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/* Read the export table symbols from a portable executable and

   convert to internal format, for GDB. Used as a last resort if no

   debugging symbols recognized.

   Copyright (C) 2003, 2007, 2008 Free Software Foundation, Inc.

   This file is part of GDB.

   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 3 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, see <http://www.gnu.org/licenses/>.

   Contributed by Raoul M. Gough (RaoulGough@yahoo.co.uk). */

#include "coff-pe-read.h"

#include "bfd.h"

#include "defs.h"

#include "gdbtypes.h"

#include "symtab.h"

#include "symfile.h"

#include "objfiles.h"

/* Internal section information */

struct read_pe_section_data

{

  CORE_ADDR vma_offset;         /* Offset to loaded address of section. */

  unsigned long rva_start;      /* Start offset within the pe. */

  unsigned long rva_end;        /* End offset within the pe. */

  enum minimal_symbol_type ms_type;     /* Type to assign symbols in section. */

};

#define PE_SECTION_INDEX_TEXT     0

#define PE_SECTION_INDEX_DATA     1

#define PE_SECTION_INDEX_BSS      2

#define PE_SECTION_TABLE_SIZE     3

#define PE_SECTION_INDEX_INVALID -1

/* Get the index of the named section in our own array, which contains

   text, data and bss in that order. Return PE_SECTION_INDEX_INVALID

   if passed an unrecognised section name. */

static int

read_pe_section_index (const char *section_name)

{

  if (strcmp (section_name, ".text") == 0)

    {

      return PE_SECTION_INDEX_TEXT;

    }

  else if (strcmp (section_name, ".data") == 0)

    {

      return PE_SECTION_INDEX_DATA;

    }

  else if (strcmp (section_name, ".bss") == 0)

    {

      return PE_SECTION_INDEX_BSS;

    }

  else

    {

      return PE_SECTION_INDEX_INVALID;

    }

}

/* Record the virtual memory address of a section. */

static void

get_section_vmas (bfd *abfd, asection *sectp, void *context)

{

  struct read_pe_section_data *sections = context;

  int sectix = read_pe_section_index (sectp->name);

  if (sectix != PE_SECTION_INDEX_INVALID)

    {

      /* Data within the section start at rva_start in the pe and at

         bfd_get_section_vma() within memory. Store the offset. */

      sections[sectix].vma_offset

        = bfd_get_section_vma (abfd, sectp) - sections[sectix].rva_start;

    }

}

/* Create a minimal symbol entry for an exported symbol. */

static void

add_pe_exported_sym (char *sym_name,

                     unsigned long func_rva,

                     const struct read_pe_section_data *section_data,

                     const char *dll_name, struct objfile *objfile)

{

  /* Add the stored offset to get the loaded address of the symbol. */

  CORE_ADDR vma = func_rva + section_data->vma_offset;

  char *qualified_name = 0;

  int dll_name_len = strlen (dll_name);

  int count;

  /* Generate a (hopefully unique) qualified name using the first part

     of the dll name, e.g. KERNEL32!AddAtomA. This matches the style

     used by windbg from the "Microsoft Debugging Tools for Windows". */

  qualified_name = xmalloc (dll_name_len + strlen (sym_name) + 2);

  strncpy (qualified_name, dll_name, dll_name_len);

  qualified_name[dll_name_len] = '!';

  strcpy (qualified_name + dll_name_len + 1, sym_name);

  prim_record_minimal_symbol (qualified_name,

                              vma, section_data->ms_type, objfile);

  xfree (qualified_name);

  /* Enter the plain name as well, which might not be unique. */

  prim_record_minimal_symbol (sym_name, vma, section_data->ms_type, objfile);

}

/* Truncate a dll_name at the first dot character. */

static void

read_pe_truncate_name (char *dll_name)

{

  while (*dll_name)

    {

      if ((*dll_name) == '.')

        {

          *dll_name = '\0';     /* truncates and causes loop exit. */

        }

      else

        {

          ++dll_name;

        }

    }

}

/* Low-level support functions, direct from the ld module pe-dll.c. */

static unsigned int

pe_get16 (bfd *abfd, int where)

{

  unsigned char b[2];

  bfd_seek (abfd, (file_ptr) where, SEEK_SET);

  bfd_bread (b, (bfd_size_type) 2, abfd);

  return b[0] + (b[1] << 8);

}

static unsigned int

pe_get32 (bfd *abfd, int where)

{

  unsigned char b[4];

  bfd_seek (abfd, (file_ptr) where, SEEK_SET);

  bfd_bread (b, (bfd_size_type) 4, abfd);

  return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);

}

static unsigned int

pe_as32 (void *ptr)

{

  unsigned char *b = ptr;

  return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);

}

/* Read the (non-debug) export symbol table from a portable

   executable. Code originally lifted from the ld function

   pe_implied_import_dll in pe-dll.c. */

void

read_pe_exported_syms (struct objfile *objfile)

{

  bfd *dll = objfile->obfd;

  unsigned long pe_header_offset, opthdr_ofs, num_entries, i;

  unsigned long export_rva, export_size, nsections, secptr, expptr;

  unsigned long exp_funcbase;

  unsigned char *expdata, *erva;

  unsigned long name_rvas, ordinals, nexp, ordbase;

  char *dll_name;

