util-linux/volume_id/util.c

   1 /*
   2  * volume_id - reads filesystem label and uuid
   3  *
   4  * Copyright (C) 2005 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  *      This library is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU Lesser General Public
   8  *      License as published by the Free Software Foundation; either
   9  *      version 2.1 of the License, or (at your option) any later version.
  10  *
  11  *      This library is distributed in the hope that it will be useful,
  12  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  *      Lesser General Public License for more details.
  15  *
  16  *      You should have received a copy of the GNU Lesser General Public
  17  *      License along with this library; if not, write to the Free Software
  18  *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  19  */
  20
  21 #include "volume_id_internal.h"
  22
  23 void volume_id_set_unicode16(char *str, size_t len, const uint8_t *buf, enum endian endianess, size_t count)
  24 {
  25         unsigned i, j;
  26         unsigned c;
  27
  28         j = 0;
  29         for (i = 0; i + 2 <= count; i += 2) {
  30                 if (endianess == LE)
  31                         c = (buf[i+1] << 8) | buf[i];
  32                 else
  33                         c = (buf[i] << 8) | buf[i+1];
  34                 if (c == 0)
  35                         break;
  36                 if (j+1 >= len)
  37                         break;
  38                 if (c < 0x80) {
  39                         /* 0xxxxxxx */
  40                 } else {
  41                         uint8_t topbits = 0xc0;
  42                         if (j+2 >= len)
  43                                 break;
  44                         if (c < 0x800) {
  45                                 /* 110yyyxx 10xxxxxx */
  46                         } else {
  47                                 if (j+3 >= len)
  48                                         break;
  49                                 /* 1110yyyy 10yyyyxx 10xxxxxx */
  50                                 str[j++] = (uint8_t) (0xe0 | (c >> 12));
  51                                 topbits = 0x80;
  52                         }
  53                         str[j++] = (uint8_t) (topbits | ((c >> 6) & 0x3f));
  54                         c = 0x80 | (c & 0x3f);
  55                 }
  56                 str[j++] = (uint8_t) c;
  57         }
  58         str[j] = '\0';
  59 }
  60
  61 #ifdef UNUSED
  62 static const char *usage_to_string(enum volume_id_usage usage_id)
  63 {
  64         switch (usage_id) {
  65         case VOLUME_ID_FILESYSTEM:
  66                 return "filesystem";
  67         case VOLUME_ID_PARTITIONTABLE:
  68                 return "partitiontable";
  69         case VOLUME_ID_OTHER:
  70                 return "other";
  71         case VOLUME_ID_RAID:
  72                 return "raid";
  73         case VOLUME_ID_DISKLABEL:
  74                 return "disklabel";
  75         case VOLUME_ID_CRYPTO:
  76                 return "crypto";
  77         case VOLUME_ID_UNPROBED:
  78                 return "unprobed";
  79         case VOLUME_ID_UNUSED:
  80                 return "unused";
  81         }
  82         return NULL;
  83 }
  84
  85 void volume_id_set_usage_part(struct volume_id_partition *part, enum volume_id_usage usage_id)
  86 {
  87         part->usage_id = usage_id;
  88         part->usage = usage_to_string(usage_id);
  89 }
  90
  91 void volume_id_set_usage(struct volume_id *id, enum volume_id_usage usage_id)
  92 {
  93         id->usage_id = usage_id;
  94         id->usage = usage_to_string(usage_id);
  95 }
  96
  97 void volume_id_set_label_raw(struct volume_id *id, const uint8_t *buf, size_t count)
  98 {
  99         memcpy(id->label_raw, buf, count);
 100         id->label_raw_len = count;
 101 }
 102 #endif
 103
 104 #ifdef NOT_NEEDED
 105 static size_t strnlen(const char *s, size_t maxlen)
 106 {
 107         size_t i;
 108         if (!maxlen) return 0;
 109         if (!s) return 0;
 110         for (i = 0; *s && i < maxlen; ++s) ++i;
 111         return i;
 112 }
 113 #endif
 114
 115 void volume_id_set_label_string(struct volume_id *id, const uint8_t *buf, size_t count)
 116 {
 117         unsigned i;
 118
 119         memcpy(id->label, buf, count);
 120
 121         /* remove trailing whitespace */
 122         i = strnlen(id->label, count);
 123         while (i--) {
 124                 if (!isspace(id->label[i]))
 125                         break;
 126         }
 127         id->label[i+1] = '\0';
 128 }
 129
 130 void volume_id_set_label_unicode16(struct volume_id *id, const uint8_t *buf, enum endian endianess, size_t count)
 131 {
 132          volume_id_set_unicode16(id->label, sizeof(id->label), buf, endianess, count);
 133 }
 134
 135 void volume_id_set_uuid(struct volume_id *id, const uint8_t *buf, enum uuid_format format)
 136 {
 137         unsigned i;
 138         unsigned count = 0;
 139
 140         switch (format) {
 141         case UUID_DOS:
 142                 count = 4;
 143                 break;
 144         case UUID_NTFS:
 145                 count = 8;
 146                 break;
 147         case UUID_DCE:
 148                 count = 16;
