git.scottworley.com Git - nixos-qemu-vm-isolation/blob - modules/util-linux-squashfs-label.patch

   1 # From https://github.com/plougher/squashfs-tools/pull/264
   2 diff --git a/libblkid/src/superblocks/squashfs.c b/libblkid/src/superblocks/squashfs.c
   3 --- a/libblkid/src/superblocks/squashfs.c
   4 +++ b/libblkid/src/superblocks/squashfs.c
   5 @@ -38,11 +38,74 @@ struct sqsh_super_block {
   6         uint64_t        export_table;
   7  } __attribute__((packed));
   8
   9 +#define SQUASHFS_COMP_OPT_FLAG        (1<<10)
  10 +#define SQUASHFS_EXTRA_INFO_FLAG      (1<<12)
  11 +
  12 +#define SQUASHFS_COMPRESSED_BIT       (1<<15)
  13 +#define SQUASHFS_METADATA_BLOCK_MAX   8192
  14 +
  15 +#define SQUASHFS_EXTRA_INFO_TAG_END   0
  16 +#define SQUASHFS_EXTRA_INFO_TAG_LABEL 1
  17 +#define SQUASHFS_EXTRA_INFO_TAG_UUID  2
  18 +
  19 +static const uint8_t *get_metadata_block(blkid_probe pr, uint64_t *pofs, uint16_t *pmetablock_len)
  20 +{
  21 +       const uint8_t *buf = blkid_probe_get_buffer(pr, *pofs, 2);
  22 +       if (!buf) return NULL;
  23 +       uint16_t metablock_len = (buf[1]<<8) | buf[0];
  24 +       if (!(metablock_len & SQUASHFS_COMPRESSED_BIT)) {
  25 +               /* a compressed metadata block is not valid here */
  26 +               return NULL;
  27 +       }
  28 +       metablock_len &= ~SQUASHFS_COMPRESSED_BIT;
  29 +       if (metablock_len > SQUASHFS_METADATA_BLOCK_MAX) {
  30 +               return NULL;
  31 +       }
  32 +       buf = blkid_probe_get_buffer(pr, *pofs + 2, metablock_len);
  33 +       if (!buf) return NULL;
  34 +       *pmetablock_len = metablock_len;
  35 +       *pofs += 2 + metablock_len;
  36 +       return buf;
  37 +}
  38 +
  39 +static void probe_extra_info(blkid_probe pr, uint16_t flags)
  40 +{
  41 +       uint64_t ofs = sizeof(struct sqsh_super_block);
  42 +       uint16_t metablock_len;
  43 +       const uint8_t *buf;
  44 +
  45 +       /* comp_opts, when present, comes right after the superblock */
  46 +       if (flags & SQUASHFS_COMP_OPT_FLAG) {
  47 +               buf = get_metadata_block(pr, &ofs, &metablock_len);
  48 +               if (!buf) return;
  49 +       }
  50 +
  51 +       /* extra_info comes next */
  52 +       buf = get_metadata_block(pr, &ofs, &metablock_len);
  53 +       if (!buf) return;
  54 +
  55 +       const uint8_t *buf_end = buf + metablock_len;
  56 +       while (buf < buf_end) {
  57 +               unsigned char type = *buf++;
  58 +               if (type == SQUASHFS_EXTRA_INFO_TAG_END || buf >= buf_end)
  59 +                       return;
  60 +               unsigned char len = *buf++;
  61 +               if (buf + len > buf_end) return;
  62 +               if (type == SQUASHFS_EXTRA_INFO_TAG_LABEL) {
  63 +                       blkid_probe_set_label(pr, buf, len);
  64 +               } else if (type == SQUASHFS_EXTRA_INFO_TAG_UUID) {
  65 +                       blkid_probe_set_uuid(pr, buf);
  66 +               }
  67 +               buf += len;
  68 +       }
  69 +}
  70 +
  71  static int probe_squashfs(blkid_probe pr, const struct blkid_idmag *mag)
  72  {
  73         const struct sqsh_super_block *sq;
  74         uint16_t vermaj;
  75         uint16_t vermin;
  76 +       uint16_t flags;
  77
  78         sq = blkid_probe_get_sb(pr, mag, struct sqsh_super_block);
  79         if (!sq)
  80 @@ -58,6 +121,10 @@ static int probe_squashfs(blkid_probe pr, const struct blkid_idmag *mag)
  81         blkid_probe_set_block_size(pr, le32_to_cpu(sq->block_size));
  82         blkid_probe_set_fssize(pr, le64_to_cpu(sq->bytes_used));
  83
  84 +       flags = le16_to_cpu(sq->flags);
  85 +       if (flags & SQUASHFS_EXTRA_INFO_FLAG) {
  86 +               probe_extra_info(pr, flags);
  87 +       }
  88         return 0;
  89  }
  90