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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>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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The same problem with the meta data header again, 16 bit read from
a buffer: copy the buffer data into a 16 bit variable instead of
casting to something potentially unaligned.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Currently, when the block processor aggreagtes fragments into a
fragment block, it applies the "don't compress" flag if any of the
original framgnets has it set, but the "align to device block" flag
is lost.
This commit ensures that both flags get applied to the fragment block
if set.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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1) If the block alignment flag is set, the padding bytes must be
inserted _before_ recording the start position, otherwise the
resulting image is not readable.
2) Also perform alignment if the flag is set on a fragment block.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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On systems like Windows, the dynamic library and applications can
easily end up being linked against different runtime libraries, so
applications cannot be expected to be able to free() any malloc'd
pointer that the library returns.
This commit adds an sqfs_free function so the application can pass
pointers back to the library to call the correct free() implementation.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This was already in the original block processor but got dropped by
accident when restructuring it.
The problem manifests itself when manually submitting fragment blocks.
They no longer get correct I/O queue tickets, clog up the queue and
the processor eventually throws an internal error.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Only clean up the fragment if it hasn't been re-assigned to the
fragment block. The NULL check is definitely wrong, because we
no longer re-assign it as NULL.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Dequeuing won't work if we have a backlog of 1 or 2 and the blocks
are used for internal buffering. Take that into account, similar to
the sync code. Also bump the minimum backlog to 3, just to make
absolutely sure we cannot run into a dequeue loop trying to allocate
a block.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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In the hash-table equals callback, if the hash and size match, do an
exact, byte-for-byte comparison of the fragment in question. The
fragment can either be in a fragment block that is in-flight (for which
we have the in-flight list), in the current, unfinished fragment block,
or it can be on disk.
In the later case, the fragment block is resolved through the fragment
table and read back from disk into a scratch buffer and decompressed.
After that, the fragment is checked for byte-for-byte equality with
the one we resolved through the hash table.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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If we want full, byte-for byte, verification of fragments during
de-duplication we need to check back with the blocks already written
to disk, or with the ones that are in flight.
The previous, extremely hacky approach simply locked up the thread
pool and investigated the queues. For the new approach, we treat the
thread pool as completely opaque and don't try to touch it.
This commit modifies the block processor to keep duplicate copies of
each submitted fragment block around, that are cleaned up once the
block is dequeued and written to disk. So instead of touching the
thread pool, we can simply investigate the in-fligth-block list and
the current block, before resorting to reading back fragment blocks
from the file.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Simply count the number of blocks we hand out (malloc'ed or recycled)
and decrease the counter when we put blocks back for recycling.
The sync() part becomes a little more complicated, because we can get
stuck with a backlog of 1 or 2 because we have a fragment or current
block buffer in use. We also need to accout for this when creating the
processor, because we need to be able to request at least 2 blocks
without stalling.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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A cleaner separation between common code, frontend code and backend
code is made.
The "is this byte blob zero" function is moved out to libutil (with
test case and everything) with a more optimized implementation.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Throw out the messy thread pool implementation and temporarily also
remove the exact fragment matching for simplicity.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit restructures the rbtree code to optionally use a pool
allocator for the nodes. The option is made depenend on the presence
of a pre-processor flag.
To the configure script is added an option to enable/disable the use
of custom allocators. It makes sense to still allow the malloc/free
based routes for better ASAN based instrumentation.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Technically, this should *never* **ever** happen, because a SquashFS
file always starts with a super block, which isn't wrapped in a meta
data block, so a valid SquashFS file will never have a reason to read
from offset 0.
However, this does bite us when doing unit tests where the meta reader
and writer are used on an otherwise empty file. When trying to read
from offset 0, the caching code assumes that we already have that
block, since tha block_offset got initialized to 0.
This commit changes the initialization to set the current block
location to the maximum 64 bit integer, a location we are never
going to read from, since it will always be after the limit.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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By storing the blocks in a tree, the de-duplication can lookup
existing blocks in logartihmic instead of linear time.
The linked list is still maintained, because we need to iterate
over the blocks in creation order during serialization.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit mainly serves the static analysis tooling.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This function creates a block processor from a structure describing it.
A stub implementation for the old sqfs_block_processor_create is added
that simply sets up such a struct and forwards the call.
The current version of the description struct only contains the exact
same parameters and a size field at the beginning.
This approach is supposed to make extending the range of parameters
easier without breaking ABI compatibillity.
Currently already planned are:
- Adding a sqfs_file_t pointer to double-check when deduplicating
fragments.
- When the scanning code reaches a usable state, add the abillity
to pass scanned fragment data, so the block processor can be used
for appending to an existing image.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Keeping a list of fragments stored away in the current fragment block
and consolidating them in the thread pool takes them out of circulation.
If we have a lot of tiny fragments, this can lead to a situation where
all the limit is reached, but we cannot do anything, because we are
waiting for a block to complete, but they are all attached to the
current fragment block and the queue is empty.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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It looks like the last commit missed a couple more occurences
where '\' was treated incorrectly.
Fixes were still needed in sqfs_dir_reader_find_by_path and
sqfs_dir_reader_get_full_hierarchy.
This path is used in extras/browse.c.
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Instead of comparing (compresed, disk-size, checksum) tuples to find
block matches, do an exact, byte-for-byte comparison of the data
stored on disk to avoid the possibility of a spurious colision.
Since this is the desired behaviour, make it the default, optionally
overrideable through a flag.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Instead of dereferencing the NULL pointer and crashing.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit fixes a bug where the block processor state machine would
not add the "last block" flag if there is only one not entirely filled
block and the "don't fragment" flag is set. If the flag isn't set, the
inode start block position is not updated and points to the beginning
of the image instead.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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The source code of a modified liblz4 and zlib are included with the
option to compile them into libsquashfs if they are not available on
the system.
So far, the source code was included directly in the compressor sub
directory within libsqsuashfs. This commit moves the libraries out
into the lib directory.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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If an xattr value is stored OOL, the value actually holds an 8 byte
reference to another, previously stored value. This reference points
to the header that we need to read to know the actual size of the
value before reading it, not the value itself, so after reading the
reference and seeking to it, the xattr reader needs to read the actual
header.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Instead of doing the fragile size comparison in both loops, simply
bail from the function if offset is out of bounds, clamp the size
to the available range of the file and abail if it is zero.
As a result, a lot of checks can be removed and the function will not
return data beyond EOF.
This problem occoured with files that have a short last block instead
of a fragment.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit fixes a build issue on BSD based systems, where alloca
is defined in stdlib.h and there is no such thing as "alloca.h".
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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It does not make any changes to the writer itself, so mark it as
const. This also requires some similar changes to the string table.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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After finding a match, reducing the reference count of the matched
elements and increasing them afterwards leaves the reference count
identical, because they refere to the same entries.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit moves the libsquashfs xattr related code into a sub
directory and splits the xattr writer code up into several files.
No actual code is changed.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Fragment deduplication really doesn't belong into the public API of
the fragment table.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Every compressor (except LC4) has a compression level parameter. This
commit pulls the compression level field out into the generic
configuration structure and applies some code clean ups as a result
from this.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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