binutils-gdb/gdb/coff-pe-read.c

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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);
}