bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2003, 2005, 2007
   3    Free Software Foundation, Inc.
   4
   5    This file is part of BFD, the Binary File Descriptor library.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 char*
  23 elf_core_file_failing_command (bfd *abfd)
  24 {
  25   return elf_tdata (abfd)->core_command;
  26 }
  27
  28 int
  29 elf_core_file_failing_signal (bfd *abfd)
  30 {
  31   return elf_tdata (abfd)->core_signal;
  32 }
  33
  34 bfd_boolean
  35 elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd)
  36 {
  37   char* corename;
  38
  39   /* xvecs must match if both are ELF files for the same target.  */
  40
  41   if (core_bfd->xvec != exec_bfd->xvec)
  42     {
  43       bfd_set_error (bfd_error_system_call);
  44       return FALSE;
  45     }
  46
  47   /* See if the name in the corefile matches the executable name.  */
  48   corename = elf_tdata (core_bfd)->core_program;
  49   if (corename != NULL)
  50     {
  51       const char* execname = strrchr (exec_bfd->filename, '/');
  52
  53       execname = execname ? execname + 1 : exec_bfd->filename;
  54
  55       if (strcmp (execname, corename) != 0)
  56         return FALSE;
  57     }
  58
  59   return TRUE;
  60 }
  61
  62 /*  Core files are simply standard ELF formatted files that partition
  63     the file using the execution view of the file (program header table)
  64     rather than the linking view.  In fact, there is no section header
  65     table in a core file.
  66
  67     The process status information (including the contents of the general
  68     register set) and the floating point register set are stored in a
  69     segment of type PT_NOTE.  We handcraft a couple of extra bfd sections
  70     that allow standard bfd access to the general registers (.reg) and the
  71     floating point registers (.reg2).  */
  72
  73 const bfd_target *
  74 elf_core_file_p (bfd *abfd)
  75 {
  76   Elf_External_Ehdr x_ehdr;     /* Elf file header, external form.  */
  77   Elf_Internal_Ehdr *i_ehdrp;   /* Elf file header, internal form.  */
  78   Elf_Internal_Phdr *i_phdrp;   /* Elf program header, internal form.  */
  79   unsigned int phindex;
  80   const struct elf_backend_data *ebd;
  81   struct bfd_preserve preserve;
  82   bfd_size_type amt;
  83
  84   preserve.marker = NULL;
  85
  86   /* Read in the ELF header in external format.  */
  87   if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
  88     {
  89       if (bfd_get_error () != bfd_error_system_call)
  90         goto wrong;
  91       else
  92         goto fail;
  93     }
  94
  95   /* Check the magic number.  */
  96   if (! elf_file_p (&x_ehdr))
  97     goto wrong;
  98
  99   /* FIXME: Check EI_VERSION here !  */
 100
 101   /* Check the address size ("class").  */
 102   if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
 103     goto wrong;
 104
 105   /* Check the byteorder.  */
 106   switch (x_ehdr.e_ident[EI_DATA])
 107     {
 108     case ELFDATA2MSB:           /* Big-endian.  */
 109       if (! bfd_big_endian (abfd))
 110         goto wrong;
 111       break;
 112     case ELFDATA2LSB:           /* Little-endian.  */
 113       if (! bfd_little_endian (abfd))
 114         goto wrong;
 115       break;
 116     default:
 117       goto wrong;
 118     }
 119
 120   if (!bfd_preserve_save (abfd, &preserve))
 121     goto fail;
 122
 123   /* Give abfd an elf_obj_tdata.  */
 124   if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
 125     goto fail;
 126   preserve.marker = elf_tdata (abfd);
 127
 128   /* Swap in the rest of the header, now that we have the byte order.  */
 129   i_ehdrp = elf_elfheader (abfd);
 130   elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);
 131
 132 #if DEBUG & 1
 133   elf_debug_file (i_ehdrp);
 134 #endif
 135
 136   ebd = get_elf_backend_data (abfd);
 137
 138   /* Check that the ELF e_machine field matches what this particular
 139      BFD format expects.  */
 140
 141   if (ebd->elf_machine_code != i_ehdrp->e_machine
 142       && (ebd->elf_machine_alt1 == 0
 143           || i_ehdrp->e_machine != ebd->elf_machine_alt1)
 144       && (ebd->elf_machine_alt2 == 0
 145           || i_ehdrp->e_machine != ebd->elf_machine_alt2))
 146     {
 147       const bfd_target * const *target_ptr;
 148
 149       if (ebd->elf_machine_code != EM_NONE)
 150         goto wrong;
 151
 152       /* This is the generic ELF target.  Let it match any ELF target
 153          for which we do not have a specific backend.  */
 154
 155       for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
 156         {
 157           const struct elf_backend_data *back;
 158
 159           if ((*target_ptr)->flavour != bfd_target_elf_flavour)
 160             continue;
 161           back = (const struct elf_backend_data *) (*target_ptr)->backend_data;
 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   /* Move to the start of the program headers.  */
 186   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
 187     goto wrong;
 188
 189   /* Allocate space for the program headers.  */
 190   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 191   i_phdrp = bfd_alloc (abfd, amt);
 192   if (!i_phdrp)
 193     goto fail;
 194
 195   elf_tdata (abfd)->phdr = i_phdrp;
 196
 197   /* Read and convert to internal form.  */
 198   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 199     {
 200       Elf_External_Phdr x_phdr;
 201
 202       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 203         goto fail;
 204
 205       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 206     }
 207
 208   /* Set the machine architecture.  Do this before processing the
 209      program headers since we need to know the architecture type
 210      when processing the notes of some systems' core files.  */
 211   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
 212       /* It's OK if this fails for the generic target.  */
 213       && ebd->elf_machine_code != EM_NONE)
 214     goto fail;
 215
 216   /* Let the backend double check the format and override global
 217      information.  We do this before processing the program headers
 218      to allow the correct machine (as opposed to just the default
 219      machine) to be set, making it possible for grok_prstatus and
 220      grok_psinfo to rely on the mach setting.  */
 221   if (ebd->elf_backend_object_p != NULL
 222       && ! ebd->elf_backend_object_p (abfd))
 223     goto wrong;
 224
 225   /* Process each program header.  */
 226   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 227     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 228       goto fail;
 229
 230   /* Save the entry point from the ELF header.  */
 231   bfd_get_start_address (abfd) = i_ehdrp->e_entry;
 232
 233   bfd_preserve_finish (abfd, &preserve);
 234   return abfd->xvec;
 235
 236 wrong:
 237   /* There is way too much undoing of half-known state here.  The caller,
 238      bfd_check_format_matches, really shouldn't iterate on live bfd's to
 239      check match/no-match like it does.  We have to rely on that a call to
 240      bfd_default_set_arch_mach with the previously known mach, undoes what
 241      was done by the first bfd_default_set_arch_mach (with mach 0) here.
 242      For this to work, only elf-data and the mach may be changed by the
 243      target-specific elf_backend_object_p function.  Note that saving the
 244      whole bfd here and restoring it would be even worse; the first thing
 245      you notice is that the cached bfd file position gets out of sync.  */
 246   bfd_set_error (bfd_error_wrong_format);
 247
 248 fail:
 249   if (preserve.marker != NULL)
 250     bfd_preserve_restore (abfd, &preserve);
 251   return NULL;
 252 }