* dwarf2.c (struct dwarf2_debug): Add fields for handling

	alternate debug info source.
	(dwarf_debug_sections): Add entries for alternate .debug_str and
	.debug_info sections.
	(dwarf_debug_section_enum): Likewise.
	(read_alt_indirect_string): New function.  Handles a
	DW_FORM_GNU_strp_alt attribute.
	(read_alt_indirect_ref): New function.  Handles a
	DW_FORM_GNU_ref_alt attribute.
	(read_attribute_value): Process DW_FORM_GNU_ref_alt and
	DW_FORM_GNU_strp_alt.
	(find_abstract_instance_name): Handle DW_FORM_GNU_ref_alt
	attributes.
	(_bfd_dwarf2_cleanup_debug_info): Free alternate debug info
	sources.
	* opncls.c (GNU_DEBUGALTLINK): Define.
	(bfd_get_alt_debug_link_info): New function.
	(separate_alt_debug_file_exists): New function.
	(find_separate_debug_file): Add parameters for fetch and check
	functions.
	(bfd_follow_gnu_debugaltlink): New function.
	* bfd-in2.h: Regenerate.

4 files changed, 320 insertions, 46 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 5169996..d1ec430 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,28 @@
+2013-05-29  Nick Clifton  <nickc@redhat.com>
+
+	* dwarf2.c (struct dwarf2_debug): Add fields for handling
+	alternate debug info source.
+	(dwarf_debug_sections): Add entries for alternate .debug_str and
+	.debug_info sections.
+	(dwarf_debug_section_enum): Likewise.
+	(read_alt_indirect_string): New function.  Handles a
+	DW_FORM_GNU_strp_alt attribute.
+	(read_alt_indirect_ref): New function.  Handles a
+	DW_FORM_GNU_ref_alt attribute.
+	(read_attribute_value): Process DW_FORM_GNU_ref_alt and
+	DW_FORM_GNU_strp_alt.
+	(find_abstract_instance_name): Handle DW_FORM_GNU_ref_alt
+	attributes.
+	(_bfd_dwarf2_cleanup_debug_info): Free alternate debug info
+	sources.
+	* opncls.c (GNU_DEBUGALTLINK): Define.
+	(bfd_get_alt_debug_link_info): New function.
+	(separate_alt_debug_file_exists): New function.
+	(find_separate_debug_file): Add parameters for fetch and check
+	functions.
+	(bfd_follow_gnu_debugaltlink): New function.
+	* bfd-in2.h: Regenerate.
+
 2013-05-28  Yufeng Zhang  <yufeng.zhang@arm.com>
 
 	* reloc.c (BFD_RELOC_AARCH64_TLSDESC_ADR_PAGE): Rename to ...
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index a6299a5..efc1a55 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -1051,8 +1051,12 @@ unsigned long bfd_calc_gnu_debuglink_crc32
 
 char *bfd_get_debug_link_info (bfd *abfd, unsigned long *crc32_out);
 
+char *bfd_get_alt_debug_link_info (bfd *abfd, unsigned long *crc32_out);
+
 char *bfd_follow_gnu_debuglink (bfd *abfd, const char *dir);
 
+char *bfd_follow_gnu_debugaltlink (bfd *abfd, const char *dir);
+
 struct bfd_section *bfd_create_gnu_debuglink_section
    (bfd *abfd, const char *filename);
 
diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index 7a1a4ae..c9349da 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -1,6 +1,5 @@
 /* DWARF 2 support.
-   Copyright 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
-   2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+   Copyright 1994-2013 Free Software Foundation, Inc.
 
    Adapted from gdb/dwarf2read.c by Gavin Koch of Cygnus Solutions
    (gavin@cygnus.com).
@@ -108,6 +107,16 @@ struct dwarf2_debug
   asection *sec;
   bfd_byte *sec_info_ptr;
 
