/* -*- Mode: C++; c-basic-offset:4 ; -*- */

/*  

 *  (C) 2001 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

#include <windows.h>

#include <stdio.h>

#include <time.h>

/* This function returns a pointer to the section header containing the RVA. Return NULL on error */

template <typename NTHeaderType> static inline PIMAGE_SECTION_HEADER GetSecHeader(DWORD rva, NTHeaderType* pNTHeader)

{

    PIMAGE_SECTION_HEADER section;

    section = IMAGE_FIRST_SECTION(pNTHeader);

    for (int i=0; i < pNTHeader->FileHeader.NumberOfSections; i++, section++){

		DWORD size = section->Misc.VirtualSize;

        DWORD secRVA = section->VirtualAddress;

        if((secRVA <= rva)  && (rva < (secRVA+size))){

            return section;

        }

    }

    return NULL;

}

/* This function returns the real address from the RVA. Returns NULL on error */

template <typename NTHeaderType> static inline LPVOID GetRealAddrFromRVA(DWORD rva, NTHeaderType* pNTHeader, PBYTE imageBase )

{

	PIMAGE_SECTION_HEADER pSectionHdr = GetSecHeader(rva, pNTHeader);

	if (!pSectionHdr){

		return NULL;

    }

    /* Since we map the DLL manually we need to calculate mapShift to get the real addr */

	INT mapShift = (INT)(pSectionHdr->VirtualAddress - pSectionHdr->PointerToRawData);

	return (PVOID)(imageBase + rva - mapShift);

}

/* This function reads the exported symbols from a dll/exe and prints a DLL definition file, compatible with gcc,

   with those symbols.

    INPUT:

        pImageBase  : Pointer to the base of the dll image, offset = 0

        pNTHeader   : Pointer to the NT header (32-bit/64-bit) section of image.

*/

template <typename NTHeaderType> void PrintDefFileWithExpSymbols(PBYTE pImageBase, NTHeaderType *pNTHeader)

{

    /* Export Section RVA */

    DWORD expSecRVA = pNTHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress;

    /* From RVA get the real addrs for the various components of the exports section */

    PIMAGE_EXPORT_DIRECTORY pExportDir = (PIMAGE_EXPORT_DIRECTORY )GetRealAddrFromRVA(expSecRVA, pNTHeader, pImageBase);

    PDWORD pszFuncNames =	(PDWORD ) GetRealAddrFromRVA( pExportDir->AddressOfNames, pNTHeader, pImageBase );

    printf("EXPORTS\n");

    for (unsigned int i=0; i < pExportDir->NumberOfFunctions; i++){

        /* FIXME: Assumes that the current DLL does not have ordinal nums */

        if(i < pExportDir->NumberOfNames){

            /* Ordinal numbers start at 1 - not 0*/

            printf("\t%s @ %d ;\n", GetRealAddrFromRVA(pszFuncNames[i], pNTHeader, pImageBase), i+1);

        }

        else{

            break;

        }

    }

}

static void HelpUsage(char *exe_name)

{

    printf("Usage: %s <DLLNAME>\n", exe_name);

    printf("\t\t The tool reads the export section from <DLLNAME> and prints the definition file for gcc to stdout\n");

}

int main(int argc, char *argv[])

{

    HANDLE hFile, hFileMapping;

    LPVOID lpFileBase;

    PIMAGE_DOS_HEADER   pImgHeader;

    PIMAGE_NT_HEADERS   pImgNTHeader;

    PIMAGE_NT_HEADERS64 pImgNTHeader64;

    if((argc < 2) || (strcmp(argv[1], "/?") == 0) || (strcmp(argv[1], "--help") == 0)){

        HelpUsage(argv[0]);

        exit(1);

    }

    /* Open the DLL and map it to memory */

    hFile = CreateFile(argv[1], GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);

    if(hFile == INVALID_HANDLE_VALUE){

        printf("Unable to open dll, %s\n", argv[1]);

        exit(-1);

    }

    hFileMapping = CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);

    if(hFileMapping == 0){

        CloseHandle(hFile);

        printf("Cannot open file mapping for dll, %s\n", argv[1]);

        exit(-1);

    }

    lpFileBase = MapViewOfFile(hFileMapping, FILE_MAP_READ, 0, 0, 0);

    if(lpFileBase == 0){

        CloseHandle(hFileMapping);

        CloseHandle(hFile);

        printf("Cannot map view of dll, %s\n", argv[1]);

        exit(-1);

    }

    /* pImgHeader points to the MS-DOS HEADER section, offset=0, of dll */

    pImgHeader = (PIMAGE_DOS_HEADER )lpFileBase;

    /* pImgNTHeader points to the NT HEADER section of the dll, pImgHeader + <File address of new exe header> */

    pImgNTHeader = (PIMAGE_NT_HEADERS )((DWORD_PTR )pImgHeader + (DWORD_PTR )pImgHeader->e_lfanew);

    /* In the case of the 64-bit dlls, the Optional header section within NT header has 64-bit fields */

    pImgNTHeader64 = (PIMAGE_NT_HEADERS64) pImgNTHeader;

    /* The Magic number is always a WORD. This number is used to determine if the dll is 32-bit or 64-bit */

    if(pImgNTHeader->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC){

        /* 64-bit dll */

        PrintDefFileWithExpSymbols((PBYTE )pImgHeader, pImgNTHeader64);

    }

    else{

        /* 32-bit dll */

        PrintDefFileWithExpSymbols((PBYTE )pImgHeader, pImgNTHeader);

    }

    UnmapViewOfFile(lpFileBase);

    CloseHandle(hFileMapping);

    CloseHandle(hFile);

}