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 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 2 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, write to the Free Software
  21    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, USA.
  23
  24    Contributed by Raoul M. Gough (RaoulGough@yahoo.co.uk). */
  25
  26 #include "coff-pe-read.h"
  27
  28 #include "bfd.h"
  29
  30 #include "defs.h"
  31 #include "gdbtypes.h"
  32
  33 #include "symtab.h"
  34 #include "symfile.h"
  35 #include "objfiles.h"
  36
  37 /* Internal section information */
  38
  39 struct read_pe_section_data
  40 {
  41   CORE_ADDR vma_offset;         /* Offset to loaded address of section. */
  42   unsigned long rva_start;      /* Start offset within the pe. */
  43   unsigned long rva_end;        /* End offset within the pe. */
  44   enum minimal_symbol_type ms_type;     /* Type to assign symbols in section. */
  45 };
  46
  47 #define PE_SECTION_INDEX_TEXT     0
  48 #define PE_SECTION_INDEX_DATA     1
  49 #define PE_SECTION_INDEX_BSS      2
  50 #define PE_SECTION_TABLE_SIZE     3
  51 #define PE_SECTION_INDEX_INVALID -1
  52 \f
  53 /* Get the index of the named section in our own array, which contains
  54    text, data and bss in that order. Return PE_SECTION_INDEX_INVALID
  55    if passed an unrecognised section name. */
  56
  57 static int
  58 read_pe_section_index (const char *section_name)
  59 {
  60   if (strcmp (section_name, ".text") == 0)
  61     {
  62       return PE_SECTION_INDEX_TEXT;
  63     }
  64
  65   else if (strcmp (section_name, ".data") == 0)
  66     {
  67       return PE_SECTION_INDEX_DATA;
  68     }
  69
  70   else if (strcmp (section_name, ".bss") == 0)
  71     {
  72       return PE_SECTION_INDEX_BSS;
  73     }
  74
  75   else
  76     {
  77       return PE_SECTION_INDEX_INVALID;
  78     }
  79 }
  80
  81 /* Record the virtual memory address of a section. */
  82
  83 static void
  84 get_section_vmas (bfd *abfd, asection *sectp, void *context)
  85 {
  86   struct read_pe_section_data *sections = context;
  87   int sectix = read_pe_section_index (sectp->name);
  88
  89   if (sectix != PE_SECTION_INDEX_INVALID)
  90     {
  91       /* Data within the section start at rva_start in the pe and at
  92          bfd_get_section_vma() within memory. Store the offset. */
  93
  94       sections[sectix].vma_offset
  95         = bfd_get_section_vma (abfd, sectp) - sections[sectix].rva_start;
  96     }
  97 }
  98 \f
  99 /* Create a minimal symbol entry for an exported symbol. */
 100
 101 static void
 102 add_pe_exported_sym (char *sym_name,
 103                      unsigned long func_rva,
 104                      const struct read_pe_section_data *section_data,
 105                      const char *dll_name, struct objfile *objfile)
 106 {
 107   /* Add the stored offset to get the loaded address of the symbol. */
 108
 109   CORE_ADDR vma = func_rva + section_data->vma_offset;
 110
 111   char *qualified_name = 0;
 112   int dll_name_len = strlen (dll_name);
 113   int count;
 114
 115   /* Generate a (hopefully unique) qualified name using the first part
 116      of the dll name, e.g. KERNEL32!AddAtomA. This matches the style
 117      used by windbg from the "Microsoft Debugging Tools for Windows". */
 118
 119   qualified_name = xmalloc (dll_name_len + strlen (sym_name) + 2);
 120
 121   strncpy (qualified_name, dll_name, dll_name_len);
 122   qualified_name[dll_name_len] = '!';
 123   strcpy (qualified_name + dll_name_len + 1, sym_name);
 124
 125   prim_record_minimal_symbol (qualified_name,
 126                               vma, section_data->ms_type, objfile);
 127
 128   xfree (qualified_name);
 129
 130   /* Enter the plain name as well, which might not be unique. */
 131   prim_record_minimal_symbol (sym_name, vma, section_data->ms_type, objfile);
 132 }
 133
 134 /* Truncate a dll_name at the first dot character. */
 135
 136 static void
 137 read_pe_truncate_name (char *dll_name)
 138 {
 139   while (*dll_name)
 140     {
 141       if ((*dll_name) == '.')
