Add support for debuginfod to the binutils (disable by default, enabled via a configure time option).

debuginfod is a lightweight web service that indexes ELF/DWARF
debugging resources by build-id and serves them over HTTP. This patch
enables objdump and readelf to query debuginfod servers when they are
otherwise not able to find separate debug files. Binutils can be built
with debuginfod using the --with-debuginfod configure option. This
requires that libdebuginfod be installed and found at configure time.
debuginfod is packaged with elfutils, starting with version 0.178. For
more information see https://sourceware.org/elfutils/.

toplevel* config/debuginfod.m4: New file. Add macro AC_DEBUGINFOD. Adds
        new configure option --with-debuginfod.
        * configure: Regenerate.
        * configure.ac: Call AC_DEBUGINFOD.

binutils* Makefile.am (readelf_LDADD, objdump_LDADD): Add libdebuginfod.
        * Makefile.in: Regenerate.
        * NEWS: Update.
        * config.in: Regenerate.
        * configure: Regenerate.
        * configure.ac: Call AC_DEBUGINFOD.
        * doc/Makefile.in: Regenerate.
        * doc/binutils.texi: Add section on using binutils
        with debuginfod.
        * dwarf.c (debuginfod_fetch_separate_debug_info): New function.
        Query debuginfod servers for the target debug file.
        (load_separate_debug_info): Call
        debuginfod_fetch_separate_debug_info if configured with
        debuginfod.
        (load_separate_debug_files): Add file argument to
        load_separate_debug_info calls.
        * dwarf.h (get_build_id): Add declaration.
        * objdump.c (get_build_id): New function. Get build-id of file.
        * readelf.c (get_build_id): Likewise.
        * testsuite/binutils-all/debuginfod.exp: New tests.
        * testsuite/binutils-all/linkdebug.s: Add .note.gnu.build-id
        section.

13 files changed, 468 insertions, 59 deletions

diff --git a/binutils/Makefile.am b/binutils/Makefile.am
index cc23012..f1f3907 100644
--- a/binutils/Makefile.am
+++ b/binutils/Makefile.am
@@ -53,6 +53,8 @@ AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
 AM_CFLAGS_FOR_BUILD = $(WARN_CFLAGS_FOR_BUILD) $(ZLIBINC)
 LIBICONV = @LIBICONV@
 
+LIBDEBUGINFOD = @LIBDEBUGINFOD@
+
 # these two are almost the same program
 AR_PROG=ar
 RANLIB_PROG=ranlib
@@ -245,7 +247,7 @@ objcopy_SOURCES = objcopy.c not-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
 strings_SOURCES = strings.c $(BULIBS)
 
 readelf_SOURCES = readelf.c version.c unwind-ia64.c dwarf.c $(ELFLIBS)
-readelf_LDADD   = $(LIBINTL) $(LIBCTF_NOBFD) $(LIBIBERTY) $(ZLIB)
+readelf_LDADD   = $(LIBINTL) $(LIBCTF_NOBFD) $(LIBIBERTY) $(ZLIB) $(LIBDEBUGINFOD)
 
 elfedit_SOURCES = elfedit.c version.c $(ELFLIBS)
 elfedit_LDADD = $(LIBINTL) $(LIBIBERTY)
@@ -256,7 +258,7 @@ nm_new_SOURCES = nm.c $(BULIBS)
 
 objdump_SOURCES = objdump.c dwarf.c prdbg.c $(DEBUG_SRCS) $(BULIBS) $(ELFLIBS)
 EXTRA_objdump_SOURCES = od-xcoff.c
-objdump_LDADD = $(OBJDUMP_PRIVATE_OFILES) $(OPCODES) $(LIBCTF) $(BFDLIB) $(LIBIBERTY) $(LIBINTL)
+objdump_LDADD = $(OBJDUMP_PRIVATE_OFILES) $(OPCODES) $(LIBCTF) $(BFDLIB) $(LIBIBERTY) $(LIBINTL) $(LIBDEBUGINFOD)
 
