GDB 7.6.50

bfd/format.c

 /* Generic BFD support for file formats.
    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002,
    2003, 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
    Written by Cygnus Support.
 
    This file is part of BFD, the Binary File Descriptor library.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
@@ skipping 77 matching lines @@
         o <<bfd_error_file_ambiguously_recognized>> -
         more than one backend recognised the file format.
 */
 
 bfd_boolean
 bfd_check_format (bfd *abfd, bfd_format format)
 {
   return bfd_check_format_matches (abfd, format, NULL);
 }
 
+struct bfd_preserve
+{
+  void *marker;
+  void *tdata;
+  flagword flags;
+  const struct bfd_arch_info *arch_info;
+  struct bfd_section *sections;
+  struct bfd_section *section_last;
+  unsigned int section_count;
+  struct bfd_hash_table section_htab;
+};
+
+/* When testing an object for compatibility with a particular target
+   back-end, the back-end object_p function needs to set up certain
+   fields in the bfd on successfully recognizing the object.  This
+   typically happens in a piecemeal fashion, with failures possible at
+   many points.  On failure, the bfd is supposed to be restored to its
+   initial state, which is virtually impossible.  However, restoring a
+   subset of the bfd state works in practice.  This function stores
+   the subset.  */
+
+static bfd_boolean
+bfd_preserve_save (bfd *abfd, struct bfd_preserve *preserve)
+{
+  preserve->tdata = abfd->tdata.any;
+  preserve->arch_info = abfd->arch_info;
+  preserve->flags = abfd->flags;
+  preserve->sections = abfd->sections;
+  preserve->section_last = abfd->section_last;
+  preserve->section_count = abfd->section_count;
+  preserve->section_htab = abfd->section_htab;
+  preserve->marker = bfd_alloc (abfd, 1);
+  if (preserve->marker == NULL)
+    return FALSE;
+
+  return bfd_hash_table_init (&abfd->section_htab, bfd_section_hash_newfunc,
+                              sizeof (struct section_hash_entry));
+}
+
+/* Clear out a subset of BFD state.  */
+
+static void
+bfd_reinit (bfd *abfd)
+{
+  abfd->tdata.any = NULL;
+  abfd->arch_info = &bfd_default_arch_struct;
+  abfd->flags &= BFD_FLAGS_SAVED;
+  bfd_section_list_clear (abfd);
+}
+
+/* Restores bfd state saved by bfd_preserve_save.  */
+
+static void
+bfd_preserve_restore (bfd *abfd, struct bfd_preserve *preserve)
+{
+  bfd_hash_table_free (&abfd->section_htab);
+
+  abfd->tdata.any = preserve->tdata;
+  abfd->arch_info = preserve->arch_info;
+  abfd->flags = preserve->flags;
+  abfd->section_htab = preserve->section_htab;
+  abfd->sections = preserve->sections;
+  abfd->section_last = preserve->section_last;
+  abfd->section_count = preserve->section_count;
+
+  /* bfd_release frees all memory more recently bfd_alloc'd than
+     its arg, as well as its arg.  */
+  bfd_release (abfd, preserve->marker);
+  preserve->marker = NULL;
+}
+
+/* Called when the bfd state saved by bfd_preserve_save is no longer
+   needed.  */
+
+static void
+bfd_preserve_finish (bfd *abfd ATTRIBUTE_UNUSED, struct bfd_preserve *preserve)
+{
+  /* It would be nice to be able to free more memory here, eg. old
+     tdata, but that's not possible since these blocks are sitting
+     inside bfd_alloc'd memory.  The section hash is on a separate
+     objalloc.  */
+  bfd_hash_table_free (&preserve->section_htab);
+  preserve->marker = NULL;
+}
+
 /*
 FUNCTION
         bfd_check_format_matches
 
 SYNOPSIS
         bfd_boolean bfd_check_format_matches
           (bfd *abfd, bfd_format format, char ***matching);
 
 DESCRIPTION
         Like <<bfd_check_format>>, except when it returns FALSE with
         <<bfd_errno>> set to <<bfd_error_file_ambiguously_recognized>>.  In that
         case, if @var{matching} is not NULL, it will be filled in with
         a NULL-terminated list of the names of the formats that matched,
         allocated with <<malloc>>.
         Then the user may choose a format and try again.
 
