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devname.c

/*
 * devname.c - get a dev by its device inode name
 *
 * Copyright (C) Andries Brouwer
 * Copyright (C) 1999, 2000, 2001, 2002, 2003 Theodore Ts'o
 * Copyright (C) 2001 Andreas Dilger
 *
 * %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>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#if HAVE_SYS_MKDEV_H
#include <sys/mkdev.h>
#endif
#include <time.h>

#include "blkidP.h"

/*
 * Find a dev struct in the cache by device name, if available.
 *
 * If there is no entry with the specified device name, and the create
 * flag is set, then create an empty device entry.
 */
blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)
{
      blkid_dev dev = NULL, tmp;
      struct list_head *p;

      if (!cache || !devname)
            return NULL;

      list_for_each(p, &cache->bic_devs) {
            tmp = list_entry(p, struct blkid_struct_dev, bid_devs);
            if (strcmp(tmp->bid_name, devname))
                  continue;

            DBG(DEBUG_DEVNAME, 
                printf("found devname %s in cache\n", tmp->bid_name));
            dev = tmp;
            break;
      }

      if (!dev && (flags & BLKID_DEV_CREATE)) {
            dev = blkid_new_dev();
            if (!dev)
                  return NULL;
            dev->bid_name = blkid_strdup(devname);
            dev->bid_cache = cache;
            list_add_tail(&dev->bid_devs, &cache->bic_devs);
            cache->bic_flags |= BLKID_BIC_FL_CHANGED;
      }

      if (flags & BLKID_DEV_VERIFY)
            dev = blkid_verify(cache, dev);
      return dev;
}

/*
 * Probe a single block device to add to the device cache.
 */
static void probe_one(blkid_cache cache, const char *ptname,
                  dev_t devno, int pri)
{
      blkid_dev dev = NULL;
      struct list_head *p;
      const char **dir;
      char *devname = NULL;

      /* See if we already have this device number in the cache. */
      list_for_each(p, &cache->bic_devs) {
            blkid_dev tmp = list_entry(p, struct blkid_struct_dev,
                                 bid_devs);
            if (tmp->bid_devno == devno) {
                  dev = blkid_verify(cache, tmp);
                  break;
            }
      }
      if (dev && dev->bid_devno == devno)
            goto set_pri;

      /*
       * Take a quick look at /dev/ptname for the device number.  We check
       * all of the likely device directories.  If we don't find it, or if
       * the stat information doesn't check out, use blkid_devno_to_devname()
       * to find it via an exhaustive search for the device major/minor.
       */
      for (dir = blkid_devdirs; *dir; dir++) {
            struct stat st;
            char device[256];

            sprintf(device, "%s/%s", *dir, ptname);
            if ((dev = blkid_get_dev(cache, device, BLKID_DEV_FIND)) &&
                dev->bid_devno == devno)
                  goto set_pri;

            if (stat(device, &st) == 0 && S_ISBLK(st.st_mode) && 
                st.st_rdev == devno) {
                  devname = blkid_strdup(device);
                  break;
            }
      }
      if (!devname) {
            devname = blkid_devno_to_devname(devno);
            if (!devname)
                  return;
      }
      dev = blkid_get_dev(cache, devname, BLKID_DEV_NORMAL);
      free(devname);

set_pri:
      if (!pri && !strncmp(ptname, "md", 2))
            pri = BLKID_PRI_MD;
      if (dev)
            dev->bid_pri = pri;
      return;
}

#define PROC_PARTITIONS "/proc/partitions"
#define VG_DIR          "/proc/lvm/VGs"

/*
 * This function initializes the UUID cache with devices from the LVM
 * proc hierarchy.  We currently depend on the names of the LVM
 * hierarchy giving us the device structure in /dev.  (XXX is this a
 * safe thing to do?)
 */
#ifdef VG_DIR
#include <dirent.h>
static dev_t lvm_get_devno(const char *lvm_device)
{
      FILE *lvf;
      char buf[1024];
      int ma, mi;
      dev_t ret = 0;

      DBG(DEBUG_DEVNAME, printf("opening %s\n", lvm_device));
      if ((lvf = fopen(lvm_device, "r")) == NULL) {
            DBG(DEBUG_DEVNAME, printf("%s: (%d) %s\n", lvm_device, errno,
                                strerror(errno)));
            return 0;
      }

      while (fgets(buf, sizeof(buf), lvf)) {
            if (sscanf(buf, "device: %d:%d", &ma, &mi) == 2) {
                  ret = makedev(ma, mi);
                  break;
            }
      }
      fclose(lvf);

      return ret;
}

static void lvm_probe_all(blkid_cache cache)
{
      DIR         *vg_list;
      struct dirent     *vg_iter;
      int         vg_len = strlen(VG_DIR);
      dev_t       dev;

      if ((vg_list = opendir(VG_DIR)) == NULL)
            return;