 objdump.@OBJEXT@:objdump.c
 if am__fastdepCC
diff --git a/binutils/Makefile.in b/binutils/Makefile.in
index 91dfe25..39f0856 100644
--- a/binutils/Makefile.in
+++ b/binutils/Makefile.in
@@ -138,7 +138,9 @@ am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
 	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
 	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
 	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
-	$(top_srcdir)/../bfd/version.m4 $(top_srcdir)/configure.ac
+	$(top_srcdir)/../bfd/version.m4 \
+	$(top_srcdir)/../config/debuginfod.m4 \
+	$(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
 DIST_COMMON = $(srcdir)/Makefile.am $(top_srcdir)/configure \
@@ -449,6 +451,7 @@ LDFLAGS = @LDFLAGS@
 LEX = `if [ -f ../flex/flex ]; then echo ../flex/flex; else echo @LEX@; fi`
 LEXLIB = @LEXLIB@
 LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@
+LIBDEBUGINFOD = @LIBDEBUGINFOD@
 LIBICONV = @LIBICONV@
 LIBINTL = @LIBINTL@
 LIBINTL_DEP = @LIBINTL_DEP@
@@ -706,14 +709,14 @@ size_SOURCES = size.c $(BULIBS)
 objcopy_SOURCES = objcopy.c not-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
 strings_SOURCES = strings.c $(BULIBS)
 readelf_SOURCES = readelf.c version.c unwind-ia64.c dwarf.c $(ELFLIBS)
-readelf_LDADD = $(LIBINTL) $(LIBCTF_NOBFD) $(LIBIBERTY) $(ZLIB)
+readelf_LDADD = $(LIBINTL) $(LIBCTF_NOBFD) $(LIBIBERTY) $(ZLIB) $(LIBDEBUGINFOD)
 elfedit_SOURCES = elfedit.c version.c $(ELFLIBS)
 elfedit_LDADD = $(LIBINTL) $(LIBIBERTY)
 strip_new_SOURCES = objcopy.c is-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
 nm_new_SOURCES = nm.c $(BULIBS)
 objdump_SOURCES = objdump.c dwarf.c prdbg.c $(DEBUG_SRCS) $(BULIBS) $(ELFLIBS)
 EXTRA_objdump_SOURCES = od-xcoff.c
-objdump_LDADD = $(OBJDUMP_PRIVATE_OFILES) $(OPCODES) $(LIBCTF) $(BFDLIB) $(LIBIBERTY) $(LIBINTL)
+objdump_LDADD = $(OBJDUMP_PRIVATE_OFILES) $(OPCODES) $(LIBCTF) $(BFDLIB) $(LIBIBERTY) $(LIBINTL) $(LIBDEBUGINFOD)
 cxxfilt_SOURCES = cxxfilt.c $(BULIBS)
 ar_SOURCES = arparse.y arlex.l ar.c not-ranlib.c arsup.c rename.c binemul.c \
 	emul_$(EMULATION).c $(BULIBS)
diff --git a/binutils/NEWS b/binutils/NEWS
index e5e0056..72a9644 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -1,5 +1,14 @@
 -*- text -*-
 
+* Binutils now supports debuginfod, an HTTP server for distributing
+  ELF/DWARF debugging information as well as source code. When built with
+  debuginfod, readelf and objdump can automatically query debuginfod
+  servers for separate debug files when they otherwise cannot be found.
+  To build binutils with debuginfod, pass --with-debuginfod to configure.
+  This requires libdebuginfod, the debuginfod client library. debuginfod
+  is distributed with elfutils, starting with version 0.178. For more
+  information see https://sourceware.org/elfutils.
+
 * Add --output option to the "ar" program.  This option can be used to specify
   the output directory when extracting members from an archive.
 
diff --git a/binutils/config.in b/binutils/config.in
index 72ead4e..703f7b1 100644
--- a/binutils/config.in
+++ b/binutils/config.in
@@ -109,6 +109,9 @@
 /* Define if your <locale.h> file defines LC_MESSAGES. */
 #undef HAVE_LC_MESSAGES
 
+/* Define to 1 if debuginfod is enabled. */
+#undef HAVE_LIBDEBUGINFOD
+
 /* Define to 1 if you have the <limits.h> header file. */
 #undef HAVE_LIMITS_H
 
