libblkid/src/topology/sysfs.c

   1 /*
   2  * sysfs based topology -- gathers topology information from Linux sysfs
   3  *
   4  * Copyright (C) 2009 Karel Zak <kzak@redhat.com>
   5  *
   6  * This file may be redistributed under the terms of the
   7  * GNU Lesser General Public License.
   8  *
   9  * For more information see Linux kernel Documentation/ABI/testing/sysfs-block.
  10  */
  11 #include <stdio.h>
  12 #include <string.h>
  13 #include <stdlib.h>
  14 #include <inttypes.h>
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17 #include <unistd.h>
  18 #include <errno.h>
  19
  20 #include "sysfs.h"
  21 #include "topology.h"
  22
  23 /*
  24  * Sysfs topology values (since 2.6.31, May 2009).
  25  */
  26 static struct topology_val {
  27
  28         /* /sys/dev/block/<maj>:<min>/<ATTR> */
  29         const char *attr;
  30
  31         /* functions to set probing resut */
  32         int (*set_ulong)(blkid_probe, unsigned long);
  33         int (*set_int)(blkid_probe, int);
  34
  35 } topology_vals[] = {
  36         { "alignment_offset", NULL, blkid_topology_set_alignment_offset },
  37         { "queue/minimum_io_size", blkid_topology_set_minimum_io_size },
  38         { "queue/optimal_io_size", blkid_topology_set_optimal_io_size },
  39         { "queue/physical_block_size", blkid_topology_set_physical_sector_size },
  40 };
  41
  42 static int probe_sysfs_tp(blkid_probe pr,
  43                 const struct blkid_idmag *mag __attribute__((__unused__)))
  44 {
  45         dev_t dev, disk = 0;
  46         int rc;
  47         struct sysfs_cxt sysfs, parent;
  48         size_t i, count = 0;
  49
  50         dev = blkid_probe_get_devno(pr);
  51         if (!dev || sysfs_init(&sysfs, dev, NULL) != 0)
  52                 return 1;
  53
  54         rc = 1;         /* nothing (default) */
  55
  56         for (i = 0; i < ARRAY_SIZE(topology_vals); i++) {
  57                 struct topology_val *val = &topology_vals[i];
  58                 int ok = sysfs_has_attribute(&sysfs, val->attr);
  59
  60                 rc = 1; /* nothing */
  61
  62                 if (!ok) {
  63                         if (!disk) {
  64                                 /*
  65                                  * Read atrributes from "disk" if the current
  66                                  * device is a partition.
  67                                  */
  68                                 disk = blkid_probe_get_wholedisk_devno(pr);
  69                                 if (disk && disk != dev) {
  70                                         if (sysfs_init(&parent, disk, NULL) != 0)
  71                                                 goto done;
  72
  73                                         sysfs.parent = &parent;
  74                                         ok = sysfs_has_attribute(&sysfs,
  75                                                                  val->attr);
  76                                 }
  77                         }
  78                         if (!ok)
  79                                 continue;       /* attrinute does not exist */
  80                 }
  81
  82                 if (val->set_ulong) {
  83                         uint64_t data;
  84
  85                         if (sysfs_read_u64(&sysfs, val->attr, &data) != 0)
  86                                 continue;
  87                         rc = val->set_ulong(pr, (unsigned long) data);
  88
  89                 } else if (val->set_int) {
  90                         int64_t data;
  91
  92                         if (sysfs_read_s64(&sysfs, val->attr, &data) != 0)
  93                                 continue;
  94                         rc = val->set_int(pr, (int) data);
  95                 }
  96
  97                 if (rc < 0)
  98                         goto done;      /* error */
  99                 if (rc == 0)
 100                         count++;
 101         }
 102
 103 done:
 104         sysfs_deinit(&sysfs);
 105         if (disk)
 106                 sysfs_deinit(&parent);
 107         if (count)
 108                 return 0;               /* success */
 109         return rc;                      /* error or nothing */
 110 }
 111
 112 const struct blkid_idinfo sysfs_tp_idinfo =
 113 {
 114         .name           = "sysfs",
 115         .probefunc      = probe_sysfs_tp,
 116         .magics         = BLKID_NONE_MAGIC
 117 };
 118