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* read.c - read the blkid cache from disk, to avoid scanning all devices
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* Copyright (C) 2001, 2003 Theodore Y. Ts'o
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* Copyright (C) 2001 Andreas Dilger
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* This file may be redistributed under the terms of the
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* GNU Lesser General Public License.
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#include <sys/types.h>
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# ifndef _XOPEN_SOURCE
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# define _XOPEN_SOURCE 600 /* for inclusion of strtoull */
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#define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */
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/* FIXME: need to support real strtoull here */
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#define STRTOULL strtoul
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#define blkid_debug_dump_dev(dev) (debug_dump_dev(dev))
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static void debug_dump_dev(blkid_dev dev);
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* <device [<NAME="value"> ...]>device_name</device>
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* The following tags are required for each entry:
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* <ID="id"> unique (within this file) ID number of this device
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* <TIME="sec.usec"> (time_t and suseconds_t) time this entry was last
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* <TYPE="type"> (detected) type of filesystem/data for this partition
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* The following tags may be present, depending on the device contents
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* <LABEL="label"> (user supplied) label (volume name, etc)
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* <UUID="uuid"> (generated) universally unique identifier (serial no)
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static char *skip_over_blank(char *cp)
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while (*cp && isspace(*cp))
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static char *skip_over_word(char *cp)
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/* If we see a backslash, skip the next character */
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if (isspace(ch) || ch == '<' || ch == '>')
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static char *strip_line(char *line)
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line = skip_over_blank(line);
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p = line + strlen(line) - 1;
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static char *parse_word(char **buf)
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word = skip_over_blank(word);
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next = skip_over_word(word);
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char *end = next - 1;
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if (*end == '"' || *end == '\'')
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if (*word == '"' || *word == '\'')
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* Start parsing a new line from the cache.
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* line starts with "<device" return 1 -> continue parsing line
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* line starts with "<foo", empty, or # return 0 -> skip line
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* line starts with other, return -BLKID_ERR_CACHE -> error
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static int parse_start(char **cp)
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/* Skip comment or blank lines. We can't just NUL the first '#' char,
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* in case it is inside quotes, or escaped.
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if (*p == '\0' || *p == '#')
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if (!strncmp(p, "<device", 7)) {
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DBG(DEBUG_READ, printf("found device header: %8s\n", p));
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return -BLKID_ERR_CACHE;
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/* Consume the remaining XML on the line (cosmetic only) */
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static int parse_end(char **cp)
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*cp = skip_over_blank(*cp);
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if (!strncmp(*cp, "</device>", 9)) {
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DBG(DEBUG_READ, printf("found device trailer %9s\n", *cp));
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return -BLKID_ERR_CACHE;
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* Allocate a new device struct with device name filled in. Will handle
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* finding the device on lines of the form:
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* <device foo=bar>devname</device>
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* <device>devname<foo>bar</foo></device>
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static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp)
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char *start, *tmp, *end, *name;
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if ((ret = parse_start(cp)) <= 0)
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start = tmp = strchr(*cp, '>');
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printf("blkid: short line parsing dev: %s\n", *cp));
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return -BLKID_ERR_CACHE;
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start = skip_over_blank(start + 1);
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end = skip_over_word(start);
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DBG(DEBUG_READ, printf("device should be %*s\n",
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(int)(end - start), start));
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if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) {
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printf("blkid: missing </device> ending: %s\n", end));
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if (end - start <= 1) {
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DBG(DEBUG_READ, printf("blkid: empty device name: %s\n", *cp));
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return -BLKID_ERR_CACHE;
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name = blkid_strndup(start, end-start);
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return -BLKID_ERR_MEM;
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DBG(DEBUG_READ, printf("found dev %s\n", name));
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if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE))) {
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return -BLKID_ERR_MEM;
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* Extract a tag of the form NAME="value" from the line.
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static int parse_token(char **name, char **value, char **cp)
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if (!name || !value || !cp)
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return -BLKID_ERR_PARAM;
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if (!(*value = strchr(*cp, '=')))
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*name = strip_line(*cp);
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*value = skip_over_blank(*value + 1);
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if (**value == '"') {
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end = strchr(*value + 1, '"');
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printf("unbalanced quotes at: %s\n", *value));
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return -BLKID_ERR_CACHE;
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end = skip_over_word(*value);
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* Extract a tag of the form <NAME>value</NAME> from the line.
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static int parse_xml(char **name, char **value, char **cp)
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if (!name || !value || !cp)
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return -BLKID_ERR_PARAM;
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*name = strip_line(*cp);
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if ((*name)[0] != '<' || (*name)[1] == '/')
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* Extract a tag from the line.
