wcsmbs/mbrtowc.c

   1 /* Copyright (C) 1996-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <assert.h>
  19 #include <dlfcn.h>
  20 #include <errno.h>
  21 #include <gconv.h>
  22 #include <wchar.h>
  23 #include <wcsmbsload.h>
  24
  25 #include <pointer_guard.h>
  26
  27 #ifndef EILSEQ
  28 # define EILSEQ EINVAL
  29 #endif
  30
  31 /* This is the private state used if PS is NULL.  */
  32 static mbstate_t state;
  33
  34 size_t
  35 __mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)
  36 {
  37   wchar_t buf[1];
  38   struct __gconv_step_data data;
  39   int status;
  40   size_t result;
  41   size_t dummy;
  42   const unsigned char *inbuf, *endbuf;
  43   unsigned char *outbuf = (unsigned char *) (pwc ?: buf);
  44   const struct gconv_fcts *fcts;
  45
  46   /* Set information for this step.  */
  47   data.__invocation_counter = 0;
  48   data.__internal_use = 1;
  49   data.__flags = __GCONV_IS_LAST;
  50   data.__statep = ps ?: &state;
  51
  52   /* A first special case is if S is NULL.  This means put PS in the
  53      initial state.  */
  54   if (s == NULL)
  55     {
  56       outbuf = (unsigned char *) buf;
  57       s = "";
  58       n = 1;
  59     }
  60
  61   if (n == 0)
  62     return (size_t) -2;
  63
  64   /* Tell where we want the result.  */
  65   data.__outbuf = outbuf;
  66   data.__outbufend = outbuf + sizeof (wchar_t);
  67
  68   /* Get the conversion functions.  */
  69   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  70
  71   /* Do a normal conversion.  */
  72   inbuf = (const unsigned char *) s;
  73   endbuf = inbuf + n;
  74   if (__glibc_unlikely (endbuf < inbuf))
  75     {
  76       endbuf = (const unsigned char *) ~(uintptr_t) 0;
  77       if (endbuf == inbuf)
  78         goto ilseq;
  79     }
  80   __gconv_fct fct = fcts->towc->__fct;
  81   if (fcts->towc->__shlib_handle != NULL)
  82     PTR_DEMANGLE (fct);
  83   status = DL_CALL_FCT (fct, (fcts->towc, &data, &inbuf, endbuf,
  84                               NULL, &dummy, 0, 1));
  85
  86   /* There must not be any problems with the conversion but illegal input
  87      characters.  The output buffer must be large enough, otherwise the
  88      definition of MB_CUR_MAX is not correct.  All the other possible
  89      errors also must not happen.  */
  90   assert (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
  91           || status == __GCONV_ILLEGAL_INPUT
  92           || status == __GCONV_INCOMPLETE_INPUT
  93           || status == __GCONV_FULL_OUTPUT);
  94
  95   if (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
  96       || status == __GCONV_FULL_OUTPUT)
  97     {
  98       if (data.__outbuf != (unsigned char *) outbuf
  99           && *(wchar_t *) outbuf == L'\0')
 100         {
 101           /* The converted character is the NUL character.  */
 102           assert (__mbsinit (data.__statep));
 103           result = 0;
 104         }
 105       else
 106         result = inbuf - (const unsigned char *) s;
 107     }
 108   else if (status == __GCONV_INCOMPLETE_INPUT)
 109     result = (size_t) -2;
 110   else
 111     {
 112     ilseq:
 113       result = (size_t) -1;
 114       __set_errno (EILSEQ);
 115     }
 116
 117   return result;
 118 }
 119 libc_hidden_def (__mbrtowc)
 120 weak_alias (__mbrtowc, mbrtowc)
 121 libc_hidden_weak (mbrtowc)