gdb/coff-pe-read.c

   1 /* Read the export table symbols from a portable executable and
   2    convert to internal format, for GDB. Used as a last resort if no
   3    debugging symbols recognized.
   4
   5    Copyright (C) 2003, 2007, 2008 Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21
  22    Contributed by Raoul M. Gough (RaoulGough@yahoo.co.uk). */
  23
  24 #include "coff-pe-read.h"
  25
  26 #include "bfd.h"
  27
  28 #include "defs.h"
  29 #include "gdbtypes.h"
  30
  31 #include "symtab.h"
  32 #include "symfile.h"
  33 #include "objfiles.h"
  34
  35 /* Internal section information */
  36
  37 struct read_pe_section_data
  38 {
  39   CORE_ADDR vma_offset;         /* Offset to loaded address of section. */
  40   unsigned long rva_start;      /* Start offset within the pe. */
  41   unsigned long rva_end;        /* End offset within the pe. */
  42   enum minimal_symbol_type ms_type;     /* Type to assign symbols in section. */
  43 };
  44
  45 #define PE_SECTION_INDEX_TEXT     0
  46 #define PE_SECTION_INDEX_DATA     1
  47 #define PE_SECTION_INDEX_BSS      2
  48 #define PE_SECTION_TABLE_SIZE     3
  49 #define PE_SECTION_INDEX_INVALID -1
  50 \f
  51 /* Get the index of the named section in our own array, which contains
  52    text, data and bss in that order. Return PE_SECTION_INDEX_INVALID
  53    if passed an unrecognised section name. */
  54
  55 static int
  56 read_pe_section_index (const char *section_name)
  57 {
  58   if (strcmp (section_name, ".text") == 0)
  59     {
  60       return PE_SECTION_INDEX_TEXT;
  61     }
  62
  63   else if (strcmp (section_name, ".data") == 0)
  64     {
  65       return PE_SECTION_INDEX_DATA;
  66     }
  67
  68   else if (strcmp (section_name, ".bss") == 0)
  69     {
  70       return PE_SECTION_INDEX_BSS;
  71     }
  72
  73   else
  74     {
  75       return PE_SECTION_INDEX_INVALID;
  76     }
  77 }
  78
  79 /* Record the virtual memory address of a section. */
  80
  81 static void
  82 get_section_vmas (bfd *abfd, asection *sectp, void *context)
  83 {
  84   struct read_pe_section_data *sections = context;
  85   int sectix = read_pe_section_index (sectp->name);
  86
  87   if (sectix != PE_SECTION_INDEX_INVALID)
  88     {
  89       /* Data within the section start at rva_start in the pe and at
  90          bfd_get_section_vma() within memory. Store the offset. */
  91
  92       sections[sectix].vma_offset
  93         = bfd_get_section_vma (abfd, sectp) - sections[sectix].rva_start;
  94     }
  95 }
  96 \f
  97 /* Create a minimal symbol entry for an exported symbol. */
  98
  99 static void
 100 add_pe_exported_sym (char *sym_name,
 101                      unsigned long func_rva,
 102                      const struct read_pe_section_data *section_data,
 103                      const char *dll_name, struct objfile *objfile)
 104 {
 105   /* Add the stored offset to get the loaded address of the symbol. */
 106
 107   CORE_ADDR vma = func_rva + section_data->vma_offset;
 108
 109   char *qualified_name = 0;
 110   int dll_name_len = strlen (dll_name);
 111   int count;
 112
 113   /* Generate a (hopefully unique) qualified name using the first part
 114      of the dll name, e.g. KERNEL32!AddAtomA. This matches the style
 115      used by windbg from the "Microsoft Debugging Tools for Windows". */
 116
 117   qualified_name = xmalloc (dll_name_len + strlen (sym_name) + 2);
 118
 119   strncpy (qualified_name, dll_name, dll_name_len);
 120   qualified_name[dll_name_len] = '!';
 121   strcpy (qualified_name + dll_name_len + 1, sym_name);
 122
 123   prim_record_minimal_symbol (qualified_name,
 124                               vma, section_data->ms_type, objfile);
 125
 126   xfree (qualified_name);
 127
 128   /* Enter the plain name as well, which might not be unique. */
 129   prim_record_minimal_symbol (sym_name, vma, section_data->ms_type, objfile);
 130 }
 131
 132 /* Truncate a dll_name at the first dot character. */
 133
 134 static void
 135 read_pe_truncate_name (char *dll_name)
 136 {
 137   while (*dll_name)
 138     {
 139       if ((*dll_name) == '.')