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* Return 1 if a valid tag was found.
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* Return 0 if no tag found.
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* Return -ve error code.
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static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp)
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return -BLKID_ERR_PARAM;
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if ((ret = parse_token(&name, &value, cp)) <= 0 /* &&
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(ret = parse_xml(&name, &value, cp)) <= 0 */)
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/* Some tags are stored directly in the device struct */
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if (!strcmp(name, "DEVNO"))
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dev->bid_devno = STRTOULL(value, 0, 0);
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else if (!strcmp(name, "PRI"))
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dev->bid_pri = strtol(value, 0, 0);
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else if (!strcmp(name, "TIME")) {
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dev->bid_time = STRTOULL(value, &end, 0);
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if (end && *end == '.')
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dev->bid_utime = STRTOULL(end + 1, 0, 0);
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ret = blkid_set_tag(dev, name, value, strlen(value));
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DBG(DEBUG_READ, printf(" tag: %s=\"%s\"\n", name, value));
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return ret < 0 ? ret : 1;
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* Parse a single line of data, and return a newly allocated dev struct.
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* Add the new device to the cache struct, if one was read.
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* Lines are of the form <device [TAG="value" ...]>/dev/foo</device>
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* Returns -ve value on error.
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* Returns 0 otherwise.
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* If a valid device was read, *dev_p is non-NULL, otherwise it is NULL
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* (e.g. comment lines, unknown XML content, etc).
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static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp)
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if (!cache || !dev_p)
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return -BLKID_ERR_PARAM;
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DBG(DEBUG_READ, printf("line: %s\n", cp));
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if ((ret = parse_dev(cache, dev_p, &cp)) <= 0)
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while ((ret = parse_tag(cache, dev, &cp)) > 0) {
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if (dev->bid_type == NULL) {
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printf("blkid: device %s has no TYPE\n",dev->bid_name));
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DBG(DEBUG_READ, blkid_debug_dump_dev(dev));
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* Parse the specified filename, and return the data in the supplied or
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* a newly allocated cache struct. If the file doesn't exist, return a
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* new empty cache struct.
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void blkid_read_cache(blkid_cache cache)
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* If the file doesn't exist, then we just return an empty
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* struct so that the cache can be populated.
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if ((fd = open(cache->bic_filename, O_RDONLY)) < 0)
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if (fstat(fd, &st) < 0)
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if ((st.st_mtime == cache->bic_ftime) ||
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(cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
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DBG(DEBUG_CACHE, printf("skipping re-read of %s\n",
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cache->bic_filename));
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DBG(DEBUG_CACHE, printf("reading cache file %s\n",
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cache->bic_filename));
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file = fdopen(fd, "r");
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while (fgets(buf, sizeof(buf), file)) {
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end = strlen(buf) - 1;
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/* Continue reading next line if it ends with a backslash */
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while (buf[end] == '\\' && end < sizeof(buf) - 2 &&
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fgets(buf + end, sizeof(buf) - end, file)) {
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end = strlen(buf) - 1;
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if (blkid_parse_line(cache, &dev, buf) < 0) {
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printf("blkid: bad format on line %d\n", lineno));
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* Initially we do not need to write out the cache file.
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cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
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cache->bic_ftime = st.st_mtime;
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static void debug_dump_dev(blkid_dev dev)
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printf(" dev: NULL\n");
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printf(" dev: name = %s\n", dev->bid_name);
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printf(" dev: DEVNO=\"0x%0llx\"\n", (long long)dev->bid_devno);
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printf(" dev: TIME=\"%ld.%ld\"\n", (long)dev->bid_time, (long)dev->bid_utime);
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printf(" dev: PRI=\"%d\"\n", dev->bid_pri);
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printf(" dev: flags = 0x%08X\n", dev->bid_flags);
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list_for_each(p, &dev->bid_tags) {
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blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
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printf(" tag: %s=\"%s\"\n", tag->bit_name,
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printf(" tag: NULL\n");
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int main(int argc, char**argv)
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blkid_cache cache = NULL;
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blkid_init_debug(DEBUG_ALL);
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fprintf(stderr, "Usage: %s [filename]\n"
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"Test parsing of the cache (filename)\n", argv[0]);
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if ((ret = blkid_get_cache(&cache, argv[1])) < 0)
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fprintf(stderr, "error %d reading cache file %s\n", ret,
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argv[1] ? argv[1] : BLKID_CACHE_FILE);
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blkid_put_cache(cache);
added
removed
shlibs/blkid/src/read.c