+  /* Support for alternate debug info sections created by the DWZ utility:
+     This includes a pointer to an alternate bfd which contains *extra*,
+     possibly duplicate debug sections, and pointers to the loaded
+     .debug_str and .debug_info sections from this bfd.  */
+  bfd *          alt_bfd_ptr;
+  bfd_byte *     alt_dwarf_str_buffer;
+  bfd_size_type  alt_dwarf_str_size;
+  bfd_byte *     alt_dwarf_info_buffer;
+  bfd_size_type  alt_dwarf_info_size;
+
   /* A pointer to the memory block allocated for info_ptr.  Neither
      info_ptr nor sec_info_ptr are guaranteed to stay pointing to the
      beginning of the malloc block.  This is used only to free the
@@ -290,6 +299,7 @@ const struct dwarf_debug_section dwarf_debug_sections[] =
   { ".debug_aranges",		".zdebug_aranges" },
   { ".debug_frame",		".zdebug_frame" },
   { ".debug_info",		".zdebug_info" },
+  { ".debug_info",		".zdebug_info" },
   { ".debug_line",		".zdebug_line" },
   { ".debug_loc",		".zdebug_loc" },
   { ".debug_macinfo",		".zdebug_macinfo" },
@@ -300,6 +310,7 @@ const struct dwarf_debug_section dwarf_debug_sections[] =
   { ".debug_static_func",	".zdebug_static_func" },
   { ".debug_static_vars",	".zdebug_static_vars" },
   { ".debug_str",		".zdebug_str", },
+  { ".debug_str",		".zdebug_str", },
   { ".debug_types",		".zdebug_types" },
   /* GNU DWARF 1 extensions */
   { ".debug_sfnames",		".zdebug_sfnames" },
@@ -312,12 +323,15 @@ const struct dwarf_debug_section dwarf_debug_sections[] =
   { NULL,			NULL },
 };
 
+/* NB/ Numbers in this enum must match up with indicies
+   into the dwarf_debug_sections[] array above.  */
 enum dwarf_debug_section_enum
 {
   debug_abbrev = 0,
   debug_aranges,
   debug_frame,
   debug_info,
+  debug_info_alt,
   debug_line,
   debug_loc,
   debug_macinfo,
@@ -328,6 +342,7 @@ enum dwarf_debug_section_enum
   debug_static_func,
   debug_static_vars,
   debug_str,
+  debug_str_alt,
   debug_types,
   debug_sfnames,
   debug_srcinfo,
@@ -484,8 +499,8 @@ read_section (bfd *           abfd,
   asection *msec;
   const char *section_name = sec->uncompressed_name;
 
-  /* read_section is a noop if the section has already been read.  */
-  if (!*section_buffer)
+  /* The section may have already been read.  */
+  if (*section_buffer == NULL)
     {
       msec = bfd_get_section_by_name (abfd, section_name);
       if (! msec)
@@ -626,6 +641,104 @@ read_indirect_string (struct comp_unit * unit,
   return str;
 }
 
