bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright (C) 1995-2015 Free Software Foundation, Inc.
   3
   4    This file is part of BFD, the Binary File Descriptor library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 char*
  22 elf_core_file_failing_command (bfd *abfd)
  23 {
  24   return elf_tdata (abfd)->core->command;
  25 }
  26
  27 int
  28 elf_core_file_failing_signal (bfd *abfd)
  29 {
  30   return elf_tdata (abfd)->core->signal;
  31 }
  32
  33 int
  34 elf_core_file_pid (bfd *abfd)
  35 {
  36   return elf_tdata (abfd)->core->pid;
  37 }
  38
  39 bfd_boolean
  40 elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd)
  41 {
  42   char* corename;
  43
  44   /* xvecs must match if both are ELF files for the same target.  */
  45
  46   if (core_bfd->xvec != exec_bfd->xvec)
  47     {
  48       bfd_set_error (bfd_error_system_call);
  49       return FALSE;
  50     }
  51
  52   /* See if the name in the corefile matches the executable name.  */
  53   corename = elf_tdata (core_bfd)->core->program;
  54   if (corename != NULL)
  55     {
  56       const char* execname = strrchr (exec_bfd->filename, '/');
  57
  58       execname = execname ? execname + 1 : exec_bfd->filename;
  59
  60       if (strcmp (execname, corename) != 0)
  61         return FALSE;
  62     }
  63
  64   return TRUE;
  65 }
  66
  67 /*  Core files are simply standard ELF formatted files that partition
  68     the file using the execution view of the file (program header table)
  69     rather than the linking view.  In fact, there is no section header
  70     table in a core file.
  71
  72     The process status information (including the contents of the general
  73     register set) and the floating point register set are stored in a
  74     segment of type PT_NOTE.  We handcraft a couple of extra bfd sections
  75     that allow standard bfd access to the general registers (.reg) and the
  76     floating point registers (.reg2).  */
  77
  78 const bfd_target *
  79 elf_core_file_p (bfd *abfd)
  80 {
  81   Elf_External_Ehdr x_ehdr;     /* Elf file header, external form.  */
  82   Elf_Internal_Ehdr *i_ehdrp;   /* Elf file header, internal form.  */
  83   Elf_Internal_Phdr *i_phdrp;   /* Elf program header, internal form.  */
  84   unsigned int phindex;
  85   const struct elf_backend_data *ebd;
  86   bfd_size_type amt;
  87
  88   /* Read in the ELF header in external format.  */
  89   if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
  90     {
  91       if (bfd_get_error () != bfd_error_system_call)
  92         goto wrong;
  93       else
  94         goto fail;
  95     }
  96
  97   /* Check the magic number.  */
  98   if (! elf_file_p (&x_ehdr))
  99     goto wrong;
 100
 101   /* FIXME: Check EI_VERSION here !  */
 102
 103   /* Check the address size ("class").  */
 104   if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
 105     goto wrong;
 106
 107   /* Check the byteorder.  */
 108   switch (x_ehdr.e_ident[EI_DATA])
 109     {
 110     case ELFDATA2MSB:           /* Big-endian.  */
 111       if (! bfd_big_endian (abfd))
 112         goto wrong;
 113       break;
 114     case ELFDATA2LSB:           /* Little-endian.  */
 115       if (! bfd_little_endian (abfd))
 116         goto wrong;
 117       break;
 118     default:
 119       goto wrong;
 120     }
 121
 122   /* Give abfd an elf_obj_tdata.  */
 123   if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
 124     goto fail;
 125
 126   /* Swap in the rest of the header, now that we have the byte order.  */
 127   i_ehdrp = elf_elfheader (abfd);
 128   elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);
 129
 130 #if DEBUG & 1
 131   elf_debug_file (i_ehdrp);
 132 #endif
 133
 134   ebd = get_elf_backend_data (abfd);
 135
 136   /* Check that the ELF e_machine field matches what this particular
 137      BFD format expects.  */
 138
 139   if (ebd->elf_machine_code != i_ehdrp->e_machine
 140       && (ebd->elf_machine_alt1 == 0
 141           || i_ehdrp->e_machine != ebd->elf_machine_alt1)
 142       && (ebd->elf_machine_alt2 == 0
 143           || i_ehdrp->e_machine != ebd->elf_machine_alt2))
 144     {
 145       const bfd_target * const *target_ptr;
 146
 147       if (ebd->elf_machine_code != EM_NONE)
 148         goto wrong;
 149
 150       /* This is the generic ELF target.  Let it match any ELF target
 151          for which we do not have a specific backend.  */
 152
 153       for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
 154         {
 155           const struct elf_backend_data *back;
 156
 157           if ((*target_ptr)->flavour != bfd_target_elf_flavour)
 158             continue;
 159           back = xvec_get_elf_backend_data (*target_ptr);
 160           if (back->s->arch_size != ARCH_SIZE)
 161             continue;
 162           if (back->elf_machine_code == i_ehdrp->e_machine
 163               || (back->elf_machine_alt1 != 0
 164                   && i_ehdrp->e_machine == back->elf_machine_alt1)
 165               || (back->elf_machine_alt2 != 0
 166                   && i_ehdrp->e_machine == back->elf_machine_alt2))
 167             {
 168               /* target_ptr is an ELF backend which matches this
 169                  object file, so reject the generic ELF target.  */
 170               goto wrong;
 171             }
