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sortix--sortix/libc/stdio/vsnprintf.cpp
Jonas 'Sortie' Termansen ec7e0cc9a6 Add cbprintf(3) and vcbprintf(3).
Thanks to Owen Shepherd of the Public Domain C Library for helping design
and formalize these interfaces.
2014-12-01 21:39:05 +01:00

65 lines
2 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdio/vsnprintf.cpp
Prints a formatted string to a limited string.
*******************************************************************************/
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
typedef struct vsnprintf_struct
{
char* str;
size_t size;
size_t produced;
size_t written;
} vsnprintf_t;
static size_t StringPrintCallback(void* user, const char* string,
size_t stringlen)
{
vsnprintf_t* info = (vsnprintf_t*) user;
if ( info->produced < info->size )
{
size_t available = info->size - info->produced;
size_t possible = (stringlen < available) ? stringlen : available;
memcpy(info->str + info->produced, string, possible);
info->written += possible;
}
info->produced += stringlen;
return stringlen;
}
extern "C"
int vsnprintf(char* restrict str, size_t size, const char* restrict format,
va_list list)
{
vsnprintf_t info;
info.str = str;
info.size = size ? size-1 : 0;
info.produced = 0;
info.written = 0;
int result = vcbprintf(&info, StringPrintCallback, format, list);
if ( size )
info.str[info.written] = '\0';
return result;
}