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-rw-r--r--stdlib/mblen.c31
1 files changed, 27 insertions, 4 deletions
diff --git a/stdlib/mblen.c b/stdlib/mblen.c
index 120551c..e43b076 100644
--- a/stdlib/mblen.c
+++ b/stdlib/mblen.c
@@ -17,14 +17,37 @@
Boston, MA 02111-1307, USA. */
#include <stdlib.h>
-
-#undef mblen
+#include <wchar.h>
/* Return the length of the multibyte character (if there is one)
- at S which is no longer than N characters. */
+ at S which is no longer than N characters.
+ The ISO C standard says that the `mblen' function must not change
+ the global state. */
int
mblen (const char *s, size_t n)
{
- return mbtowc ((wchar_t *) NULL, s, n);
+ mbstate_t state;
+ int result;
+
+ /* If S is NULL the function has to return null or not null
+ depending on the encoding having a state depending encoding or
+ not. This is nonsense because any multibyte encoding has a
+ state. The ISO C amendment 1 corrects this while introducing the
+ restartable functions. We simply say here all encodings have a
+ state. */
+ if (s == NULL)
+ return 1;
+
+ state.count = 0;
+ state.value = 0;
+
+ result = __mbrtowc (NULL, s, n, &state);
+
+ /* The `mbrtowc' functions tell us more than we need. Fold the -1
+ and -2 result into -1. */
+ if (result < 0)
+ result = -1;
+
+ return result;
}