blob-object/subprojects/blob-object-coff/src/main.c

#ifndef _WIN32
#include <errno.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "coff.h"

static const char* const usage =
    "usage: blob-object-coff <output file> <section name> <symbol name> <blob file>\n";

int main(int argc, char** argv) {
    if (argc < 5) {
        fprintf(stderr, "not enough arguments\n%s", usage);
        return 1;
    }
    if (argc > 5) {
        fprintf(stderr, "too many arguments\n%s", usage);
        return 1;
    }

    char* output_file_name = argv[1];
    char* section_name = argv[2];
    uint32_t section_name_size = strlen(section_name);
    char* symbol_name = argv[3];
    uint32_t symbol_name_size = strlen(symbol_name) + 1;
    char* blob_file_name = argv[4];

    if (section_name_size > 8) {
        fprintf(stderr, "section name is too long for COFF\n");
        return 1;
    }

    FILE* blob_file = fopen(blob_file_name, "rb");
    if (blob_file == NULL) {
        goto blob_fail;
    }
    if (fseek(blob_file, 0, SEEK_END) != 0) {
        goto blob_fail;
    }
    long blob_size = ftell(blob_file);
    if (blob_size == -1L) {
        goto blob_fail;
    }
    rewind(blob_file);
    void* blob = malloc(blob_size);
    if (fread(blob, 1, blob_size, blob_file) < blob_size) {
        goto blob_fail;
    }
    fclose(blob_file);

    FILE* output_file = fopen(output_file_name, "wb");
    if (output_file == NULL) {
        goto output_fail;
    }

    uint32_t size_name_size = symbol_name_size + 5;
    uint32_t blob_name_size = symbol_name_size;

    uint32_t strtab_size_name_off = 4;
    uint32_t strtab_blob_name_off = strtab_size_name_off + size_name_size;
    uint32_t strtab_size = 4 + strtab_blob_name_off + blob_name_size;

    uint32_t coff_header_off = 0;
    uint32_t section_header_off = sizeof(struct coff_header);
    uint32_t symbol_header_off = section_header_off + sizeof(struct coff_section);
    uint32_t size_symbol_off = symbol_header_off;
    uint32_t blob_symbol_off = size_symbol_off + COFF_SYMTAB_SIZE;
    uint32_t string_table_off = blob_symbol_off + COFF_SYMTAB_SIZE;
    uint32_t blob_size_off = string_table_off + strtab_size;
    uint32_t blob_data_off = blob_size_off + sizeof(uint64_t);
    uint32_t file_end_off = blob_data_off + blob_size;

    uint8_t* data = calloc(file_end_off, 1);

    time_t now = time(0);
    *(struct coff_header*) (data + coff_header_off) = (struct coff_header) {
        .magic = MAGIC_AMD64,
        .nscns = 1,
        .timdat = (uint32_t) now,
        .symptr = symbol_header_off,
        .nsyms = 2,
        .opthdr = 0,
        .flags = 0,
    };

    struct coff_section data_section = {
        .name = 0,
        .paddr = 0,
        .vaddr = 0,
        .size = sizeof(uint64_t) + blob_size,
        .scnptr = blob_size_off,
        .relptr = 0,
        .lnnoptr = 0,
        .nreloc = 0,
        .nlnno = 0,
        .flags = STYP_DATA,
    };
    strncpy(data_section.name, section_name, section_name_size);
    memcpy(data + section_header_off, &data_section, sizeof(struct coff_section));

    struct coff_symtab size_symbol = {
        .zeroes = 0,
        .name = strtab_size_name_off,
        .value = 0,
        .scnum = 1,
        .type = 0,
        .sclass = C_EXT,
        .numaux = 0,
    };
    memcpy(data + size_symbol_off, &size_symbol, COFF_SYMTAB_SIZE);

    struct coff_symtab blob_symbol = {
        .zeroes = 0,
        .name = strtab_blob_name_off,
        .value = sizeof(uint64_t),
        .scnum = 1,
        .type = 0,
        .sclass = C_EXT,
        .numaux = 0,
    };
    memcpy(data + blob_symbol_off, &blob_symbol, COFF_SYMTAB_SIZE);

    memcpy(data + string_table_off, &strtab_size, 4);
    memcpy(
        data + string_table_off + strtab_size_name_off,
        symbol_name,
        size_name_size - 1
    );
    memcpy(
        data + string_table_off + strtab_size_name_off + symbol_name_size - 1,
        "_size\0",
        6
    );
    memcpy(
        data + string_table_off + strtab_blob_name_off,
        symbol_name,
        blob_name_size
    );

    *(uint64_t*) (data + blob_size_off) = blob_size;
    memcpy(data + blob_data_off, blob, blob_size);

    if (fwrite(data, 1, file_end_off, output_file) < file_end_off) {
        goto output_fail;
    }
    if (fflush(output_file) != 0) {
        goto output_fail;
    }

    return 0;

    blob_fail:
    fprintf(
        stderr,
        "failed to read blob file %s: %s\n%s",
        blob_file_name,
        strerror(errno),
        usage
    );
    return 1;

    output_fail:
    fprintf(
        stderr,
        "failed to write output file %s: %s\n %s",
        output_file_name,
        strerror(errno),
        usage
    );
    return 1;
}