On a properly set system, LANG and LC_ALL is always defined.
However, some distros like Debian, Gentoo and their variants
start with those undefioned.

When Sphinx tries to set a locale with:

	locale.setlocale(locale.LC_ALL, '')

It raises an exception, making Sphinx fail. This is more likely
to happen with test containers.

Add a logic to detect and workaround such issue by setting
locale to C.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 tools/docs/sphinx-build-wrapper | 11 +++++++++++
 tools/docs/sphinx-pre-install   | 14 +++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/tools/docs/sphinx-build-wrapper b/tools/docs/sphinx-build-wrapper
index 0fe21b343e7a..6c2580303e8e 100755
--- a/tools/docs/sphinx-build-wrapper
+++ b/tools/docs/sphinx-build-wrapper
@@ -45,6 +45,7 @@ the newer version.
 """
 
 import argparse
+import locale
 import os
 import shlex
 import shutil
@@ -565,6 +566,16 @@ class SphinxBuilder:
         if not sphinxdirs:
             sphinxdirs = os.environ.get("SPHINXDIRS", ".")
 
+        #
+        # The sphinx-build tool has a bug: internally, it tries to set
+        # locale with locale.setlocale(locale.LC_ALL, ''). This causes a
+        # crash if language is not set. Detect and fix it.
+        #
+        try:
+            locale.setlocale(locale.LC_ALL, '')
+        except locale.Error:
+            self.env["LC_ALL"] = "C"
+
         #
         # sphinxdirs can be a list or a whitespace-separated string
         #
diff --git a/tools/docs/sphinx-pre-install b/tools/docs/sphinx-pre-install
index d6d673b7945c..663d4e2a3f57 100755
--- a/tools/docs/sphinx-pre-install
+++ b/tools/docs/sphinx-pre-install
@@ -26,6 +26,7 @@ system pacage install is recommended.
 """
 
 import argparse
+import locale
 import os
 import re
 import subprocess
@@ -422,8 +423,19 @@ class MissingCheckers(AncillaryMethods):
         """
         Gets sphinx-build version.
         """
+        env = os.environ.copy()
+
+        # The sphinx-build tool has a bug: internally, it tries to set
+        # locale with locale.setlocale(locale.LC_ALL, ''). This causes a
+        # crash if language is not set. Detect and fix it.
         try:
-            result = self.run([cmd, "--version"],
+            locale.setlocale(locale.LC_ALL, '')
+        except Exception:
+            env["LC_ALL"] = "C"
+            env["LANG"] = "C"
+
+        try:
+            result = self.run([cmd, "--version"], env=env,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.STDOUT,
                               text=True, check=True)
-- 
2.51.0