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squash4: fix handling of fragments and sparse files 

1. Do not assume block list and fragment are mutually exclusive. Squash
can pack file tail as fragment (unless -no-fragments is specified); so
check read offset and read either from block list or from fragments as
appropriate.

2. Support sparse files with zero blocks.

3. Fix fragment read - frag.offset is absolute fragment position,
not offset relative to ino.chunk.

Reported and tested by Carlo Caione <carlo@endlessm.com>
This commit is contained in:
Andrei Borzenkov 2017-02-24 19:10:43 +03:00
parent 512bb31cbc
commit 951306c509
1 changed files with 37 additions and 20 deletions
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57
grub-core/fs/squash4.c
View File

@ -823,7 +823,12 @@ direct_read (struct grub_squash_data *data,
curread = data->blksz - boff;
if (curread > len)
curread = len;
if (!(ino->block_sizes[i]
if (!ino->block_sizes[i])
{
/* Sparse block */
grub_memset (buf, '\0', curread);
}
else if (!(ino->block_sizes[i]
& grub_cpu_to_le32_compile_time (SQUASH_BLOCK_UNCOMPRESSED)))
{
char *block;
@ -873,36 +878,57 @@ direct_read (struct grub_squash_data *data,
static grub_ssize_t
grub_squash_read_data (struct grub_squash_data *data,
struct grub_squash_cache_inode *ino,
grub_off_t off, char *buf, grub_size_t len)
grub_squash_read (grub_file_t file, char *buf, grub_size_t len)
{
struct grub_squash_data *data = file->data;
struct grub_squash_cache_inode *ino = &data->ino;
grub_off_t off = file->offset;
grub_err_t err;
grub_uint64_t a = 0, b;
grub_uint64_t a, b;
grub_uint32_t fragment = 0;
int compressed = 0;
struct grub_squash_frag_desc frag;
grub_off_t direct_len;
grub_uint64_t mask = grub_le_to_cpu32 (data->sb.block_size) - 1;
grub_size_t orig_len = len;
switch (ino->ino.type)
{
case grub_cpu_to_le16_compile_time (SQUASH_TYPE_LONG_REGULAR):
a = grub_le_to_cpu64 (ino->ino.long_file.chunk);
fragment = grub_le_to_cpu32 (ino->ino.long_file.fragment);
break;
case grub_cpu_to_le16_compile_time (SQUASH_TYPE_REGULAR):
a = grub_le_to_cpu32 (ino->ino.file.chunk);
fragment = grub_le_to_cpu32 (ino->ino.file.fragment);
break;
}
if (fragment == 0xffffffff)
return direct_read (data, ino, off, buf, len);
/* Squash may pack file tail as fragment. So read initial part directly and
get tail from fragments */
direct_len = fragment == 0xffffffff ? file->size : file->size & ~mask;
if (off < direct_len)
{
grub_size_t read_len = direct_len - off;
grub_ssize_t res;
if (read_len > len)
read_len = len;
res = direct_read (data, ino, off, buf, read_len);
if ((grub_size_t) res != read_len)
return -1; /* FIXME: is short read possible here? */
len -= read_len;
if (!len)
return read_len;
buf += read_len;
off = 0;
}
else
off -= direct_len;
err = read_chunk (data, &frag, sizeof (frag),
data->fragments, sizeof (frag) * fragment);
if (err)
return -1;
a += grub_le_to_cpu64 (frag.offset);
a = grub_le_to_cpu64 (frag.offset);
compressed = !(frag.size & grub_cpu_to_le32_compile_time (SQUASH_BLOCK_UNCOMPRESSED));
if (ino->ino.type == grub_cpu_to_le16_compile_time (SQUASH_TYPE_LONG_REGULAR))
b = grub_le_to_cpu32 (ino->ino.long_file.offset) + off;
@ -943,16 +969,7 @@ grub_squash_read_data (struct grub_squash_data *data,
if (err)
return -1;
}
return len;
}
static grub_ssize_t
grub_squash_read (grub_file_t file, char *buf, grub_size_t len)
{
struct grub_squash_data *data = file->data;
return grub_squash_read_data (data, &data->ino,
file->offset, buf, len);
return orig_len;
}
static grub_err_t