/*

 * 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));

      ret = 0;

      goto done;

    }

  }

  /* 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));

    ret = 0;

    goto done;

  }

  /*

   * 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 done;

  }

  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));

      }

    }

  }

done:

  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