diff --git a/binutils/configure b/binutils/configure
index 50f8d5b..aa91e1b 100755
--- a/binutils/configure
+++ b/binutils/configure
@@ -684,6 +684,7 @@ WARN_WRITE_STRINGS
 NO_WERROR
 WARN_CFLAGS_FOR_BUILD
 WARN_CFLAGS
+LIBDEBUGINFOD
 OTOOL64
 OTOOL
 LIPO
@@ -813,6 +814,7 @@ enable_largefile
 enable_targets
 enable_deterministic_archives
 enable_default_strings_all
+with_debuginfod
 enable_werror
 enable_build_warnings
 enable_nls
@@ -1483,6 +1485,8 @@ Optional Packages:
   --with-pic              try to use only PIC/non-PIC objects [default=use
                           both]
   --with-gnu-ld           assume the C compiler uses GNU ld [default=no]
+  --with-debuginfod       Enable debuginfo lookups with debuginfod
+                          (auto/yes/no)
   --with-system-zlib      use installed libz
   --with-gnu-ld           assume the C compiler uses GNU ld default=no
   --with-libiconv-prefix[=DIR]  search for libiconv in DIR/include and DIR/lib
@@ -1932,6 +1936,52 @@ $as_echo "$ac_res" >&6; }
 
 } # ac_fn_c_check_func
 
+# ac_fn_c_check_decl LINENO SYMBOL VAR INCLUDES
+# ---------------------------------------------
+# Tests whether SYMBOL is declared in INCLUDES, setting cache variable VAR
+# accordingly.
+ac_fn_c_check_decl ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  as_decl_name=`echo $2|sed 's/ *(.*//'`
+  as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
+$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
+if eval \${$3+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+$4
+int
+main ()
+{
+#ifndef $as_decl_name
+#ifdef __cplusplus
+  (void) $as_decl_use;
+#else
+  (void) $as_decl_name;
+#endif
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$3=yes"
+else
+  eval "$3=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+eval ac_res=\$$3
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+
+} # ac_fn_c_check_decl
+
 # ac_fn_c_compute_int LINENO EXPR VAR INCLUDES
 # --------------------------------------------
 # Tries to find the compile-time value of EXPR in a program that includes
@@ -2168,52 +2218,6 @@ $as_echo "$ac_res" >&6; }
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
 
 } # ac_fn_c_check_type
-
-# ac_fn_c_check_decl LINENO SYMBOL VAR INCLUDES
-# ---------------------------------------------
-# Tests whether SYMBOL is declared in INCLUDES, setting cache variable VAR
-# accordingly.
-ac_fn_c_check_decl ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  as_decl_name=`echo $2|sed 's/ *(.*//'`
-  as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
-$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
-if eval \${$3+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$4
-int
-main ()
-{
-#ifndef $as_decl_name
-#ifdef __cplusplus
-  (void) $as_decl_use;
-#else
-  (void) $as_decl_name;
-#endif
-#endif
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  eval "$3=yes"
-else
-  eval "$3=no"
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-eval ac_res=\$$3
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-
-} # ac_fn_c_check_decl
 cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
@@ -11523,7 +11527,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11526 "configure"
+#line 11530 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11629,7 +11633,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11632 "configure"
+#line 11636 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12236,6 +12240,90 @@ fi
 
 
 
+# Enable debuginfod
+
+# Check whether --with-debuginfod was given.
+if test "${with_debuginfod+set}" = set; then :
+  withval=$with_debuginfod;
+else
+  with_debuginfod=auto
+fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to use debuginfod" >&5
+$as_echo_n "checking whether to use debuginfod... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_debuginfod" >&5
+$as_echo "$with_debuginfod" >&6; }
+
+if test "${with_debuginfod}" = no; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: debuginfod support disabled; some features may be unavailable." >&5
+$as_echo "$as_me: WARNING: debuginfod support disabled; some features may be unavailable." >&2;}
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for debuginfod_begin in -ldebuginfod" >&5
+$as_echo_n "checking for debuginfod_begin in -ldebuginfod... " >&6; }
+if ${ac_cv_lib_debuginfod_debuginfod_begin+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-ldebuginfod  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char debuginfod_begin ();
+int
+main ()
+{
+return debuginfod_begin ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_debuginfod_debuginfod_begin=yes
+else
+  ac_cv_lib_debuginfod_debuginfod_begin=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_debuginfod_debuginfod_begin" >&5
+$as_echo "$ac_cv_lib_debuginfod_debuginfod_begin" >&6; }
+if test "x$ac_cv_lib_debuginfod_debuginfod_begin" = xyes; then :
+  have_debuginfod_lib=yes
+fi
+
+  ac_fn_c_check_decl "$LINENO" "debuginfod_begin" "ac_cv_have_decl_debuginfod_begin" "#include <elfutils/debuginfod.h>
+"
+if test "x$ac_cv_have_decl_debuginfod_begin" = xyes; then :
+  have_debuginfod_h=yes
+fi
+
+  if test "x$have_debuginfod_lib" = "xyes" -a \
+          "x$have_debuginfod_h" = "xyes"; then
+
+$as_echo "#define HAVE_LIBDEBUGINFOD 1" >>confdefs.h
+
+    LIBDEBUGINFOD="-ldebuginfod"
+
+  else
+
+    if test "$with_debuginfod" = yes; then
+      as_fn_error $? "debuginfod is missing or unusable" "$LINENO" 5
+    else
+      { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: debuginfod is missing or unusable; some features may be unavailable." >&5
+$as_echo "$as_me: WARNING: debuginfod is missing or unusable; some features may be unavailable." >&2;}
+    fi
+  fi
+fi
+
+
+
 cat >>confdefs.h <<_ACEOF
 #define DEFAULT_STRINGS_ALL $default_strings_all
 _ACEOF
diff --git a/binutils/configure.ac b/binutils/configure.ac
index d77161f..385ab01 100644
--- a/binutils/configure.ac
+++ b/binutils/configure.ac
@@ -18,6 +18,7 @@ dnl <http://www.gnu.org/licenses/>.
 dnl
 
