Adding a new sysroot method for finding debug files

Hi all,

I've never sent or discuss the patch before, thus I am unsure I reach
the correct mailing list, but I ll still try.

I've been using internally the patch below for my own setup for about
a year, and I was wondering if it could help other people too and also
put my own setup in production.

Basically, that patch makes it easier to use sysroot ... as a normal
sysroot : debug files would additionally be searched in
<sysroot>/<debugdir>, instead of just <debugdir>/<sysroot>.

It allows to create a sample of the targeted OS anywhere (i.e. :
extracting necessary packages & debuginfo), and pointing gdb_sysroot
to it : gdb will search all the required files from within
gdb_sysroot.

Benefits :
 - no need for recreating a full OS or a container to open a coredump.
 - you can use a modern GDB, with your own plugins and scripts, to
diagnose a coredump created on an old OS
 - you can export the recreated OS sample and let other people mount
and use their own gdb to look at the coredump.

There might be a bit of additional changes required, such as similar
changes for searching the source, so that gdb can find them within the
sysroot as well. But that patch made my life a lot simpler.

I am unsure this was sufficiently clearly explained, but I hope I will
trigger your interest.

:) If you have a better way of easy opening coredump without building
a whole OS/container and without that patch, please let me know

Cedric

diff --git a/gdb/symfile.c b/gdb/symfile.c
index 84858dc..0f68885 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1533,6 +1533,18 @@ find_separate_debug_file (const char *dir,
              do_cleanups (back_to);
              return debugfile;
            }
+
+          /* or we can try to inject debugdir between sysroot and
normal path */
+          strcpy (debugfile, gdb_sysroot);
+          strcat (debugfile, debugdir);
+          strcat (debugfile, canon_dir + strlen (gdb_sysroot));
+          strcat (debugfile, "/");
+          strcat (debugfile, debuglink);
+          if (separate_debug_file_exists (debugfile, crc32, objfile))
+            {
+              do_cleanups (back_to);
+              return debugfile;
+            }
        }
     }