Allow gdb to find debug symbols file by build-id for PE file format also

This promotes BFD's struct elf_build_id to the generic struct bfd_build_id,
populated when an ELF or PE BFD is read.

gdb is updated to use that, and to use the build-id to find symbols for PE files
also.

There is currently no generic way to extract the build-id from an object file,
perhaps an option to objdump to do this might make sense?

On x86_64-pc-cygwin, gdb's sepdebug.exp changes:

-# of unsupported tests          1
+# of expected passes            90

I don't seem to get consistent testsuite runs on i686-linux-gnu, but there
don't appear to be any regressions.

bfd/ChangeLog:

2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>

	* elf-bfd.h : Remove struct elf_build_id.
	* bfd.c : Add struct bfd_build_id.
	* bfd-in2.h: Regenerate.
	* elf.c (elfobj_grok_gnu_build_id): Update to use bfd_build_id.
	* libpei.h: Add protoype and macros for
	bfd_XXi_slurp_codeview_record.
	* peXXigen.c (_bfd_XXi_slurp_codeview_record): Make public
	* peicode.h (pe_bfd_read_buildid): Add.
	(pe_bfd_object_p): Use pe_bfd_read_buildid().

gdb/ChangeLog:

2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>

	* build-id.c: Don't include elf-bfd.h.
	(build_id_bfd_get): Use bfd_build_id.
	(build_id_verify): Ditto.
	* build-id.h: Ditto.
	(find_separate_debug_file_by_buildid): Ditto.
	* python/py-objfile.c: Don't include elf-bfd.h.
	(objfpy_get_build_id) Use bfd_build_id.
	(objfpy_build_id_matches, objfpy_lookup_objfile_by_build_id): Ditto.
	* coffread.c: Include build-id.h.
	(coff_symfile_read): Try find_separate_debug_file_by_buildid.

gdb/doc/ChangeLog:

2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>

	* gdb.texinfo (Separate Debug Files): Document that PE is also
	supported.

gdb/testsuite/ChangeLog:

2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>

	* gdb.base/sepdebug.exp: Add EXEEXT where needed.
	* lib/gdb.exp (get_build_id): Teach how to extract build-id from a
	PE file.
	* lib/future.exp (gdb_find_objdump): Add gdb_find_objdump.

Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>

bfd/ChangeLog

@@ -1,3 +1,15 @@
+2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>
+
+	* elf-bfd.h : Remove struct elf_build_id.
+	* bfd.c : Add struct bfd_build_id.
+	* bfd-in2.h: Regenerate.
+	* elf.c (elfobj_grok_gnu_build_id): Update to use bfd_build_id.
+	* libpei.h: Add protoype and macros for
+	bfd_XXi_slurp_codeview_record.
+	* peXXigen.c (_bfd_XXi_slurp_codeview_record): Make public
+	* peicode.h (pe_bfd_read_buildid): Add.
+	(pe_bfd_object_p): Use pe_bfd_read_buildid().
+
 2015-06-15  Renlin Li  <renlin.li@arm.com>
 
 	* reloc.c (BFD_RELOC_AARCH64_LD64_GOTOFF_LO15): New entry.

bfd/bfd-in2.h

@@ -6326,6 +6326,12 @@ enum bfd_plugin_format
     bfd_plugin_no = 2
   };
 
+struct bfd_build_id
+  {
+    size_t size;
+    bfd_byte data[1];
+  };
+
 struct bfd
 {
   /* The filename the application opened the BFD with.  */
@@ -6610,6 +6616,9 @@ struct bfd
      struct objalloc *, but we use void * to avoid requiring the inclusion
      of objalloc.h.  */
   void *memory;
+
+  /* For input BFDs, the build ID, if the object has one. */
+  const struct bfd_build_id *build_id;
 };
 
 /* See note beside bfd_set_section_userdata.  */

bfd/bfd.c

@@ -51,6 +51,12 @@ CODE_FRAGMENT
 .    bfd_plugin_no = 2
 .  };
 .
+.struct bfd_build_id
+.  {
+.    size_t size;
+.    bfd_byte data[1];
+.  };
+.
 .struct bfd
 .{
 .  {* The filename the application opened the BFD with.  *}
@@ -335,6 +341,9 @@ CODE_FRAGMENT
 .     struct objalloc *, but we use void * to avoid requiring the inclusion
 .     of objalloc.h.  *}
 .  void *memory;
+.
+.  {* For input BFDs, the build ID, if the object has one. *}
+.  const struct bfd_build_id *build_id;
 .};
 .
 .{* See note beside bfd_set_section_userdata.  *}

bfd/elf-bfd.h

@@ -1563,13 +1563,6 @@ struct sdt_note
   bfd_byte data[1];
 };
 
