In situations where one is getting information about a single known device, it
+ * does not impact performance whether the cache is used or not (unless you are
+ * not able to read the block device directly).  If you are dealing with multiple
+ * devices, use of the cache is highly recommended (even if empty) as devices will
+ * be scanned at most one time and the on-disk cache will be updated if possible.
+ * There is rarely a reason not to use the cache.
+ *
+ * In some cases (modular kernels), block devices are not even visible until after
+ * they are accessed the first time, so it is critical that there is some way to
+ * locate these devices without enumerating only visible devices, so the use of
+ * the cache file is required in this situation.
+ */
+static const char *get_default_cache_filename(void)
+{
+	struct stat st;
+
+	if (stat(BLKID_RUNTIME_TOPDIR, &st) == 0 && S_ISDIR(st.st_mode))
+		return BLKID_CACHE_FILE;	/* cache in /run */
+
+	return BLKID_CACHE_FILE_OLD;	/* cache in /etc */
+}
+
+/* returns allocated path to cache */
+char *blkid_get_cache_filename(struct blkid_config *conf)
+{
+	char *filename;
+
+	filename = safe_getenv("BLKID_FILE");
+	if (filename)
+		filename = strdup(filename);
+	else if (conf)
+		filename = conf->cachefile ? strdup(conf->cachefile) : NULL;
+	else {
+		struct blkid_config *c = blkid_read_config(NULL);
+		if (!c)
+			filename = strdup(get_default_cache_filename());
+		else {
+			filename = c->cachefile;  /* already allocated */
+			c->cachefile = NULL;
+			blkid_free_config(c);
+		}
+	}
+	return filename;
+}
+
+/**
+ * blkid_get_cache:
+ * @cache: pointer to return cache handler
+ * @filename: path to the cache file or NULL for the default path
+ *
+ * Allocates and initialize library cache handler.
+ *
+ * Returns: 0 on success or number less than zero in case of error.
+ */
+int blkid_get_cache(blkid_cache *ret_cache, const char *filename)
+{
+	blkid_cache cache;
+
+	if (!ret_cache)
+		return -BLKID_ERR_PARAM;
+
+	blkid_init_debug(0);
+
+	if (!(cache = calloc(1, sizeof(struct blkid_struct_cache))))
+		return -BLKID_ERR_MEM;
+
+	DBG(CACHE, ul_debugobj(cache, "alloc (from %s)", filename ? filename : "default cache"));
+	INIT_LIST_HEAD(&cache->bic_devs);
+	INIT_LIST_HEAD(&cache->bic_tags);
+
+	if (filename && !*filename)
+		filename = NULL;
+	if (filename)
+		cache->bic_filename = strdup(filename);
+	else
+		cache->bic_filename = blkid_get_cache_filename(NULL);
+
+	blkid_read_cache(cache);
+	*ret_cache = cache;
+	return 0;
+}
+
+/**
+ * blkid_put_cache:
+ * @cache: cache handler
+ *
+ * Saves changes to cache file.
+ */
+void blkid_put_cache(blkid_cache cache)
+{
+	if (!cache)
+		return;
+
+	(void) blkid_flush_cache(cache);
+
+	DBG(CACHE, ul_debugobj(cache, "freeing cache struct"));
+
+	/* DBG(CACHE, ul_debug_dump_cache(cache)); */
+
+	while (!list_empty(&cache->bic_devs)) {
+		blkid_dev dev = list_entry(cache->bic_devs.next,
+					   struct blkid_struct_dev,
+					    bid_devs);
+		blkid_free_dev(dev);
+	}
+
+	DBG(CACHE, ul_debugobj(cache, "freeing cache tag heads"));
+	while (!list_empty(&cache->bic_tags)) {
+		blkid_tag tag = list_entry(cache->bic_tags.next,
+					   struct blkid_struct_tag,
+					   bit_tags);
+
+		while (!list_empty(&tag->bit_names)) {
+			blkid_tag bad = list_entry(tag->bit_names.next,
+						   struct blkid_struct_tag,
+						   bit_names);
+
+			DBG(CACHE, ul_debugobj(cache, "warning: unfreed tag %s=%s",
+						bad->bit_name, bad->bit_val));
+			blkid_free_tag(bad);
+		}
+		blkid_free_tag(tag);
+	}
+
+	blkid_free_probe(cache->probe);
+
+	free(cache->bic_filename);
+	free(cache);
+}
+
+/**
+ * blkid_gc_cache:
+ * @cache: cache handler
+ *
+ * Removes garbage (non-existing devices) from the cache.
+ */
+void blkid_gc_cache(blkid_cache cache)
+{
+	struct list_head *p, *pnext;
+	struct stat st;
+
+	if (!cache)
+		return;
+
+	list_for_each_safe(p, pnext, &cache->bic_devs) {
+		blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs);
+		if (stat(dev->bid_name, &st) < 0) {
+			DBG(CACHE, ul_debugobj(cache, "freeing non-exiting %s", dev->bid_name));
+			blkid_free_dev(dev);
+			cache->bic_flags |= BLKID_BIC_FL_CHANGED;
+		} else {
+			DBG(CACHE, ul_debug("Device %s exists", dev->bid_name));
+		}
+	}
+}
+
+#ifdef TEST_PROGRAM
+int main(int argc, char** argv)
+{
+	blkid_cache cache = NULL;
+	int ret;
+
+	blkid_init_debug(BLKID_DEBUG_ALL);
+
+	if ((argc > 2)) {
+		fprintf(stderr, "Usage: %s [filename] \n", argv[0]);
+		exit(1);
+	}
+
+	if ((ret = blkid_get_cache(&cache, argv[1])) < 0) {
+		fprintf(stderr, "error %d parsing cache file %s\n", ret,
+			argv[1] ? argv[1] : blkid_get_cache_filename(NULL));
+		exit(1);
+	}
+	if ((ret = blkid_get_cache(&cache, "/dev/null")) != 0) {
+		fprintf(stderr, "%s: error creating cache (%d)\n",
+			argv[0], ret);
+		exit(1);
+	}
+	if ((ret = blkid_probe_all(cache)) < 0)
+		fprintf(stderr, "error probing devices\n");
+
+	blkid_put_cache(cache);
+
+	return ret;
+}
+#endif