 172         }
 173     }
 174
 175   /* If there is no program header, or the type is not a core file, then
 176      we are hosed.  */
 177   if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
 178     goto wrong;
 179
 180   /* Does BFD's idea of the phdr size match the size
 181      recorded in the file? */
 182   if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
 183     goto wrong;
 184
 185   /* If the program header count is PN_XNUM(0xffff), the actual
 186      count is in the first section header.  */
 187   if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM)
 188     {
 189       Elf_External_Shdr x_shdr;
 190       Elf_Internal_Shdr i_shdr;
 191       bfd_signed_vma where = i_ehdrp->e_shoff;
 192
 193       if (where != (file_ptr) where)
 194         goto wrong;
 195
 196       /* Seek to the section header table in the file.  */
 197       if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
 198         goto fail;
 199
 200       /* Read the first section header at index 0, and convert to internal
 201          form.  */
 202       if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
 203         goto fail;
 204       elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);
 205
 206       if (i_shdr.sh_info != 0)
 207         {
 208           i_ehdrp->e_phnum = i_shdr.sh_info;
 209           if (i_ehdrp->e_phnum != i_shdr.sh_info)
 210             goto wrong;
 211         }
 212     }
 213
 214   /* Sanity check that we can read all of the program headers.
 215      It ought to be good enough to just read the last one.  */
 216   if (i_ehdrp->e_phnum > 1)
 217     {
 218       Elf_External_Phdr x_phdr;
 219       Elf_Internal_Phdr i_phdr;
 220       bfd_signed_vma where;
 221
 222       /* Check that we don't have a totally silly number of
 223          program headers.  */
 224       if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
 225           || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
 226         goto wrong;
 227
 228       where = i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr);
 229       if (where != (file_ptr) where)
 230         goto wrong;
 231       if ((bfd_size_type) where <= i_ehdrp->e_phoff)
 232         goto wrong;
 233
 234       if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
 235         goto fail;
 236       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 237         goto fail;
 238     }
 239
 240   /* Move to the start of the program headers.  */
 241   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
 242     goto wrong;
 243
 244   /* Allocate space for the program headers.  */
 245   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 246   i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
 247   if (!i_phdrp)
 248     goto fail;
 249
 250   elf_tdata (abfd)->phdr = i_phdrp;
 251
 252   /* Read and convert to internal form.  */
 253   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 254     {
 255       Elf_External_Phdr x_phdr;
 256
 257       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 258         goto fail;
 259
 260       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 261     }
 262
 263   /* Set the machine architecture.  Do this before processing the
 264      program headers since we need to know the architecture type
 265      when processing the notes of some systems' core files.  */
 266   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
 267       /* It's OK if this fails for the generic target.  */
 268       && ebd->elf_machine_code != EM_NONE)
 269     goto fail;
 270
 271   /* Let the backend double check the format and override global
 272      information.  We do this before processing the program headers
 273      to allow the correct machine (as opposed to just the default
 274      machine) to be set, making it possible for grok_prstatus and
 275      grok_psinfo to rely on the mach setting.  */
 276   if (ebd->elf_backend_object_p != NULL
 277       && ! ebd->elf_backend_object_p (abfd))
 278     goto wrong;
 279
 280   /* Process each program header.  */
 281   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 282     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 283       goto fail;
 284
 285   /* Check for core truncation.  */
 286   {
 287     bfd_size_type high = 0;
 288     struct stat statbuf;
 289     for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 290       {
 291         Elf_Internal_Phdr *p = i_phdrp + phindex;
 292         if (p->p_filesz)
 293           {
 294             bfd_size_type current = p->p_offset + p->p_filesz;
 295             if (high < current)
 296               high = current;
 297           }
 298       }
 299     if (bfd_stat (abfd, &statbuf) == 0)
 300       {
 301         if ((bfd_size_type) statbuf.st_size < high)
 302           {
 303             (*_bfd_error_handler)
 304               (_("Warning: %B is truncated: expected core file "
 305                  "size >= %lu, found: %lu."),
 306                abfd, (unsigned long) high, (unsigned long) statbuf.st_size);
 307           }
 308       }
 309   }
 310
 311   /* Save the entry point from the ELF header.  */
 312   bfd_get_start_address (abfd) = i_ehdrp->e_entry;
 313   return abfd->xvec;
 314
 315 wrong:
 316   bfd_set_error (bfd_error_wrong_format);
 317 fail:
 318   return NULL;
 319 }