keysym: fix locale dependence in xkb_keysym_from_name()

We currently use strcasecmp, which is locale-dependent. In particular,
one well-known surprise even if restricted just ASCII input is found in
the tr_TR (Turkish) locale, see e.g.
https://msdn.microsoft.com/en-us/library/ms973919.aspx#stringsinnet20_topic5

We have known to avoid locale-dependent functions before, but in this
case, we forgot.

Fix it by implementing our own simple ASCII-only strcasecmp/strncasecmp.
Might have been possible to use strcasecmp_l() with the C locale, but
went the easy route.

Side advantage is that even this non-optimized version is faster than
the optimized libc one (__strcasecmp_l_sse42) since it doesn't need to
do the locale stuff. xkb_keysym_from_name(), which uses strcasecmp
heavily, becomes faster, and so for example Compose file parsing, which
uses xkb_keysym_from_name() heavily, becomes ~20% faster.

Resolves https://github.com/xkbcommon/libxkbcommon/issues/42
Signed-off-by: Ran Benita <ran234@gmail.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/keysym.c b/src/keysym.c
index db0e973..9e7b4fb 100644
--- a/src/keysym.c
+++ b/src/keysym.c
@@ -76,7 +76,7 @@ compare_by_name(const void *a, const void *b)
 {
     const char *key = a;
     const struct name_keysym *entry = b;
-    return strcasecmp(key, get_name(entry));
+    return istrcmp(key, get_name(entry));
 }
 
 XKB_EXPORT int
@@ -109,7 +109,7 @@ xkb_keysym_get_name(xkb_keysym_t ks, char *buffer, size_t size)
 /*
  * Find the correct keysym if one case-insensitive match is given.
  *
- * The name_to_keysym table is sorted by strcasecmp(). So bsearch() may return
+ * The name_to_keysym table is sorted by istrcmp(). So bsearch() may return
  * _any_ of all possible case-insensitive duplicates. This function searches the
  * returned entry @entry, all previous and all next entries that match by
  * case-insensitive comparison and returns the exact match to @name. If @icase
@@ -138,7 +138,7 @@ find_sym(const struct name_keysym *entry, const char *name, bool icase)
     for (iter = entry - 1; iter >= name_to_keysym; --iter) {
         if (!icase && strcmp(get_name(iter), name) == 0)
             return iter;
-        if (strcasecmp(get_name(iter), get_name(entry)) != 0)
+        if (istrcmp(get_name(iter), get_name(entry)) != 0)
             break;
         if (icase && xkb_keysym_is_lower(iter->keysym))
             return iter;
@@ -148,7 +148,7 @@ find_sym(const struct name_keysym *entry, const char *name, bool icase)
     for (iter = entry + 1; iter < last; ++iter) {
         if (!icase && strcmp(get_name(iter), name) == 0)
             return iter;
-        if (strcasecmp(get_name(iter), get_name(entry)) != 0)
+        if (istrcmp(get_name(iter), get_name(entry)) != 0)
             break;
         if (icase && xkb_keysym_is_lower(iter->keysym))
             return iter;