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>

2 files changed, 44 insertions, 20 deletions

diff --git a/gdb/testsuite/lib/future.exp b/gdb/testsuite/lib/future.exp
index 2fb635b..a27e120 100644
--- a/gdb/testsuite/lib/future.exp
+++ b/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] {
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 41797e7..21a4638 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/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"]
-    set objcopy_program [gdb_find_objcopy]
-
-    set result [catch "exec $objcopy_program -j .note.gnu.build-id -O binary $filename $tmp" output]
-    verbose "result is $result"
-    verbose "output is $output"
-    if {$result == 1} {
-	return ""
+    if { ([istarget "*-*-mingw*"]
+	  || [istarget *-*-cygwin*]) } {
+	set objdump_program [gdb_find_objdump]
+	set result [catch {set data [exec $objdump_program -p $filename | grep signature | cut "-d " -f4]} output]
+	verbose "result is $result"
+	verbose "output is $output"
+	if {$result == 1} {
+	    return ""
+	}
+	return $data
     }
-    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 $data ""] then {
-	return ""
+    else
+    {
+	set tmp [standard_output_file "${filename}-tmp"]
+	set objcopy_program [gdb_find_objcopy]
+	set result [catch "exec $objcopy_program -j .note.gnu.build-id -O binary $filename $tmp" output]
+	verbose "result is $result"
+	verbose "output is $output"
+	if {$result == 1} {
+	    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)