 142         {
 143           *dll_name = '\0';     /* truncates and causes loop exit. */
 144         }
 145
 146       else
 147         {
 148           ++dll_name;
 149         }
 150     }
 151 }
 152 \f
 153 /* Low-level support functions, direct from the ld module pe-dll.c. */
 154 static unsigned int
 155 pe_get16 (bfd *abfd, int where)
 156 {
 157   unsigned char b[2];
 158
 159   bfd_seek (abfd, (file_ptr) where, SEEK_SET);
 160   bfd_bread (b, (bfd_size_type) 2, abfd);
 161   return b[0] + (b[1] << 8);
 162 }
 163
 164 static unsigned int
 165 pe_get32 (bfd *abfd, int where)
 166 {
 167   unsigned char b[4];
 168
 169   bfd_seek (abfd, (file_ptr) where, SEEK_SET);
 170   bfd_bread (b, (bfd_size_type) 4, abfd);
 171   return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
 172 }
 173
 174 static unsigned int
 175 pe_as32 (void *ptr)
 176 {
 177   unsigned char *b = ptr;
 178
 179   return b[0] + (b[1] << 8) + (b[2] << 16) + (b[3] << 24);
 180 }
 181 \f
 182 /* Read the (non-debug) export symbol table from a portable
 183    executable. Code originally lifted from the ld function
 184    pe_implied_import_dll in pe-dll.c. */
 185
 186 void
 187 read_pe_exported_syms (struct objfile *objfile)
 188 {
 189   bfd *dll = objfile->obfd;
 190   unsigned long pe_header_offset, opthdr_ofs, num_entries, i;
 191   unsigned long export_rva, export_size, nsections, secptr, expptr;
 192   unsigned long exp_funcbase;
 193   unsigned char *expdata, *erva;
 194   unsigned long name_rvas, ordinals, nexp, ordbase;
 195   char *dll_name;
 196
 197   /* Array elements are for text, data and bss in that order
 198      Initialization with start_rva > end_rva guarantees that
 199      unused sections won't be matched. */
 200   struct read_pe_section_data section_data[PE_SECTION_TABLE_SIZE]
 201     = { {0, 1, 0, mst_text},
 202   {0, 1, 0, mst_data},
 203   {0, 1, 0, mst_bss}
 204   };
 205
 206   struct cleanup *back_to = 0;
 207
 208   char const *target = bfd_get_target (objfile->obfd);
 209
 210   if ((strcmp (target, "pe-i386") != 0) && (strcmp (target, "pei-i386") != 0))
 211     {
 212       /* This is not an i386 format file. Abort now, because the code
 213          is untested on anything else. *FIXME* test on further
 214          architectures and loosen or remove this test. */
 215       return;
 216     }
 217
 218   /* Get pe_header, optional header and numbers of export entries.  */
 219   pe_header_offset = pe_get32 (dll, 0x3c);
 220   opthdr_ofs = pe_header_offset + 4 + 20;
 221   num_entries = pe_get32 (dll, opthdr_ofs + 92);
 222
 223   if (num_entries < 1)          /* No exports.  */
 224     {
 225       return;
 226     }
 227
 228   export_rva = pe_get32 (dll, opthdr_ofs + 96);
 229   export_size = pe_get32 (dll, opthdr_ofs + 100);
 230   nsections = pe_get16 (dll, pe_header_offset + 4 + 2);
 231   secptr = (pe_header_offset + 4 + 20 +
 232             pe_get16 (dll, pe_header_offset + 4 + 16));
 233   expptr = 0;
 234
 235   /* Get the rva and size of the export section.  */
 236   for (i = 0; i < nsections; i++)
 237     {
 238       char sname[8];
 239       unsigned long secptr1 = secptr + 40 * i;
 240       unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
 241       unsigned long vsize = pe_get32 (dll, secptr1 + 16);
 242       unsigned long fptr = pe_get32 (dll, secptr1 + 20);
 243
 244       bfd_seek (dll, (file_ptr) secptr1, SEEK_SET);
 245       bfd_bread (sname, (bfd_size_type) 8, dll);
 246
 247       if (vaddr <= export_rva && vaddr + vsize > export_rva)
