/* vi: set sw=4 ts=4: */ /* * 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 <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" 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)); fprintf(file, "<device DEVNO=\"0x%04lx\" TIME=\"%lu\"", (unsigned long) dev->bid_devno, 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 = xmalloc(strlen(filename) + 8); sprintf(tmp, "%s-XXXXXX", filename); fd = mkstemp(tmp); if (fd >= 0) { file = fdopen(fd, "w"); opened = tmp; } fchmod(fd, 0644); } if (!file) { file = fopen_for_write(filename); 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) { unlink(opened); DBG(DEBUG_SAVE, printf("unlinked temp cache %s\n", opened)); } else { char *backup; backup = xmalloc(strlen(filename) + 5); sprintf(backup, "%s.old", filename); unlink(backup); link(filename, backup); free(backup); rename(opened, filename); 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, bb_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