/* -*- Mode: C; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 *  Copyright (C) 2009  Kouhei Sutou <kou@clear-code.com>
 *
 *  This library is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <stdio.h>
#include <string.h>
#include <windows.h>

int
main (int argc, char **argv)
{
    char *content = NULL;
    IMAGE_NT_HEADERS *nt_headers;
    IMAGE_SECTION_HEADER *text_section = NULL;
    IMAGE_SECTION_HEADER *edata_section = NULL;

    if (argc < 2) {
        printf("Usage: %s XXX.dll\n", argv[0]);
        return 0;
    }

    {
        FILE *file;
        char buffer[4096];
        size_t bytes, total_bytes = 0;

        file = fopen(argv[1], "rb");
        if (!file) {
            perror("failed to fopen()");
            return -1;
        }
        while (!feof(file)) {
            char *original_content;

            bytes = fread(buffer, 1, sizeof(buffer), file);
            total_bytes += bytes;
            original_content = content;
            content = realloc(content, total_bytes);
            if (!content) {
                free(original_content);
                fclose(file);
                perror("failed to realloc()");
                return -1;
            }
            memcpy(content + total_bytes - bytes, buffer, bytes);
        }
        fclose(file);
    }

    {
        IMAGE_DOS_HEADER *dos_header;

        dos_header = (IMAGE_DOS_HEADER *)content;
        nt_headers = (IMAGE_NT_HEADERS *)(content + dos_header->e_lfanew);
        if (nt_headers->Signature != IMAGE_NT_SIGNATURE) {
            printf("not PE\n");
            return -1;
        }

        if (!(nt_headers->FileHeader.Characteristics & IMAGE_FILE_DLL)) {
            printf("not DLL\n");
            return -1;
        }
    }

    {
        WORD i;
        IMAGE_SECTION_HEADER *first_section;

        first_section = IMAGE_FIRST_SECTION(nt_headers);
        for (i = 0; i < nt_headers->FileHeader.NumberOfSections; i++) {
            const char *section_name;

            section_name = (const char *)((first_section + i)->Name);
            if (strcmp(".edata", section_name) == 0) {
                edata_section = first_section + i;
            } else if (strcmp(".text", section_name) == 0) {
                text_section = first_section + i;
            }
        }

        if (!text_section) {
            printf("no .text section\n");
            return -1;
        }

        if (!edata_section) {
            printf("no .edata section\n");
            return -1;
        }
    }

    {
        WORD i;
        IMAGE_EXPORT_DIRECTORY *export_directory;
        const char *base_address;
        ULONG *name_addresses;
        ULONG *function_addresses;
        DWORD min_text_section_address, max_text_section_address;

        export_directory =
            (IMAGE_EXPORT_DIRECTORY *)(content +
                                       edata_section->PointerToRawData);

        base_address =
            content +
            edata_section->PointerToRawData -
            edata_section->VirtualAddress;
        name_addresses =
            (ULONG *)(base_address + export_directory->AddressOfNames);
        function_addresses =
            (ULONG *)(base_address + export_directory->AddressOfFunctions);
        min_text_section_address = text_section->VirtualAddress;
        max_text_section_address =
            min_text_section_address + text_section->SizeOfRawData;
        for (i = 0; i < export_directory->NumberOfNames; i++) {
            const char *name;
            DWORD function_address;

            name = base_address + name_addresses[i];
            function_address = function_addresses[i];
            if (min_text_section_address < function_address &&
                function_address < max_text_section_address)
                printf("found: %s\n", name);
        }
    }

    free(content);

    return 0;
}