/* -------------------------------------------------------------- */
/*
 * tiny_impdef creates an export definition file (.def) from a dll
 * on MS-Windows. Usage: tiny_impdef library.dll [-o outputfile]"
 * 
 *  Copyright (c) 2005,2007 grischka
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef TINY_IMPDEF_GET_EXPORT_NAMES_ONLY

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#include <io.h>
#include <malloc.h>

char *get_export_names(int fd);
#define tcc_free free
#define tcc_realloc realloc

/* extract the basename of a file */
static char *file_basename(const char *name)
{
    const char *p = strchr(name, 0);
    while (p > name
        && p[-1] != '/'
        && p[-1] != '\\'
        )
        --p;
    return (char*)p;
}

int main(int argc, char **argv)
{
    int ret, v, i;
    char infile[MAX_PATH];
    char outfile[MAX_PATH];

    static const char *ext[] = { ".dll", ".exe", NULL };
    const char *file, **pp;
    char path[MAX_PATH], *p, *q;
    FILE *fp, *op;

    infile[0] = 0;
    outfile[0] = 0;
    fp = op = NULL;
    v = 0;
    ret = 1;
    p = NULL;

    for (i = 1; i < argc; ++i) {
        const char *a = argv[i];
        if ('-' == a[0]) {
            if (0 == strcmp(a, "-v")) {
                v = 1;
            } else if (0 == strcmp(a, "-o")) {
                if (++i == argc)
                    goto usage;
                strcpy(outfile, argv[i]);
            } else
                goto usage;
        } else if (0 == infile[0])
            strcpy(infile, a);
        else
            goto usage;
    }

    if (0 == infile[0]) {
usage:
        fprintf(stderr,
            "tiny_impdef: create export definition file (.def) from a dll\n"
            "Usage: tiny_impdef library.dll [-o outputfile]\n"
            );
        goto the_end;
    }

    if (0 == outfile[0])
    {
        strcpy(outfile, file_basename(infile));
        q = strrchr(outfile, '.');
        if (NULL == q)
            q = strchr(outfile, 0);
        strcpy(q, ".def");
    }

    file = infile;

#ifdef _WIN32
    pp = ext;
    do if (SearchPath(NULL, file, *pp, sizeof path, path, NULL)) {
       file = path;
       break;
    } while (*pp++);
#endif

    fp = fopen(file, "rb");
    if (NULL == fp) {
        fprintf(stderr, "tiny_impdef: no such file: %s\n", infile);
        goto the_end;
    }
    if (v)
        printf("--> %s\n", file);

    p = get_export_names(fileno(fp));
    if (NULL == p) {
        fprintf(stderr, "tiny_impdef: could not get exported function names.\n");
        goto the_end;
    }

    op = fopen(outfile, "w");
    if (NULL == op) {
        fprintf(stderr, "tiny_impdef: could not create output file: %s\n", outfile);
        goto the_end;
    }

    fprintf(op, "LIBRARY %s\n\nEXPORTS\n", file_basename(file));
    for (q = p, i = 0; *q; ++i) {
        fprintf(op, "%s\n", q);
        q += strlen(q) + 1;
    }

    if (v) {
        printf("<-- %s\n", outfile);
        printf("%d symbol(s) found\n", i);
    }

    ret = 0;

the_end:
    if (p)
        free(p);
    if (fp)
        fclose(fp);
    if (op)
        fclose(op);
    return ret;
}

int read_mem(int fd, unsigned offset, void *buffer, unsigned len)
{
    lseek(fd, offset, SEEK_SET);
    return len == read(fd, buffer, len);
}

/* -------------------------------------------------------------- */

/* -------------------------------------------------------------- */
#endif

char *get_export_names(int fd)
{
    int l, i, n, n0;
    char *p;

    IMAGE_SECTION_HEADER ish;
    IMAGE_EXPORT_DIRECTORY ied;
    IMAGE_DOS_HEADER dh;
    IMAGE_FILE_HEADER ih;
    DWORD sig, ref, addr, ptr, namep;
#ifdef TCC_TARGET_X86_64
    IMAGE_OPTIONAL_HEADER64 oh;
    const int MACHINE = 0x8664;
#else
    IMAGE_OPTIONAL_HEADER32 oh;
    const int MACHINE = 0x014C;
#endif
    int pef_hdroffset, opt_hdroffset, sec_hdroffset;

    n = n0 = 0;
    p = NULL;

    if (!read_mem(fd, 0, &dh, sizeof dh))
        goto the_end;
    if (!read_mem(fd, dh.e_lfanew, &sig, sizeof sig))
        goto the_end;
    if (sig != 0x00004550)
        goto the_end;
    pef_hdroffset = dh.e_lfanew + sizeof sig;
    if (!read_mem(fd, pef_hdroffset, &ih, sizeof ih))
        goto the_end;
    if (MACHINE != ih.Machine)
        goto the_end;
    opt_hdroffset = pef_hdroffset + sizeof ih;
    sec_hdroffset = opt_hdroffset + sizeof oh;
    if (!read_mem(fd, opt_hdroffset, &oh, sizeof oh))
        goto the_end;

    if (IMAGE_DIRECTORY_ENTRY_EXPORT >= oh.NumberOfRvaAndSizes)
        goto the_end;

    addr = oh.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress;
    //printf("addr: %08x\n", addr);
    for (i = 0; i < ih.NumberOfSections; ++i) {
        if (!read_mem(fd, sec_hdroffset + i * sizeof ish, &ish, sizeof ish))
            goto the_end;
        //printf("vaddr: %08x\n", ish.VirtualAddress);
        if (addr >= ish.VirtualAddress && addr < ish.VirtualAddress + ish.SizeOfRawData)
            goto found;
    }
    goto the_end;

found:
    ref = ish.VirtualAddress - ish.PointerToRawData;
    if (!read_mem(fd, addr - ref, &ied, sizeof ied))
        goto the_end;

    namep = ied.AddressOfNames - ref;
    for (i = 0; i < ied.NumberOfNames; ++i) {
        if (!read_mem(fd, namep, &ptr, sizeof ptr))
            goto the_end;
        namep += sizeof ptr;
        for (l = 0;;) {
            if (n+1 >= n0)
                p = tcc_realloc(p, n0 = n0 ? n0 * 2 : 256);
            if (!read_mem(fd, ptr - ref + l, p + n, 1) || ++l >= 80) {
                tcc_free(p), p = NULL;
                goto the_end;
            }
            if (p[n++] == 0)
                break;
        }
    }
    if (p)
        p[n] = 0;
the_end:
    return p;
}

/* -------------------------------------------------------------- */