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sortix--sortix/libc/ioleast/writeleast.cpp
2013-12-17 14:30:43 +01:00

45 lines
1.5 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012, 2013.
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/>.
ioleast/writeleast.cpp
Writes at least as much data as requested or more.
*******************************************************************************/
#include <errno.h>
#include <ioleast.h>
#include <stdint.h>
#include <unistd.h>
extern "C" size_t writeleast(int fd, const void* buf, size_t least, size_t max)
{
ssize_t amount = write(fd, buf, max);
if ( amount < 0 )
return 0;
if ( least && !amount )
return errno = EEOF, 0;
if ( (size_t) amount < least )
{
const void* nextbuf = (const uint8_t*) buf + amount;
size_t nextleast = least - amount;
size_t nextmax = max - amount;
amount += writeleast(fd, nextbuf, nextleast, nextmax);
}
return amount;
}