bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2003, 2005, 2007,
   3    2008 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 = xvec_get_elf_backend_data (*target_ptr);
 162           if (back->s->arch_size != ARCH_SIZE)
 163             continue;
 164           if (back->elf_machine_code == i_ehdrp->e_machine
 165               || (back->elf_machine_alt1 != 0
 166                   && i_ehdrp->e_machine == back->elf_machine_alt1)
 167               || (back->elf_machine_alt2 != 0
 168                   && i_ehdrp->e_machine == back->elf_machine_alt2))
 169             {
 170               /* target_ptr is an ELF backend which matches this
 171                  object file, so reject the generic ELF target.  */
 172               goto wrong;
 173             }
 174         }
 175     }
 176
 177   /* If there is no program header, or the type is not a core file, then
 178      we are hosed.  */
 179   if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
 180     goto wrong;
 181
 182   /* Does BFD's idea of the phdr size match the size
 183      recorded in the file? */
 184   if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
 185     goto wrong;
 186
 187   /* Move to the start of the program headers.  */
 188   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
 189     goto wrong;
 190
 191   /* Allocate space for the program headers.  */
 192   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 193   i_phdrp = bfd_alloc (abfd, amt);
 194   if (!i_phdrp)
 195     goto fail;
 196
 197   elf_tdata (abfd)->phdr = i_phdrp;
 198
 199   /* Read and convert to internal form.  */
 200   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 201     {
 202       Elf_External_Phdr x_phdr;
 203
 204       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 205         goto fail;
 206
 207       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 208     }
 209
 210   /* Set the machine architecture.  Do this before processing the
 211      program headers since we need to know the architecture type
 212      when processing the notes of some systems' core files.  */
 213   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
 214       /* It's OK if this fails for the generic target.  */
 215       && ebd->elf_machine_code != EM_NONE)
 216     goto fail;
 217
 218   /* Let the backend double check the format and override global
 219      information.  We do this before processing the program headers
 220      to allow the correct machine (as opposed to just the default
 221      machine) to be set, making it possible for grok_prstatus and
 222      grok_psinfo to rely on the mach setting.  */
 223   if (ebd->elf_backend_object_p != NULL
 224       && ! ebd->elf_backend_object_p (abfd))
 225     goto wrong;
 226
 227   /* Process each program header.  */
 228   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 229     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 230       goto fail;
 231
 232   /* Check for core truncation.  */
 233   {
 234     bfd_size_type high = 0;
 235     struct stat statbuf;
 236     for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 237       {
 238         Elf_Internal_Phdr *p = i_phdrp + phindex;
 239         if (p->p_filesz)
 240           {
 241             bfd_size_type current = p->p_offset + p->p_filesz;
 242             if (high < current)
 243               high = current;
 244           }
 245       }
 246     if (bfd_stat (abfd, &statbuf) == 0)
 247       {
 248         if ((bfd_size_type) statbuf.st_size < high)
 249           {
 250             (*_bfd_error_handler)
 251               (_("Warning: %B is truncated: expected core file "
 252                  "size >= %lu, found: %lu."),
 253                abfd, (unsigned long) high, (unsigned long) statbuf.st_size);
 254           }
 255       }
 256   }
 257
 258   /* Save the entry point from the ELF header.  */
 259   bfd_get_start_address (abfd) = i_ehdrp->e_entry;
 260
 261   bfd_preserve_finish (abfd, &preserve);
 262   return abfd->xvec;
 263
 264 wrong:
 265   /* There is way too much undoing of half-known state here.  The caller,
 266      bfd_check_format_matches, really shouldn't iterate on live bfd's to
 267      check match/no-match like it does.  We have to rely on that a call to
 268      bfd_default_set_arch_mach with the previously known mach, undoes what
 269      was done by the first bfd_default_set_arch_mach (with mach 0) here.
 270      For this to work, only elf-data and the mach may be changed by the
 271      target-specific elf_backend_object_p function.  Note that saving the
 272      whole bfd here and restoring it would be even worse; the first thing
 273      you notice is that the cached bfd file position gets out of sync.  */
 274   bfd_set_error (bfd_error_wrong_format);
 275
 276 fail:
 277   if (preserve.marker != NULL)
 278     bfd_preserve_restore (abfd, &preserve);
 279   return NULL;
 280 }