+/* Like read_indirect_string but uses a .debug_str located in
+   an alternate filepointed to by the .gnu_debuglink section.
+   Used to impement DW_FORM_GNU_strp_alt.  */
+
+static char *
+read_alt_indirect_string (struct comp_unit * unit,
+			  bfd_byte *         buf,
+			  unsigned int *     bytes_read_ptr)
+{
+  bfd_uint64_t offset;
+  struct dwarf2_debug *stash = unit->stash;
+  char *str;
+
+  if (unit->offset_size == 4)
+    offset = read_4_bytes (unit->abfd, buf);
+  else
+    offset = read_8_bytes (unit->abfd, buf);
+
+  *bytes_read_ptr = unit->offset_size;
+
+  if (stash->alt_bfd_ptr == NULL)
+    {
+      bfd *  debug_bfd;
+      char * debug_filename = bfd_follow_gnu_debugaltlink (unit->abfd, DEBUGDIR);
+
+      if (debug_filename == NULL)
+	return NULL;
+
+      if ((debug_bfd = bfd_openr (debug_filename, NULL)) == NULL
+	  || ! bfd_check_format (debug_bfd, bfd_object))
+	{
+	  if (debug_bfd)
+	    bfd_close (debug_bfd);
+
+	  /* FIXME: Should we report our failure to follow the debuglink ?  */
+	  free (debug_filename);
+	  return NULL;
+	}
+      stash->alt_bfd_ptr = debug_bfd;
+    }
+  
+  if (! read_section (unit->stash->alt_bfd_ptr,
+		      stash->debug_sections + debug_str_alt,
+		      NULL, /* FIXME: Do we need to load alternate symbols ?  */
+		      offset,
+		      &stash->alt_dwarf_str_buffer,
+		      &stash->alt_dwarf_str_size))
+    return NULL;
+
+  str = (char *) stash->alt_dwarf_str_buffer + offset;
+  if (*str == '\0')
+    return NULL;
+
+  return str;
+}
+
+/* Resolve an alternate reference from UNIT at OFFSET.
+   Returns a pointer into the loaded alternate CU upon success
+   or NULL upon failure.  */
+
+static bfd_byte *
+read_alt_indirect_ref (struct comp_unit * unit,
+		       bfd_uint64_t       offset)
+{
+  struct dwarf2_debug *stash = unit->stash;
+
+  if (stash->alt_bfd_ptr == NULL)
+    {
+      bfd *  debug_bfd;
+      char * debug_filename = bfd_follow_gnu_debugaltlink (unit->abfd, DEBUGDIR);
+
+      if (debug_filename == NULL)
+	return FALSE;
+
+      if ((debug_bfd = bfd_openr (debug_filename, NULL)) == NULL
+	  || ! bfd_check_format (debug_bfd, bfd_object))
+	{
+	  if (debug_bfd)
+	    bfd_close (debug_bfd);
+
+	  /* FIXME: Should we report our failure to follow the debuglink ?  */
+	  free (debug_filename);
+	  return NULL;
+	}
+      stash->alt_bfd_ptr = debug_bfd;
+    }
+  
+  if (! read_section (unit->stash->alt_bfd_ptr,
+		      stash->debug_sections + debug_info_alt,
+		      NULL, /* FIXME: Do we need to load alternate symbols ?  */
+		      offset,
+		      &stash->alt_dwarf_info_buffer,
+		      &stash->alt_dwarf_info_size))
+    return NULL;
+
+  return stash->alt_dwarf_info_buffer + offset;
+}
+
 static bfd_uint64_t
 read_address (struct comp_unit *unit, bfd_byte *buf)
 {
@@ -829,6 +942,7 @@ read_attribute_value (struct attribute *attr,
       attr->u.val = read_address (unit, info_ptr);
       info_ptr += unit->addr_size;
       break;
+    case DW_FORM_GNU_ref_alt:
     case DW_FORM_sec_offset:
       if (unit->offset_size == 4)
 	attr->u.val = read_4_bytes (unit->abfd, info_ptr);
@@ -878,6 +992,10 @@ read_attribute_value (struct attribute *attr,
       attr->u.str = read_indirect_string (unit, info_ptr, &bytes_read);
       info_ptr += bytes_read;
       break;
+    case DW_FORM_GNU_strp_alt:
+      attr->u.str = read_alt_indirect_string (unit, info_ptr, &bytes_read);
+      info_ptr += bytes_read;
+      break;
     case DW_FORM_exprloc:
     case DW_FORM_block:
       amt = sizeof (struct dwarf_block);
@@ -950,7 +1068,7 @@ read_attribute_value (struct attribute *attr,
       info_ptr = read_attribute_value (attr, form, unit, info_ptr);
       break;
     default:
-      (*_bfd_error_handler) (_("Dwarf Error: Invalid or unhandled FORM value: %u."),
+      (*_bfd_error_handler) (_("Dwarf Error: Invalid or unhandled FORM value: %#x."),
 			     form);
       bfd_set_error (bfd_error_bad_value);
       return NULL;
@@ -1996,7 +2114,7 @@ find_abstract_instance_name (struct comp_unit *unit,
   struct abbrev_info *abbrev;
   bfd_uint64_t die_ref = attr_ptr->u.val;
   struct attribute attr;
-  char *name = 0;
+  char *name = NULL;
 
   /* DW_FORM_ref_addr can reference an entry in a different CU. It
      is an offset from the .debug_info section, not the current CU.  */
@@ -2009,8 +2127,20 @@ find_abstract_instance_name (struct comp_unit *unit,
 
       info_ptr = unit->sec_info_ptr + die_ref;
     }
+  else if (attr_ptr->form == DW_FORM_GNU_ref_alt)
+    {
+      info_ptr = read_alt_indirect_ref (unit, die_ref);
+      if (info_ptr == NULL)
+	{
+	  (*_bfd_error_handler)
+	    (_("Dwarf Error: Unable to read alt ref %u."), die_ref);
+	  bfd_set_error (bfd_error_bad_value);
+	  return name;
+	}
+    }
   else
     info_ptr = unit->info_ptr_unit + die_ref;
+
   abbrev_number = read_unsigned_leb128 (abfd, info_ptr, &bytes_read);
   info_ptr += bytes_read;
 
