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.

1 files changed, 107 insertions, 3 deletions

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)