 m4_include([../bfd/version.m4])
+m4_include([../config/debuginfod.m4])
 AC_INIT([binutils], BFD_VERSION)
 AC_CONFIG_SRCDIR(ar.c)
 
@@ -63,6 +64,8 @@ else
   default_strings_all=1
 fi], [default_strings_all=1])
 
+AC_DEBUGINFOD
+
 AC_DEFINE_UNQUOTED(DEFAULT_STRINGS_ALL, $default_strings_all,
 		   [Should strings use -a behavior by default?])
 
diff --git a/binutils/doc/Makefile.in b/binutils/doc/Makefile.in
index 52c39ba..b0e7b7b 100644
--- a/binutils/doc/Makefile.in
+++ b/binutils/doc/Makefile.in
@@ -127,7 +127,9 @@ am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
 	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
 	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
 	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
-	$(top_srcdir)/../bfd/version.m4 $(top_srcdir)/configure.ac
+	$(top_srcdir)/../bfd/version.m4 \
+	$(top_srcdir)/../config/debuginfod.m4 \
+	$(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
 DIST_COMMON = $(srcdir)/Makefile.am $(am__DIST_COMMON)
@@ -284,6 +286,7 @@ LDFLAGS = @LDFLAGS@
 LEX = @LEX@
 LEXLIB = @LEXLIB@
 LEX_OUTPUT_ROOT = @LEX_OUTPUT_ROOT@
+LIBDEBUGINFOD = @LIBDEBUGINFOD@
 LIBICONV = @LIBICONV@
 LIBINTL = @LIBINTL@
 LIBINTL_DEP = @LIBINTL_DEP@
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index f938e74..71af6c5 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -154,6 +154,7 @@ in the section entitled ``GNU Free Documentation License''.
 * elfedit::                     Update ELF header and property of ELF files
 * Common Options::              Command-line options for all utilities
 * Selecting the Target System:: How these utilities determine the target
+* debuginfod::                  Using binutils with debuginfod
 * Reporting Bugs::              Reporting Bugs
 * GNU Free Documentation License::  GNU Free Documentation License
 * Binutils Index::              Binutils Index
@@ -5201,6 +5202,23 @@ Ways to specify:
 deduced from the input file
 @end enumerate
 
+@node debuginfod
+@chapter debuginfod
+@cindex separate debug files
+
+debuginfod is a web service that indexes ELF/DWARF debugging resources
+by build-id and serves them over HTTP.
+
+Binutils can be built with the debuginfod client library
+@code{libdebuginfod} using the @option{--with-debuginfod} configure option.
+This option is enabled by default if @code{libdebuginfod} is installed
+and found at configure time. This allows @command{objdump} and
+@command{readelf} to automatically query debuginfod servers for
+separate debug files when the files are otherwise not found.
+
+debuginfod is packaged with elfutils, starting with version 0.178.
+You can get the latest version from `https://sourceware.org/elfutils/'.
+
 @node Reporting Bugs
 @chapter Reporting Bugs
 @cindex bugs
diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 130ba10..9c96f47 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -32,6 +32,10 @@
 #include "safe-ctype.h"
 #include <assert.h>
 
