compat/lib/bylabel.c

   1 /*
   2  * mount_by_label.c - aeb
   3  *
   4  * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
   5  * - added Native Language Support
   6  * 2000-01-20 James Antill <james@and.org>
   7  * - Added error message if /proc/partitions cannot be opened
   8  * 2000-05-09 Erik Troan <ewt@redhat.com>
   9  * - Added cache for UUID and disk labels
  10  * Wed Aug 16 2000 Erik Troan <ewt@redhat.com>
  11  * - Ported to dump/restore
  12  */
  13
  14 #include <config.h>
  15 #include <stdio.h>
  16 #include <sys/param.h>
  17 #include <string.h>
  18 #include <ctype.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <malloc.h>
  22 #include "bylabel.h"
  23
  24 #define PROC_PARTITIONS "/proc/partitions"
  25 #define DEVLABELDIR     "/dev"
  26
  27 #define EXT2_SUPER_MAGIC 0xEF53
  28 struct ext2_super_block {
  29         unsigned char   s_dummy1[56];
  30         unsigned char   s_magic[2];
  31         unsigned char   s_dummy2[46];
  32         unsigned char   s_uuid[16];
  33         unsigned char   s_volume_name[16];
  34 };
  35 #define ext2magic(s)    ((unsigned int) s.s_magic[0] + (((unsigned int) s.s_magic[1]) << 8))
  36
  37 void msg __P((const char *fmt, ...));
  38
  39 static struct uuidCache_s {
  40         struct uuidCache_s *next;
  41         char uuid[16];
  42         char *label;
  43         char *device;
  44 } *uuidCache = NULL;
  45
  46 /* for now, only ext2 is supported */
  47 static int
  48 get_label_uuid(const char *device, char **label, char *uuid) {
  49
  50         /* start with a test for ext2, taken from mount_guess_fstype */
  51         /* should merge these later */
  52         int fd;
  53         struct ext2_super_block e2sb;
  54
  55         fd = open(device, O_RDONLY);
  56         if (fd < 0)
  57                 return 1;
  58
  59         if (lseek(fd, 1024, SEEK_SET) != 1024
  60             || read(fd, (char *) &e2sb, sizeof(e2sb)) != sizeof(e2sb)
  61             || (ext2magic(e2sb) != EXT2_SUPER_MAGIC)) {
  62                 close(fd);
  63                 return 1;
  64         }
  65
  66         close(fd);
  67
  68         /* superblock is ext2 - now what is its label? */
  69         memcpy(uuid, e2sb.s_uuid, sizeof(e2sb.s_uuid));
  70         *label = strdup(e2sb.s_volume_name);
  71
  72         return 0;
  73 }
  74
  75 static void
  76 uuidcache_addentry(char *device, char *label, char *uuid) {
  77         struct uuidCache_s *last;
  78
  79         if (!uuidCache) {
  80                 last = uuidCache = (struct uuidCache_s *)malloc(sizeof(*uuidCache));
  81         } else {
  82                 for (last = uuidCache; last->next; last = last->next) ;
  83                 last->next = (struct uuidCache_s *)malloc(sizeof(*uuidCache));
  84                 last = last->next;
  85         }
  86         last->next = NULL;
  87         last->device = device;
  88         last->label = label;
  89         memcpy(last->uuid, uuid, sizeof(last->uuid));
  90 }
  91
  92 static void
  93 uuidcache_init(void) {
  94         char line[100];
  95         char *s;
  96         int ma, mi, sz;
  97         static char ptname[100];
  98         FILE *procpt;
  99         char uuid[16], *label;
 100         char device[110];
 101         int firstPass;
 102         int handleOnFirst;
 103
 104         if (uuidCache)
 105                 return;
 106
 107         procpt = fopen(PROC_PARTITIONS, "r");
 108         if (!procpt)
 109                 return;
 110
 111         for (firstPass = 1; firstPass >= 0; firstPass--) {
 112             fseek(procpt, 0, SEEK_SET);
 113
 114             while (fgets(line, sizeof(line), procpt)) {
 115                 if (sscanf (line, " %d %d %d %[^\n ]",
 116                             &ma, &mi, &sz, ptname) != 4)
 117                         continue;
 118
 119                 /* skip extended partitions (heuristic: size 1) */
 120                 if (sz == 1)
 121                         continue;
 122
 123                 /* look only at md devices on first pass */
 124                 handleOnFirst = !strncmp(ptname, "md", 2);
 125                 if (firstPass != handleOnFirst)
 126                         continue;
 127
 128                 /* skip entire disk (minor 0, 64, ... on ide;
 129                    0, 16, ... on sd) */
 130                 /* heuristic: partition name ends in a digit */
 131
 132                 for(s = ptname; *s; s++);
 133                 if (isdigit(s[-1])) {
 134                 /*
 135                  * Note: this is a heuristic only - there is no reason
 136                  * why these devices should live in /dev.
