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