Cross-Platform C library for peeking/poking/handling virtual memory

#define CHARACTER_HEALTH_ADDR 0xDEADBEEF /* In foreign address space */
unsigned health;
vas_t *vas = vas_open(process_id, 0);
vas_read(vas, CHARACTER_HEALTH_ADDR, &health, sizeof (unsigned));
printf("Character health is %u\n", health);

Features

• Cross-Platform: Runs on Windows, Linux, BSD, MacOS, SunOS and a probably a couple more systems
• Read/Write/Remap other processes' memory
• Allocate those nifty virtual-memory-mirrored ring buffers
• Duplicate memory with Copy-on-Write semantics
• Portably map files

Install

Binary releases for Windows, macOS and Linux are available at the Github releases page.

Otherwise, with Perl (and enough disk space for package dependencies) available, you can run:

cpan Alien::libvas
ln $(perl -MAlien::libvas -e 'print Alien::libvas->dist_dir')/share/pkgconfig/libvas.pc /usr/local/share/pkgconfig/

This fetches CMake if unavailable, uses it to build the library, installs the Perl wrapper and runs both the C and Perl test suite. See Alien::libvas for details.

Afterwards you can use pkg-config --libs libvas and pkg-config --cflags libvas in your build scripts.

Manual install

git clone https://github.com/a3f/libvas.git && cd libvas
mkdir build && cd build
cmake ..
make
ctest
make install

Some manual tests/examples are available in test/manual/. Applicable tests in test/ are run automatically on ctest.

Platforms

Multiple backends are available, each corresponding to a directory in the source hierarchy:

• win32      - Windows API's {Read,Write}ProcessMemory
• mach       - Mach Virtual Memory API (vm_copy) - macOS and possibly GNU Hurd
• process_vm - process_vm_{readv, writev} on Linux 3.2+
• procfs     - /proc/$pid/mem on Linux and some BSDs, /proc/$pid/as on SunOS
• ptrace     - ptrace(2), available on many Unices
• memcpy     - Trivial implementation that doesn't supports foreign address spaces

The appropriate backend is selected by CMake at configuration time. You can override the selection by specifying e.g. cmake -DBACKEND=ptrace.

libvas has no external non-OS dependencies and is written in C++-compatible C89 and should compilable by any standard C or C++ compiler.

TODO

• Add support for ptrace(PT_IO, ...) on BSD
• CheatEngine's dbk32.sys driver as another Win32 Backend
• Change page access permissions
• Better error reporting
• Report errors on Windows
• Make global errors thread-local
• run onchild_fork test on macOS without super user privileges
• Make Backends selectable at run time
• Partition backends: ringbuffer, CoW, memory peek/poke?
• Trapping access violations
• Guard page allocation?
• Wrappers for scripting languages besides Perl
• Provide all configurations in the release package: universal libraries on macOS, Both 32 bit and 64 bit on Linux and *.lib as well as *.a on Windows

License

libvas is released under the LGPL. It contains code from Stijus' MemoryScanner, released under the MIT License.