 137                  * Perhaps this directory should be specifiable by option.
 138                  * One might for example have /devlabel with links to /dev
 139                  * for the devices that may be accessed in this way.
 140                  * (This is useful, if the cdrom on /dev/hdc must not
 141                  * be accessed.)
 142                  */
 143                         sprintf(device, "%s/%s", DEVLABELDIR, ptname);
 144                         if (!get_label_uuid(device, &label, uuid))
 145                                 uuidcache_addentry(strdup(device), label, uuid);
 146                 }
 147             }
 148         }
 149
 150         fclose(procpt);
 151 }
 152
 153 #define UUID   1
 154 #define VOL    2
 155
 156 static char *
 157 get_spec_by_x(int n, const char *t) {
 158         struct uuidCache_s *uc;
 159
 160         uuidcache_init();
 161         uc = uuidCache;
 162
 163         while(uc) {
 164                 switch (n) {
 165                 case UUID:
 166                         if (!memcmp(t, uc->uuid, sizeof(uc->uuid)))
 167                                 return strdup(uc->device);
 168                         break;
 169                 case VOL:
 170                         if (!strcmp(t, uc->label))
 171                                 return strdup(uc->device);
 172                         break;
 173                 }
 174                 uc = uc->next;
 175         }
 176         return NULL;
 177 }
 178
 179 static u_char
 180 fromhex(char c) {
 181         if (isdigit(c))
 182                 return (c - '0');
 183         else if (islower(c))
 184                 return (c - 'a' + 10);
 185         else
 186                 return (c - 'A' + 10);
 187 }
 188
 189 static char *
 190 get_spec_by_uuid(const char *s) {
 191         u_char uuid[16];
 192         int i;
 193
 194         if (strlen(s) != 36 ||
 195             s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-')
 196                 goto bad_uuid;
 197         for (i=0; i<16; i++) {
 198             if (*s == '-') s++;
 199             if (!isxdigit(s[0]) || !isxdigit(s[1]))
 200                     goto bad_uuid;
 201             uuid[i] = ((fromhex(s[0])<<4) | fromhex(s[1]));
 202             s += 2;
 203         }
 204         return get_spec_by_x(UUID, uuid);
 205
 206  bad_uuid:
 207         msg("mount: bad UUID\n");
 208         return NULL;            /* just for gcc */
 209 }
 210
 211 static char *
 212 get_spec_by_volume_label(const char *s) {
 213         return get_spec_by_x(VOL, s);
 214 }
 215
 216 const char *
 217 get_device_name(const char * item) {
 218         const char * rc;
 219
 220         if (!strncmp(item, "UUID=", 5)) {
 221                 rc = get_spec_by_uuid(item+5);
 222         }
 223         else
 224                 if (!strncmp(item, "LABEL=", 6)) {
 225                         rc = get_spec_by_volume_label(item+6);
 226                 }
 227                 else {
 228                         rc = item;
 229                 }
 230
 231         return rc;
 232 }
 233
 234 const char *
 235 get_device_label(const char * spec) {
 236         struct uuidCache_s *uc;
 237
 238         uuidcache_init();
 239         uc = uuidCache;
 240
 241         while(uc) {
 242                 if (!strcmp(spec, uc->device))
 243                         return uc->label[0] == '\0' ? NULL : strdup(uc->label);
 244                 uc = uc->next;
 245         }
 246         return NULL;
 247 }