common: Extend utf8_charcount to include the string's length.

* common/stringhelp.c (utf8_charcount): Take additional parameter,
len.  Process at most LEN bytes.

--
Signed-off-by: Neal H. Walfield <neal@g10code.com>

agent/genkey.c

@@ -221,7 +221,7 @@ check_passphrase_constraints (ctrl_t ctrl, const char *pw,
 
   /* Now check the constraints and collect the error messages unless
      in in silent mode which returns immediately.  */
-  if (utf8_charcount (pw) < minlen )
+  if (utf8_charcount (pw, -1) < minlen )
     {
       if (!failed_constraint)
         {

common/stringhelp.c

@@ -746,16 +746,30 @@ sanitize_buffer (const void *p_arg, size_t n, int delim)
 
 /* Given a string containing an UTF-8 encoded text, return the number
    of characters in this string.  It differs from strlen in that it
-   only counts complete UTF-8 characters.  Note, that this function
-   does not take combined characters into account.  */
+   only counts complete UTF-8 characters.  SIZE is the maximum length
+   of the string in bytes.  If SIZE is -1, then a NUL character is
+   taken to be the end of the string.  Note, that this function does
+   not take combined characters into account.  */
 size_t
-utf8_charcount (const char *s)
+utf8_charcount (const char *s, int len)
 {
   size_t n;
 
+  if (len == 0)
+    return 0;
+
   for (n=0; *s; s++)
-    if ( (*s&0xc0) != 0x80 ) /* Exclude continuation bytes: 10xxxxxx */
-      n++;
+    {
+      if ( (*s&0xc0) != 0x80 ) /* Exclude continuation bytes: 10xxxxxx */
+        n++;
+
+      if (len != -1)
+        {
+          len --;
+          if (len == 0)
+            break;
+        }
+    }
 
   return n;
 }

common/stringhelp.h

@@ -64,7 +64,7 @@ int hextobyte (const char *s);
 char *sanitize_buffer (const void *p, size_t n, int delim);
 
 
-size_t utf8_charcount (const char *s);
+size_t utf8_charcount (const char *s, int len);
 
 
 #ifdef HAVE_W32_SYSTEM

g10/gpg.c

@@ -1043,7 +1043,7 @@ build_list (const char *text, char letter,
   if (maybe_setuid)
     gcry_control (GCRYCTL_INIT_SECMEM, 0, 0);  /* Drop setuid. */
 
-  indent = utf8_charcount (text);
+  indent = utf8_charcount (text, -1);
   len = 0;
   init_membuf (&mb, 512);