From 4873021e373542bec71187410b1bd9fff6ef2ca5 Mon Sep 17 00:00:00 2001
From: Renaud Fivet <renaud.fivet@gmail.com>
Date: Tue, 16 May 2017 12:13:12 +0800
Subject: [PATCH] &left and &mid handling of UTF-8 encoded characters.

---
 eval.c | 48 +++++++++++++++++++++++++++++++++++++++++++-----
 utf8.c |  8 +++-----
 2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/eval.c b/eval.c
index cc67543..379bf0c 100644
--- a/eval.c
+++ b/eval.c
@@ -412,8 +412,22 @@ static char *gtfun( char *fname) {
 		retstr = result ;
 	}
 		break ;
-	case UFLEFT | DYNAMIC:
-		sz = atoi( arg2) ;
+	case UFLEFT | DYNAMIC: {
+		int	sz1, i ;
+
+		sz1 = strlen( arg1) ;
+		sz = 0 ;
+		for( i = atoi( arg2) ; i > 0 ; i -= 1) {
+			unicode_t c ;
+			int bytc ;
+
+			bytc = utf8_to_unicode( arg1, sz, sz1, &c) ;
+			if( bytc == 0)
+				break ;
+			else
+				sz += bytc ;
+		}
+
 		if( sz >= ressize) {
 			free( result) ;
 			result = malloc( sz + 1) ;
@@ -423,6 +437,7 @@ static char *gtfun( char *fname) {
 		strncpy( result, arg1, sz) ;
 		result[ sz] = 0 ;
 		retstr = result ;
+	}
 		break ;
 	case UFRIGHT | DYNAMIC:
 		sz = atoi( arg2) ;
@@ -434,17 +449,40 @@ static char *gtfun( char *fname) {
 		
 		retstr = strcpy( result, &arg1[ strlen( arg1) - sz]) ;
 		break ;
-	case UFMID | TRINAMIC:
-		sz = atoi( arg3) ;
+	case UFMID | TRINAMIC: {
+		int sz1, start, i, bytc ;
+		unicode_t c ;
+
+		sz1 = strlen( arg1) ;
+		start = 0 ;
+		for( i = atoi( arg2) - 1 ; i > 0 ; i -= 1) {
+			bytc = utf8_to_unicode( arg1, start, sz1, &c) ;
+			if( bytc == 0)
+				break ;
+			else
+				start += bytc ;
+		}
+
+		sz = start ;
+		for( i = atoi( arg3) ; i > 0 ; i -= 1) {
+			bytc = utf8_to_unicode( arg1, sz, sz1, &c) ;
+			if( bytc == 0)
+				break ;
+			else
+				sz += bytc ;
+		}
+
+		sz -= start ;
 		if( sz >= ressize) {
 			free( result) ;
 			result = malloc( sz + 1) ;
 			ressize = sz + 1 ;
 		}
 
-		strncpy( result, &arg1[ atoi( arg2) - 1], sz) ;
+		strncpy( result, &arg1[ start], sz) ;
 		result[ sz] = 0 ;
 		retstr = result ;
+	}
 		break ;
 	case UFNOT | MONAMIC:
 		retstr = ltos( stol( arg1) == FALSE) ;
diff --git a/utf8.c b/utf8.c
index 175d3d2..511e4d7 100644
--- a/utf8.c
+++ b/utf8.c
@@ -17,17 +17,15 @@
  * NOTE 2! This does *not* verify things like minimality. So overlong forms
  * are happily accepted and decoded, as are the various "invalid values".
  */
-unsigned utf8_to_unicode(char *line, unsigned index, unsigned len, unicode_t *res)
-{
+unsigned utf8_to_unicode( char *line, unsigned index, unsigned len,
+															unicode_t *res) {
     unicode_t   value ;
     unsigned	c ;
     unsigned	bytes, mask, i;
 
-	assert( index < len) ;
-#ifdef NDEBUG
 	if( index >= len)
 		return 0 ;
-#endif	
+
     *res = c = line[ index] & 0xFFU ;
 
     /*