 248         {
 249           expptr = fptr + (export_rva - vaddr);
 250           if (export_rva + export_size > vaddr + vsize)
 251             export_size = vsize - (export_rva - vaddr);
 252           break;
 253         }
 254     }
 255
 256   if (export_size == 0)
 257     {
 258       /* Empty export table. */
 259       return;
 260     }
 261
 262   /* Scan sections and store the base and size of the relevant sections. */
 263   for (i = 0; i < nsections; i++)
 264     {
 265       unsigned long secptr1 = secptr + 40 * i;
 266       unsigned long vsize = pe_get32 (dll, secptr1 + 8);
 267       unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
 268       unsigned long flags = pe_get32 (dll, secptr1 + 36);
 269       char sec_name[9];
 270       int sectix;
 271
 272       sec_name[8] = '\0';
 273       bfd_seek (dll, (file_ptr) secptr1 + 0, SEEK_SET);
 274       bfd_bread (sec_name, (bfd_size_type) 8, dll);
 275
 276       sectix = read_pe_section_index (sec_name);
 277
 278       if (sectix != PE_SECTION_INDEX_INVALID)
 279         {
 280           section_data[sectix].rva_start = vaddr;
 281           section_data[sectix].rva_end = vaddr + vsize;
 282         }
 283     }
 284
 285   expdata = (unsigned char *) xmalloc (export_size);
 286   back_to = make_cleanup (xfree, expdata);
 287
 288   bfd_seek (dll, (file_ptr) expptr, SEEK_SET);
 289   bfd_bread (expdata, (bfd_size_type) export_size, dll);
 290   erva = expdata - export_rva;
 291
 292   nexp = pe_as32 (expdata + 24);
 293   name_rvas = pe_as32 (expdata + 32);
 294   ordinals = pe_as32 (expdata + 36);
 295   ordbase = pe_as32 (expdata + 16);
 296   exp_funcbase = pe_as32 (expdata + 28);
 297
 298   /* Use internal dll name instead of full pathname. */
 299   dll_name = pe_as32 (expdata + 12) + erva;
 300
 301   bfd_map_over_sections (dll, get_section_vmas, section_data);
 302
 303   /* Adjust the vma_offsets in case this PE got relocated. This
 304      assumes that *all* sections share the same relocation offset
 305      as the text section. */
 306   for (i = 0; i < PE_SECTION_TABLE_SIZE; i++)
 307     {
 308       section_data[i].vma_offset
 309         += ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
 310     }
 311
 312   printf_filtered (_("Minimal symbols from %s..."), dll_name);
 313   wrap_here ("");
 314
 315   /* Truncate name at first dot. Should maybe also convert to all
 316      lower case for convenience on Windows. */
 317   read_pe_truncate_name (dll_name);
 318
 319   /* Iterate through the list of symbols.  */
 320   for (i = 0; i < nexp; i++)
 321     {
 322       /* Pointer to the names vector.  */
 323       unsigned long name_rva = pe_as32 (erva + name_rvas + i * 4);
 324
 325       /* Pointer to the function address vector.  */
 326       unsigned long func_rva = pe_as32 (erva + exp_funcbase + i * 4);
 327
 328       /* Find this symbol's section in our own array. */
 329       int sectix = 0;
 330
 331       for (sectix = 0; sectix < PE_SECTION_TABLE_SIZE; ++sectix)
 332         {
 333           if ((func_rva >= section_data[sectix].rva_start)
 334               && (func_rva < section_data[sectix].rva_end))
 335             {
 336               add_pe_exported_sym (erva + name_rva,
 337                                    func_rva,
 338                                    section_data + sectix, dll_name, objfile);
 339               break;
 340             }
 341         }
 342     }
 343
 344   /* discard expdata. */
 345   do_cleanups (back_to);
 346 }