Cxbx-Reloaded / zydis

Fast and lightweight x86/x86-64 disassembler library

Fast and lightweight x86/x86-64 disassembler library.

Features

• Supports all x86 and x86-64 (AMD64) instructions and extensions
• Optimized for high performance
• No dynamic memory allocation ("malloc")
• Thread-safe by design
• Very small file-size overhead compared to other common disassembler libraries
• Complete doxygen documentation
• Absolutely no dependencies — not even libc
  • Should compile on any platform with a working C99 compiler
  • Tested on Windows, macOS, FreeBSD and Linux, both user and kernel mode

Quick Example

The following example program uses Zydis to disassemble a given memory buffer and prints the output to the console.

#include <stdio.h>
#include <inttypes.h>
#include <Zydis/Zydis.h>

int main()
{
    uint8_t data[] =
    {
        0x51, 0x8D, 0x45, 0xFF, 0x50, 0xFF, 0x75, 0x0C, 0xFF, 0x75,
        0x08, 0xFF, 0x15, 0xA0, 0xA5, 0x48, 0x76, 0x85, 0xC0, 0x0F,
        0x88, 0xFC, 0xDA, 0x02, 0x00
    };

    // Initialize decoder context.
    ZydisDecoder decoder;
    ZydisDecoderInit(
        &decoder,
        ZYDIS_MACHINE_MODE_LONG_64,
        ZYDIS_ADDRESS_WIDTH_64);

    // Initialize formatter. Only required when you actually plan to
    // do instruction formatting ("disassembling"), like we do here.
    ZydisFormatter formatter;
    ZydisFormatterInit(&formatter, ZYDIS_FORMATTER_STYLE_INTEL);

    // Loop over the instructions in our buffer.
    // The IP is chosen arbitrary here in order to better visualize
    // relative addressing.
    uint64_t instructionPointer = 0x007FFFFFFF400000;
    size_t offset = 0;
    size_t length = sizeof(data);
    ZydisDecodedInstruction instruction;
    while (ZYDIS_SUCCESS(ZydisDecoderDecodeBuffer(
        &decoder, data + offset, length - offset,
        instructionPointer, &instruction)))
    {
        // Print current instruction pointer.
        printf("%016" PRIX64 "  ", instructionPointer);

        // Format & print the binary instruction
        // structure to human readable format.
        char buffer[256];
        ZydisFormatterFormatInstruction(
            &formatter, &instruction, buffer, sizeof(buffer));
        puts(buffer);

        offset += instruction.length;
        instructionPointer += instruction.length;
    }
}

Sample Output

The above example program generates the following output:

007FFFFFFF400000   push rcx
007FFFFFFF400001   lea eax, [rbp-0x01]
007FFFFFFF400004   push rax
007FFFFFFF400005   push qword ptr [rbp+0x0C]
007FFFFFFF400008   push qword ptr [rbp+0x08]
007FFFFFFF40000B   call [0x008000007588A5B1]
007FFFFFFF400011   test eax, eax
007FFFFFFF400013   js 0x007FFFFFFF42DB15

Build

Unix

Zydis builds cleanly on most platforms without any external dependencies. You can use CMake to generate project files for your favorite C99 compiler.

git clone 'https://github.com/zyantific/zydis.git'
cd zydis
mkdir build && cd build
cmake ..
make

Windows

Either use the Visual Studio 2017 project or build Zydis using CMake (video guide).

ZydisInfo tool

Credits

• Intel (for open-sourcing XED, allowing for automatic comparision of our tables against theirs, improving both)
• LLVM (for providing pretty solid instruction data as well)
• Christian Ludloff (http://sandpile.org, insanely helpful)
• LekoArts (for creating the project logo)
• Our contributors on GitHub

License

Zydis is licensed under the MIT license.