assemble.cpp

#include <stdio.h>
#include <stdlib.h>

#include "assemble.h"

using std::string;
using std::vector;

const static char AArch64LLVMMC[] = "llvm-mc -filetype=obj -triple=aarch64 -mattr=+sve %s -o %s";
const static char X86LLVMMC[] = "llvm-mc -filetype=obj -triple=x86_64 -x86-asm-syntax=intel %s -o %s";

#ifndef NDEBUG
const static char AArch64LLVMMC_DISPLAY[] =
    "llvm-mc -filetype=asm -show-encoding -triple=aarch64 -mattr=+sve %s";
const static char X86_64LLVMMC_DISPLAY[] = "llvm-mc -filetype=asm -show-encoding -x86-asm-syntax=intel -triple=x86_64 %s";
#endif

const static unsigned MaxInstNum = 0x100000;

bool assemble(ArchType arch, const string &asmcode, InstBytes &bincode) {
    char asmfilename[260];
    char objfilename[260];
    tmpnam(asmfilename);
    tmpnam(objfilename);
    FILE *asmfile = fopen(asmfilename, "w");
    if (asmfile == nullptr)
        return false;
    fputs(asmcode.c_str(), asmfile);
    fclose(asmfile);

    char cmd[256];
    sprintf(cmd, (arch == ArchType::X86_64) ? X86LLVMMC : AArch64LLVMMC, asmfilename, objfilename);
    system(cmd);

#ifndef NDEBUG
    sprintf(cmd, (arch == ArchType::X86_64) ? X86_64LLVMMC_DISPLAY : AArch64LLVMMC_DISPLAY,
            asmfilename);
    system(cmd);
#endif

    remove(asmfilename);

    FILE *objfile = fopen(objfilename, "rb");
    if (objfile == nullptr)
        return false;

    const unsigned elf_header_szie = 64;
    char elf_header[elf_header_szie];
    size_t readsize;
    readsize = fread(elf_header, 1, elf_header_szie, objfile);
    if (readsize != elf_header_szie) {
        fclose(objfile);
        remove(objfilename);
        return false;
    }

    unsigned buffersize = *(unsigned *)(elf_header + 40) - 0x40 + 0xa0;
    void *instbuff = malloc(buffersize);
    readsize = fread(instbuff, 1, buffersize, objfile);
    if (readsize != buffersize || buffersize >= MaxInstNum) {
        fclose(objfile);
        remove(objfilename);
        return false;
    }

    unsigned instsize = 0;
    readsize = fread(&instsize, 1, 4, objfile);
    if (readsize != 4 || instsize >= MaxInstNum) {
        free(instbuff);
        fclose(objfile);
        remove(objfilename);
        return false;
    }

    bincode.resize(instsize);
    memcpy(&bincode[0], instbuff, instsize);
    free(instbuff);
    fclose(objfile);
    remove(objfilename);

    return true;
}