-/* NT_GNU_BUILD_ID note type info for input BFDs.  */
-struct elf_build_id
-{
-  size_t size;
-  bfd_byte data[1];
-};
-
 /* tdata information grabbed from an elf core file.  */
 struct core_elf_obj_tdata
 {
@@ -1704,9 +1697,6 @@ struct elf_obj_tdata
   obj_attribute known_obj_attributes[2][NUM_KNOWN_OBJ_ATTRIBUTES];
   obj_attribute_list *other_obj_attributes[2];
 
-  /* NT_GNU_BUILD_ID note type.  */
-  struct elf_build_id *build_id;
-
   /* Linked-list containing information about every Systemtap section
      found in the object file.  Each section corresponds to one entry
      in the list.  */

bfd/elf.c

@@ -9116,18 +9116,18 @@ elfcore_grok_note (bfd *abfd, Elf_Internal_Note *note)
 static bfd_boolean
 elfobj_grok_gnu_build_id (bfd *abfd, Elf_Internal_Note *note)
 {
-  struct elf_obj_tdata *t;
+  struct bfd_build_id* build_id;
 
   if (note->descsz == 0)
     return FALSE;
 
-  t = elf_tdata (abfd);
+  build_id = bfd_alloc (abfd, sizeof (struct bfd_build_id) - 1 + note->descsz);
-  t->build_id = bfd_alloc (abfd, sizeof (*t->build_id) - 1 + note->descsz);
+  if (build_id == NULL)
-  if (t->build_id == NULL)
     return FALSE;
 
-  t->build_id->size = note->descsz;
+  build_id->size = note->descsz;
-  memcpy (t->build_id->data, note->descdata, note->descsz);
+  memcpy (build_id->data, note->descdata, note->descsz);
+  abfd->build_id = build_id;
 
   return TRUE;
 }

bfd/libpei.h

@@ -238,6 +238,7 @@
 #define _bfd_XXi_swap_debugdir_in			_bfd_pex64i_swap_debugdir_in
 #define _bfd_XXi_swap_debugdir_out			_bfd_pex64i_swap_debugdir_out
 #define _bfd_XXi_write_codeview_record			_bfd_pex64i_write_codeview_record
+#define _bfd_XXi_slurp_codeview_record			_bfd_pex64i_slurp_codeview_record
 
 #elif defined COFF_WITH_pep
 
@@ -272,6 +273,7 @@
 #define _bfd_XXi_swap_debugdir_in			_bfd_pepi_swap_debugdir_in
 #define _bfd_XXi_swap_debugdir_out			_bfd_pepi_swap_debugdir_out
 #define _bfd_XXi_write_codeview_record			_bfd_pepi_write_codeview_record
+#define _bfd_XXi_slurp_codeview_record			_bfd_pepi_slurp_codeview_record
 
 #else /* !COFF_WITH_pep */
 
@@ -306,6 +308,7 @@
 #define _bfd_XXi_swap_debugdir_in			_bfd_pei_swap_debugdir_in
 #define _bfd_XXi_swap_debugdir_out			_bfd_pei_swap_debugdir_out
 #define _bfd_XXi_write_codeview_record			_bfd_pei_write_codeview_record
+#define _bfd_XXi_slurp_codeview_record			_bfd_pei_slurp_codeview_record
 
 #endif /* !COFF_WITH_pep */
 
@@ -351,6 +354,7 @@ bfd_boolean _bfd_XXi_final_link_postscript (bfd *, struct coff_final_link_info *
 void        _bfd_XXi_swap_debugdir_in (bfd *, void *, void *);
 unsigned    _bfd_XXi_swap_debugdir_out (bfd *, void *, void *);
 unsigned    _bfd_XXi_write_codeview_record (bfd *, file_ptr, CODEVIEW_INFO *);
+CODEVIEW_INFO * _bfd_XXi_slurp_codeview_record (bfd * abfd, file_ptr where, unsigned long length, CODEVIEW_INFO *cvinfo);
 