+#ifdef HAVE_LIBDEBUGINFOD
+#include <elfutils/debuginfod.h>
+#endif
+
 #undef MAX
 #undef MIN
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
@@ -10128,12 +10132,83 @@ add_separate_debug_file (const char * filename, void * handle)
   first_separate_info = i;
 }
 
+#if HAVE_LIBDEBUGINFOD
+/* Query debuginfod servers for the target debuglink or debugaltlink
+   file. If successful, store the path of the file in filename and
+   return TRUE, otherwise return FALSE.  */
+
+static bfd_boolean
+debuginfod_fetch_separate_debug_info (struct dwarf_section * section,
+                                      char ** filename,
+                                      void * file)
+{
+  size_t build_id_len;
+  unsigned char * build_id;
+
+  if (strcmp (section->uncompressed_name, ".gnu_debuglink") == 0)
+    {
+      /* Get the build-id of file.  */
+      build_id = get_build_id (file);
+      build_id_len = 0;
+    }
+  else if (strcmp (section->uncompressed_name, ".gnu_debugaltlink") == 0)
+    {
+      /* Get the build-id of the debugaltlink file.  */
+      unsigned int filelen;
+
+      filelen = strnlen ((const char *)section->start, section->size);
+      if (filelen == section->size)
+        /* Corrupt debugaltlink.  */
+        return FALSE;
+
+      build_id = section->start + filelen + 1;
+      build_id_len = section->size - (filelen + 1);
+
+      if (build_id_len == 0)
+        return FALSE;
+    }
+  else
+    return FALSE;
+
+  if (build_id)
+    {
+      int fd;
+      debuginfod_client * client;
+
+      client = debuginfod_begin ();
+      if (client == NULL)
+        return FALSE;
+
+      /* Query debuginfod servers for the target file. If found its path
+         will be stored in filename.  */
+      fd = debuginfod_find_debuginfo (client, build_id, build_id_len, filename);
+      debuginfod_end (client);
+
+      /* Only free build_id if we allocated space for a hex string
+         in get_build_id ().  */
+      if (build_id_len == 0)
+        free (build_id);
+
+      if (fd >= 0)
+        {
+          /* File successfully retrieved. Close fd since we want to
+             use open_debug_file () on filename instead.  */
+          close (fd);
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+#endif
+
 static void *
 load_separate_debug_info (const char *            main_filename,
 			  struct dwarf_section *  xlink,
 			  parse_func_type         parse_func,
 			  check_func_type         check_func,
-			  void *                  func_data)
+			  void *                  func_data,
+                          void *                  file ATTRIBUTE_UNUSED)
 {
   const char *   separate_filename;
   char *         debug_filename;
@@ -10235,6 +10310,23 @@ load_separate_debug_info (const char *            main_filename,
   if (check_func (debug_filename, func_data))
     goto found;
 
+#if HAVE_LIBDEBUGINFOD
+  {
+    char * tmp_filename;
+
+    if (debuginfod_fetch_separate_debug_info (xlink,
+                                              & tmp_filename,
+                                              file))
+      {
+        /* File successfully downloaded from server, replace
+           debug_filename with the file's path.  */
+        free (debug_filename);
+        debug_filename = tmp_filename;
+        goto found;
+      }
+  }
+#endif
+
   /* Failed to find the file.  */
   warn (_("could not find separate debug file '%s'\n"), separate_filename);
   warn (_("tried: %s\n"), debug_filename);
@@ -10264,6 +10356,16 @@ load_separate_debug_info (const char *            main_filename,
   sprintf (debug_filename, "%s", separate_filename);
   warn (_("tried: %s\n"), debug_filename);
 
+#if HAVE_LIBDEBUGINFOD
+  {
+    char *urls = getenv (DEBUGINFOD_URLS_ENV_VAR);
+    if (urls == NULL)
+      urls = "";
+
+    warn (_("tried: DEBUGINFOD_URLS=%s\n"), urls);
+  }
+#endif
+
   free (canon_dir);
   free (debug_filename);
   return NULL;
@@ -10410,7 +10512,8 @@ load_separate_debug_files (void * file, const char * filename)
 				& debug_displays[gnu_debugaltlink].section,
 				parse_gnu_debugaltlink,
 				check_gnu_debugaltlink,
-				& build_id_data);
+				& build_id_data,
+				file);
     }
 
