Bug 1215480

Summary:	[gdb/symtab] build-id debuginfo link doesn't work when debugging from outside container
Product:	[openSUSE] openSUSE Distribution	Reporter:	Tom de Vries <tdevries>
Component:	Development	Assignee:	Tom de Vries <tdevries>
Status:	NEW ---	QA Contact:	E-mail List <qa-bugs>
Severity:	Normal
Priority:	P5 - None	CC:	mjambor
Version:	Leap 15.4
Target Milestone:	---
Hardware:	Other
OS:	Other
Whiteboard:
Found By:	---	Services Priority:
Business Priority:		Blocker:	---
Marketing QA Status:	---	IT Deployment:	---

Description Tom de Vries 2023-09-19 11:43:04 UTC

[ This might be a dup of PR1197415. ]

Consider this upstream PR ( https://sourceware.org/bugzilla/show_bug.cgi?id=30866 ): "[gdb/symtab] symbolic links to debuginfo not followed when debugging from outside container".

It exercises 4 scenarios for finding debug info: 2 from inside the container, two from outside. For the former both work, for the latter the build-id case works but the .gnu_debuglink case doesn't (which is the subject of the upstream PR).

The latter cases are with gdb build from current source, and the results reproduce with the gdb-12-branch.

However, when using system gdb (12.1 based), also the build-id case doesn't work:
...
Looking for separate debug info (build-id) for target:/lib64-symlink/libc.so.6
Trying /usr/lib/debug/.build-id/76/7aa1e4d4fc7c106971b202b6b00e92f47411dc.debug... Trying target:/usr/lib/debug/.build-id/76/7aa1e4d4fc7c106971b202b6b00e92f47411dc.debug...
Looking for separate debug info (debug link) for target:/lib64-symlink/libc.so.6
Trying target:/lib64-symlink/libc-2.31.so-2.31-150300.52.2.x86_64.debug... no, unable to open.
Trying target:/lib64-symlink/.debug/libc-2.31.so-2.31-150300.52.2.x86_64.debug... no, unable to open.
Trying target:/usr/lib/debug//lib64-symlink/libc-2.31.so-2.31-150300.52.2.x86_64.debug... no, unable to open.
Trying target:/usr/lib/debug/lib64-symlink//libc-2.31.so-2.31-150300.52.2.x86_64.debug... no, unable to open.
Trying target:target:/usr/lib/debug/lib64-symlink//libc-2.31.so-2.31-150300.52.2.x86_64.debug... no, unable to open.
Missing separate debuginfo for target:/lib64-symlink/libc.so.6
...

This looks like a problem with one of the fedora patches.

Comment 1 Tom de Vries 2023-09-19 11:44:29 UTC

Tentative patch:
...
diff --git a/gdb/build-id.c b/gdb/build-id.c
index c90daab5592..a110958d34b 100644
--- a/gdb/build-id.c
+++ b/gdb/build-id.c
@@ -523,6 +523,8 @@ build_id_to_debug_bfd_1 (const std::string &orig_link, size_t build_id_len,
 
       if (seqno > 0)
 	{
+	  break;
+
 	  /* There can be multiple build-id symlinks pointing to real files
 	     with the same build-id (such as hard links).  Some of the real
 	     files may not be installed.  */
@@ -532,6 +534,7 @@ build_id_to_debug_bfd_1 (const std::string &orig_link, size_t build_id_len,
 
       ret_link = link;
 
+#if 0
       struct stat statbuf_trash;
 
       /* `access' automatically dereferences LINK.  */
@@ -540,6 +543,7 @@ build_id_to_debug_bfd_1 (const std::string &orig_link, size_t build_id_len,
 	  /* Stop increasing SEQNO.  */
 	  break;
 	}
+#endif
 
       /* lrealpath() is expensive even for the usually non-existent files.  */
       gdb::unique_xmalloc_ptr<char> filename_holder;
...

Comment 2 Tom de Vries 2023-09-19 12:43:50 UTC

(In reply to Tom de Vries from comment #0)
> This looks like a problem with one of the fedora patches.

Reported by email to gdb maintainers affiliated with Red Hat.