squashfs-tools-ng.git/lib, branch v0.9.1

Fix: use 0644 as default permissions when creating files

2020-05-02T23:43:11+00:00

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

Enable uint128_t path

2020-04-27T10:49:25+00:00

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

Add hash table code to libutil.a

2020-04-27T10:08:58+00:00

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

Import and use Mesa's hash table

2020-04-22T12:48:46+00:00

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

Skip PAX global headers

2020-04-22T12:22:44+00:00

Tar archives can contain set two kinds of PAX headers: - local headers that modify the attributes of the next file - global headers that set defaults for all files The later is used "... not widely used", according to tar(5) and has been deliberately not implemented. Some programs (e.g. git-archive) *do* generate them (in the case of git, it stores the commit hash). This commit adds a code path that skips a PAX global header entirely and resumes tar parsing, instead of erroneusly reporting it as an entry. Signed-off-by: David Oberhollenzer

Remove some configure time sizeof checks

2020-04-17T21:52:52+00:00

In libtar, the sizeof time_t checked when trying to store a time value. It is pointless using the preprocessor here, as we can simply do an if (sizeof(time_t) < ...) check and the compiler will take care optimizing away one or the other branch. After changing the libtar check and the corresponding unit tests, the sizeof check can be removed from configure.ac, along with other unused sizeof checks. Signed-off-by: David Oberhollenzer

Cleanup: split read_header.c in libtar.a

2020-04-17T21:31:32+00:00

Simply moving the pax header decoding to a separate file and splitting out the common helper functions should be a good start. Signed-off-by: David Oberhollenzer

tar2sqfs & gensquashfs: Delete the output file on failure

2020-04-16T03:17:29+00:00

This commit changes the tar2sqfs & gensquashfs code to pass the exit status on to sqfs_writer_cleanup in libcommon. The function sqfs writer code in libcommon is changed to retain the output file name and delete it if the status passed to the cleanup function is anything other than EXIT_SUCCESS. Signed-off-by: David Oberhollenzer

Fix missing header without LZO

2020-04-01T16:28:54+00:00

lib/common/compress.c: In function 'compressor_get_default': lib/common/compress.c:39:2: warning: implicit declaration of function 'assert' [-Wimplicit-function-declaration] 39 | assert(0); | ^~~~~~ lib/common/compress.c:8:1: note: 'assert' is defined in header ''; did you forget to '#include '? 7 | #include "common.h" +++ |+#include 8 |

Fix compressor availability check in libcommon

2020-03-19T22:09:17+00:00

Initialize have_compressor to false before testing, to make the check work. Signed-off-by: David Oberhollenzer