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The tar header has a 100 byte field for symlink and hard link targets.
If the target is longer than 100 bytes, an extension header has to be
used.
However, it is perfectly valid to fill all 100 bytes to the brim
without adding a null terminator. In case of a symlink, this can
result in garbage link targets, while for hard links it results in
an immediate error since the target cannot be resolved later on.
This commit attempts to fix the problem by replacing the strdup of
the link target with an strndup that copies at most the size of the
target header field.
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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Instead of the convoluted logic, simply use a small number of LUTs
that point to the available compressor flags for each compressor,
the avaialble options and their ranges.
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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Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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The LZMA compressor (through the xz-utils library) supports basically
the same options for micro management as the XZ compressor.
This commit enables support for those options in the compressor, the
option parser and adds an option field to the configuration structure.
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 commit adds propper defines in the super block header and removes
some of the hard coded constants.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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- Move the xattr extraction and repacking to xattr.c
- Don't on-the-fly delete the tar xattr list, use the function
from libtar.a
- Split minor tasks into static helper functions
- creating a libtar xattr struct from libsqfs xattr data
- finding a hard link entry from current path and inode number
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 commit modifies the block processor to support operating without
a fragment table. If that is the case, fragment deduplication is
essentially disabled and fragment blocks aren't indexed anymore.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This function allows submission of raw blocks to the block processor,
completely bypassing the file API.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit adds 2 new user settable flags to the block processor:
- A flag to ignore sparse blocks and treat them like normal
data blocks.
- A flag to disable checksum computation altogether.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit modifies the block processor to support associating a user
data pointer with data blocks that it forwards to the block writer,
which is modified to accept an optional user data pointer.
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 way, everything that could be done through the hooks (and more)
can be done by simply providign a custom implementation. The result is
a lot clener that the previous hook based version.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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- the "bytes submitted" can be moved over to the block processor
- the number of blocks submitted are already there (implcitily, by
adding the data block count to the fragment block count)
- actual data bytes written can be computed from the super block
- the remaining block count can be changed to simple counter that
can be obtained through a function.
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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- Move the inode modifications out of do_block. The inode may be
reallocated in parallel by the process_completed_block function, so
it is not safe to store the fragment location in the do_block
function which is used from the worker threads.
- Move the accounting of fragment blocks to the
process_completed_block function.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This commit breaks the common code up again by moving the data submission
code to a separate file, making both a little bit more readable.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Instead of [potentially] allocating a new fragment block, take an
existing fragment and promote it to the fragmenet block. This saves
as a potential block allocation and a memcpy of the initial data.
Also it *definitely* removes block allocation from the backend path
of the block processor.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Instead of merging fragments into the fragment block inside the
process_completed_fragment function, store a linked list of fragments
in the fragment block and do the actual merging (several memcpy calls
totaling of up to 1M of data in worst case) in the worker thread
instead of the locked, serial path.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Instead of freeing/allocating blocks all the time in the locked,
serial path, use a free list to "recycle" blocks. Once a block is
no longer used, throw it onto the free list. If a new block is,
needed try to get one from the free list before calling malloc.
After a few iterations, the block processor should stop allocating
new blocks and only re-use the ones it already has.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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In the block processor, the payload area is only accessed up to
the indicated size. Even the part that is accessed is initialized
by copying data into the block before increasing the size, so there
is no real point in zero-initializing hundres of kilobytes if not
megabytes of payload area, especially since this is done in the
locked, serial path of the block processor.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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In the zstd compressor, the compression level from the configuration
structure wasn't used at all. Instead, the zstd compressor was told
to use level 0 and compressor options with that parameter were written
to disk.
This commit makes sure the level parameter is propperly initialized.
Reported-by: Sébastien Gross
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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Its purely informational, but make sure other programs don't print
out scary messages that imply the data has been ineficiently.
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 commit attempts to fix the following two problems:
- The number of digits computation returning an off-by-one result
if the number is 10, or the resulting digit string starts
with "10". This results in one-too-many padding bytes, corrupting
the rest of the archive since the headers now don't start at
multiples of 512 anymore.