 /* The following are needed only for ONE of pe or pei, but don't
    otherwise vary; peicode.h fixes up ifdefs but we provide the

bfd/peXXigen.c

@@ -1140,7 +1140,7 @@ _bfd_XXi_swap_debugdir_out (bfd * abfd, void * inp, void * extp)
   return sizeof (struct external_IMAGE_DEBUG_DIRECTORY);
 }
 
-static CODEVIEW_INFO *
+CODEVIEW_INFO *
 _bfd_XXi_slurp_codeview_record (bfd * abfd, file_ptr where, unsigned long length, CODEVIEW_INFO *cvinfo)
 {
   char buffer[256+1];

bfd/peicode.h

@@ -1255,6 +1255,87 @@ pe_ILF_object_p (bfd * abfd)
   return abfd->xvec;
 }
 
+static void
+pe_bfd_read_buildid(bfd *abfd)
+{
+  pe_data_type *pe = pe_data (abfd);
+  struct internal_extra_pe_aouthdr *extra = &pe->pe_opthdr;
+  asection *section;
+  bfd_byte *data = 0;
+  bfd_size_type dataoff;
+  unsigned int i;
+
+  bfd_vma addr = extra->DataDirectory[PE_DEBUG_DATA].VirtualAddress;
+  bfd_size_type size = extra->DataDirectory[PE_DEBUG_DATA].Size;
+
+  if (size == 0)
+    return;
+
+  addr += extra->ImageBase;
+
+  /* Search for the section containing the DebugDirectory */
+  for (section = abfd->sections; section != NULL; section = section->next)
+    {
+      if ((addr >= section->vma) && (addr < (section->vma + section->size)))
+        break;
+    }
+
+  if (section == NULL)
+    {
+      return;
+    }
+  else if (!(section->flags & SEC_HAS_CONTENTS))
+    {
+      return;
+    }
+
+  dataoff = addr - section->vma;
+
+  /* Read the whole section. */
+  if (!bfd_malloc_and_get_section (abfd, section, &data))
+    {
+      if (data != NULL)
+	free (data);
+      return;
+    }
+
+  /* Search for a CodeView entry in the DebugDirectory */
+  for (i = 0; i < size / sizeof (struct external_IMAGE_DEBUG_DIRECTORY); i++)
+    {
+      struct external_IMAGE_DEBUG_DIRECTORY *ext
+	= &((struct external_IMAGE_DEBUG_DIRECTORY *)(data + dataoff))[i];
+      struct internal_IMAGE_DEBUG_DIRECTORY idd;
+
+      _bfd_XXi_swap_debugdir_in (abfd, ext, &idd);
+
+      if (idd.Type == PE_IMAGE_DEBUG_TYPE_CODEVIEW)
+        {
+          char buffer[256 + 1];
+          CODEVIEW_INFO *cvinfo = (CODEVIEW_INFO *) buffer;
+
+          /*
+            The debug entry doesn't have to have to be in a section, in which
+            case AddressOfRawData is 0, so always use PointerToRawData.
+          */
+          if (_bfd_XXi_slurp_codeview_record (abfd,
+                                              (file_ptr) idd.PointerToRawData,
+                                              idd.SizeOfData, cvinfo))
+            {
+              struct bfd_build_id* build_id = bfd_alloc(abfd,
+                         sizeof(struct bfd_build_id) + cvinfo->SignatureLength);
+              if (build_id)
+                {
+                  build_id->size = cvinfo->SignatureLength;
+                  memcpy(build_id->data,  cvinfo->Signature,
+                         cvinfo->SignatureLength);
+                  abfd->build_id = build_id;
+                }
+            }
+          break;
+        }
+    }
+}
+
 static const bfd_target *
 pe_bfd_object_p (bfd * abfd)
 {
@@ -1265,6 +1346,7 @@ pe_bfd_object_p (bfd * abfd)
   struct internal_aouthdr internal_a;
   file_ptr opt_hdr_size;
   file_ptr offset;
+  const bfd_target *result;
 
