diff options
Diffstat (limited to 'libblkid/verify.c')
| -rw-r--r-- | libblkid/verify.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/libblkid/verify.c b/libblkid/verify.c new file mode 100644 index 000000000..bd756e7a7 --- /dev/null +++ b/libblkid/verify.c @@ -0,0 +1,221 @@ +/* + * Copyright (C) 2008 Karel Zak <kzak@redhat.com> + * + * This file may be redistributed under the terms of the + * GNU Lesser General Public License. + */ + +#include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include <unistd.h> +#include <fcntl.h> +#include <time.h> +#include <sys/time.h> +#include <sys/types.h> +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif +#ifdef HAVE_ERRNO_H +#include <errno.h> +#endif +#include "blkidP.h" + +static void blkid_probe_to_tags(blkid_probe pr, blkid_dev dev) +{ + const char *data; + const char *name; + int nvals, n; + size_t len; + + nvals = blkid_probe_numof_values(pr); + + for (n = 0; n < nvals; n++) { + if (blkid_probe_get_value(pr, n, &name, &data, &len) != 0) + continue; + if (strncmp(name, "PART_ENTRY_", 11) == 0) { + if (strcmp(name, "PART_ENTRY_UUID") == 0) + blkid_set_tag(dev, "PARTUUID", data, len); + else if (strcmp(name, "PART_ENTRY_NAME") == 0) + blkid_set_tag(dev, "PARTLABEL", data, len); + + } else if (!strstr(name, "_ID")) { + /* superblock UUID, LABEL, ... + * but not {SYSTEM,APPLICATION,..._ID} */ + blkid_set_tag(dev, name, data, len); + } + } +} + +/* + * Verify that the data in dev is consistent with what is on the actual + * block device (using the devname field only). Normally this will be + * called when finding items in the cache, but for long running processes + * is also desirable to revalidate an item before use. + * + * If we are unable to revalidate the data, we return the old data and + * do not set the BLKID_BID_FL_VERIFIED flag on it. + */ +blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev) +{ + blkid_tag_iterate iter; + const char *type, *value; + struct stat st; + time_t diff, now; + int fd; + + if (!dev || !cache) + return NULL; + + now = time(0); + diff = now - dev->bid_time; + + if (stat(dev->bid_name, &st) < 0) { + DBG(DEBUG_PROBE, + printf("blkid_verify: error %m (%d) while " + "trying to stat %s\n", errno, + dev->bid_name)); + open_err: + if ((errno == EPERM) || (errno == EACCES) || (errno == ENOENT)) { + /* We don't have read permission, just return cache data. */ + DBG(DEBUG_PROBE, printf("returning unverified data for %s\n", + dev->bid_name)); + return dev; + } + blkid_free_dev(dev); + return NULL; + } + + if (now >= dev->bid_time && +#ifdef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC + (st.st_mtime < dev->bid_time || + (st.st_mtime == dev->bid_time && + st.st_mtim.tv_nsec / 1000 <= dev->bid_utime)) && +#else + st.st_mtime <= dev->bid_time && +#endif + (diff < BLKID_PROBE_MIN || + (dev->bid_flags & BLKID_BID_FL_VERIFIED && + diff < BLKID_PROBE_INTERVAL))) + return dev; + +#ifndef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC + DBG(DEBUG_PROBE, + printf("need to revalidate %s (cache time %lu, stat time %lu,\n\t" + "time since last check %lu)\n", + dev->bid_name, (unsigned long)dev->bid_time, + (unsigned long)st.st_mtime, (unsigned long)diff)); +#else + DBG(DEBUG_PROBE, + printf("need to revalidate %s (cache time %lu.%lu, stat time %lu.%lu,\n\t" + "time since last check %lu)\n", + dev->bid_name, + (unsigned long)dev->bid_time, (unsigned long)dev->bid_utime, + (unsigned long)st.st_mtime, (unsigned long)st.st_mtim.tv_nsec / 1000, + (unsigned long)diff)); +#endif + + if (!cache->probe) { + cache->probe = blkid_new_probe(); + if (!cache->probe) { + blkid_free_dev(dev); + return NULL; + } + } + + fd = open(dev->bid_name, O_RDONLY|O_CLOEXEC); + if (fd < 0) { + DBG(DEBUG_PROBE, printf("blkid_verify: error %m (%d) while " + "opening %s\n", errno, + dev->bid_name)); + goto open_err; + } + + if (blkid_probe_set_device(cache->probe, fd, 0, 0)) { + /* failed to read the device */ + close(fd); + blkid_free_dev(dev); + return NULL; + } + + /* remove old cache info */ + iter = blkid_tag_iterate_begin(dev); + while (blkid_tag_next(iter, &type, &value) == 0) + blkid_set_tag(dev, type, NULL, 0); + blkid_tag_iterate_end(iter); + + /* enable superblocks probing */ + blkid_probe_enable_superblocks(cache->probe, TRUE); + blkid_probe_set_superblocks_flags(cache->probe, + BLKID_SUBLKS_LABEL | BLKID_SUBLKS_UUID | + BLKID_SUBLKS_TYPE | BLKID_SUBLKS_SECTYPE); + + /* enable partitions probing */ + blkid_probe_enable_partitions(cache->probe, TRUE); + blkid_probe_set_partitions_flags(cache->probe, BLKID_PARTS_ENTRY_DETAILS); + + /* probe */ + if (blkid_do_safeprobe(cache->probe)) { + /* found nothing or error */ + blkid_free_dev(dev); + dev = NULL; + } + + if (dev) { +#ifdef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC + struct timeval tv; + if (!gettimeofday(&tv, NULL)) { + dev->bid_time = tv.tv_sec; + dev->bid_utime = tv.tv_usec; + } else +#endif + dev->bid_time = time(0); + + dev->bid_devno = st.st_rdev; + dev->bid_flags |= BLKID_BID_FL_VERIFIED; + cache->bic_flags |= BLKID_BIC_FL_CHANGED; + + blkid_probe_to_tags(cache->probe, dev); + + DBG(DEBUG_PROBE, printf("%s: devno 0x%04llx, type %s\n", + dev->bid_name, (long long)st.st_rdev, dev->bid_type)); + } + + blkid_reset_probe(cache->probe); + blkid_probe_reset_superblocks_filter(cache->probe); + close(fd); + return dev; +} + +#ifdef TEST_PROGRAM +int main(int argc, char **argv) +{ + blkid_dev dev; + blkid_cache cache; + int ret; + + if (argc != 2) { + fprintf(stderr, "Usage: %s device\n" + "Probe a single device to determine type\n", argv[0]); + exit(1); + } + if ((ret = blkid_get_cache(&cache, "/dev/null")) != 0) { + fprintf(stderr, "%s: error creating cache (%d)\n", + argv[0], ret); + exit(1); + } + dev = blkid_get_dev(cache, argv[1], BLKID_DEV_NORMAL); + if (!dev) { + printf("%s: %s has an unsupported type\n", argv[0], argv[1]); + return (1); + } + printf("TYPE='%s'\n", dev->bid_type ? dev->bid_type : "(null)"); + if (dev->bid_label) + printf("LABEL='%s'\n", dev->bid_label); + if (dev->bid_uuid) + printf("UUID='%s'\n", dev->bid_uuid); + + blkid_free_dev(dev); + return (0); +} +#endif |