@@ -3694,4 +3824,10 @@ _bfd_dwarf2_cleanup_debug_info (bfd *abfd, void **pinfo)
     free (stash->info_ptr_memory);
   if (stash->close_on_cleanup)
     bfd_close (stash->bfd_ptr);
+  if (stash->alt_dwarf_str_buffer)
+    free (stash->alt_dwarf_str_buffer);
+  if (stash->alt_dwarf_info_buffer)
+    free (stash->alt_dwarf_info_buffer);
+  if (stash->alt_bfd_ptr)
+    bfd_close (stash->alt_bfd_ptr);
 }
diff --git a/bfd/opncls.c b/bfd/opncls.c
index 3879a65..cd9c826 100644
--- a/bfd/opncls.c
+++ b/bfd/opncls.c
@@ -1048,10 +1048,11 @@ bfd_release (bfd *abfd, void *block)
 
    This facilitates "optional" provision of debugging information, without
    having to provide two complete copies of every binary object (with and
-   without debug symbols).
-*/
+   without debug symbols).  */
+
+#define GNU_DEBUGLINK		".gnu_debuglink"
+#define GNU_DEBUGALTLINK	".gnu_debugaltlink"
 
-#define GNU_DEBUGLINK	".gnu_debuglink"
 /*
 FUNCTION
 	bfd_calc_gnu_debuglink_crc32
@@ -1189,6 +1190,54 @@ bfd_get_debug_link_info (bfd *abfd, unsigned long *crc32_out)
 }
 
 /*
+FUNCTION
+	bfd_get_alt_debug_link_info
+
+SYNOPSIS
+	char *bfd_get_alt_debug_link_info (bfd *abfd, unsigned long *crc32_out);
+
+DESCRIPTION
+	Fetch the filename and BuildID value for any alternate debuginfo
+	associated with @var{abfd}.  Return NULL if no such info found,
+	otherwise return filename and update @var{buildid_out}.  The
+	returned filename is allocated with @code{malloc}; freeing it
+	is the responsibility of the caller.
+*/
+
+char *
+bfd_get_alt_debug_link_info (bfd * abfd, unsigned long * buildid_out)
+{
+  asection *sect;
+  bfd_byte *contents;
+  int buildid_offset;
+  char *name;
+
+  BFD_ASSERT (abfd);
+  BFD_ASSERT (buildid_out);
+
+  sect = bfd_get_section_by_name (abfd, GNU_DEBUGALTLINK);
+
+  if (sect == NULL)
+    return NULL;
+
+  if (!bfd_malloc_and_get_section (abfd, sect, & contents))
+    {
+      if (contents != NULL)
+	free (contents);
+      return NULL;
+    }
+
+  /* BuildID value is stored after the filename, aligned up to 4 bytes.  */
+  name = (char *) contents;
+  buildid_offset = strlen (name) + 1;
+  buildid_offset = (buildid_offset + 3) & ~3;
+
+  * buildid_out = bfd_get_32 (abfd, contents + buildid_offset);
+
+  return name;
+}
+
+/*
 INTERNAL_FUNCTION
 	separate_debug_file_exists
 
@@ -1223,6 +1272,37 @@ separate_debug_file_exists (const char *name, const unsigned long crc)
   return crc == file_crc;
 }
 
+/*
+INTERNAL_FUNCTION
+	separate_alt_debug_file_exists
+
+SYNOPSIS
+	bfd_boolean separate_alt_debug_file_exists
+	  (char *name, unsigned long crc32);
+
+DESCRIPTION
+	Checks to see if @var{name} is a file and if its BuildID
+	matches @var{buildid}.
+*/
+
+static bfd_boolean
+separate_alt_debug_file_exists (const char *name,
+				const unsigned long buildid ATTRIBUTE_UNUSED)
+{
+  FILE *f;
+
+  BFD_ASSERT (name);
+
+  f = real_fopen (name, FOPEN_RB);
+  if (f == NULL)
+    return FALSE;
+
+  /* FIXME: Add code to check buildid.  */
+
+  fclose (f);
+
+  return TRUE;
+}
 
 /*
 INTERNAL_FUNCTION
@@ -1232,16 +1312,24 @@ SYNOPSIS
 	char *find_separate_debug_file (bfd *abfd);
 
 DESCRIPTION
-	Searches @var{abfd} for a reference to separate debugging
-	information, scans various locations in the filesystem, including
-	the file tree rooted at @var{debug_file_directory}, and returns a
-	filename of such debugging information if the file is found and has
-	matching CRC32.  Returns NULL if no reference to debugging file
-	exists, or file cannot be found.
+	Searches @var{abfd} for a section called @var{section_name} which
+	is expected to contain a reference to a file containing separate
+	debugging information.  The function scans various locations in
+	the filesystem, including the file tree rooted at
+	@var{debug_file_directory}, and returns the first matching
+	filename that it finds.  If @var{check_crc} is TRUE then the
+	contents of the file must also match the CRC value contained in
+	@var{section_name}.  Returns NULL if no valid file could be found.
 */
 