   if (load_debug_section (gnu_debuglink, file))
@@ -10421,7 +10524,8 @@ load_separate_debug_files (void * file, const char * filename)
 				& debug_displays[gnu_debuglink].section,
 				parse_gnu_debuglink,
 				check_gnu_debuglink,
-				& crc32);
+				& crc32,
+				file);
     }
 
   if (first_separate_info != NULL)
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 3335858..6956692 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -256,6 +256,10 @@ extern bfd_boolean reloc_at (struct dwarf_section *, dwarf_vma);
 extern dwarf_vma read_leb128 (unsigned char *, const unsigned char *const,
 			      bfd_boolean, unsigned int *, int *);
 
+#if HAVE_LIBDEBUGINFOD
+extern unsigned char * get_build_id (void *);
+#endif
+
 static inline void
 report_leb_status (int status)
 {
diff --git a/binutils/objdump.c b/binutils/objdump.c
index 210b67e..27b0fb6 100644
--- a/binutils/objdump.c
+++ b/binutils/objdump.c
@@ -2945,6 +2945,33 @@ open_debug_file (const char * pathname)
   return data;
 }
 
+#if HAVE_LIBDEBUGINFOD
+/* Return a hex string represention of the build-id.  */
+
+unsigned char *
+get_build_id (void * data)
+{
+  unsigned i;
+  char * build_id_str;
+  bfd * abfd = (bfd *) data;
+  const struct bfd_build_id * build_id;
+
+  build_id = abfd->build_id;
+  if (build_id == NULL)
+    return NULL;
+
+  build_id_str = malloc (build_id->size * 2 + 1);
+  if (build_id_str == NULL)
+    return NULL;
+
+  for (i = 0; i < build_id->size; i++)
+    sprintf (build_id_str + (i * 2), "%02x", build_id->data[i]);
+  build_id_str[build_id->size * 2] = '\0';
+
+  return (unsigned char *)build_id_str;
+}
+#endif /* HAVE_LIBDEBUGINFOD */
+
 static void
 dump_dwarf_section (bfd *abfd, asection *section,
 		    void *arg ATTRIBUTE_UNUSED)
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 17c27ce..4326cd0 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -14194,6 +14194,138 @@ load_specific_debug_section (enum dwarf_section_display_enum  debug,
   return TRUE;
 }
 
