usr/src/lib/libc/port/locale/mbftowc.c

   1 /*
   2  * This file and its contents are supplied under the terms of the
   3  * Common Development and Distribution License ("CDDL"), version 1.0.
   4  * You may only use this file in accordance with the terms of version
   5  * 1.0 of the CDDL.
   6  *
   7  * A full copy of the text of the CDDL should have accompanied this
   8  * source.  A copy of the CDDL is also available via the Internet at
   9  * http://www.illumos.org/license/CDDL.
  10  */
  11
  12 /*
  13  * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
  14  */
  15
  16 #include "lint.h"
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <wchar.h>
  20
  21 /*
  22  * This function is apparently referenced by parts of ON.  It is
  23  * not intended for public API usage -- and it is not documented.
  24  *
  25  * The usage appears to be to consume bytes until a character is
  26  * gathered, using a supplied function.   It reads exactly one
  27  * character and returns the number of bytes in the multibyte string
  28  * that were consumed.
  29  *
  30  * The string "s" is storage for the multibyte string, the
  31  * wc will receive the interpreted character, the peek function
  32  * obtains the next character (as an int so we can get EOF),
  33  * and errorc is stuffed with the character that is responsible
  34  * for a parse error, if any.
  35  */
  36
  37 int
  38 _mbftowc(char *s, wchar_t *wc, int (*peek)(void), int *errorc)
  39 {
  40         int             c;
  41         mbstate_t       mbs;
  42         char            *start = s;
  43         size_t          cons = 0;
  44
  45         for (;;) {
  46                 c = peek();
  47                 if (c < 0) {
  48                         /* No bytes returned? */
  49                         return (s - start);
  50                 }
  51
  52                 *s = (char)c;
  53                 s++;
  54
  55                 (void) memset(&mbs, 0, sizeof (mbs));
  56                 cons = mbrtowc(wc, start, s - start, &mbs);
  57                 if ((int)cons >= 0) {
  58                         /* fully translated character */
  59                         return (cons);
  60                 }
  61                 if (cons == (size_t)-2) {
  62                         /* incomplete, recycle */
  63                         continue;
  64                 }
  65
  66                 /*
  67                  * Parse error, don't consider the first character part
  68                  * of the error.
  69                  */
  70                 s--;
  71                 cons = (s - start);
  72                 *errorc = c >= 0 ?  c : 0;
  73                 break;
  74         }
  75
  76         return (cons);
  77 }