- Adding the line length prefix affects the line length (duh). If it
grows far enough to require more digits, the result is a similar
problem. This is a converging series that we need to compute the
limit of.
Unit tests for this still need to be added. Or maybe I can convince a
bored undergrad student to provide an induction proof.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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This patch allows external users to fiddle with the XZ compressors
compression strength, alignment and other values.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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If a file consisting of multiple blocks is produced, the last block is
short and the don't fragment flag is set, the last block flag has to
be set on the block when we flush it, so the processing pipeline does
it's job correctly.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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Until now, when packing or unpacking a SquashFS image, files where
created with paranoid permissions (i.e. 0600). The rational behind
this was that otherwise, the tools may inadvertently expose secrets,
e.g. if a root user packs files that that aren't world readable,
such as the /etc/shadows file, but the packed SquashFS image is, we
have accidentally leaked this file to other users that can access
the newly created SquashFS image. The same line of reasoning also
applies when unpacking files.
Unfortunately, this breaks a list of other, more common standard use
cases (e.g. a build server where the an image is built by a deamon
running as user X but then has to be accessed by another deamon
running as Y).
This commit changes to a more standard approach of using permissive
file permissions by default and asking paranoid users to simply use
a paranoid umask.
For tar2sqfs & gensquashfs this simply means chaning the default
permissions in the libsquashfs file implementation.
For rdsquashfs on the other hand there is still the use case where
the unpacked files get the permissions from the [secret] image, so
setting a strict umask is not applicable and changing to permissive
file mode leaks something. For this case a second code path needs to
be added that derives the permissions from the ones in the image.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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I forgot to enable this when I copied it over from Mesa. Mesa's
meson configuration system checks that a C program using the uint128_t
type compiles, but I think this is likely unnecessary. Simply check the
macro that clang and gcc define.
This cuts the .text size of hash_table.o by 160 bytes or about 4% on my
system.
Signed-off-by: Matt Turner <mattst88@gmail.com>
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Not only does this build the hashtable into libutil.a, it also makes
sure the headers end up in the distribution tarball.
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
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With `perf record`/`perf report` I saw that 30% of the time was spent in
`sqfs_frag_table_find_tail_end` with tar2sqfs for a tarball containing
the Gentoo ebuild repository (many thousands of small files).
The reason was the bucketing hash table in frag_table.c: too many
elements in too few buckets meant lots of walking over the linked lists.
This patch replaces that hash table with the hash table implementation
from Mesa. Its implementation is more complex (is is an open-addressing,
linear-reprobing) hash table, but it is much better suited for the task.
On my 4c/8t Skylake, the time to run tar2sqfs drops from 7.5s to less
than 3s. CPU usage increases from ~207% to ~356%, presumably indicating
an increase in available parallelism due to the removal of the hash
table as a bottleneck. The `perf report` profile with this patch shows
that the time spent in `sqfs_frag_table_find_tail_end` has dropped from
~30% to 0.01%.
Output from ministat:
x before
+ after
N Min Max Median Avg Stddev
x 20 7.476 7.685 7.5725 7.5615 0.051254268
+ 20 2.79 2.901 2.846 2.84475 0.03543842
Difference at 95.0% confidence
-4.71675 +/- 0.0282015
-62.3785% +/- 0.241477%
(Student's t, pooled s = 0.0440618)
I imported only the bits of the hash table implementation that were
needed for frag_table.c. Among the changes I made after importing are
- removed usage of ralloc, Mesa's recursive memory allocator
- Replaced ralloc -> malloc
ralloc_free -> free
rzalloc_array -> calloc
- Removed mem_ctx parameters
- Added free()s to the appropriate places (valgrind confirms there
are no leaks)
- removed _mesa_-prefix from function names
Fixes: #40
Signed-off-by: Matt Turner <mattst88@gmail.com>
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