bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright 1995, 1996, 1997, 1998, 2000, 2001, 2002
   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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 char*
  22 elf_core_file_failing_command (abfd)
  23      bfd *abfd;
  24 {
  25   return elf_tdata (abfd)->core_command;
  26 }
  27
  28 int
  29 elf_core_file_failing_signal (abfd)
  30      bfd *abfd;
  31 {
  32   return elf_tdata (abfd)->core_signal;
  33 }
  34
  35 boolean
  36 elf_core_file_matches_executable_p (core_bfd, exec_bfd)
  37      bfd *core_bfd;
  38      bfd *exec_bfd;
  39 {
  40   char* corename;
  41
  42   /* xvecs must match if both are ELF files for the same target.  */
  43
  44   if (core_bfd->xvec != exec_bfd->xvec)
  45     {
  46       bfd_set_error (bfd_error_system_call);
  47       return false;
  48     }
  49
  50   /* See if the name in the corefile matches the executable name.  */
  51
  52   corename = elf_tdata (core_bfd)->core_program;
  53   if (corename != NULL)
  54     {
  55       const char* execname = strrchr (exec_bfd->filename, '/');
  56       execname = execname ? execname + 1 : exec_bfd->filename;
  57
  58       if (strcmp(execname, corename) != 0)
  59         return false;
  60     }
  61
  62   return true;
  63 }
  64
  65 /*  Core files are simply standard ELF formatted files that partition
  66     the file using the execution view of the file (program header table)
  67     rather than the linking view.  In fact, there is no section header
  68     table in a core file.
  69
  70     The process status information (including the contents of the general
  71     register set) and the floating point register set are stored in a
  72     segment of type PT_NOTE.  We handcraft a couple of extra bfd sections
  73     that allow standard bfd access to the general registers (.reg) and the
  74     floating point registers (.reg2).
  75
  76  */
  77
  78 const bfd_target *
  79 elf_core_file_p (abfd)
  80      bfd *abfd;
  81 {
  82   Elf_External_Ehdr x_ehdr;     /* Elf file header, external form */
  83   Elf_Internal_Ehdr *i_ehdrp;   /* Elf file header, internal form */
  84   Elf_Internal_Phdr *i_phdrp;   /* Elf program header, internal form */
  85   unsigned int phindex;
  86   struct elf_backend_data *ebd;
  87   struct bfd_preserve preserve;
  88   struct elf_obj_tdata *new_tdata = NULL;
  89   bfd_size_type amt;
  90
  91   preserve.arch_info = abfd->arch_info;
  92
  93   /* Read in the ELF header in external format.  */
  94   if (bfd_bread ((PTR) &x_ehdr, (bfd_size_type) sizeof (x_ehdr), abfd)
  95       != sizeof (x_ehdr))
  96     {
  97       if (bfd_get_error () != bfd_error_system_call)
  98         bfd_set_error (bfd_error_wrong_format);
  99       return NULL;
 100     }
 101
 102   /* Check the magic number.  */
 103   if (! elf_file_p (&x_ehdr))
 104     goto wrong;
 105
 106   /* FIXME: Check EI_VERSION here ! */
 107
 108   /* Check the address size ("class").  */
 109   if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
 110     goto wrong;
 111
 112   /* Check the byteorder.  */
 113   switch (x_ehdr.e_ident[EI_DATA])
 114     {
 115     case ELFDATA2MSB:           /* Big-endian */
 116       if (! bfd_big_endian (abfd))
 117         goto wrong;
 118       break;
 119     case ELFDATA2LSB:           /* Little-endian */
 120       if (! bfd_little_endian (abfd))
 121         goto wrong;
 122       break;
 123     default:
 124       goto wrong;
 125     }
 126
 127   /* Give abfd an elf_obj_tdata.  */
 128   amt = sizeof (struct elf_obj_tdata);
 129   new_tdata = (struct elf_obj_tdata *) bfd_zalloc (abfd, amt);
 130   if (new_tdata == NULL)
 131     return NULL;
 132   preserve.tdata = elf_tdata (abfd);
 133   elf_tdata (abfd) = new_tdata;
 134
 135   /* Clear section information, since there might be a recognized bfd that
 136      we now check if we can replace, and we don't want to append to it.  */
 137   preserve.sections = abfd->sections;
 138   preserve.section_tail = abfd->section_tail;
 139   preserve.section_count = abfd->section_count;
 140   preserve.section_htab = abfd->section_htab;
 141   abfd->sections = NULL;
 142   abfd->section_tail = &abfd->sections;
 143   abfd->section_count = 0;
 144   if (!bfd_hash_table_init (&abfd->section_htab, bfd_section_hash_newfunc))
 145     goto fail;
 146
 147   /* Swap in the rest of the header, now that we have the byte order.  */
 148   i_ehdrp = elf_elfheader (abfd);
 149   elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);
 150
 151 #if DEBUG & 1
 152   elf_debug_file (i_ehdrp);
 153 #endif
 154
 155   ebd = get_elf_backend_data (abfd);
 156
 157   /* Check that the ELF e_machine field matches what this particular
 158      BFD format expects.  */
