bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright (C) 1995-2017 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       file_ptr where = (file_ptr) i_ehdrp->e_shoff;
 192
 193       /* Seek to the section header table in the file.  */
 194       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 195         goto fail;
 196
 197       /* Read the first section header at index 0, and convert to internal
 198          form.  */
 199       if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
 200         goto fail;
 201       elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);
 202
 203       if (i_shdr.sh_info != 0)
 204         {
 205           i_ehdrp->e_phnum = i_shdr.sh_info;
 206           if (i_ehdrp->e_phnum != i_shdr.sh_info)
 207             goto wrong;
 208         }
 209     }
 210
 211   /* Sanity check that we can read all of the program headers.
 212      It ought to be good enough to just read the last one.  */
 213   if (i_ehdrp->e_phnum > 1)
 214     {
 215       Elf_External_Phdr x_phdr;
 216       Elf_Internal_Phdr i_phdr;
 217       file_ptr where;
 218
 219       /* Check that we don't have a totally silly number of
 220          program headers.  */
 221       if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
 222           || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
 223         goto wrong;
 224
 225       where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr));
 226       if ((bfd_size_type) where <= i_ehdrp->e_phoff)
 227         goto wrong;
 228
 229       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 230         goto fail;
 231       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 232         goto fail;
 233     }
 234
 235   /* Move to the start of the program headers.  */
 236   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
 237     goto wrong;
 238
 239   /* Allocate space for the program headers.  */
 240   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 241   i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
 242   if (!i_phdrp)
 243     goto fail;
 244
 245   elf_tdata (abfd)->phdr = i_phdrp;
 246
 247   /* Read and convert to internal form.  */
 248   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 249     {
 250       Elf_External_Phdr x_phdr;
 251
 252       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 253         goto fail;
 254
 255       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 256     }
 257
 258   /* Set the machine architecture.  Do this before processing the
 259      program headers since we need to know the architecture type
 260      when processing the notes of some systems' core files.  */
 261   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
 262       /* It's OK if this fails for the generic target.  */
 263       && ebd->elf_machine_code != EM_NONE)
 264     goto fail;
 265
 266   /* Let the backend double check the format and override global
 267      information.  We do this before processing the program headers
 268      to allow the correct machine (as opposed to just the default
 269      machine) to be set, making it possible for grok_prstatus and
 270      grok_psinfo to rely on the mach setting.  */
 271   if (ebd->elf_backend_object_p != NULL
 272       && ! ebd->elf_backend_object_p (abfd))
 273     goto wrong;
 274
 275   /* Process each program header.  */
 276   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 277     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 278       goto fail;
 279
 280   /* Check for core truncation.  */
 281   {
 282     bfd_size_type high = 0;
 283     struct stat statbuf;
 284     for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 285       {
 286         Elf_Internal_Phdr *p = i_phdrp + phindex;
 287         if (p->p_filesz)
 288           {
 289             bfd_size_type current = p->p_offset + p->p_filesz;
 290             if (high < current)
 291               high = current;
 292           }
 293       }
 294     if (bfd_stat (abfd, &statbuf) == 0)
 295       {
 296         if ((bfd_size_type) statbuf.st_size < high)
 297           {
 298             _bfd_error_handler
 299               /* xgettext:c-format */
 300               (_("warning: %B is truncated: expected core file "
 301                  "size >= %Lu, found: %llu"),
 302                abfd, high, (unsigned long long) statbuf.st_size);
 303           }
 304       }
 305   }
 306
 307   /* Save the entry point from the ELF header.  */
 308   bfd_get_start_address (abfd) = i_ehdrp->e_entry;
 309   return abfd->xvec;
 310
 311 wrong:
 312   bfd_set_error (bfd_error_wrong_format);
 313 fail:
 314   return NULL;
 315 }