  /* Array elements are for text, data and bss in that order

     Initialization with start_rva > end_rva guarantees that

     unused sections won't be matched. */

  struct read_pe_section_data section_data[PE_SECTION_TABLE_SIZE]

    = { {0, 1, 0, mst_text},

  {0, 1, 0, mst_data},

  {0, 1, 0, mst_bss}

  };

  struct cleanup *back_to = 0;

  char const *target = bfd_get_target (objfile->obfd);

  if ((strcmp (target, "pe-i386") != 0) && (strcmp (target, "pei-i386") != 0))

    {

      /* This is not an i386 format file. Abort now, because the code

         is untested on anything else. *FIXME* test on further

         architectures and loosen or remove this test. */

      return;

    }

  /* Get pe_header, optional header and numbers of export entries.  */

  pe_header_offset = pe_get32 (dll, 0x3c);

  opthdr_ofs = pe_header_offset + 4 + 20;

  num_entries = pe_get32 (dll, opthdr_ofs + 92);

  if (num_entries < 1)          /* No exports.  */

    {

      return;

    }

  export_rva = pe_get32 (dll, opthdr_ofs + 96);

  export_size = pe_get32 (dll, opthdr_ofs + 100);

  nsections = pe_get16 (dll, pe_header_offset + 4 + 2);

  secptr = (pe_header_offset + 4 + 20 +

            pe_get16 (dll, pe_header_offset + 4 + 16));

  expptr = 0;

  /* Get the rva and size of the export section.  */

  for (i = 0; i < nsections; i++)

    {

      char sname[8];

      unsigned long secptr1 = secptr + 40 * i;

      unsigned long vaddr = pe_get32 (dll, secptr1 + 12);

      unsigned long vsize = pe_get32 (dll, secptr1 + 16);

      unsigned long fptr = pe_get32 (dll, secptr1 + 20);

      bfd_seek (dll, (file_ptr) secptr1, SEEK_SET);

      bfd_bread (sname, (bfd_size_type) 8, dll);

      if (vaddr <= export_rva && vaddr + vsize > export_rva)

        {

          expptr = fptr + (export_rva - vaddr);

          if (export_rva + export_size > vaddr + vsize)

            export_size = vsize - (export_rva - vaddr);

          break;

        }

    }

  if (export_size == 0)

    {

      /* Empty export table. */

      return;

    }

  /* Scan sections and store the base and size of the relevant sections. */

  for (i = 0; i < nsections; i++)

    {

      unsigned long secptr1 = secptr + 40 * i;

      unsigned long vsize = pe_get32 (dll, secptr1 + 8);

      unsigned long vaddr = pe_get32 (dll, secptr1 + 12);

      unsigned long flags = pe_get32 (dll, secptr1 + 36);

      char sec_name[9];

      int sectix;

      sec_name[8] = '\0';

      bfd_seek (dll, (file_ptr) secptr1 + 0, SEEK_SET);

      bfd_bread (sec_name, (bfd_size_type) 8, dll);

      sectix = read_pe_section_index (sec_name);

      if (sectix != PE_SECTION_INDEX_INVALID)

        {

          section_data[sectix].rva_start = vaddr;

          section_data[sectix].rva_end = vaddr + vsize;

        }

    }

  expdata = (unsigned char *) xmalloc (export_size);

  back_to = make_cleanup (xfree, expdata);

  bfd_seek (dll, (file_ptr) expptr, SEEK_SET);

  bfd_bread (expdata, (bfd_size_type) export_size, dll);

  erva = expdata - export_rva;

  nexp = pe_as32 (expdata + 24);

  name_rvas = pe_as32 (expdata + 32);

  ordinals = pe_as32 (expdata + 36);

  ordbase = pe_as32 (expdata + 16);

  exp_funcbase = pe_as32 (expdata + 28);

  /* Use internal dll name instead of full pathname. */

  dll_name = pe_as32 (expdata + 12) + erva;

  bfd_map_over_sections (dll, get_section_vmas, section_data);

  /* Adjust the vma_offsets in case this PE got relocated. This

     assumes that *all* sections share the same relocation offset

     as the text section. */

  for (i = 0; i < PE_SECTION_TABLE_SIZE; i++)

    {

      section_data[i].vma_offset

        += ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));

    }

  /* Truncate name at first dot. Should maybe also convert to all

     lower case for convenience on Windows. */

  read_pe_truncate_name (dll_name);

  /* Iterate through the list of symbols.  */

  for (i = 0; i < nexp; i++)

    {

      /* Pointer to the names vector.  */

      unsigned long name_rva = pe_as32 (erva + name_rvas + i * 4);

      /* Pointer to the function address vector.  */

      unsigned long func_rva = pe_as32 (erva + exp_funcbase + i * 4);

      /* Find this symbol's section in our own array. */

      int sectix = 0;

      for (sectix = 0; sectix < PE_SECTION_TABLE_SIZE; ++sectix)

        {

          if ((func_rva >= section_data[sectix].rva_start)

              && (func_rva < section_data[sectix].rva_end))

            {

              add_pe_exported_sym (erva + name_rva,

                                   func_rva,

                                   section_data + sectix, dll_name, objfile);

              break;

            }

        }

    }

  /* discard expdata. */

  do_cleanups (back_to);

}