system: Modify GDB skeleton to find debug files for any profile.

Instead of hard coding the debug directory to that of the user profile, use
Guile scripting in combination with a new search path specification on GDB to
specify the debug file directories.

* gnu/packages/gdb.scm (gdb-9.1): Add a search path specification for the
GDB_DEBUG_FILE_DIRECTORY environment variable.
* gnu/system/shadow.scm (default-skeletons)[gdbinit]: Derive the value of
DEBUG-FILE-DIRECTORY via the GDB_DEBUG_FILE_DIRECTORY environment variable.
* doc/guix.texi (Installing Debugging Files): Document it.

2 files changed, 14 insertions, 1 deletions

diff --git a/gnu/packages/gdb.scm b/gnu/packages/gdb.scm
index 830121751fe..11e0bb3e763 100644
--- a/gnu/packages/gdb.scm
+++ b/gnu/packages/gdb.scm
@@ -5,6 +5,7 @@
 ;;; Copyright © 2020 Marius Bakke <mbakke@fastmail.com>
 ;;; Copyright © 2020 Vincent Legoll <vincent.legoll@gmail.com>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -117,6 +118,12 @@
         ("dejagnu" ,dejagnu)
         ("pkg-config" ,pkg-config)
         ,@(if (hurd-target?) `(("mig" ,mig)) '())))
+    ;; TODO: Add support for the GDB_DEBUG_FILE_DIRECTORY environment variable
+    ;; in GDB itself instead of relying on some glue code in the Guix-provided
+    ;; .gdbinit file.
+    (native-search-paths (list (search-path-specification
+                                (variable "GDB_DEBUG_FILE_DIRECTORY")
+                                (files '("lib/debug")))))
     (home-page "https://www.gnu.org/software/gdb/")
     (synopsis "The GNU debugger")
     (description
diff --git a/gnu/system/shadow.scm b/gnu/system/shadow.scm
index a69339bc074..8c76bc2b113 100644
--- a/gnu/system/shadow.scm
+++ b/gnu/system/shadow.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2016 Alex Griffin <a@ajgrf.com>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
+;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -162,7 +163,12 @@ XTerm*utf8: always
 XTerm*metaSendsEscape: true\n"))
         (gdbinit   (plain-file "gdbinit" "\
 # Tell GDB where to look for separate debugging files.
-set debug-file-directory ~/.guix-profile/lib/debug
+guile
+(use-modules (gdb))
+(execute (string-append \"set debug-file-directory \"
+                        (or (getenv \"GDB_DEBUG_FILE_DIRECTORY\")
+                            \"~/.guix-profile/lib/debug\")))
+end
 
 # Authorize extensions found in the store, such as the
 # pretty-printers of libstdc++.