proxmox-mirrors/libgit2
1
0
Fork 0
mirror of https://git.proxmox.com/git/libgit2 synced 2025-12-26 19:42:35 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity
1,689 Commits 2 Branches 0 Tags 22 MiB
C 98.4%
CMake 0.9%
Shell 0.5%
Python 0.2%
c51065e3e9
Go to file
Roberto Tyley c51065e3e9 Tolerate zlib deflation with window size < 32Kb 
libgit2 currently identifies loose objects as corrupt if they've been
deflated using a window size less than 32Kb, because the
is_zlib_compressed_data() function doesn't recognise the header
byte as a zlib header. This patch makes the method tolerant of
all valid window sizes (15-bit to 8-bit) - but doesn't sacrifice
it's accuracy in distingushing the standard loose-object format
from the experimental (now abandoned) format. It's based on a patch
which has been merged into C-Git master branch:

https://github.com/git/git/commit/7f684a2aff636f44a506

On memory constrained systems zlib may use a much smaller window
size - working on Agit, I found that Android uses a 4KB window;
giving a header byte of 0x48, not 0x78. Consequently all loose
objects generated by the Android platform appear 'corrupt' :(

It might appear that this patch changes isStandardFormat() to the
point where it could incorrectly identify the experimental format as
the standard one, but the two criteria (bitmask & checksum) can only
give a false result for an experimental object where both of the
following are true:

1) object size is exactly 8 bytes when uncompressed (bitmask)
2) [single-byte in-pack git type&size header] * 256
   + [1st byte of the following zlib header] % 31 = 0 (checksum)

As it happens, for all possible combinations of valid object type
(1-4) and window bits (0-7), the only time when the checksum will be
divisible by 31 is for 0x1838 - ie object type *1*, a Commit - which,
due the fields all Commit objects must contain, could never be as
small as 8 bytes in size.

Given this, the combination of the two criteria (bitmask & checksum)
always correctly determines the buffer format, and is more tolerant
than the previous version.

References:

Android uses a 4KB window for deflation:
http://android.git.kernel.org/?p=platform/libcore.git;a=blob;f=luni/src/main/native/java_util_zip_Deflater.cpp;h=c0b2feff196e63a7b85d97cf9ae5bb258

Code snippet searching for false positives with the zlib checksum:
https://gist.github.com/1118177

Change-Id: Ifd84cd2bd6b46f087c9984fb4cbd8309f483dec0
2011-10-24 14:39:03 -07:00
deps msvc: Remove superfluous includes 2011-10-05 13:44:27 -07:00
examples examples: add ls-remote, fetch and index-pack examples 2011-10-03 02:32:32 +02:00
include tree: Fix name lookups once and for all 2011-10-20 02:40:14 +02:00
src Tolerate zlib deflation with window size < 32Kb 2011-10-24 14:39:03 -07:00
tests tests: propagate errors from open_temp_repo() instead of exiting 2011-10-14 16:20:23 -07:00
tests-clay tree: Add git_tree_frompath() which, given a relative path to a tree entry, retrieves the tree object containing this tree entry 2011-10-13 23:30:07 +02:00
.gitattributes Add git attributes settings for *.c and *.h to force line endings to LF. 2011-05-08 12:30:16 -07:00
.gitignore include version information in git2.dll on Windows 2011-10-09 18:55:28 +02:00
.HEADER Switch the license from BSD to GPL+libgcc exception 2008-11-01 15:55:47 -07:00
api.docurium update examples content to be compilable and up to date 2011-06-15 09:40:06 -07:00
AUTHORS Who makes the magic possible? 2011-09-19 06:14:54 +03:00
CMakeLists.txt CMake: use -O0 in debug mode 2011-10-22 12:26:56 +02:00
CONVENTIONS Move include files to include/git/, drop git_ prefix from file names 2008-11-01 15:42:23 -07:00
COPYING Cleanup legal data 2011-09-19 01:54:32 +03:00
git.git-authors Add myself to the list of Git authors who consent 2011-09-08 17:13:32 +02:00
libgit2.pc.in Create and install pkg-config file 2011-08-07 18:44:08 +02:00
Makefile.embed Add src/transports to Makefile sources 2011-10-13 19:05:03 -06:00
README.md Explain how to build universal OSX binaries 2011-10-11 18:14:13 +02:00

README.md

libgit2 - the Git linkable library

libgit2 is a portable, pure C implementation of the Git core methods provided as a re-entrant linkable library with a solid API, allowing you to write native speed custom Git applications in any language with bindings.

libgit2 is licensed under a very permissive license (GPLv2 with a special Linking Exception). This basically means that you can link it (unmodified) with any kind of software without having to release its source code.

What It Can Do

libgit2 is already very usable.

  • SHA conversions, formatting and shortening
  • abstracked ODB backend system
  • commit, tag, tree and blob parsing, editing, and write-back
  • tree traversal
  • revision walking
  • index file (staging area) manipulation
  • reference management (including packed references)
  • config file management
  • high level repository management
  • thread safety and reentrancy
  • descriptive and detailed error messages
  • ...and more (over 175 different API calls)

Building libgit2 - Using CMake

libgit2 builds cleanly on most platforms without any external dependencies. Under Unix-like systems, like Linux, * BSD and Mac OS X, libgit2 expects pthreads to be available; they should be installed by default on all systems. Under Windows, libgit2 uses the native Windows API for threading.

The libgit2 library is built using CMake 2.6+ (http://www.cmake.org) on all platforms.

On most systems you can build the library using the following commands

$ mkdir build && cd build
$ cmake ..
$ cmake --build .

Alternatively you can point the CMake GUI tool to the CMakeLists.txt file and generate platform specific build project or IDE workspace.

To install the library you can specify the install prefix by setting:

$ cmake .. -DCMAKE_INSTALL_PREFIX=/install/prefix
$ cmake --build . --target install

If you want to build a universal binary for Mac OS X, CMake sets it all up for you if you use -DCMAKE_OSX_ARCHITECTURES="i386;x86_64" when configuring.

For more advanced use or questions about CMake please read http://www.cmake.org/Wiki/CMake_FAQ.

The following CMake variables are declared:

  • INSTALL_BIN: Where to install binaries to.
  • INSTALL_LIB: Where to install libraries to.
  • INSTALL_INC: Where to install headers to.
  • BUILD_SHARED_LIBS: Build libgit2 as a Shared Library (defaults to ON)
  • BUILD_TESTS: Build the libgit2 test suite (defaults to ON)
  • THREADSAFE: Build libgit2 with threading support (defaults to OFF)

Language Bindings

Here are the bindings to libgit2 that are currently available:

If you start another language binding to libgit2, please let us know so we can add it to the list.

How Can I Contribute

Fork libgit2/libgit2 on GitHub, add your improvement, push it to a branch in your fork named for the topic, send a pull request.

You can also file bugs or feature requests under the libgit2 project on GitHub, or join us on the mailing list by sending an email to:

libgit2@librelist.com

License

libgit2 is under GPL2 with linking exemption. This means you can link to the library with any program, commercial, open source or other. However, you cannot modify libgit2 and distribute it without supplying the source.

See the COPYING file for the full license text.