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pread.c revision 1.6 
      1 /*	$NetBSD: pread.c,v 1.6 2003/01/18 11:33:09 thorpej Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 __RCSID("$NetBSD: pread.c,v 1.6 2003/01/18 11:33:09 thorpej Exp $");
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/types.h>
     43 #include <sys/syscall.h>
     44 #include <unistd.h>
     45 
     46 #ifdef __weak_alias
     47 __weak_alias(pread,_sys_pread)
     48 __weak_alias(_pread,_sys_pread)
     49 #endif
     50 
     51 ssize_t	 _sys_pread __P((int, void *, size_t, off_t));
     52 
     53 /*
     54  * This function provides 64-bit offset padding that
     55  * is not supplied by GCC 1.X but is supplied by GCC 2.X.
     56  */
     57 ssize_t
     58 _sys_pread(fd, buf, nbyte, offset)
     59 	int fd;
     60 	void *buf;
     61 	size_t nbyte;
     62 	off_t offset;
     63 {
     64 	quad_t q;
     65 	int rv;
     66 
     67 	q = __syscall((quad_t)SYS_pread, fd, buf, nbyte, 0, offset);
     68 	if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t) ||
     69 	    /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN)
     70 		rv = (int)q;
     71 	else
     72 		rv = (int)((u_quad_t)q >> 32);
     73 	return rv;
     74 }
     75