Add UTF-8-delimiter-support to cut(1)

Now you can specify a multibyte-delimiter to cut, which should
definitely be possible for the end-user (Fuck POSIX).
Looking at GNU/coreutils' cut(1)[0], which basically ignores the difference
between characters and bytes, the -n-option and which is bloated as hell,
one has to wonder why they are still default. This is insane!
Things like this personally keep me motivated to make sbase better
every day.

[0]: http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/cut.c;hb=HEAD
     NSFW! You have been warned.

README

@@ -22,7 +22,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
 =* comm            yes                             none
 =  cp              no                              -H, -i, -L
 =* cron            non-posix                       none
- * cut             yes                             none
+#* cut             yes                             none
 =  date            yes                             none
 =  dirname         yes                             none
 =  du              no                              -H, -L, -x

cut.1

@@ -1,4 +1,4 @@
-.Dd January 18, 2015
+.Dd January 22, 2015
 .Dt CUT 1 sbase\-VERSION
 .Sh NAME
 .Nm cut
@@ -67,4 +67,4 @@ utility is compliant with the
 specification.
 .Pp
 The possibility of separating numbers and ranges with a space
-is an extension to that specification.
+and specifying multibyte delimiters is an extension to that specification.

cut.c

@@ -4,6 +4,7 @@
 #include <string.h>
 
 #include "text.h"
+#include "utf.h"
 #include "util.h"
 
 typedef struct Range {
@@ -13,7 +14,8 @@ typedef struct Range {
 
 static Range *list     = NULL;
 static char   mode     = 0;
-static char delim = '\t';
+static Rune   delim    = '\t';
+static size_t delimlen = 1;
 static int    nflag    = 0;
 static int    sflag    = 0;
 
@@ -70,10 +72,11 @@ static size_t
 seek(const char *s, size_t pos, size_t *prev, size_t count)
 {
 	const char *t;
-	size_t n = pos - *prev;
+	size_t n = pos - *prev, i;
+	Rune r;
 
 	if (mode == 'b') {
-		if ((t = memchr(s, 0, n)))
+		if ((t = memchr(s, '\0', n)))
 			return t - s;
 		if (nflag)
 			while (n && !UTF8_POINT(s[n]))
@@ -85,11 +88,18 @@ seek(const char *s, size_t pos, size_t *prev, size_t count)
 			if (UTF8_POINT(*t) && !--n)
 				break;
 	} else {
-		for (t = (count < 2) ? s : s + 1; n && *t; t++)
-			if (*t == delim && !--n && count)
+		for (t = (count < delimlen + 1) ? s : s + delimlen; n && *t; ) {
+			for (i = 1; t[i]; i++)
+				if (fullrune(t, i))
 					break;
+			charntorune(&r, t, i);
+			if (r == delim && !--n && count)
+				break;
+			t += i;
+		}
 	}
 	*prev = pos;
+
 	return t - s;
 }
 
@@ -106,20 +116,22 @@ cut(FILE *fp)
 	while ((len = getline(&buf, &size, fp)) != -1) {
 		if (len && buf[len - 1] == '\n')
 			buf[len - 1] = '\0';
-		if (mode == 'f' && !strchr(buf, delim)) {
+		if (mode == 'f' && !utfrune(buf, delim)) {
 			if (!sflag)
 				puts(buf);
 			continue;
 		}
 		for (i = 0, p = 1, s = buf, r = list; r; r = r->next, s += n) {
-			s += seek(s, r->min, &p, i++);
+			s += seek(s, r->min, &p, i);
+			i += (mode == 'f') ? delimlen : 1;
 			if (!*s)
 				break;
 			if (!r->max) {
 				fputs(s, stdout);
 				break;
 			}
-			n = seek(s, r->max + 1, &p, i++);
+			n = seek(s, r->max + 1, &p, i);
+			i += (mode == 'f') ? delimlen : 1;
 			if (fwrite(s, 1, n, stdout) != n)
 				eprintf("write error:");
 		}
@@ -139,16 +151,27 @@ int
 main(int argc, char *argv[])
 {
 	FILE *fp;
+	int i;
+	char *m, *d;
 
 	ARGBEGIN {
 	case 'b':
 	case 'c':
 	case 'f':
 		mode = ARGC();
-		parselist(ARGF());
+		m = ARGF();
+		if (!m)
+			usage();
+		parselist(m);
 		break;
 	case 'd':
-		delim = *ARGF();
+		if(!(d = ARGF()))
+			usage();
+		for (i = 1; i <= strlen(d); i++)
+			if (fullrune(d, i))
+				break;
+		charntorune(&delim, d, i);
+		delimlen = i;
 		break;
 	case 'n':
 		nflag = 1;
@@ -162,7 +185,6 @@ main(int argc, char *argv[])
 
 	if (!mode)
 		usage();
-
 	if (!argc)
 		cut(stdin);
 	else for (; argc--; argv++) {