diff options
Diffstat (limited to 'libblkid/src/save.c')
| -rw-r--r-- | libblkid/src/save.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/libblkid/src/save.c b/libblkid/src/save.c new file mode 100644 index 0000000..1a617c0 --- /dev/null +++ b/libblkid/src/save.c @@ -0,0 +1,244 @@ +/* + * 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_ERRNO_H +#include <errno.h> +#endif + +#include "closestream.h" +#include "fileutils.h" + +#include "blkidP.h" + + +static void save_quoted(const char *data, FILE *file) +{ + const char *p; + + fputc('"', file); + for (p = data; p && *p; p++) { + if ((unsigned char) *p == 0x22 || /* " */ + (unsigned char) *p == 0x5c) /* \ */ + fputc('\\', file); + + fputc(*p, file); + } + fputc('"', file); +} +static int save_dev(blkid_dev dev, FILE *file) +{ + struct list_head *p; + + if (!dev || dev->bid_name[0] != '/') + return 0; + + DBG(SAVE, ul_debug("device %s, type %s", dev->bid_name, dev->bid_type ? + dev->bid_type : "(null)")); + + fprintf(file, "<device DEVNO=\"0x%04lx\" TIME=\"%lld.%lld\"", + (unsigned long) dev->bid_devno, + (long long) dev->bid_time, + (long long) dev->bid_utime); + + 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); + + fputc(' ', file); /* space between tags */ + fputs(tag->bit_name, file); /* tag NAME */ + fputc('=', file); /* separator between NAME and VALUE */ + save_quoted(tag->bit_val, file); /* tag "VALUE" */ + } + 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; + char *opened = NULL; + char *filename; + FILE *file = NULL; + int fd, ret = 0; + struct stat st; + + if (list_empty(&cache->bic_devs) || + !(cache->bic_flags & BLKID_BIC_FL_CHANGED)) { + DBG(SAVE, ul_debug("skipping cache file write")); + return 0; + } + + filename = cache->bic_filename ? cache->bic_filename : + blkid_get_cache_filename(NULL); + if (!filename) + return -BLKID_ERR_PARAM; + + if (strncmp(filename, + BLKID_RUNTIME_DIR "/", sizeof(BLKID_RUNTIME_DIR)) == 0) { + + /* default destination, create the directory if necessary */ + if (stat(BLKID_RUNTIME_DIR, &st) + && errno == ENOENT + && mkdir(BLKID_RUNTIME_DIR, S_IWUSR| + S_IRUSR|S_IRGRP|S_IROTH| + S_IXUSR|S_IXGRP|S_IXOTH) != 0 + && errno != EEXIST) { + DBG(SAVE, ul_debug("can't create %s directory for cache file", + BLKID_RUNTIME_DIR)); + return 0; + } + } + + /* 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(SAVE, ul_debug("can't write to cache file %s", 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)) { + size_t len = strlen(filename) + 8; + tmp = malloc(len); + if (tmp) { + snprintf(tmp, len, "%s-XXXXXX", filename); + fd = mkstemp_cloexec(tmp); + if (fd >= 0) { + if (fchmod(fd, 0644) != 0) + DBG(SAVE, ul_debug("%s: fchmod failed", filename)); + else if ((file = fdopen(fd, "w" UL_CLOEXECSTR))) + opened = tmp; + if (!file) + close(fd); + } + } + } + + if (!file) { + file = fopen(filename, "w" UL_CLOEXECSTR); + opened = filename; + } + + DBG(SAVE, ul_debug("writing cache file %s (really %s)", + 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 || (dev->bid_flags & BLKID_BID_FL_REMOVABLE)) + continue; + if ((ret = save_dev(dev, file)) < 0) + break; + } + + if (ret >= 0) { + cache->bic_flags &= ~BLKID_BIC_FL_CHANGED; + ret = 1; + } + + if (close_stream(file) != 0) + DBG(SAVE, ul_debug("write failed: %s", filename)); + + if (opened != filename) { + if (ret < 0) { + unlink(opened); + DBG(SAVE, ul_debug("unlinked temp cache %s", opened)); + } else { + char *backup; + size_t len = strlen(filename) + 5; + + backup = malloc(len); + if (backup) { + snprintf(backup, len, "%s.old", filename); + unlink(backup); + if (link(filename, backup)) { + DBG(SAVE, ul_debug("can't link %s to %s", + filename, backup)); + } + free(backup); + } + if (rename(opened, filename)) { + ret = errno; + DBG(SAVE, ul_debug("can't rename %s to %s", + opened, filename)); + } else { + DBG(SAVE, ul_debug("moved temp cache %s", opened)); + } + } + } + +errout: + free(tmp); + if (filename != cache->bic_filename) + free(filename); + return ret; +} + +#ifdef TEST_PROGRAM +int main(int argc, char **argv) +{ + blkid_cache cache = NULL; + int ret; + + blkid_init_debug(BLKID_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 = 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 |