 140         {
 141           *dll_name = '\0';     /* truncates and causes loop exit. */
 142         }
 143
 144       else
 145         {
 146           ++dll_name;
 147         }
 148     }
 149 }
 150 \f
 151 /* Low-level support functions, direct from the ld module pe-dll.c. */
 152 static unsigned int
 153 pe_get16 (bfd *abfd, int where)
 154 {
 155   unsigned char b[2];
 156
 157   bfd_seek (abfd, (file_ptr) where, SEEK_SET);
 158   bfd_bread (b, (bfd_size_type) 2, abfd);
 159   return b[0] + (b[1] << 8);
 160 }
 161
 162 static unsigned int
 163 pe_get32 (bfd *abfd, int where)
 164 {
 165   unsigned char b[4];
 166
 167   bfd_seek (abfd, (file_ptr) where, SEEK_SET);
 168   bfd_bread (b, (bfd_size_type) 4, abfd);
 169   return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
 170 }
 171
 172 static unsigned int
 173 pe_as32 (void *ptr)
 174 {
 175   unsigned char *b = ptr;
 176
 177   return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
 178 }
 179 \f
 180 /* Read the (non-debug) export symbol table from a portable
 181    executable. Code originally lifted from the ld function
 182    pe_implied_import_dll in pe-dll.c. */
 183
 184 void
 185 read_pe_exported_syms (struct objfile *objfile)
 186 {
 187   bfd *dll = objfile->obfd;
 188   unsigned long pe_header_offset, opthdr_ofs, num_entries, i;
 189   unsigned long export_rva, export_size, nsections, secptr, expptr;
 190   unsigned long exp_funcbase;
 191   unsigned char *expdata, *erva;
 192   unsigned long name_rvas, ordinals, nexp, ordbase;
 193   char *dll_name;
 194
 195   /* Array elements are for text, data and bss in that order
 196      Initialization with start_rva > end_rva guarantees that
 197      unused sections won't be matched. */
 198   struct read_pe_section_data section_data[PE_SECTION_TABLE_SIZE]
 199     = { {0, 1, 0, mst_text},
 200   {0, 1, 0, mst_data},
 201   {0, 1, 0, mst_bss}
 202   };
 203
 204   struct cleanup *back_to = 0;
 205
 206   char const *target = bfd_get_target (objfile->obfd);
 207
 208   if ((strcmp (target, "pe-i386") != 0) && (strcmp (target, "pei-i386") != 0))
 209     {
 210       /* This is not an i386 format file. Abort now, because the code
 211          is untested on anything else. *FIXME* test on further
 212          architectures and loosen or remove this test. */
 213       return;
 214     }
 215
 216   /* Get pe_header, optional header and numbers of export entries.  */
 217   pe_header_offset = pe_get32 (dll, 0x3c);
 218   opthdr_ofs = pe_header_offset + 4 + 20;
 219   num_entries = pe_get32 (dll, opthdr_ofs + 92);
 220
 221   if (num_entries < 1)          /* No exports.  */
 222     {
 223       return;
 224     }
 225
 226   export_rva = pe_get32 (dll, opthdr_ofs + 96);
 227   export_size = pe_get32 (dll, opthdr_ofs + 100);
 228   nsections = pe_get16 (dll, pe_header_offset + 4 + 2);
 229   secptr = (pe_header_offset + 4 + 20 +
 230             pe_get16 (dll, pe_header_offset + 4 + 16));
 231   expptr = 0;
 232
 233   /* Get the rva and size of the export section.  */
 234   for (i = 0; i < nsections; i++)
 235     {
 236       char sname[8];
 237       unsigned long secptr1 = secptr + 40 * i;
 238       unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
 239       unsigned long vsize = pe_get32 (dll, secptr1 + 16);
 240       unsigned long fptr = pe_get32 (dll, secptr1 + 20);
 241
 242       bfd_seek (dll, (file_ptr) secptr1, SEEK_SET);
 243       bfd_bread (sname, (bfd_size_type) 8, dll);
 244
