Add the ability to the BFD library to read build-ids from core flies.

	* elf-bfd.h (elf_backend_data) <elf_backend_core_find_build_id>:
	New field.
	(_bfd_elf32_core_find_build_id, _bfd_elf64_core_find_build_id):
	New functions.
	(elf_read_notes): Add declaration.
	* elf.c (elf_read_notes): Move elf-bfd.h.
	(_bfd_elf_core_find_build_id): New function.
	(bfd_section_from_phdr): Scan core file PT_LOAD segments for
	build-id if none is known.
	(elf_parse_notes): For core files, scan for notes.
	* elfcore.h (elf_core_file_matches_executable_p): If both
	BFDs have identical build-ids, then they match.
	(_bfd_elf_core_find_build_id): New function.
	* elfxx-target.h (elf_backend_core_find_build_id): Define.
	(elfNN_bed): Add elf_backend_core_find_build_id.

1 files changed, 106 insertions, 0 deletions

diff --git a/bfd/elfcore.h b/bfd/elfcore.h
index 3550eaa..1279327 100644
--- a/bfd/elfcore.h
+++ b/bfd/elfcore.h
@@ -49,6 +49,14 @@ elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd)
       return FALSE;
     }
 
+  /* If both BFDs have identical build-ids, then they match.  */
+  if (core_bfd->build_id != NULL
+      && exec_bfd->build_id != NULL
+      && core_bfd->build_id->size == exec_bfd->build_id->size
+      && memcmp (core_bfd->build_id->data, exec_bfd->build_id->data,
+		 core_bfd->build_id->size) == 0)
+    return TRUE;
+
   /* See if the name in the corefile matches the executable name.  */
   corename = elf_tdata (core_bfd)->core->program;
   if (corename != NULL)
@@ -313,3 +321,101 @@ wrong:
 fail:
   return NULL;
 }
+
+/* Attempt to find a build-id in a core file from the core file BFD.
+   OFFSET is the file offset to a PT_LOAD segment that may contain
+   the build-id note.  Returns TRUE upon success, FALSE otherwise.  */
+
+bfd_boolean
+NAME(_bfd_elf, core_find_build_id)
+  (bfd *abfd,
+   bfd_vma offset)
+{
+  Elf_External_Ehdr x_ehdr;	/* Elf file header, external form.   */
+  Elf_Internal_Ehdr i_ehdr;	/* Elf file header, internal form.   */
+  Elf_Internal_Phdr *i_phdr;
+  unsigned int i;
+
+  /* Seek to the position of the segment at OFFSET.  */
+  if (bfd_seek (abfd, offset, SEEK_SET) != 0)
+    goto fail;
+
+  /* Read in the ELF header in external format.  */
+  if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
+    {
+      if (bfd_get_error () != bfd_error_system_call)
+	goto wrong;
+      else
+	goto fail;
+    }
+
+  /* Now check to see if we have a valid ELF file, and one that BFD can
+     make use of.  The magic number must match, the address size ('class')
+     and byte-swapping must match our XVEC entry, and it must have a
+     section header table (FIXME: See comments re sections at top of this
+     file).  */
+  if (! elf_file_p (&x_ehdr)
+      || x_ehdr.e_ident[EI_VERSION] != EV_CURRENT
+      || x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
+    goto wrong;
+
+  /* Check that file's byte order matches xvec's.  */
+  switch (x_ehdr.e_ident[EI_DATA])
+    {
+    case ELFDATA2MSB:		/* Big-endian.  */
+      if (! bfd_header_big_endian (abfd))
+	goto wrong;
+      break;
+    case ELFDATA2LSB:		/* Little-endian.  */
+      if (! bfd_header_little_endian (abfd))
+	goto wrong;
+      break;
+    case ELFDATANONE:		/* No data encoding specified.  */
+    default:			/* Unknown data encoding specified . */
+      goto wrong;
+    }
+
+  elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr);
+#if DEBUG
+  elf_debug_file (&i_ehdr);
+#endif
+
+  if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) || i_ehdr.e_phnum == 0)
+    goto fail;
+
+  /* Read in program headers.  */
+  i_phdr = (Elf_Internal_Phdr *) bfd_alloc2 (abfd, i_ehdr.e_phnum,
+					     sizeof (*i_phdr));
+  if (i_phdr == NULL)
+    goto fail;
+
+  if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff), SEEK_SET) != 0)
+    goto fail;
+
+  /* Read in program headers and parse notes.  */
+  for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr)
+    {
+      Elf_External_Phdr x_phdr;
+
+      if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
+	goto fail;
+      elf_swap_phdr_in (abfd, &x_phdr, i_phdr);
+
+      if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
+	{
+	  elf_read_notes (abfd, offset + i_phdr->p_offset,
+			  i_phdr->p_filesz, i_phdr->p_align);
+	  if (abfd->build_id != NULL)
+	    return TRUE;
+	}
+    }
+
+  /* Having gotten this far, we have a valid ELF section, but no
+     build-id was found.  */
+  goto fail;
+
+wrong:
+  bfd_set_error (bfd_error_wrong_format);
+fail:
+  return FALSE;
+}