uclibc-ng/libc/sysdeps/linux/common/truncate64.c

/*
 * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
 *
 * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
 */
/* truncate64 syscall.  Copes with 64 bit and 32 bit machines
 * and on 32 bit machines this sends things into the kernel as
 * two 32-bit arguments (high and low 32 bits of length) that
 * are ordered based on endianess.  It turns out endian.h has
 * just the macro we need to order things, __LONG_LONG_PAIR.
 */

#include <features.h>
#include <unistd.h>
#include <errno.h>
#include <endian.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/syscall.h>

#if defined __UCLIBC_HAS_LFS__

#if defined __NR_truncate64

#if __WORDSIZE == 64

/* For a 64 bit machine, life is simple... */
_syscall2(int, truncate64, const char *, path, __off64_t, length)

#elif __WORDSIZE == 32

#ifndef INLINE_SYSCALL
#define INLINE_SYSCALL(name, nr, args...) __syscall_truncate64(args)
#define __NR___syscall_truncate64 __NR_truncate64
#if defined(__UCLIBC_TRUNCATE64_HAS_4_ARGS__)
static __inline__ _syscall4(int, __syscall_truncate64, const char *, path,
	uint32_t, pad, unsigned long, high_length, unsigned long, low_length)
#else
static __inline__ _syscall3(int, __syscall_truncate64, const char *, path,
	unsigned long, high_length, unsigned long, low_length)
#endif
#endif

/* The exported truncate64 function.  */
int truncate64(const char * path, __off64_t length)
{
	uint32_t low = length & 0xffffffff;
	uint32_t high = length >> 32;
#if defined(__UCLIBC_TRUNCATE64_HAS_4_ARGS__)
	return INLINE_SYSCALL(truncate64, 4, path, 0,
			__LONG_LONG_PAIR(high, low));
#else
	return INLINE_SYSCALL(truncate64, 3, path,
			__LONG_LONG_PAIR(high, low));
#endif
}

#else /* __WORDSIZE */
#error Your machine is not 64 bit nor 32 bit, I am dazed and confused.
#endif /* __WORDSIZE */

#else  /* __NR_truncate64 */

/* libc_hidden_proto(truncate) */

int truncate64(const char * path, __off64_t length)
{
	__off_t x = (__off_t) length;

	if (x == length) {
		return truncate(path, x);
	}

	__set_errno((x < 0) ? EINVAL : EFBIG);

	return -1;
}

#endif /* __NR_truncate64 */

#endif /* __UCLIBC_HAS_LFS__ */