 245       if (vaddr <= export_rva && vaddr + vsize > export_rva)
 246         {
 247           expptr = fptr + (export_rva - vaddr);
 248           if (export_rva + export_size > vaddr + vsize)
 249             export_size = vsize - (export_rva - vaddr);
 250           break;
 251         }
 252     }
 253
 254   if (export_size == 0)
 255     {
 256       /* Empty export table. */
 257       return;
 258     }
 259
 260   /* Scan sections and store the base and size of the relevant sections. */
 261   for (i = 0; i < nsections; i++)
 262     {
 263       unsigned long secptr1 = secptr + 40 * i;
 264       unsigned long vsize = pe_get32 (dll, secptr1 + 8);
 265       unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
 266       unsigned long flags = pe_get32 (dll, secptr1 + 36);
 267       char sec_name[9];
 268       int sectix;
 269
 270       sec_name[8] = '\0';
 271       bfd_seek (dll, (file_ptr) secptr1 + 0, SEEK_SET);
 272       bfd_bread (sec_name, (bfd_size_type) 8, dll);
 273
 274       sectix = read_pe_section_index (sec_name);
 275
 276       if (sectix != PE_SECTION_INDEX_INVALID)
 277         {
 278           section_data[sectix].rva_start = vaddr;
 279           section_data[sectix].rva_end = vaddr + vsize;
 280         }
 281     }
 282
 283   expdata = (unsigned char *) xmalloc (export_size);
 284   back_to = make_cleanup (xfree, expdata);
 285
 286   bfd_seek (dll, (file_ptr) expptr, SEEK_SET);
 287   bfd_bread (expdata, (bfd_size_type) export_size, dll);
 288   erva = expdata - export_rva;
 289
 290   nexp = pe_as32 (expdata + 24);
 291   name_rvas = pe_as32 (expdata + 32);
 292   ordinals = pe_as32 (expdata + 36);
 293   ordbase = pe_as32 (expdata + 16);
 294   exp_funcbase = pe_as32 (expdata + 28);
 295
 296   /* Use internal dll name instead of full pathname. */
 297   dll_name = pe_as32 (expdata + 12) + erva;
 298
 299   bfd_map_over_sections (dll, get_section_vmas, section_data);
 300
 301   /* Adjust the vma_offsets in case this PE got relocated. This
 302      assumes that *all* sections share the same relocation offset
 303      as the text section. */
 304   for (i = 0; i < PE_SECTION_TABLE_SIZE; i++)
 305     {
 306       section_data[i].vma_offset
 307         += ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
 308     }
 309
 310   /* Truncate name at first dot. Should maybe also convert to all
 311      lower case for convenience on Windows. */
 312   read_pe_truncate_name (dll_name);
 313
 314   /* Iterate through the list of symbols.  */
 315   for (i = 0; i < nexp; i++)
 316     {
 317       /* Pointer to the names vector.  */
 318       unsigned long name_rva = pe_as32 (erva + name_rvas + i * 4);
 319
 320       /* Pointer to the function address vector.  */
 321       unsigned long func_rva = pe_as32 (erva + exp_funcbase + i * 4);
 322
 323       /* Find this symbol's section in our own array. */
 324       int sectix = 0;
 325
 326       for (sectix = 0; sectix < PE_SECTION_TABLE_SIZE; ++sectix)
 327         {
 328           if ((func_rva >= section_data[sectix].rva_start)
 329               && (func_rva < section_data[sectix].rva_end))
 330             {
 331               add_pe_exported_sym (erva + name_rva,
 332                                    func_rva,
 333                                    section_data + sectix, dll_name, objfile);
 334               break;
 335             }
 336         }
 337     }
 338
 339   /* discard expdata. */
 340   do_cleanups (back_to);
 341 }