Re: [PATCH] gdb: Check for nullptr when computing srcpath

[Aaron Merey <amerey@redhat.com>]

On Thu, Feb 27, 2020 at 2:18 PM Simon Marchi <simark@simark.ca> wrote:
> Please provide in the commit message an explanation of what this fixes, including
> how to reproduce the crash.  Since this fixes the execution of an existing test
> case, you can include the "make check" command line used to run it, like:
>
>   make check TESTS="gdb.dwarf2/dw2-ranges-base"

Fixed.

> Also, do you think you'd be able to send your patches using git-send-email?  That makes
> it much easier to read and comment on.

Sure.

On Thu, Feb 27, 2020 at 2:33 PM Christian Biesinger <cbiesinger@google.com> wrote:
> +   if (build_id != nullptr && srcpath.size () > 0)
>
> I usually prefer !srcpath.empty ()

Fixed.

Aaron


From d048f84f027006782cd96dc66a10477ed5a78243 Mon Sep 17 00:00:00 2001
From: Aaron Merey <amerey@redhat.com>
Date: Thu, 27 Feb 2020 15:51:11 -0500
Subject: [PATCH] gdb: Check for nullptr when computing srcpath

This fixes a regression caused by commit 0d79cdc494d5:

  $ make check TESTS="gdb.dwarf2/dw2-ranges-base.exp"
  [...]
  ERROR: GDB process no longer exists

This error is caused by an abort during the computation of srcpath
when SYMTAB_DIRNAME (s) == NULL.

Computing srcpath only when SYMTAB_DIRNAME (s) is not NULL fixes this
error. Also change the condition for calling debuginfod_source_query
to include whether srcpath could be computed.

gdb/ChangeLog:

2020-02-27  Aaron Merey  <amerey@redhat.com>

        * source.c (open_source_file): Check for nullptr when computing
        srcpath.
---
 gdb/ChangeLog | 4 ++++
 gdb/source.c  | 4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4376161673..371ef91421 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-02-27  Aaron Merey  <amerey@redhat.com>
+	* source.c (open_source_file): Check for nullptr when computing
+	srcpath.
+
 2020-02-27  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* gdbtypes.c (create_array_type_with_stride): Use std::abs not
diff --git a/gdb/source.c b/gdb/source.c
index 051caf5c57..50de93952b 100644
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -1160,7 +1160,7 @@ open_source_file (struct symtab *s)
 	  std::string srcpath;
 	  if (IS_ABSOLUTE_PATH (s->filename))
 	    srcpath = s->filename;
-	  else
+	  else if (SYMTAB_DIRNAME (s) != nullptr)
 	    {
 	      srcpath = SYMTAB_DIRNAME (s);
 	      srcpath += SLASH_STRING;
@@ -1170,7 +1170,7 @@ open_source_file (struct symtab *s)
 	  const struct bfd_build_id *build_id = build_id_bfd_get (ofp->obfd);
 
 	  /* Query debuginfod for the source file.  */
-	  if (build_id != nullptr)
+	  if (build_id != nullptr && !srcpath.empty ())
 	    fd = debuginfod_source_query (build_id->data,
 					  build_id->size,
 					  srcpath.c_str (),
-- 
2.24.1