diff options
| author | David Oberhollenzer <david.oberhollenzer@sigma-star.at> | 2021-07-21 09:41:47 +0200 |
|---|---|---|
| committer | David Oberhollenzer <david.oberhollenzer@sigma-star.at> | 2021-07-21 09:56:31 +0200 |
| commit | 248494992442fbde7eb6ca3979a778d82fa86016 (patch) | |
| tree | 3ba8d5100aef7cf0d1f1aeae9f306fd5e6053503 /lib/sqfs | |
| parent | 5333fbe46bcbf70b4888bcc6655681f2cd0f161b (diff) | |
Fix libsquashfs directory writer size accounting
The squashfs readdir() implementation in the Linux kernel returns
non-existing "." and ".." entries for offsets 0 and 1, and after
that reads from disk. For convenience, it was decided to store an
off-by-3 value on disk instead of doing complex primary school math
to adjust for this. This didn't show up until now, because the kernel
implementation trusts the value from the directory header more than
the actual size in the inode and happily reads 3 more than the inode
would allow it to. This only showed up with 7-zip which subtracts 3
from the size and expects the result to be exact and bails if the
directory headers suggest otherwise.
And yes, I did consider making a "Holy Hand Granade of Antioch"
reference, but consciously decided not to.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib/sqfs')
| -rw-r--r-- | lib/sqfs/dir_writer.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/lib/sqfs/dir_writer.c b/lib/sqfs/dir_writer.c index 908bb01..ad44458 100644 --- a/lib/sqfs/dir_writer.c +++ b/lib/sqfs/dir_writer.c @@ -379,7 +379,7 @@ sqfs_inode_generic_t block_offset = writer->dir_ref & 0xFFFF; if (xattr != 0xFFFFFFFF || start_block > 0xFFFFFFFFUL || - writer->dir_size > 0xFFFF) { + writer->dir_size > (0xFFFF - 3)) { inode->base.type = SQFS_INODE_EXT_DIR; } else { inode->base.type = SQFS_INODE_DIR; @@ -388,12 +388,12 @@ sqfs_inode_generic_t if (inode->base.type == SQFS_INODE_DIR) { inode->data.dir.start_block = start_block; inode->data.dir.nlink = writer->ent_count + hlinks + 2; - inode->data.dir.size = writer->dir_size; + inode->data.dir.size = writer->dir_size + 3; inode->data.dir.offset = block_offset; inode->data.dir.parent_inode = parent_ino; } else { inode->data.dir_ext.nlink = writer->ent_count + hlinks + 2; - inode->data.dir_ext.size = writer->dir_size; + inode->data.dir_ext.size = writer->dir_size + 3; inode->data.dir_ext.start_block = start_block; inode->data.dir_ext.parent_inode = parent_ino; inode->data.dir_ext.offset = block_offset; |