overhaul locale internals to treat categories roughly uniformly

previously, LC_MESSAGES was treated specially as the only category
which could be set to a locale name without a definition file, in
order to facilitate gettext message translations when no libc locale
was available. LC_NUMERIC was completely un-settable, and LC_CTYPE
stored a flag intended to be used for a possible future byte-based C
locale, instead of storing a __locale_map pointer like the other
categories use.

this patch changes all categories to be represented by pointers to
__locale_map structures, and allows locale names without definition
files to be treated as valid locales with trivial definition when used
in any category. outwardly visible functional changes should be minor,
limited mainly to the strings read back from setlocale and the way
gettext handles translations in categories other than LC_MESSAGES.

various internal refactoring has also been performed, and improvements
in const correctness have been made.

1 files changed, 63 insertions, 53 deletions

diff --git a/src/locale/__setlocalecat.c b/src/locale/__setlocalecat.c
index e829da56..30aa7fcc 100644
--- a/src/locale/__setlocalecat.c
+++ b/src/locale/__setlocalecat.c
@@ -15,24 +15,60 @@ const unsigned char *__map_file(const char *, size_t *);
 int __munmap(void *, size_t);
 char *__strchrnul(const char *, int);
 
-static struct __locale_map *findlocale(const char *name, size_t n)
+static const char envvars[][12] = {
+	"LC_CTYPE",
+	"LC_NUMERIC",
+	"LC_TIME",
+	"LC_COLLATE",
+	"LC_MONETARY",
+	"LC_MESSAGES",
+};
+
+static const uint32_t empty_mo[] = { 0x950412de, 0, -1, -1, -1 };
+
+static const struct __locale_map c_dot_utf8 = {
+	.map = empty_mo,
+	.map_size = sizeof empty_mo,
+	.name = "C.UTF-8"
+};
+
+const struct __locale_map *__get_locale(int cat, const char *val)
 {
 	static int lock[2];
 	static void *volatile loc_head;
-	struct __locale_map *p, *new = 0;
+	const struct __locale_map *p;
+	struct __locale_map *new = 0;
 	const char *path = 0, *z;
 	char buf[256];
-	size_t l;
-	const void *map;
-	size_t map_size;
+	size_t l, n;
+
+	if (!*val) {
+		(val = getenv("LC_ALL")) && *val ||
+		(val = getenv(envvars[cat])) && *val ||
+		(val = getenv("LANG")) && *val ||
+		(val = "C.UTF-8");
+	}
+
+	/* Limit name length and forbid leading dot or any slashes. */
+	for (n=0; n<LOCALE_NAME_MAX && val[n] && val[n]!='/'; n++);
+	if (val[0]=='.' || val[n]) val = "C.UTF-8";
+	int builtin = (val[0]=='C' && !val[1])
+		|| !strcmp(val, "C.UTF-8")
+		|| !strcmp(val, "POSIX");
+
+	if (builtin) {
+		if (cat == LC_CTYPE && val[1]=='.')
+			return (void *)&c_dot_utf8;
+		return 0;
+	}
 
 	for (p=loc_head; p; p=p->next)
-		if (!strcmp(name, p->name)) return p;
+		if (!strcmp(val, p->name)) return p;
 
 	LOCK(lock);
 
 	for (p=loc_head; p; p=p->next)
-		if (!strcmp(name, p->name)) {
+		if (!strcmp(val, p->name)) {
 			UNLOCK(lock);
 			return p;
 		}
@@ -46,9 +82,10 @@ static struct __locale_map *findlocale(const char *name, size_t n)
 		if (l >= sizeof buf - n - 2) continue;
 		memcpy(buf, path, l);
 		buf[l] = '/';
-		memcpy(buf+l+1, name, n);
+		memcpy(buf+l+1, val, n);
 		buf[l+1+n] = 0;
-		map = __map_file(buf, &map_size);
+		size_t map_size;
+		const void *map = __map_file(buf, &map_size);
 		if (map) {
 			new = malloc(sizeof *new);
 			if (!new) {
@@ -57,58 +94,31 @@ static struct __locale_map *findlocale(const char *name, size_t n)
 			}
 			new->map = map;
 			new->map_size = map_size;
-			memcpy(new->name, name, n);
+			memcpy(new->name, val, n);
 			new->name[n] = 0;
 			new->next = loc_head;
 			loc_head = new;
 			break;
 		}
 	}
-	UNLOCK(lock);
-	return new;
-}
-
-static const char envvars[][12] = {
-	"LC_CTYPE",
-	"LC_NUMERIC",
-	"LC_TIME",
-	"LC_COLLATE",
-	"LC_MONETARY",
-	"LC_MESSAGES",
-};
 
-int __setlocalecat(locale_t loc, int cat, const char *val)
-{
-	if (!*val) {
-		(val = getenv("LC_ALL")) && *val ||
-		(val = getenv(envvars[cat])) && *val ||
-		(val = getenv("LANG")) && *val ||
-		(val = "C.UTF-8");
+	/* If no locale definition was found, make a locale map
+	 * object anyway to store the name, which is kept for the
+	 * sake of being able to do message translations at the
+	 * application level. */
+	if (!new && (new = malloc(sizeof *new))) {
+		new->map = empty_mo;
+		new->map_size = sizeof empty_mo;
+		memcpy(new->name, val, n);
+		new->name[n] = 0;
+		new->next = loc_head;
+		loc_head = new;
 	}
 
-	size_t n;
-	for (n=0; n<LOCALE_NAME_MAX && val[n] && val[n]!='/'; n++);
-	if (val[0]=='.' || val[n]) val = "C.UTF-8";
-	int builtin = (val[0]=='C' && !val[1])
-		|| !strcmp(val, "C.UTF-8")
-		|| !strcmp(val, "POSIX");
+	/* For LC_CTYPE, never return a null pointer unless the
+	 * requested name was "C" or "POSIX". */
+	if (!new && cat == LC_CTYPE) new = (void *)&c_dot_utf8;
 
-	switch (cat) {
-	case LC_CTYPE:
-		loc->ctype_utf8 = !builtin || val[1]=='.';
-		break;
-	case LC_MESSAGES:
-		if (builtin) {
-			loc->messages_name[0] = 0;
-		} else {
-			memcpy(loc->messages_name, val, n);
-			loc->messages_name[n] = 0;
-		}
-		/* fall through */
-	default:
-		loc->cat[cat-2] = builtin ? 0 : findlocale(val, n);
-	case LC_NUMERIC:
-		break;
-	}
-	return 0;
+	UNLOCK(lock);
+	return new;
 }