      DBG(DEBUG_DEVNAME, printf("probing LVM devices under %s\n", VG_DIR));

      while ((vg_iter = readdir(vg_list)) != NULL) {
            DIR         *lv_list;
            char        *vdirname;
            char        *vg_name;
            struct dirent     *lv_iter;

            vg_name = vg_iter->d_name;
            if (!strcmp(vg_name, ".") || !strcmp(vg_name, ".."))
                  continue;
            vdirname = malloc(vg_len + strlen(vg_name) + 8);
            if (!vdirname)
                  goto exit;
            sprintf(vdirname, "%s/%s/LVs", VG_DIR, vg_name);

            lv_list = opendir(vdirname);
            free(vdirname);
            if (lv_list == NULL)
                  continue;

            while ((lv_iter = readdir(lv_list)) != NULL) {
                  char        *lv_name, *lvm_device;

                  lv_name = lv_iter->d_name;
                  if (!strcmp(lv_name, ".") || !strcmp(lv_name, ".."))
                        continue;

                  lvm_device = malloc(vg_len + strlen(vg_name) +
                                  strlen(lv_name) + 8);
                  if (!lvm_device) {
                        closedir(lv_list);
                        goto exit;
                  }
                  sprintf(lvm_device, "%s/%s/LVs/%s", VG_DIR, vg_name,
                        lv_name);
                  dev = lvm_get_devno(lvm_device);
                  sprintf(lvm_device, "%s/%s", vg_name, lv_name);
                  DBG(DEBUG_DEVNAME, printf("LVM dev %s: devno 0x%04X\n",
                                      lvm_device,
                                      (unsigned int) dev));
                  probe_one(cache, lvm_device, dev, BLKID_PRI_LVM);
                  free(lvm_device);
            }
            closedir(lv_list);
      }
exit:
      closedir(vg_list);
}
#endif

#define PROC_EVMS_VOLUMES "/proc/evms/volumes"

static int
evms_probe_all(blkid_cache cache)
{
      char line[100];
      int ma, mi, sz, num = 0;
      FILE *procpt;
      char device[110];

      procpt = fopen(PROC_EVMS_VOLUMES, "r");
      if (!procpt)
            return 0;
      while (fgets(line, sizeof(line), procpt)) {
            if (sscanf (line, " %d %d %d %*s %*s %[^\n ]",
                      &ma, &mi, &sz, device) != 4)
                  continue;

            DBG(DEBUG_DEVNAME, printf("Checking partition %s (%d, %d)\n",
                                device, ma, mi));

            probe_one(cache, device, makedev(ma, mi), BLKID_PRI_EVMS);
            num++;
      }
      fclose(procpt);
      return num;
}

/*
 * Read the device data for all available block devices in the system.
 */
int blkid_probe_all(blkid_cache cache)
{
      FILE *proc;
      char line[1024];
      char ptname0[128], ptname1[128], *ptname = 0;
      char *ptnames[2];
      dev_t devs[2];
      int ma, mi;
      unsigned long long sz;
      int lens[2] = { 0, 0 };
      int which = 0, last = 0;

      ptnames[0] = ptname0;
      ptnames[1] = ptname1;

      if (!cache)
            return -BLKID_ERR_PARAM;

      if (cache->bic_flags & BLKID_BIC_FL_PROBED &&
          time(0) - cache->bic_time < BLKID_PROBE_INTERVAL)
            return 0;

      blkid_read_cache(cache);
      evms_probe_all(cache);
#ifdef VG_DIR
      lvm_probe_all(cache);
#endif

      proc = fopen(PROC_PARTITIONS, "r");
      if (!proc)
            return -BLKID_ERR_PROC;

      while (fgets(line, sizeof(line), proc)) {
            last = which;
            which ^= 1;
            ptname = ptnames[which];

            if (sscanf(line, " %d %d %llu %128[^\n ]",
                     &ma, &mi, &sz, ptname) != 4)
                  continue;
            devs[which] = makedev(ma, mi);

            DBG(DEBUG_DEVNAME, printf("read partition name %s\n", ptname));

            /* Skip whole disk devs unless they have no partitions
             * If we don't have a partition on this dev, also
             * check previous dev to see if it didn't have a partn.
             * heuristic: partition name ends in a digit.
             *
             * Skip extended partitions.
             * heuristic: size is 1
             *
             * FIXME: skip /dev/{ida,cciss,rd} whole-disk devs
             */

            lens[which] = strlen(ptname);
            if (isdigit(ptname[lens[which] - 1])) {
                  DBG(DEBUG_DEVNAME,
                      printf("partition dev %s, devno 0x%04X\n",
                           ptname, (unsigned int) devs[which]));

                  if (sz > 1)
                        probe_one(cache, ptname, devs[which], 0);
                  lens[which] = 0;
                  lens[last] = 0;
            } else if (lens[last] && strncmp(ptnames[last], ptname,
                                     lens[last])) {
                  DBG(DEBUG_DEVNAME,
                      printf("whole dev %s, devno 0x%04X\n",
                           ptnames[last], (unsigned int) devs[last]));
                  probe_one(cache, ptnames[last], devs[last], 0);
                  lens[last] = 0;
            }
      }

      /* Handle the last device if it wasn't partitioned */
      if (lens[which])
            probe_one(cache, ptname, devs[which], 0);

      fclose(proc);

      cache->bic_time = time(0);
      cache->bic_flags |= BLKID_BIC_FL_PROBED;
      blkid_flush_cache(cache);
      return 0;
}

#ifdef TEST_PROGRAM
int main(int argc, char **argv)
{
      blkid_cache cache = NULL;
      int ret;

      blkid_debug_mask = DEBUG_ALL;
      if (argc != 1) {
            fprintf(stderr, "Usage: %s\n"
                  "Probe all devices and exit\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 (blkid_probe_all(cache) < 0)
            printf("%s: error probing devices\n", argv[0]);

      blkid_put_cache(cache);
      return (0);
}
#endif

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