+typedef char *      (* get_func_type) (bfd *, unsigned long *);
+typedef bfd_boolean (* check_func_type) (const char *, const unsigned long);
+
 static char *
-find_separate_debug_file (bfd *abfd, const char *debug_file_directory)
+find_separate_debug_file (bfd *           abfd,
+			  const char *    debug_file_directory,
+			  get_func_type   get_func,
+			  check_func_type check_func)
 {
   char *base;
   char *dir;
@@ -1262,7 +1350,8 @@ find_separate_debug_file (bfd *abfd, const char *debug_file_directory)
       return NULL;
     }
 
-  base = bfd_get_debug_link_info (abfd, & crc32);
+  base = get_func (abfd, & crc32);
+    
   if (base == NULL)
     return NULL;
 
@@ -1301,37 +1390,22 @@ find_separate_debug_file (bfd *abfd, const char *debug_file_directory)
                   + strlen (base)
                   + 1);
   if (debugfile == NULL)
-    {
-      free (base);
-      free (dir);
-      free (canon_dir);
-      return NULL;
-    }
+    goto found; /* Actually this returns NULL.  */
 
   /* First try in the same directory as the original file:  */
   strcpy (debugfile, dir);
   strcat (debugfile, base);
 
-  if (separate_debug_file_exists (debugfile, crc32))
-    {
-      free (base);
-      free (dir);
-      free (canon_dir);
-      return debugfile;
-    }
+  if (check_func (debugfile, crc32))
+    goto found;
 
   /* Then try in a subdirectory called .debug.  */
   strcpy (debugfile, dir);
   strcat (debugfile, ".debug/");
   strcat (debugfile, base);
 
-  if (separate_debug_file_exists (debugfile, crc32))
-    {
-      free (base);
-      free (dir);
-      free (canon_dir);
-      return debugfile;
-    }
+  if (check_func (debugfile, crc32))
+    goto found;
 
   /* Then try in the global debugfile directory.  */
   strcpy (debugfile, debug_file_directory);
@@ -1343,19 +1417,18 @@ find_separate_debug_file (bfd *abfd, const char *debug_file_directory)
   strcat (debugfile, canon_dir);
   strcat (debugfile, base);
 
-  if (separate_debug_file_exists (debugfile, crc32))
-    {
-      free (base);
-      free (dir);
-      free (canon_dir);
-      return debugfile;
-    }
+  if (check_func (debugfile, crc32))
+    goto found;
 
+  /* Failed to find the file.  */
   free (debugfile);
+  debugfile = NULL;
+
+ found:
   free (base);
   free (dir);
   free (canon_dir);
-  return NULL;
+  return debugfile;
 }
 
 
@@ -1388,7 +1461,43 @@ RETURNS
 char *
 bfd_follow_gnu_debuglink (bfd *abfd, const char *dir)
 {
-  return find_separate_debug_file (abfd, dir);
+  return find_separate_debug_file (abfd, dir,
+				   bfd_get_debug_link_info,
+				   separate_debug_file_exists);
+}
+
+/*
+FUNCTION
+	bfd_follow_gnu_debugaltlink
+
+SYNOPSIS
+	char *bfd_follow_gnu_debugaltlink (bfd *abfd, const char *dir);
+
+DESCRIPTION
+
+	Takes a BFD and searches it for a .gnu_debugaltlink section.  If this
+	section is found, it examines the section for the name of a file
+	containing auxiliary debugging information.  It	then searches the
+	filesystem for this file in a set of standard locations, including
+	the directory tree rooted at @var{dir}, and if found returns the
+	full filename.
+
+	If @var{dir} is NULL, it will search a default path configured into
+	libbfd at build time.  [FIXME: This feature is not currently
+	implemented].
+
+RETURNS
+	<<NULL>> on any errors or failure to locate the debug file,
+	otherwise a pointer to a heap-allocated string containing the
+	filename.  The caller is responsible for freeing this string.
+*/
+
+char *
+bfd_follow_gnu_debugaltlink (bfd *abfd, const char *dir)
+{
+  return find_separate_debug_file (abfd, dir,
+				   bfd_get_alt_debug_link_info,
+				   separate_alt_debug_file_exists);
 }
 
 /*