#ifndef LINTstatic const char rcsid[] = "$Id: ftruncate.c,v 1.1 2001/03/29 06:30:32 marka Exp $";#endif/* * ftruncate - set file size, BSD Style * * shortens or enlarges the file as neeeded * uses some undocumented locking call. It is known to work on SCO unix, * other vendors should try. * The #error directive prevents unsupported OSes */#include "port_before.h"#if defined(M_UNIX)#define OWN_FTRUNCATE#include <stdio.h>#ifdef _XOPEN_SOURCE#undef _XOPEN_SOURCE#endif#ifdef _POSIX_SOURCE#undef _POSIX_SOURCE#endif#include <fcntl.h>#include "port_after.h"int__ftruncate(int fd, long wantsize) {	long cursize;	/* determine current file size */	if ((cursize = lseek(fd, 0L, 2)) == -1)		return (-1);	/* maybe lengthen... */	if (cursize < wantsize) {		if (lseek(fd, wantsize - 1, 0) == -1 ||		    write(fd, "", 1) == -1) {			return (-1);		}		return (0);	}	/* maybe shorten... */	if (wantsize < cursize) {		struct flock fl;		fl.l_whence = 0;		fl.l_len = 0;		fl.l_start = wantsize;		fl.l_type = F_WRLCK;		return (fcntl(fd, F_FREESP, &fl));	}	return (0);}#endif#ifndef OWN_FTRUNCATEint __bindcompat_ftruncate;#endif