chanegs

Author: edcdecl

README.md

@@ -0,0 +1,129 @@
+bsdiff/bspatch
+==============
+bsdiff and bspatch are libraries for building and applying patches to binary
+files.
+
+The original algorithm and implementation was developed by Colin Percival.  The
+algorithm is detailed in his paper, [Naïve Differences of Executable Code](http://www.daemonology.net/papers/bsdiff.pdf).  For more information, visit his
+website at <http://www.daemonology.net/bsdiff/>.
+
+I maintain this project separately from Colin's work, with the goal of making
+the core functionality easily embeddable in existing projects.
+
+Contact
+-------
+[@MatthewEndsley](https://twitter.com/#!/MatthewEndsley)  
+<https://github.com/mendsley/bsdiff>
+
+License
+-------
+Copyright 2003-2005 Colin Percival  
+Copyright 2012 Matthew Endsley
+
+This project is governed by the BSD 2-clause license. For details see the file
+titled LICENSE in the project root folder.
+
+Overview
+--------
+There are two separate libraries in the project, bsdiff and bspatch. Each are
+self contained in bsdiff.c and bspatch.c The easiest way to integrate is to
+simply copy the c file to your source folder and build it.
+
+The overarching goal was to modify the original bsdiff/bspatch code from Colin
+and eliminate external dependencies and provide a simple interface to the core
+functionality.
+
+I've exposed relevant functions via the `_stream` classes. The only external
+dependency not exposed is `memcmp` in `bsdiff`.
+
+This library generates patches that are not compatible with the original bsdiff
+tool. The incompatibilities were motivated by the patching needs for the game
+AirMech <https://www.carbongames.com> and the following requirements:
+
+* Eliminate/minimize any seek operations when applying patches
+* Eliminate any required disk I/O and support embedded streams
+* Ability to easily embed the routines as a library instead of an external binary
+* Compile+run on all platforms we use to build the game (Windows, Linux, NaCl, OSX)
+
+Compiling
+---------
+The libraries should compile warning free in any moderately recent version of
+gcc. The project uses `<stdint.h>` which is technically a C99 file and not
+available in Microsoft Visual Studio. The easiest solution here is to use the
+msinttypes version of stdint.h from <https://code.google.com/p/msinttypes/>.
+The direct link for the lazy people is:
+<https://msinttypes.googlecode.com/svn/trunk/stdint.h>.
+
+If your compiler does not provide an implementation of `<stdint.h>` you can
+remove the header from the bsdiff/bspatch files and provide your own typedefs
+for the following symbols: `uint8_t`, `uint64_t` and `int64_t`.
+
+Examples
+--------
+Each project has an optional main function that serves as an example for using
+the library. Simply defined `BSDIFF_EXECUTABLE` or `BSPATCH_EXECUTABLE` to
+enable building the standalone tools.
+
+Reference
+---------
+### bsdiff
+
+	struct bsdiff_stream
+	{
+		void* opaque;
+		void* (*malloc)(size_t size);
+		void  (*free)(void* ptr);
+		int   (*write)(struct bsdiff_stream* stream,
+					   const void* buffer, int size);
+	};
+
+	int bsdiff(const uint8_t* old, int64_t oldsize, const uint8_t* new,
+	           int64_t newsize, struct bsdiff_stream* stream);
+
+
+In order to use `bsdiff`, you need to define functions for allocating memory and
+writing binary data. This behavior is controlled by the `stream` parameter
+passed to to `bsdiff(...)`.
+
+The `opaque` field is never read or modified from within the `bsdiff` function.
+The caller can use this field to store custom state data needed for the callback
+functions.
+
+The `malloc` and `free` members should point to functions that behave like the
+standard `malloc` and `free` C functions.
+
+The `write` function is called by bsdiff to write a block of binary data to the
+stream. The return value for `write` should be `0` on success and non-zero if
+the callback failed to write all data. In the default example, bzip2 is used to
+compress output data.
+
+`bsdiff` returns `0` on success and `-1` on failure.
+
+### bspatch
+
+	struct bspatch_stream
+	{
+		void* opaque;
+		int (*read)(const struct bspatch_stream* stream,
+		            void* buffer, int length);
+	};
+
+	int bspatch(const uint8_t* old, int64_t oldsize, uint8_t* new,
+	            int64_t newsize, struct bspatch_stream* stream);
+
+The `bspatch` function transforms the data for a file using data generated from
+`bsdiff`. The caller takes care of loading the old file and allocating space for
+new file data.  The `stream` parameter controls the process for reading binary
+patch data.
+
+The `opaque` field is never read or modified from within the bspatch function.
+The caller can use this field to store custom state data needed for the read
+function.
+
+The `read` function is called by `bspatch` to read a block of binary data from
+the stream.  The return value for `read` should be `0` on success and non-zero
+if the callback failed to read the requested amount of data. In the default
+example, bzip2 is used to decompress input data.
+
+`bspatch` returns `0` on success and `-1` on failure. On success, `new` contains
+the data for the patched file.