 149                 break;
 150         case UUID_DCE_STRING:
 151                 /* 36 is ok, id->uuid has one extra byte for NUL */
 152                 count = VOLUME_ID_UUID_SIZE;
 153                 break;
 154         }
 155 //      memcpy(id->uuid_raw, buf, count);
 156 //      id->uuid_raw_len = count;
 157
 158         /* if set, create string in the same format, the native platform uses */
 159         for (i = 0; i < count; i++)
 160                 if (buf[i] != 0)
 161                         goto set;
 162         return; /* all bytes are zero, leave it empty ("") */
 163
 164 set:
 165         switch (format) {
 166         case UUID_DOS:
 167                 sprintf(id->uuid, "%02X%02X-%02X%02X",
 168                         buf[3], buf[2], buf[1], buf[0]);
 169                 break;
 170         case UUID_NTFS:
 171                 sprintf(id->uuid, "%02X%02X%02X%02X%02X%02X%02X%02X",
 172                         buf[7], buf[6], buf[5], buf[4],
 173                         buf[3], buf[2], buf[1], buf[0]);
 174                 break;
 175         case UUID_DCE:
 176                 sprintf(id->uuid,
 177                         "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
 178                         buf[0], buf[1], buf[2], buf[3],
 179                         buf[4], buf[5],
 180                         buf[6], buf[7],
 181                         buf[8], buf[9],
 182                         buf[10], buf[11], buf[12], buf[13], buf[14], buf[15]);
 183                 break;
 184         case UUID_DCE_STRING:
 185                 memcpy(id->uuid, buf, count);
 186                 id->uuid[count] = '\0';
 187                 break;
 188         }
 189 }
 190
 191 /* Do not use xlseek here. With it, single corrupted filesystem
 192  * may result in attempt to seek past device -> exit.
 193  * It's better to ignore such fs and continue.  */
 194 void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
 195 {
 196         uint8_t *dst;
 197         unsigned small_off;
 198         ssize_t read_len;
 199
 200         dbg("get buffer off 0x%llx(%llu), len 0x%zx",
 201                 (unsigned long long) off, (unsigned long long) off, len);
 202
 203         /* check if requested area fits in superblock buffer */
 204         if (off + len <= SB_BUFFER_SIZE
 205          /* && off <= SB_BUFFER_SIZE - want this paranoid overflow check? */
 206         ) {
 207                 if (id->sbbuf == NULL) {
 208                         id->sbbuf = xmalloc(SB_BUFFER_SIZE);
 209                 }
 210                 small_off = off;
 211                 dst = id->sbbuf;
 212
 213                 /* check if we need to read */
 214                 len += off;
 215                 if (len <= id->sbbuf_len)
 216                         goto ret; /* we already have it */
 217
 218                 dbg("read sbbuf len:0x%x", (unsigned) len);
 219                 id->sbbuf_len = len;
 220                 off = 0;
 221                 goto do_read;
 222         }
 223
 224         if (len > SEEK_BUFFER_SIZE) {
 225                 dbg("seek buffer too small %d", SEEK_BUFFER_SIZE);
 226                 return NULL;
 227         }
 228         dst = id->seekbuf;
 229
 230         /* check if we need to read */
 231         if ((off >= id->seekbuf_off)
 232          && ((off + len) <= (id->seekbuf_off + id->seekbuf_len))
 233         ) {
 234                 small_off = off - id->seekbuf_off; /* can't overflow */
 235                 goto ret; /* we already have it */
 236         }
 237
 238         id->seekbuf_off = off;
 239         id->seekbuf_len = len;
 240         id->seekbuf = xrealloc(id->seekbuf, len);
 241         small_off = 0;
 242         dst = id->seekbuf;
 243         dbg("read seekbuf off:0x%llx len:0x%zx",
 244                                 (unsigned long long) off, len);
 245  do_read:
 246         if (lseek(id->fd, off, SEEK_SET) != off) {
 247                 dbg("seek(0x%llx) failed", (unsigned long long) off);
 248                 goto err;
 249         }
 250         read_len = full_read(id->fd, dst, len);
 251         if (read_len != len) {
 252                 dbg("requested 0x%x bytes, got 0x%x bytes",
 253                                 (unsigned) len, (unsigned) read_len);
 254  err:
 255                 /* No filesystem can be this tiny. It's most likely
 256                  * non-associated loop device, empty drive and so on.
 257                  * Flag it, making it possible to short circuit future
 258                  * accesses. Rationale:
 259                  * users complained of slow blkid due to empty floppy drives.
 260                  */
 261                 if (off < 64*1024)
 262                         id->error = 1;
 263                 /* id->seekbuf_len or id->sbbuf_len is wrong now! Fixing. */
 264                 volume_id_free_buffer(id);
 265                 return NULL;
 266         }
 267  ret:
 268         return dst + small_off;
 269 }
 270
 271 void volume_id_free_buffer(struct volume_id *id)
 272 {
 273         free(id->sbbuf);
 274         id->sbbuf = NULL;
 275         id->sbbuf_len = 0;
 276         free(id->seekbuf);
 277         id->seekbuf = NULL;
 278         id->seekbuf_len = 0;
 279         id->seekbuf_off = 0; /* paranoia */
 280 }