diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/multibyte/mbtowc.c | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/src/multibyte/mbtowc.c b/src/multibyte/mbtowc.c index b5dd7e3c..ec9e54ad 100644 --- a/src/multibyte/mbtowc.c +++ b/src/multibyte/mbtowc.c @@ -10,10 +10,44 @@ #include <errno.h> #include "internal.h" - -int mbtowc(wchar_t *restrict wc, const char *restrict s, size_t n) +#include <stdio.h> +int mbtowc(wchar_t *restrict wc, const char *restrict src, size_t n) { - mbstate_t st = { 0 }; - n = mbrtowc(wc, s, n, &st); - return n+2 ? n : -1; + unsigned c; + const unsigned char *s = (const void *)src; + + if (!s) return 0; + if (!n) goto ilseq; + if (!wc) wc = (void *)&wc; + + if (*s < 0x80) return !!(*wc = *s); + if (*s-SA > SB-SA) goto ilseq; + c = bittab[*s++-SA]; + + /* Avoid excessive checks against n: If shifting the state n-1 + * times does not clear the high bit, then the value of n is + * insufficient to read a character */ + if (n<4 && ((c<<(6*n-6)) & (1U<<31))) goto ilseq; + + if (OOB(c,*s)) goto ilseq; + c = c<<6 | *s++-0x80; + if (!(c&(1U<<31))) { + *wc = c; + return 2; + } + + if (*s-0x80u >= 0x40) goto ilseq; + c = c<<6 | *s++-0x80; + if (!(c&(1U<<31))) { + *wc = c; + return 3; + } + + if (*s-0x80u >= 0x40) goto ilseq; + *wc = c<<6 | *s++-0x80; + return 4; + +ilseq: + errno = EILSEQ; + return -1; } |