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-rw-r--r--lib/linestack.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/lib/linestack.c b/lib/linestack.c
index 39ba0993..44667106 100644
--- a/lib/linestack.c
+++ b/lib/linestack.c
@@ -80,6 +80,37 @@ struct linestack *linestack_load(char *name)
return ls;
}
+// Convert utf8 sequence to a unicode wide character
+int utf8towc(wchar_t *wc, char *str, unsigned len)
+{
+ unsigned result, mask, first;
+ char *s, c;
+
+ // fast path ASCII
+ if (len && *str<128) return !!(*wc = *str);
+
+ result = first = *(s = str++);
+ for (mask = 6; (first&0xc0)==0xc0; mask += 5, first <<= 1) {
+ if (!--len) return -2;
+ c = *(str++);
+ if ((c&0xc0) != 0x80) return -1;
+ result = (result<<6)|(c&0x3f);
+ }
+ result &= (1<<mask)-1;
+ c = str-s;
+ if (mask==6 || mask>21) return -1;
+
+ // Avoid overlong encodings
+ if (mask==6 || mask>21 || result<(unsigned []){0x80,0x800,0x10000}[c-2])
+ return -1;
+
+ // Limit unicode so it can't encode anything UTF-16 can't.
+ if (result>0x10ffff || (result>=0xd800 && result<=0xdfff)) return -1;
+ *wc = result;
+
+ return str-s;
+}
+
// Show width many columns, negative means from right edge, out=0 just measure
// if escout, send it unprintable chars, otherwise pass through raw data.
// Returns width in columns, moves *str to end of data consumed.