         When done with the list that @var{matching} points to, the caller
         should free it.
 */
 
 bfd_boolean
 bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
 {
   extern const bfd_target binary_vec;
   const bfd_target * const *target;
   const bfd_target **matching_vector = NULL;
   const bfd_target *save_targ, *right_targ, *ar_right_targ, *match_targ;
   int match_count, best_count, best_match;
   int ar_match_index;
+  struct bfd_preserve preserve;
 
   if (matching != NULL)
     *matching = NULL;
 
   if (!bfd_read_p (abfd)
       || (unsigned int) abfd->format >= (unsigned int) bfd_type_end)
     {
       bfd_set_error (bfd_error_invalid_operation);
       return FALSE;
     }
 
   if (abfd->format != bfd_unknown)
     return abfd->format == format;
 
-  /* Since the target type was defaulted, check them
-     all in the hope that one will be uniquely recognized.  */
-  save_targ = abfd->xvec;
-  match_count = 0;
-  ar_match_index = _bfd_target_vector_entries;
-
   if (matching != NULL || *bfd_associated_vector != NULL)
     {
       bfd_size_type amt;
 
       amt = sizeof (*matching_vector) * 2 * _bfd_target_vector_entries;
       matching_vector = (const bfd_target **) bfd_malloc (amt);
       if (!matching_vector)
         return FALSE;
     }
 
-  right_targ = 0;
-  ar_right_targ = 0;
-  match_targ = 0;
-  best_match = 256;
-  best_count = 0;
-
   /* Presume the answer is yes.  */
   abfd->format = format;
+  save_targ = abfd->xvec;
+  preserve.marker = NULL;
 
   /* If the target type was explicitly specified, just check that target.  */
   if (!abfd->target_defaulted)
     {
       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0) /* rewind! */
         goto err_ret;
 
       right_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 
       if (right_targ)
         goto ok_ret;
 
       /* For a long time the code has dropped through to check all
          targets if the specified target was wrong.  I don't know why,
          and I'm reluctant to change it.  However, in the case of an
          archive, it can cause problems.  If the specified target does
          not permit archives (e.g., the binary target), then we should
          not allow some other target to recognize it as an archive, but
          should instead allow the specified target to recognize it as an
          object.  When I first made this change, it broke the PE target,
          because the specified pei-i386 target did not recognize the
          actual pe-i386 archive.  Since there may be other problems of
          this sort, I changed this test to check only for the binary
          target.  */
       if (format == bfd_archive && save_targ == &binary_vec)
         goto err_unrecog;
     }
 
+  /* Since the target type was defaulted, check them all in the hope
+     that one will be uniquely recognized.  */
+  right_targ = NULL;
+  ar_right_targ = NULL;
+  match_targ = NULL;
+  best_match = 256;
+  best_count = 0;
+  match_count = 0;
+  ar_match_index = _bfd_target_vector_entries;
+
   for (target = bfd_target_vector; *target != NULL; target++)
     {
       const bfd_target *temp;
-      bfd_error_type err;
 
       /* Don't check the default target twice.  */
       if (*target == &binary_vec
           || (!abfd->target_defaulted && *target == save_targ)
           || (*target)->match_priority > best_match)
         continue;
 
-      abfd->xvec = *target;     /* Change BFD's target temporarily.  */
+      /* If we already tried a match, the bfd is modified and may
+         have sections attached, which will confuse the next
+         _bfd_check_format call.  */
+      bfd_reinit (abfd);
+
+      /* Change BFD's target temporarily.  */
+      abfd->xvec = *target;
 
       if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
         goto err_ret;
 
       /* If _bfd_check_format neglects to set bfd_error, assume
          bfd_error_wrong_format.  We didn't used to even pay any
          attention to bfd_error, so I suspect that some
          _bfd_check_format might have this problem.  */
       bfd_set_error (bfd_error_wrong_format);
 
       temp = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
       if (temp)
-        match_targ = temp;
+        {
+          match_targ = temp;
+          if (preserve.marker != NULL)
+            bfd_preserve_finish (abfd, &preserve);
 
-      if (temp && (abfd->format != bfd_archive || bfd_has_map (abfd)))
-        {
-          /* This format checks out as ok!  */
-          right_targ = temp;
+          if (abfd->format != bfd_archive
+              || (bfd_has_map (abfd)
+                  && bfd_get_error () != bfd_error_wrong_object_format))
+            {
+              /* This format checks out as ok!  */
+              right_targ = temp;
 
-          /* If this is the default target, accept it, even if other
-             targets might match.  People who want those other targets
-             have to set the GNUTARGET variable.  */
-          if (temp == bfd_default_vector[0])
-            goto ok_ret;
+              /* If this is the default target, accept it, even if
+                 other targets might match.  People who want those
+                 other targets have to set the GNUTARGET variable.  */
+              if (temp == bfd_default_vector[0])
+                goto ok_ret;
 
-          if (matching_vector)
-            matching_vector[match_count] = temp;
-          match_count++;
+              if (matching_vector)
+                matching_vector[match_count] = temp;
+              match_count++;
 