   /* Detect if this a Microsoft Import Library Format element.  */
   /* First read the beginning of the header.  */
@@ -1358,10 +1440,20 @@ pe_bfd_object_p (bfd * abfd)
 	return NULL;
     }
 
-  return coff_real_object_p (abfd, internal_f.f_nscns, &internal_f,
+
-                            (opt_hdr_size != 0
+  result = coff_real_object_p (abfd, internal_f.f_nscns, &internal_f,
-                             ? &internal_a
+                               (opt_hdr_size != 0
-                             : (struct internal_aouthdr *) NULL));
+                                ? &internal_a
+                                : (struct internal_aouthdr *) NULL));
+
+
+  if (result)
+    {
+      /* Now the whole header has been processed, see if there is a build-id */
+      pe_bfd_read_buildid(abfd);
+    }
+
+  return result;
 }
 
 #define coff_object_p pe_bfd_object_p

gdb/ChangeLog

@@ -1,3 +1,16 @@
+2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>
+
+	* build-id.c: Don't include elf-bfd.h.
+	(build_id_bfd_get): Use bfd_build_id.
+	(build_id_verify): Ditto.
+	* build-id.h: Ditto.
+	(find_separate_debug_file_by_buildid): Ditto.
+	* python/py-objfile.c: Don't include elf-bfd.h.
+	(objfpy_get_build_id) Use bfd_build_id.
+	(objfpy_build_id_matches, objfpy_lookup_objfile_by_build_id): Ditto.
+	* coffread.c: Include build-id.h.
+	(coff_symfile_read): Try find_separate_debug_file_by_buildid.
+
 2015-06-03  Jon Turney  <jon.turney@dronecode.org.uk>
 
 	* windows-nat.c (do_windows_fetch_inferior_registers)

gdb/build-id.c

@@ -19,7 +19,6 @@
 
 #include "defs.h"
 #include "bfd.h"
-#include "elf-bfd.h"
 #include "gdb_bfd.h"
 #include "build-id.h"
 #include "gdb_vecs.h"
@@ -30,19 +29,17 @@
 
 /* See build-id.h.  */
 
-const struct elf_build_id *
+const struct bfd_build_id *
 build_id_bfd_get (bfd *abfd)
 {
-  if (!bfd_check_format (abfd, bfd_object)
+  if (!bfd_check_format (abfd, bfd_object))
-      || bfd_get_flavour (abfd) != bfd_target_elf_flavour
-      /* Although this is ELF_specific, it is safe to do in generic
-	 code because it does not rely on any ELF-specific symbols at
-	 link time, and if the ELF code is not available in BFD, then
-	 ABFD will not have the ELF flavour.  */
-      || elf_tdata (abfd)->build_id == NULL)
     return NULL;
 
-  return elf_tdata (abfd)->build_id;
+  if (abfd->build_id != NULL)
+    return abfd->build_id;
+
+  /* No build-id */
+  return NULL;
 }
 
 /* See build-id.h.  */
@@ -50,7 +47,7 @@ build_id_bfd_get (bfd *abfd)
 int
 build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
 {
-  const struct elf_build_id *found;
+  const struct bfd_build_id *found;
   int retval = 0;
 
   found = build_id_bfd_get (abfd);
@@ -139,7 +136,7 @@ build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
 char *
 find_separate_debug_file_by_buildid (struct objfile *objfile)
 {
-  const struct elf_build_id *build_id;
+  const struct bfd_build_id *build_id;
 
   build_id = build_id_bfd_get (objfile->obfd);
   if (build_id != NULL)

gdb/build-id.h

@@ -22,7 +22,7 @@
 
 /* Locate NT_GNU_BUILD_ID from ABFD and return its content.  */
 
-extern const struct elf_build_id *build_id_bfd_get (bfd *abfd);
+extern const struct bfd_build_id *build_id_bfd_get (bfd *abfd);
 
 /* Return true if ABFD has NT_GNU_BUILD_ID matching the CHECK value.
    Otherwise, issue a warning and return false.  */

gdb/coffread.c

@@ -41,6 +41,7 @@
 #include "coff-pe-read.h"
 
 #include "psymtab.h"
+#include "build-id.h"
 
 extern void _initialize_coffread (void);
 
@@ -738,7 +739,10 @@ coff_symfile_read (struct objfile *objfile, int symfile_flags)
     {
       char *debugfile;
 
