test_skipdata.c

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/* Capstone Disassembler Engine */
/* By Nguyen Anh Quynh <aquynh@gmail.com>, 2013-2019 */
 
#include <stdio.h>
#include <stdlib.h>
 
#include <capstone/platform.h>
#include <capstone/capstone.h>
 
struct platform {
    cs_arch arch;
    cs_mode mode;
    unsigned char *code;
    size_t size;
    const char *comment;
    cs_opt_type opt_type;
    cs_opt_value opt_value;
    cs_opt_type opt_skipdata;
    size_t skipdata;
};
 
static void print_string_hex(unsigned char *str, size_t len)
{
    unsigned char *c;
 
    printf("Code: ");
    for (c = str; c < str + len; c++) {
        printf("0x%02x ", *c & 0xff);
    }
    printf("\n");
}
 
#ifdef CAPSTONE_HAS_ARM
static size_t CAPSTONE_API mycallback(const uint8_t *buffer, size_t buffer_size, size_t offset, void *p)
{
    // always skip 2 bytes when encountering data
    return 2;
}
#endif
 
static void test()
{
#ifdef CAPSTONE_HAS_X86
#define X86_CODE32 "\x8d\x4c\x32\x08\x01\xd8\x81\xc6\x34\x12\x00\x00\x00\x91\x92"
#endif
#define RANDOM_CODE "\xed\x00\x00\x00\x00\x1a\x5a\x0f\x1f\xff\xc2\x09\x80\x00\x00\x00\x07\xf7\xeb\x2a\xff\xff\x7f\x57\xe3\x01\xff\xff\x7f\x57\xeb\x00\xf0\x00\x00\x24\xb2\x4f\x00\x78"
 
#if defined(CAPSTONE_HAS_X86)
    cs_opt_skipdata skipdata = {
        // rename default "data" instruction from ".byte" to "db"
        "db",
    };
#endif
 
#ifdef CAPSTONE_HAS_ARM
    cs_opt_skipdata skipdata_callback = {
        "db",
        &mycallback,
    };
#endif
 
    struct platform platforms[] = {
#ifdef CAPSTONE_HAS_X86
        {
            CS_ARCH_X86,
            CS_MODE_32,
            (unsigned char*)X86_CODE32,
            sizeof(X86_CODE32) - 1,
            "X86 32 (Intel syntax) - Skip data",
        },
        {
            CS_ARCH_X86,
            CS_MODE_32,
            (unsigned char*)X86_CODE32,
            sizeof(X86_CODE32) - 1,
            "X86 32 (Intel syntax) - Skip data with custom mnemonic",
            CS_OPT_INVALID,
            CS_OPT_OFF,
            CS_OPT_SKIPDATA_SETUP,
            (size_t) &skipdata,
        },
#endif
#ifdef CAPSTONE_HAS_ARM
        {
            CS_ARCH_ARM,
            CS_MODE_ARM,
            (unsigned char*)RANDOM_CODE,
            sizeof(RANDOM_CODE) - 1,
            "Arm - Skip data",
        },
        {
            CS_ARCH_ARM,
            CS_MODE_ARM,
            (unsigned char*)RANDOM_CODE,
            sizeof(RANDOM_CODE) - 1,
            "Arm - Skip data with callback",
            CS_OPT_INVALID,
            CS_OPT_OFF,
            CS_OPT_SKIPDATA_SETUP,
            (size_t) &skipdata_callback,
        },
#endif
    };
 
    csh handle;
    uint64_t address = 0x1000;
    cs_insn *insn;
    cs_err err;
    int i;
    size_t count;
 
    for (i = 0; i < sizeof(platforms)/sizeof(platforms[0]); i++) {
        printf("****************\n");
        printf("Platform: %s\n", platforms[i].comment);
        err = cs_open(platforms[i].arch, platforms[i].mode, &handle);
        if (err) {
            printf("Failed on cs_open() with error returned: %u\n", err);
            abort();
        }
 
        if (platforms[i].opt_type)
            cs_option(handle, platforms[i].opt_type, platforms[i].opt_value);
 
        // turn on SKIPDATA mode
        cs_option(handle, CS_OPT_SKIPDATA, CS_OPT_ON);
        cs_option(handle, platforms[i].opt_skipdata, platforms[i].skipdata);
 
        count = cs_disasm(handle, platforms[i].code, platforms[i].size, address, 0, &insn);
        if (count) {
            size_t j;
 
            print_string_hex(platforms[i].code, platforms[i].size);
            printf("Disasm:\n");
 
            for (j = 0; j < count; j++) {
                printf("0x%" PRIx64 ":\t%s\t\t%s\n",
                        insn[j].address, insn[j].mnemonic, insn[j].op_str);
            }
 
            // print out the next offset, after the last insn
            printf("0x%" PRIx64 ":\n", insn[j-1].address + insn[j-1].size);
 
            // free memory allocated by cs_disasm()
            cs_free(insn, count);
        } else {
            printf("****************\n");
            printf("Platform: %s\n", platforms[i].comment);
            print_string_hex(platforms[i].code, platforms[i].size);
            printf("ERROR: Failed to disasm given code!\n");
            abort();
        }
 
        printf("\n");
 
        cs_close(&handle);
    }
}
 
int main()
{
    test();
 
#if 0
    #define offsetof(st, m) __builtin_offsetof(st, m)
 
    cs_insn insn;
    printf("size: %lu\n", sizeof(insn));
    printf("@id: %lu\n", offsetof(cs_insn, id));
    printf("@address: %lu\n", offsetof(cs_insn, address));
    printf("@size: %lu\n", offsetof(cs_insn, size));
    printf("@bytes: %lu\n", offsetof(cs_insn, bytes));
    printf("@mnemonic: %lu\n", offsetof(cs_insn, mnemonic));
    printf("@op_str: %lu\n", offsetof(cs_insn, op_str));
    printf("@regs_read: %lu\n", offsetof(cs_insn, regs_read));
    printf("@regs_read_count: %lu\n", offsetof(cs_insn, regs_read_count));
    printf("@regs_write: %lu\n", offsetof(cs_insn, regs_write));
    printf("@regs_write_count: %lu\n", offsetof(cs_insn, regs_write_count));
    printf("@groups: %lu\n", offsetof(cs_insn, groups));
    printf("@groups_count: %lu\n", offsetof(cs_insn, groups_count));
    printf("@arch: %lu\n", offsetof(cs_insn, x86));
#endif
 
    return 0;
}