[PATCH] lto-streamer: Ensure src_pwd is remapped

[Morten Linderud]

I've made an attempt at patching this issue as it produces unreproducible
unreproducible binaries for Golang. I don't know C/C++ and it's my first gcc
patch so please bear with me :)

-- >8 --

When -flto is used with line macros containing bare symbols instead of
absolute paths the full path is added but never remapped with
-ffile-prefix-map. This could produce unreproducible binaries.

Fixes: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108534

Signed-off-by: Morten Linderud <morten@linderud.pw>
---
 gcc/lto-streamer-in.cc  | 6 ++++--
 gcc/lto-streamer-out.cc | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/gcc/lto-streamer-in.cc b/gcc/lto-streamer-in.cc
index ad0ca24007a..799f9eec478 100644
--- a/gcc/lto-streamer-in.cc
+++ b/gcc/lto-streamer-in.cc
@@ -44,6 +44,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "debug.h"
 #include "alloc-pool.h"
 #include "toplev.h"
+#include "file-prefix-map.h" /* remap_debug_filename()  */
 
 /* Allocator used to hold string slot entries for line map streaming.  */
 static struct object_allocator<struct string_slot> *string_slot_allocator;
@@ -557,11 +558,12 @@ lto_location_cache::input_location_and_block (location_t *loc,
 	{
 	  const char *pwd = bp_unpack_string (data_in, bp);
 	  const char *src_pwd = get_src_pwd ();
-	  if (strcmp (pwd, src_pwd) == 0)
+	  const char *remapped_src_pwd = remap_debug_filename (src_pwd);
+	  if (strcmp (pwd, remapped_src_pwd) == 0)
 	    stream_relative_path_prefix = NULL;
 	  else
 	    stream_relative_path_prefix
-	      = canon_relative_path_prefix (pwd, src_pwd);
+	      = canon_relative_path_prefix (pwd, remapped_src_pwd);
 	}
       stream_file = canon_file_name (stream_relative_path_prefix,
 				     bp_unpack_string (data_in, bp));
diff --git a/gcc/lto-streamer-out.cc b/gcc/lto-streamer-out.cc
index d4f728094ed..379e256a1e7 100644
--- a/gcc/lto-streamer-out.cc
+++ b/gcc/lto-streamer-out.cc
@@ -230,8 +230,10 @@ lto_output_location_1 (struct output_block *ob, struct bitpack_d *bp,
 	      ob->emit_pwd = false;
 	    }
 	  bp_pack_value (bp, stream_pwd, 1);
-	  if (stream_pwd)
-	    bp_pack_string (ob, bp, get_src_pwd (), true);
+	  if (stream_pwd){
+	    const char *remapped_pwd = remap_debug_filename (get_src_pwd ());
+	    bp_pack_string (ob, bp, remapped_pwd, true);
+	  }
 	  bp_pack_string (ob, bp, remapped, true);
 	  bp_pack_value (bp, xloc.sysp, 1);
 	}
-- 
2.44.0