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/*
* 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
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