Subject: [bug#75007] [PATCH] guile-launcher: Avoid the “C” locale and try “C.UTF-8”.

From: Ludovic Courtès <[email-masked]>
Date: Sat, 21 Dec 2024 11:44:27 +0100

This is a followup to ed0cd12a82b429bc5058f693a0f75f2ba0ee47c4, which
adds the C.UTF-8 locale to the glibc package, and
ee4e79f871bc2f848ce4b4a176bb725ab71e3cd6, which changed the default to
“C.UTF-8” for ‘guix’ commands.

Fixes a bug whereby starting ‘guix’ in an environment where the LC_*
variables are unset would start it in the “C” locale:

  echo '(pk (setlocale LC_ALL))' | guix shell -CW coreutils -- guix repl

This would lead to breakage for commands such as ‘guix substitute’ that
need to run in a UTF-8 locale.

* gnu/packages/aux-files/guile-launcher.c (main): Try “C.UTF-8” before
“en_US.UTF-8”.  Do that also when the current locale is “C”.
* guix/ui.scm (install-locale): Likewise.

Change-Id: I36da4db8f898f1083b33760e1ab46c3a257de811
---
 gnu/packages/aux-files/guile-launcher.c | 16 +++++++++++-----
 guix/ui.scm                             |  4 +++-
 2 files changed, 14 insertions(+), 6 deletions(-)

Hi!

Until now, ‘guix’ wouldn’t mind running in the C locale, but that’s not
good for ‘guix substitute’ and other commands started by ‘guix-daemon’.

This is something colleagues and I noticed while running ‘guix-daemon’
in a GitLab-CI container where LC_* were unset.

Thoughts?

Ludo’.

diff --git a/gnu/packages/aux-files/guile-launcher.c b/gnu/packages/aux-files/guile-launcher.c
index c205477f64..44f7e1f432 100644
--- a/gnu/packages/aux-files/guile-launcher.c
+++ b/gnu/packages/aux-files/guile-launcher.c
@@ -84,11 +84,17 @@ int
 main (int argc, char **argv)
 {
   /* Try to install the current locale; remain silent if it fails.  */
-  if (setlocale (LC_ALL, "") == NULL)
-    /* The 'guix pull'-provided 'guix' includes at least en_US.utf8 so use
-       that.  That gives us UTF-8 support for 'scm_to_locale_string', etc.,
-       which is always preferable over the C locale.  */
-    setlocale (LC_ALL, "en_US.utf8");
+  char *locale = setlocale (LC_ALL, "");
+  if (locale == NULL || strcmp (locale, "C") == 0)
+    {
+      /* The 'guix pull'-provided 'guix' includes at least C.UTF-8 (which is
+	 baked into glibc, except when cross-compiling) so use that, and fall
+	 back to en_US.UTF-8.  That gives us UTF-8 support for
+	 'scm_to_locale_string', etc., which is always preferable over the C
+	 locale.  */
+      if (setlocale (LC_ALL, "C.UTF-8") == NULL)
+	setlocale (LC_ALL, "en_US.utf8");
+    }
 
   const char *str;
   str = getenv ("GUILE_LOAD_PATH");
diff --git a/guix/ui.scm b/guix/ui.scm
index eba12c8616..14d6874795 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -521,7 +521,9 @@ (define (install-locale)
   "Install the current locale settings."
   (catch 'system-error
     (lambda _
-      (setlocale LC_ALL ""))
+      (when (string=? (setlocale LC_ALL "") "C")
+        ;; If the current locale is "C", prefer "C.UTF-8".
+        (setlocale LC_ALL "C.UTF-8")))
     (lambda args
       (display-hint (G_ "Consider installing the @code{glibc-locales} package
 and defining @code{GUIX_LOCPATH}, along these lines:

base-commit: 777fde8299d5b0050cae661d403374a7dd87f6ab
-- 
2.46.0