1.\" Copyright (c) 2002-2004 Tim J. Robbins 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.Dd August 7, 2020 27.Dt MBSRTOWCS 3 28.Os 29.Sh NAME 30.Nm mbsrtowcs , 31.Nm mbsnrtowcs 32.Nd "convert a character string to a wide-character string (restartable)" 33.Sh LIBRARY 34.Lb libc 35.Sh SYNOPSIS 36.In wchar.h 37.Ft size_t 38.Fo mbsrtowcs 39.Fa "wchar_t * restrict dst" "const char ** restrict src" "size_t len" 40.Fa "mbstate_t * restrict ps" 41.Fc 42.Ft size_t 43.Fo mbsnrtowcs 44.Fa "wchar_t * restrict dst" "const char ** restrict src" "size_t nms" 45.Fa "size_t len" "mbstate_t * restrict ps" 46.Fc 47.Sh DESCRIPTION 48The 49.Fn mbsrtowcs 50function converts a sequence of multibyte characters pointed to indirectly by 51.Fa src 52into a sequence of corresponding wide characters and stores at most 53.Fa len 54of them in the 55.Vt wchar_t 56array pointed to by 57.Fa dst , 58until it encounters a terminating null character 59.Pq Li '\e0' . 60.Pp 61If 62.Fa dst 63is 64.Dv NULL , 65no characters are stored. 66.Pp 67If 68.Fa dst 69is not 70.Dv NULL , 71the pointer pointed to by 72.Fa src 73is updated to point to the character after the one that conversion stopped at. 74If conversion stops because a null character is encountered, 75.Fa *src 76is set to 77.Dv NULL . 78.Pp 79The 80.Vt mbstate_t 81argument, 82.Fa ps , 83is used to keep track of the shift state. 84If it is 85.Dv NULL , 86.Fn mbsrtowcs 87uses an internal, static 88.Vt mbstate_t 89object, which is initialized to the initial conversion state 90at program startup. 91.Pp 92The 93.Fn mbsnrtowcs 94function behaves identically to 95.Fn mbsrtowcs , 96except that conversion stops after reading at most 97.Fa nms 98bytes from the buffer pointed to by 99.Fa src . 100.Sh RETURN VALUES 101If successful, and 102.Fa dst 103is not NULL, the 104.Fn mbsrtowcs 105and 106.Fn mbsnrtowcs 107functions return the number of wide characters stored in 108the array pointed to by 109.Fa dst . 110.Pp 111If 112.Fa dst 113was NULL then the functions 114.Fn mbsrtowcs 115and 116.Fn mbsnrtowcs 117return the number of wide characters that would have been stored where 118.Fa dst 119points to an infinitely large array. 120.Pp 121If either one of the functions is not successful then 122.Po Vt size_t Pc Ns \-1 123is returned. 124.Sh ERRORS 125The 126.Fn mbsrtowcs 127and 128.Fn mbsnrtowcs 129functions will fail if: 130.Bl -tag -width Er 131.It Bq Er EILSEQ 132An invalid multibyte character sequence was encountered. 133.It Bq Er EINVAL 134The conversion state is invalid. 135.El 136.Sh SEE ALSO 137.Xr mbrtowc 3 , 138.Xr mbstowcs 3 , 139.Xr multibyte 3 , 140.Xr wcsrtombs 3 141.Sh STANDARDS 142The 143.Fn mbsrtowcs 144function conforms to 145.St -isoC-99 . 146.Pp 147The 148.Fn mbsnrtowcs 149function is an extension to the standard. 150