-          if (temp->match_priority < best_match)
+              if (temp->match_priority < best_match)
+                {
+                  best_match = temp->match_priority;
+                  best_count = 0;
+                }
+              best_count++;
+            }
+          else
             {
-              best_match = temp->match_priority;
-              best_count = 0;
+              /* An archive with no armap or objects of the wrong
+                 type.  We want this target to match if we get no
+                 better matches.  */
+              if (ar_right_targ != bfd_default_vector[0])
+                ar_right_targ = *target;
+              if (matching_vector)
+                matching_vector[ar_match_index] = *target;
+              ar_match_index++;
             }
-          best_count++;
+
+          if (!bfd_preserve_save (abfd, &preserve))
+            goto err_ret;
         }
-      else if (temp
-               || (err = bfd_get_error ()) == bfd_error_wrong_object_format
-               || err == bfd_error_file_ambiguously_recognized)
-        {
-          /* An archive with no armap or objects of the wrong type,
-             or an ambiguous match.  We want this target to match
-             if we get no better matches.  */
-          if (ar_right_targ != bfd_default_vector[0])
-            ar_right_targ = *target;
-          if (matching_vector)
-            matching_vector[ar_match_index] = *target;
-          ar_match_index++;
-        }
-      else if (err != bfd_error_wrong_format)
+      else if (bfd_get_error () != bfd_error_wrong_format)
         goto err_ret;
     }
 
   if (best_count == 1)
     match_count = 1;
 
   if (match_count == 0)
     {
       /* Try partial matches.  */
       right_targ = ar_right_targ;
 
       if (right_targ == bfd_default_vector[0])
         {
           match_count = 1;
         }
       else
         {
           match_count = ar_match_index - _bfd_target_vector_entries;
 
           if (matching_vector && match_count > 1)
             memcpy (matching_vector,
                     matching_vector + _bfd_target_vector_entries,
                     sizeof (*matching_vector) * match_count);
         }
     }
 
+  /* We have more than one equally good match.  If any of the best
+     matches is a target in config.bfd targ_defvec or targ_selvecs,
+     choose it.  */
   if (match_count > 1)
     {
       const bfd_target * const *assoc = bfd_associated_vector;
 
       while ((right_targ = *assoc++) != NULL)
         {
           int i = match_count;
 
           while (--i >= 0)
-            if (matching_vector[i] == right_targ)
+            if (matching_vector[i] == right_targ
+                && right_targ->match_priority <= best_match)
               break;
 
           if (i >= 0)
             {
               match_count = 1;
               break;
             }
         }
     }
 
+  /* We still have more than one equally good match, and at least some
+     of the targets support match priority.  Choose the first of the
+     best matches.  */
+  if (match_count > 1 && best_count != match_count)
+    {
+      int i;
+
+      for (i = 0; i < match_count; i++)
+        {
+          right_targ = matching_vector[i];
+          if (right_targ->match_priority <= best_match)
+            break;
+        }
+      match_count = 1;
+    }
+
+  /* There is way too much undoing of half-known state here.  We
+     really shouldn't iterate on live bfd's.  Note that saving the
+     whole bfd and restoring it would be even worse; the first thing
+     you notice is that the cached bfd file position gets out of sync.  */
+  if (preserve.marker != NULL)
+    bfd_preserve_restore (abfd, &preserve);
+
   if (match_count == 1)
     {
       abfd->xvec = right_targ;
       /* If we come out of the loop knowing that the last target that
          matched is the one we want, then ABFD should still be in a usable
          state (except possibly for XVEC).  */
       if (match_targ != right_targ)
         {
+          bfd_reinit (abfd);
           if (bfd_seek (abfd, (file_ptr) 0, SEEK_SET) != 0)
             goto err_ret;
           match_targ = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
+          BFD_ASSERT (match_targ != NULL);
         }
 
     ok_ret:
       /* If the file was opened for update, then `output_has_begun'
          some time ago when the file was created.  Do not recompute
          sections sizes or alignments in _bfd_set_section_contents.
          We can not set this flag until after checking the format,
          because it will interfere with creation of BFD sections.  */
       if (abfd->direction == both_direction)
         abfd->output_has_begun = TRUE;
 
       if (matching_vector)
         free (matching_vector);
-      return TRUE;                      /* File position has moved, BTW.  */
+
+      /* File position has moved, BTW.  */
+      return TRUE;
     }
 
   if (match_count == 0)
     {
     err_unrecog:
       bfd_set_error (bfd_error_file_not_recognized);
     err_ret:
       abfd->xvec = save_targ;
       abfd->format = bfd_unknown;
       if (matching_vector)
         free (matching_vector);
+      if (preserve.marker != NULL)
+        bfd_preserve_restore (abfd, &preserve);
       return FALSE;
     }
 
-  abfd->xvec = save_targ;               /* Restore original target type.  */
-  abfd->format = bfd_unknown;           /* Restore original format.  */
+  /* Restore original target type and format.  */
+  abfd->xvec = save_targ;
+  abfd->format = bfd_unknown;
   bfd_set_error (bfd_error_file_ambiguously_recognized);
 
   if (matching)
     {
       *matching = (char **) matching_vector;
       matching_vector[match_count] = NULL;
       /* Return target names.  This is a little nasty.  Maybe we
          should do another bfd_malloc?  */
       while (--match_count >= 0)
         {
@@ skipping 68 matching lines @@
     case bfd_object:
       return "object";          /* Linker/assembler/compiler output.  */
     case bfd_archive:
       return "archive";         /* Object archive file.  */
     case bfd_core:
       return "core";            /* Core dump.  */
     default:
       return "unknown";
     }
 }