-      debugfile = find_separate_debug_file_by_debuglink (objfile);
+      debugfile = find_separate_debug_file_by_buildid (objfile);
+
+      if (debugfile == NULL)
+	debugfile = find_separate_debug_file_by_debuglink (objfile);
       make_cleanup (xfree, debugfile);
 
       if (debugfile)

gdb/doc/ChangeLog

@@ -1,3 +1,8 @@
+2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>
+
+	* gdb.texinfo (Separate Debug Files): Document that PE is also
+	supported.
+
 2015-06-13  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* gdb.texinfo (TUI Commands): Bring all 'tui reg' commands into a

gdb/doc/gdb.texinfo

@@ -18170,7 +18170,7 @@ the executable and the debug file came from the same build.
 @item
 The executable contains a @dfn{build ID}, a unique bit string that is
 also present in the corresponding debug info file.  (This is supported
-only on some operating systems, notably those which use the ELF format
+only on some operating systems, when using the ELF or PE file formats
 for binary files and the @sc{gnu} Binutils.)  For more details about
 this feature, see the description of the @option{--build-id}
 command-line option in @ref{Options, , Command Line Options, ld.info,

gdb/python/py-objfile.c

@@ -23,7 +23,6 @@
 #include "objfiles.h"
 #include "language.h"
 #include "build-id.h"
-#include "elf-bfd.h"
 #include "symtab.h"
 
 typedef struct
@@ -134,7 +133,7 @@ objfpy_get_build_id (PyObject *self, void *closure)
 {
   objfile_object *obj = (objfile_object *) self;
   struct objfile *objfile = obj->objfile;
-  const struct elf_build_id *build_id = NULL;
+  const struct bfd_build_id *build_id = NULL;
 
   OBJFPY_REQUIRE_VALID (obj);
 
@@ -484,7 +483,7 @@ objfpy_build_id_ok (const char *string)
    It is assumed that objfpy_build_id_ok (string) returns TRUE.  */
 
 static int
-objfpy_build_id_matches (const struct elf_build_id *build_id,
+objfpy_build_id_matches (const struct bfd_build_id *build_id,
 			 const char *string)
 {
   size_t i;
@@ -542,7 +541,7 @@ objfpy_lookup_objfile_by_build_id (const char *build_id)
 
   ALL_OBJFILES (objfile)
     {
-      const struct elf_build_id *obfd_build_id;
+      const struct bfd_build_id *obfd_build_id;
 
       if (objfile->obfd == NULL)
 	continue;

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2015-06-10  Jon Turney  <jon.turney@dronecode.org.uk>
+
+	* gdb.base/sepdebug.exp: Add EXEEXT where needed.
+	* lib/gdb.exp (get_build_id): Teach how to extract build-id from a
+	PE file.
+	* lib/future.exp (gdb_find_objdump): Add gdb_find_objdump.
+
 2015-06-12  Antoine Tremblay  <antoine.tremblay@ericsson.com>
 
 	PR breakpoints/16465

gdb/testsuite/gdb.base/sepdebug.exp

@@ -42,7 +42,7 @@ if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {deb
 # the name of a debuginfo only file. This file will be stored in the
 # gdb.base/ subdirectory.
 
-if [gdb_gnu_strip_debug $binfile] {
+if [gdb_gnu_strip_debug $binfile$EXEEXT] {
     # check that you have a recent version of strip and objcopy installed
     unsupported "cannot produce separate debug info files"
     return -1
@@ -60,7 +60,7 @@ set new_name [standard_output_file ${testfile}${EXEEXT}]
 remote_exec build "rm -rf [file dirname $new_name]"
 
 remote_exec build "mkdir [file dirname $new_name]"
-remote_exec build "ln -s ${binfile} $new_name"
+remote_exec build "ln -s ${binfile}${EXEEXT} $new_name"
 clean_restart ${testfile}${EXEEXT}
 if { $gdb_file_cmd_debug_info != "debug" } then {
     fail "No debug information found."
@@ -716,10 +716,10 @@ proc test_different_dir {type test_different_dir xfail} {
 # the "set debug-file-directory" command.
 
