git.maemo.org Git - busybox4maemo/blob - e2fsprogs/old_e2fsprogs/blkid/save.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * save.c - write the cache struct to disk
   4  *
   5  * Copyright (C) 2001 by Andreas Dilger
   6  * Copyright (C) 2003 Theodore Ts'o
   7  *
   8  * %Begin-Header%
   9  * This file may be redistributed under the terms of the
  10  * GNU Lesser General Public License.
  11  * %End-Header%
  12  */
  13
  14 #include <stdio.h>
  15 #include <string.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <sys/types.h>
  19 #ifdef HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #ifdef HAVE_SYS_MKDEV_H
  23 #include <sys/mkdev.h>
  24 #endif
  25 #ifdef HAVE_ERRNO_H
  26 #include <errno.h>
  27 #endif
  28 #include "blkidP.h"
  29
  30 static int save_dev(blkid_dev dev, FILE *file)
  31 {
  32         struct list_head *p;
  33
  34         if (!dev || dev->bid_name[0] != '/')
  35                 return 0;
  36
  37         DBG(DEBUG_SAVE,
  38             printf("device %s, type %s\n", dev->bid_name, dev->bid_type));
  39
  40         fprintf(file,
  41                 "<device DEVNO=\"0x%04lx\" TIME=\"%lu\"",
  42                 (unsigned long) dev->bid_devno, dev->bid_time);
  43         if (dev->bid_pri)
  44                 fprintf(file, " PRI=\"%d\"", dev->bid_pri);
  45         list_for_each(p, &dev->bid_tags) {
  46                 blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
  47                 fprintf(file, " %s=\"%s\"", tag->bit_name,tag->bit_val);
  48         }
  49         fprintf(file, ">%s</device>\n", dev->bid_name);
  50
  51         return 0;
  52 }
  53
  54 /*
  55  * Write out the cache struct to the cache file on disk.
  56  */
  57 int blkid_flush_cache(blkid_cache cache)
  58 {
  59         struct list_head *p;
  60         char *tmp = NULL;
  61         const char *opened = NULL;
  62         const char *filename;
  63         FILE *file = NULL;
  64         int fd, ret = 0;
  65         struct stat st;
  66
  67         if (!cache)
  68                 return -BLKID_ERR_PARAM;
  69
  70         if (list_empty(&cache->bic_devs) ||
  71             !(cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
  72                 DBG(DEBUG_SAVE, printf("skipping cache file write\n"));
  73                 return 0;
  74         }
  75
  76         filename = cache->bic_filename ? cache->bic_filename: BLKID_CACHE_FILE;
  77
  78         /* If we can't write to the cache file, then don't even try */
  79         if (((ret = stat(filename, &st)) < 0 && errno != ENOENT) ||
  80             (ret == 0 && access(filename, W_OK) < 0)) {
  81                 DBG(DEBUG_SAVE,
  82                     printf("can't write to cache file %s\n", filename));
  83                 return 0;
  84         }
  85
  86         /*
  87          * Try and create a temporary file in the same directory so
  88          * that in case of error we don't overwrite the cache file.
  89          * If the cache file doesn't yet exist, it isn't a regular
  90          * file (e.g. /dev/null or a socket), or we couldn't create
  91          * a temporary file then we open it directly.
  92          */
  93         if (ret == 0 && S_ISREG(st.st_mode)) {
  94                 tmp = xmalloc(strlen(filename) + 8);
  95                 sprintf(tmp, "%s-XXXXXX", filename);
  96                 fd = mkstemp(tmp);
  97                 if (fd >= 0) {
  98                         file = fdopen(fd, "w");
  99                         opened = tmp;
 100                 }
 101                 fchmod(fd, 0644);
 102         }
 103
 104         if (!file) {
 105                 file = fopen(filename, "w");
 106                 opened = filename;
 107         }
 108
 109         DBG(DEBUG_SAVE,
 110             printf("writing cache file %s (really %s)\n",
 111                    filename, opened));
 112
 113         if (!file) {
 114                 ret = errno;
 115                 goto errout;
 116         }
 117
 118         list_for_each(p, &cache->bic_devs) {
 119                 blkid_dev dev = list_entry(p, struct blkid_struct_dev, bid_devs);
 120                 if (!dev->bid_type)
 121                         continue;
 122                 if ((ret = save_dev(dev, file)) < 0)
 123                         break;
 124         }
 125
 126         if (ret >= 0) {
 127                 cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
 128                 ret = 1;
 129         }
 130
 131         fclose(file);
 132         if (opened != filename) {
 133                 if (ret < 0) {
 134                         unlink(opened);
 135                         DBG(DEBUG_SAVE,
 136                             printf("unlinked temp cache %s\n", opened));
 137                 } else {
 138                         char *backup;
 139
 140                         backup = xmalloc(strlen(filename) + 5);
 141                         sprintf(backup, "%s.old", filename);
 142                         unlink(backup);
 143                         link(filename, backup);
 144                         free(backup);
 145                         rename(opened, filename);
 146                         DBG(DEBUG_SAVE,
 147                             printf("moved temp cache %s\n", opened));
 148                 }
 149         }
 150
 151 errout:
 152         free(tmp);
 153         return ret;
 154 }
 155
 156 #ifdef TEST_PROGRAM
 157 int main(int argc, char **argv)
 158 {
 159         blkid_cache cache = NULL;
 160         int ret;
 161
 162         blkid_debug_mask = DEBUG_ALL;
 163         if (argc > 2) {
 164                 fprintf(stderr, "Usage: %s [filename]\n"
 165                         "Test loading/saving a cache (filename)\n", argv[0]);
 166                 exit(1);
 167         }
 168
 169         if ((ret = blkid_get_cache(&cache, bb_dev_null)) != 0) {
 170                 fprintf(stderr, "%s: error creating cache (%d)\n",
 171                         argv[0], ret);
 172                 exit(1);
 173         }
 174         if ((ret = blkid_probe_all(cache)) < 0) {
 175                 fprintf(stderr, "error (%d) probing devices\n", ret);
 176                 exit(1);
 177         }
 178         cache->bic_filename = blkid_strdup(argv[1]);
 179
 180         if ((ret = blkid_flush_cache(cache)) < 0) {
 181                 fprintf(stderr, "error (%d) saving cache\n", ret);
 182                 exit(1);
 183         }
 184
 185         blkid_put_cache(cache);
 186
 187         return ret;
 188 }
 189 #endif