 159
 160   if (ebd->elf_machine_code != i_ehdrp->e_machine
 161       && (ebd->elf_machine_alt1 == 0
 162           || i_ehdrp->e_machine != ebd->elf_machine_alt1)
 163       && (ebd->elf_machine_alt2 == 0
 164           || i_ehdrp->e_machine != ebd->elf_machine_alt2))
 165     {
 166       const bfd_target * const *target_ptr;
 167
 168       if (ebd->elf_machine_code != EM_NONE)
 169         goto wrong;
 170
 171       /* This is the generic ELF target.  Let it match any ELF target
 172          for which we do not have a specific backend.  */
 173
 174       for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
 175         {
 176           struct elf_backend_data *back;
 177
 178           if ((*target_ptr)->flavour != bfd_target_elf_flavour)
 179             continue;
 180           back = (struct elf_backend_data *) (*target_ptr)->backend_data;
 181           if (back->elf_machine_code == i_ehdrp->e_machine)
 182             {
 183               /* target_ptr is an ELF backend which matches this
 184                  object file, so reject the generic ELF target.  */
 185               goto wrong;
 186             }
 187         }
 188     }
 189
 190   /* If there is no program header, or the type is not a core file, then
 191      we are hosed.  */
 192   if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
 193     goto wrong;
 194
 195   /* Does BFD's idea of the phdr size match the size
 196      recorded in the file? */
 197   if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
 198     goto wrong;
 199
 200   /* Move to the start of the program headers.  */
 201   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
 202     goto wrong;
 203
 204   /* Allocate space for the program headers.  */
 205   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 206   i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
 207   if (!i_phdrp)
 208     goto fail;
 209
 210   elf_tdata (abfd)->phdr = i_phdrp;
 211
 212   /* Read and convert to internal form.  */
 213   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 214     {
 215       Elf_External_Phdr x_phdr;
 216       if (bfd_bread ((PTR) &x_phdr, (bfd_size_type) sizeof (x_phdr), abfd)
 217           != sizeof (x_phdr))
 218         goto fail;
 219
 220       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 221     }
 222
 223   /* Set the machine architecture.  Do this before processing the
 224      program headers since we need to know the architecture type
 225      when processing the notes of some systems' core files.  */
 226   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0))
 227     {
 228       /* It's OK if this fails for the generic target.  */
 229       if (ebd->elf_machine_code != EM_NONE)
 230         goto fail;
 231     }
 232
 233   /* Process each program header.  */
 234   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 235     {
 236       if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 237         goto fail;
 238     }
 239
 240   /* Save the entry point from the ELF header.  */
 241   bfd_get_start_address (abfd) = i_ehdrp->e_entry;
 242
 243   /* Let the backend double check the format and override global
 244      information.  */
 245   if (ebd->elf_backend_object_p)
 246     {
 247       if (! (*ebd->elf_backend_object_p) (abfd))
 248         goto wrong;
 249     }
 250
 251   bfd_hash_table_free (&preserve.section_htab);
 252   return abfd->xvec;
 253
 254 wrong:
 255   /* There is way too much undoing of half-known state here.  The caller,
 256      bfd_check_format_matches, really shouldn't iterate on live bfd's to
 257      check match/no-match like it does.  We have to rely on that a call to
 258      bfd_default_set_arch_mach with the previously known mach, undoes what
 259      was done by the first bfd_default_set_arch_mach (with mach 0) here.
 260      For this to work, only elf-data and the mach may be changed by the
 261      target-specific elf_backend_object_p function.  Note that saving the
 262      whole bfd here and restoring it would be even worse; the first thing
 263      you notice is that the cached bfd file position gets out of sync.  */
 264   bfd_set_error (bfd_error_wrong_format);
 265
 266 fail:
 267   abfd->arch_info = preserve.arch_info;
 268   if (new_tdata != NULL)
 269     {
 270       /* bfd_release frees all memory more recently bfd_alloc'd than
 271          its arg, as well as its arg.  */
 272       bfd_release (abfd, new_tdata);
 273       elf_tdata (abfd) = preserve.tdata;
 274       abfd->section_htab = preserve.section_htab;
 275       abfd->sections = preserve.sections;
 276       abfd->section_tail = preserve.section_tail;
 277       abfd->section_count = preserve.section_count;
 278     }
 279   return NULL;
 280 }