sortix--sortix/ext/ioleast.h

/*
 * Copyright (c) 2012, 2013, 2015 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * ioleast.h
 * Versions of {,p}{read,write} that don't return until it has returned as much
 * data as requested, end of file, or an error occurs. This is sometimes needed
 * as read(2) and write(2) is not always guaranteed to fill up the entire
 * buffer or write it all.
 */

#ifndef SORTIX_COMPATIBILITY_INCLUDE_IOLEAST_H
#define SORTIX_COMPATIBILITY_INCLUDE_IOLEAST_H

#if defined(__sortix__) || defined(__sortix_libc__)

#include_next <ioleast.h>

#else

#include <sys/types.h>

#include <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>

#if !defined(EEOF) && defined(EIO)
#define EEOF EIO
#endif

__attribute__((unused)) static inline
size_t readleast(int fd, void* buf_ptr, size_t least, size_t max)
{
	assert(least <= max);
	unsigned char* buf = (unsigned char*) buf_ptr;
	size_t done = 0;
	do
	{
		ssize_t amount = read(fd, buf + done, max - done);
		if ( amount < 0 )
			return done;
		if ( !amount && done < least )
			return errno = EEOF, done;
		if ( !amount )
			break;
		done += amount;
	} while ( done < least );
	return done;
}

__attribute__((unused)) static inline
size_t writeleast(int fd, const void* buf_ptr, size_t least, size_t max)
{
	assert(least <= max);
	const unsigned char* buf = (const unsigned char*) buf_ptr;
	size_t done = 0;
	do
	{
		ssize_t amount = write(fd, buf + done, max - done);
		if ( amount < 0 )
			return done;
		if ( !amount && done < least )
			return errno = EEOF, done;
		if ( !amount )
			break;
		done += amount;
	} while ( done < least );
	return done;
}

__attribute__((unused)) static inline
size_t preadleast(int fd, void* buf_ptr, size_t least, size_t max, off_t off)
{
	assert(least <= max);
	unsigned char* buf = (unsigned char*) buf_ptr;
	size_t done = 0;
	do
	{
		ssize_t amount = pread(fd, buf + done, max - done, off + done);
		if ( amount < 0 )
			return done;
		if ( !amount && done < least )
			return errno = EEOF, done;
		if ( !amount )
			break;
		done += amount;
	} while ( done < least );
	return done;
}

__attribute__((unused)) static inline
size_t pwriteleast(int fd, const void* buf_ptr, size_t least, size_t max, off_t off)
{
	assert(least <= max);
	const unsigned char* buf = (const unsigned char*) buf_ptr;
	size_t done = 0;
	do
	{
		ssize_t amount = pwrite(fd, buf + done, max - done, off + done);
		if ( amount < 0 )
			return done;
		if ( !amount && done < least )
			return errno = EEOF, done;
		if ( !amount )
			break;
		done += amount;
	} while ( done < least );
	return done;
}

__attribute__((unused)) static inline
size_t readall(int fd, void* buf, size_t count)
{
	return readleast(fd, buf, count, count);
}

__attribute__((unused)) static inline
size_t writeall(int fd, const void* buf, size_t count)
{
	return writeleast(fd, buf, count, count);
}

__attribute__((unused)) static inline
size_t preadall(int fd, void* buf, size_t count, off_t off)
{
	return preadleast(fd, buf, count, count, off);
}

__attribute__((unused)) static inline
size_t pwriteall(int fd, const void* buf, size_t count, off_t off)
{
	return pwriteleast(fd, buf, count, count, off);
}

#endif

#endif