/*

 * sysfs based topology -- gathers topology information from Linux sysfs

 *

 * Copyright (C) 2009 Karel Zak <kzak@redhat.com>

 *

 * This file may be redistributed under the terms of the

 * GNU Lesser General Public License.

 *

 * For more information see Linux kernel Documentation/ABI/testing/sysfs-block.

 */

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <inttypes.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <errno.h>

#include "sysfs.h"

#include "topology.h"

/*

 * Sysfs topology values (since 2.6.31, May 2009).

 */

static const struct topology_val {

  /* /sys/dev/block/<maj>:<min>/<ATTR> */

  const char * const attr;

  /* functions to set probing result */

  int (*set_ulong)(blkid_probe, unsigned long);

  int (*set_int)(blkid_probe, int);

  int (*set_u64)(blkid_probe, uint64_t);

} topology_vals[] = {

  { "alignment_offset", NULL, blkid_topology_set_alignment_offset },

  { "queue/minimum_io_size", blkid_topology_set_minimum_io_size },

  { "queue/optimal_io_size", blkid_topology_set_optimal_io_size },

  { "queue/physical_block_size", blkid_topology_set_physical_sector_size },

  { "queue/dax", blkid_topology_set_dax },

  { "diskseq", .set_u64 = blkid_topology_set_diskseq },

};

static int probe_sysfs_tp(blkid_probe pr,

    const struct blkid_idmag *mag __attribute__((__unused__)))

{

  dev_t dev;

  int rc, set_parent = 1;

  struct path_cxt *pc;

  size_t i, count = 0;

  dev = blkid_probe_get_devno(pr);

  if (!dev)

    return 1;

  pc = ul_new_sysfs_path(dev, NULL, NULL);

  if (!pc)

    return 1;

  ul_path_refer_vfs(pc, pr->vfs);

  rc = 1;   /* nothing (default) */

  for (i = 0; i < ARRAY_SIZE(topology_vals); i++) {

    const struct topology_val *val = &topology_vals[i];

    int ok = ul_path_access(pc, F_OK, val->attr) == 0;

    rc = 1; /* nothing */

    if (!ok && set_parent) {

      dev_t disk = blkid_probe_get_wholedisk_devno(pr);

      set_parent = 0;

      /*

       * Read attributes from "disk" if the current device is

       * a partition. Note that sysfs ul_path_* API is able

       * to redirect requests to attributes if parent is set.

       */

      if (disk && disk != dev) {

        struct path_cxt *parent = ul_new_sysfs_path(disk, NULL, NULL);

        if (!parent)

          goto done;

        sysfs_blkdev_set_parent(pc, parent);

        ul_unref_path(parent);

        /* try it again */

        ok = ul_path_access(pc, F_OK, val->attr) == 0;

      }

    }

    if (!ok)

      continue; /* attribute does not exist */

    if (val->set_ulong) {

      uint64_t data;

      if (ul_path_read_u64(pc, &data, val->attr) != 0)

        continue;

      rc = val->set_ulong(pr, (unsigned long) data);

    } else if (val->set_int) {

      int64_t data;

      if (ul_path_read_s64(pc, &data, val->attr) != 0)

        continue;

      rc = val->set_int(pr, (int) data);

    } else if (val->set_u64) {

      uint64_t data;

      if (ul_path_read_u64(pc, &data, val->attr) != 0)

        continue;

      rc = val->set_u64(pr, data);

    }

    if (rc < 0)

      goto done; /* error */

    if (rc == 0)

      count++;

  }

done:

  ul_unref_path(pc);    /* unref pc and parent */

  if (count)

    return 0;   /* success */

  return rc;     /* error or nothing */

}

const struct blkid_idinfo sysfs_tp_idinfo =

{

  .name   = "sysfs",

  .probefunc  = probe_sysfs_tp,

  .magics   = BLKID_NONE_MAGIC

};