 set different_dir [standard_output_file ${testfile}.dir]
-set debugfile "${different_dir}/[standard_output_file ${testfile}.debug]"
+set debugfile "${different_dir}/[standard_output_file ${testfile}${EXEEXT}.debug]"
 remote_exec build "rm -rf $different_dir"
 remote_exec build "mkdir -p [file dirname $debugfile]"
-remote_exec build "mv -f [standard_output_file ${testfile}.debug] $debugfile"
+remote_exec build "mv -f [standard_output_file ${testfile}${EXEEXT}.debug] $debugfile"
 
 test_different_dir debuglink $different_dir 0
 
@@ -727,7 +727,7 @@ test_different_dir debuglink $different_dir 0
 # Test CRC mismatch is reported.
 
 if {[build_executable sepdebug.exp sepdebug2 sepdebug2.c debug] != -1
-    && ![gdb_gnu_strip_debug [standard_output_file sepdebug2]]} {
+    && ![gdb_gnu_strip_debug [standard_output_file sepdebug2]$EXEEXT]} {
 
     remote_exec build "cp ${debugfile} [standard_output_file sepdebug2.debug]"
 
@@ -743,7 +743,7 @@ if {[build_executable sepdebug.exp sepdebug2 sepdebug2.c debug] != -1
 
 # NT_GNU_BUILD_ID / .note.gnu.build-id test:
 
-set build_id_debug_filename [build_id_debug_filename_get $binfile]
+set build_id_debug_filename [build_id_debug_filename_get $binfile$EXEEXT]
 if ![string compare $build_id_debug_filename ""] then {
     unsupported "build-id is not supported by the compiler"
 

gdb/testsuite/lib/future.exp

@@ -104,6 +104,17 @@ proc gdb_find_objcopy {} {
     return $objcopy
 }
 
+# find target objdump
+proc gdb_find_objdump {} {
+    global OBJDUMP_FOR_TARGET
+    if [info exists OBJDUMP_FOR_TARGET] {
+	set objdump $OBJDUMP_FOR_TARGET
+    } else {
+	set objdump [transform objdump]
+    }
+    return $objdump
+}
+
 proc gdb_find_readelf {} {
     global READELF_FOR_TARGET
     if [info exists READELF_FOR_TARGET] {

gdb/testsuite/lib/gdb.exp

@@ -4539,28 +4539,41 @@ gdb_caching_proc gdb_has_argv0 {
 # Returns "" if there is none.
 
 proc get_build_id { filename } {
-    set tmp [standard_output_file "${filename}-tmp"]
+    if { ([istarget "*-*-mingw*"]
-    set objcopy_program [gdb_find_objcopy]
+	  || [istarget *-*-cygwin*]) } {
-
+	set objdump_program [gdb_find_objdump]
-    set result [catch "exec $objcopy_program -j .note.gnu.build-id -O binary $filename $tmp" output]
+	set result [catch {set data [exec $objdump_program -p $filename | grep signature | cut "-d " -f4]} output]
-    verbose "result is $result"
+	verbose "result is $result"
-    verbose "output is $output"
+	verbose "output is $output"
-    if {$result == 1} {
+	if {$result == 1} {
-	return ""
+	    return ""
+	}
+	return $data
     }
-    set fi [open $tmp]
+    else
-    fconfigure $fi -translation binary
+    {
-    # Skip the NOTE header.
+	set tmp [standard_output_file "${filename}-tmp"]
-    read $fi 16
+	set objcopy_program [gdb_find_objcopy]
-    set data [read $fi]
+	set result [catch "exec $objcopy_program -j .note.gnu.build-id -O binary $filename $tmp" output]
-    close $fi
+	verbose "result is $result"
-    file delete $tmp
+	verbose "output is $output"
-    if ![string compare $data ""] then {
+	if {$result == 1} {
-	return ""
+	    return ""
+	}
+	set fi [open $tmp]
+	fconfigure $fi -translation binary
+	# Skip the NOTE header.
+	read $fi 16
+	set data [read $fi]
+	close $fi
+	file delete $tmp
+	if ![string compare $data ""] then {
+	    return ""
+	}
+	# Convert it to hex.
+	binary scan $data H* data
+	return $data
     }
-    # Convert it to hex.
-    binary scan $data H* data
-    return $data
 }
 
 # Return the build-id hex string (usually 160 bits as 40 hex characters)