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 30static 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 */ 57int 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 151errout: 152 free(tmp); 153 return ret; 154} 155 156#ifdef TEST_PROGRAM 157int 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 190