diff options
Diffstat (limited to 'lib/blkid/save.c')
| -rw-r--r-- | lib/blkid/save.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/lib/blkid/save.c b/lib/blkid/save.c new file mode 100644 index 0000000..6f4499c --- /dev/null +++ b/lib/blkid/save.c @@ -0,0 +1,213 @@ +/* + * save.c - write the cache struct to disk + * + * Copyright (C) 2001 by 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% + */ + +#include "config.h" +#include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/types.h> +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif +#ifdef HAVE_SYS_MKDEV_H +#include <sys/mkdev.h> +#endif +#ifdef HAVE_ERRNO_H +#include <errno.h> +#endif +#include "blkidP.h" + +#ifdef _WIN32 +#include "windows.h" +#endif + +static int save_dev(blkid_dev dev, FILE *file) +{ + struct list_head *p; + + if (!dev || dev->bid_name[0] != '/') + return 0; + + DBG(DEBUG_SAVE, + printf("device %s, type %s\n", dev->bid_name, dev->bid_type ? + dev->bid_type : "(null)")); + + fprintf(file, + "<device DEVNO=\"0x%04lx\" TIME=\"%ld\"", + (unsigned long) dev->bid_devno, (long) dev->bid_time); + if (dev->bid_pri) + fprintf(file, " PRI=\"%d\"", dev->bid_pri); + list_for_each(p, &dev->bid_tags) { + blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags); + fprintf(file, " %s=\"%s\"", tag->bit_name,tag->bit_val); + } + fprintf(file, ">%s</device>\n", dev->bid_name); + + return 0; +} + +/* + * Write out the cache struct to the cache file on disk. + */ +int blkid_flush_cache(blkid_cache cache) +{ + struct list_head *p; + char *tmp = NULL; + const char *opened = NULL; + const char *filename; + FILE *file = NULL; + int fd, ret = 0; + struct stat st; + + if (!cache) + return -BLKID_ERR_PARAM; + + if (list_empty(&cache->bic_devs) || + !(cache->bic_flags & BLKID_BIC_FL_CHANGED)) { + DBG(DEBUG_SAVE, printf("skipping cache file write\n")); + return 0; + } + + filename = cache->bic_filename ? cache->bic_filename: BLKID_CACHE_FILE; + + /* If we can't write to the cache file, then don't even try */ + if (((ret = stat(filename, &st)) < 0 && errno != ENOENT) || + (ret == 0 && access(filename, W_OK) < 0)) { + DBG(DEBUG_SAVE, + printf("can't write to cache file %s\n", filename)); + return 0; + } + + /* + * Try and create a temporary file in the same directory so + * that in case of error we don't overwrite the cache file. + * If the cache file doesn't yet exist, it isn't a regular + * file (e.g. /dev/null or a socket), or we couldn't create + * a temporary file then we open it directly. + */ + if (ret == 0 && S_ISREG(st.st_mode)) { + tmp = malloc(strlen(filename) + 8); + if (tmp) { + mode_t save_umask = umask(022); + sprintf(tmp, "%s-XXXXXX", filename); + fd = mkstemp(tmp); + umask(save_umask); + if (fd >= 0) { + file = fdopen(fd, "w"); + opened = tmp; + } +#ifndef _WIN32 + fchmod(fd, 0644); +#else + chmod(tmp, 0644); +#endif + } + } + + if (!file) { + file = fopen(filename, "w"); + opened = filename; + } + + DBG(DEBUG_SAVE, + printf("writing cache file %s (really %s)\n", + filename, opened)); + + if (!file) { + ret = errno; + goto errout; + } + + list_for_each(p, &cache->bic_devs) { + blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs); + if (!dev->bid_type) + continue; + if ((ret = save_dev(dev, file)) < 0) + break; + } + + if (ret >= 0) { + cache->bic_flags &= ~BLKID_BIC_FL_CHANGED; + ret = 1; + } + + fclose(file); + if (opened != filename) { + if (ret < 0) { + (void) unlink(opened); + DBG(DEBUG_SAVE, + printf("unlinked temp cache %s\n", opened)); + } else { + char *backup; + + backup = malloc(strlen(filename) + 5); + if (backup) { + sprintf(backup, "%s.old", filename); + unlink(backup); +#if defined(__GNUC__) && __GNUC__ >= 5 +/* explicit (void) cast is not enough with glibc and _FORTIFY_SOURCE */ +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wunused-result" +#endif + (void) link(filename, backup); +#if defined(__GNUC__) && __GNUC__ >= 5 +#pragma GCC diagnostic pop +#endif + free(backup); + } + if (rename(opened, filename) < 0) + (void) unlink(opened); + DBG(DEBUG_SAVE, + printf("moved temp cache %s\n", opened)); + } + } + +errout: + free(tmp); + return ret; +} + +#ifdef TEST_PROGRAM +int main(int argc, char **argv) +{ + blkid_cache cache = NULL; + int ret; + + blkid_debug_mask = DEBUG_ALL; + if (argc > 2) { + fprintf(stderr, "Usage: %s [filename]\n" + "Test loading/saving a cache (filename)\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); + } + if ((ret = blkid_probe_all(cache)) < 0) { + fprintf(stderr, "error (%d) probing devices\n", ret); + exit(1); + } + cache->bic_filename = blkid_strdup(argv[1]); + + if ((ret = blkid_flush_cache(cache)) < 0) { + fprintf(stderr, "error (%d) saving cache\n", ret); + exit(1); + } + + blkid_put_cache(cache); + + return ret; +} +#endif |