+#if HAVE_LIBDEBUGINFOD
+/* Return a hex string representation of the build-id.  */
+unsigned char *
+get_build_id (void * data)
+{
+  Filedata * filedata = (Filedata *)data;
+  Elf_Internal_Shdr * shdr;
+  unsigned long i;
+
+  /* Iterate through notes to find note.gnu.build-id.  */
+  for (i = 0, shdr = filedata->section_headers;
+       i < filedata->file_header.e_shnum && shdr != NULL;
+       i++, shdr++)
+    {
+      if (shdr->sh_type != SHT_NOTE)
+        continue;
+
+      char * next;
+      char * end;
+      size_t data_remaining;
+      size_t min_notesz;
+      Elf_External_Note * enote;
+      Elf_Internal_Note inote;
+
+      bfd_vma offset = shdr->sh_offset;
+      bfd_vma align = shdr->sh_addralign;
+      bfd_vma length = shdr->sh_size;
+
+      enote = (Elf_External_Note *) get_section_contents (shdr, filedata);
+      if (enote == NULL)
+        continue;
+
+      if (align < 4)
+        align = 4;
+      else if (align != 4 && align != 8)
+        continue;
+
+      end = (char *) enote + length;
+      data_remaining = end - (char *) enote;
+
+      if (!is_ia64_vms (filedata))
+        {
+          min_notesz = offsetof (Elf_External_Note, name);
+          if (data_remaining < min_notesz)
+            {
+              warn (ngettext ("debuginfod: Corrupt note: only %ld byte remains, "
+                              "not enough for a full note\n",
+                              "Corrupt note: only %ld bytes remain, "
+                              "not enough for a full note\n",
+                              data_remaining),
+                    (long) data_remaining);
+              break;
+            }
+          data_remaining -= min_notesz;
+
+          inote.type     = BYTE_GET (enote->type);
+          inote.namesz   = BYTE_GET (enote->namesz);
+          inote.namedata = enote->name;
+          inote.descsz   = BYTE_GET (enote->descsz);
+          inote.descdata = ((char *) enote
+                            + ELF_NOTE_DESC_OFFSET (inote.namesz, align));
+          inote.descpos  = offset + (inote.descdata - (char *) enote);
+          next = ((char *) enote
+                  + ELF_NOTE_NEXT_OFFSET (inote.namesz, inote.descsz, align));
+        }
+      else
+        {
+          Elf64_External_VMS_Note *vms_enote;
+
+          /* PR binutils/15191
+             Make sure that there is enough data to read.  */
+          min_notesz = offsetof (Elf64_External_VMS_Note, name);
+          if (data_remaining < min_notesz)
+            {
+              warn (ngettext ("debuginfod: Corrupt note: only %ld byte remains, "
+                              "not enough for a full note\n",
+                              "Corrupt note: only %ld bytes remain, "
+                              "not enough for a full note\n",
+                              data_remaining),
+                    (long) data_remaining);
+              break;
+            }
+          data_remaining -= min_notesz;
+
+          vms_enote = (Elf64_External_VMS_Note *) enote;
+          inote.type     = BYTE_GET (vms_enote->type);
+          inote.namesz   = BYTE_GET (vms_enote->namesz);
+          inote.namedata = vms_enote->name;
+          inote.descsz   = BYTE_GET (vms_enote->descsz);
+          inote.descdata = inote.namedata + align_power (inote.namesz, 3);
+          inote.descpos  = offset + (inote.descdata - (char *) enote);
+          next = inote.descdata + align_power (inote.descsz, 3);
+        }
+
+      /* Skip malformed notes.  */
+      if ((size_t) (inote.descdata - inote.namedata) < inote.namesz
+          || (size_t) (inote.descdata - inote.namedata) > data_remaining
+          || (size_t) (next - inote.descdata) < inote.descsz
+          || ((size_t) (next - inote.descdata)
+              > data_remaining - (size_t) (inote.descdata - inote.namedata)))
+        {
+          warn (_("debuginfod: note with invalid namesz and/or descsz found\n"));
+          warn (_(" type: 0x%lx, namesize: 0x%08lx, descsize: 0x%08lx, alignment: %u\n"),
+                inote.type, inote.namesz, inote.descsz, (int) align);
+          continue;
+        }
+
+      /* Check if this is the build-id note. If so then convert the build-id
+         bytes to a hex string.  */
+      if (inote.namesz > 0
+          && const_strneq (inote.namedata, "GNU")
+          && inote.type == NT_GNU_BUILD_ID)
+        {
+          unsigned long j;
+          char * build_id;
+
+          build_id = malloc (inote.descsz * 2 + 1);
+          if (build_id == NULL)
+              return NULL;
+
+          for (j = 0; j < inote.descsz; ++j)
+            sprintf (build_id + (j * 2), "%02x", inote.descdata[j] & 0xff);
+          build_id[inote.descsz * 2] = '\0';
+
+          return (unsigned char *)build_id;
+        }
+    }
+
+  return NULL;
+}
+#endif /* HAVE_LIBDEBUGINFOD */
+
 /* If this is not NULL, load_debug_section will only look for sections
    within the list of sections given here.  */
 static unsigned int * section_subset = NULL;
diff --git a/binutils/testsuite/binutils-all/linkdebug.s b/binutils/testsuite/binutils-all/linkdebug.s
index a13a4c6..518f0ce 100644
--- a/binutils/testsuite/binutils-all/linkdebug.s
+++ b/binutils/testsuite/binutils-all/linkdebug.s
@@ -18,9 +18,22 @@
 	
 /* This is the separate debug info file.  */
 
-/* Create a .debug_abbrev section for use by the .debug_info section
+/* Create .note.gnu.build-id note for use by the .gnu_debugaltlink
    in the main object file.  */
-   
+
+	.section	.note.gnu.build-id,"a",%note
+	.balign	4
+	.dc.l	0x04	;# Name size
+	.dc.l	0x18	;# Description size
+	.dc.l	0x03	;# Type
+	.asciz	"GNU"	;# Name
+	.dc.b	0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77
+	.dc.b	0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff
+	.dc.b	0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef
+
+ /* Create a .debug_abbrev section for use by the .debug_info section
+   in the main object file.  */
+
 	.section	.debug_abbrev,"",%progbits
 abbrevs:
 	.uleb128 0x01	;# Abbrev code.