[GSoC Patch 1/2] gettext: fall back to env-derived charset when unset

`is_utf8_locale()` relies on the static `charset` variable, which is
normally initialized by `init_gettext_charset()`. That initialization
only happens when `git_setup_gettext()` successfully locates the locale
directory.

When running directly from the source tree without `make install`, or in
other environments where the locale directory is unavailable,
`git_setup_gettext()` returns early, leaving `charset` unset (NULL).
Because `is_encoding_utf8(NULL)` defaults to 1, `is_utf8_locale()` would
mistakenly report a UTF-8 locale even in non-UTF-8 environments (e.g.
under `LC_ALL=C`).

The fallback that derives the charset from `LC_ALL`, `LC_CTYPE`, or
`LANG` was previously compiled only under `NO_GETTEXT`. That left
gettext-enabled builds without a fallback when `charset` remains
uninitialized.

Make the fallback conditional on `charset` being unset rather than on
`NO_GETTEXT`. This ensures `is_utf8_locale()` accurately inspects the
environment-derived charset regardless of whether gettext support is
enabled.

Mentored-by: Justin Tobler [off-list ref]
Mentored-by: Lucas Seiki Oshiro [off-list ref]
Signed-off-by: K Jayatheerth <redacted>
---
 gettext.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/gettext.c b/gettext.c
index 8d08a61f84..5376a0de0f 100644
--- a/gettext.c
+++ b/gettext.c

@@ -141,19 +141,23 @@ int gettext_width(const char *s)
 
 int is_utf8_locale(void)
 {
-#ifdef NO_GETTEXT
-	if (!charset) {
-		const char *env = getenv("LC_ALL");
-		if (!env || !*env)
-			env = getenv("LC_CTYPE");
-		if (!env || !*env)
-			env = getenv("LANG");
-		if (!env)
-			env = "";
-		if (strchr(env, '.'))
-			env = strchr(env, '.') + 1;
-		charset = xstrdup(env);
+	const char *c = charset;
+
+	if (!c) {
+		static char fallback_charset[64];
+		if (!*fallback_charset) {
+			const char *env = getenv("LC_ALL");
+			if (!env || !*env)
+				env = getenv("LC_CTYPE");
+			if (!env || !*env)
+				env = getenv("LANG");
+			if (!env)
+				env = "";
+			if (strchr(env, '.'))
+				env = strchr(env, '.') + 1;
+			strlcpy(fallback_charset, env, sizeof(fallback_charset));
+		}
+		c = fallback_charset;
 	}
-#endif
-	return is_encoding_utf8(charset);
+	return is_encoding_utf8(c);
 }

-- 
2.55.GIT