1#ifndef LINT 2static const char rcsid[] = "$Id: ftruncate.c,v 1.3 2005/04/27 18:16:45 sra Exp $"; 3#endif 4 5/*! \file 6 * \brief 7 * ftruncate - set file size, BSD Style 8 * 9 * shortens or enlarges the file as neeeded 10 * uses some undocumented locking call. It is known to work on SCO unix, 11 * other vendors should try. 12 * The #error directive prevents unsupported OSes 13 */ 14 15#include "port_before.h" 16 17#if defined(M_UNIX) 18#define OWN_FTRUNCATE 19#include <stdio.h> 20#ifdef _XOPEN_SOURCE 21#undef _XOPEN_SOURCE 22#endif 23#ifdef _POSIX_SOURCE 24#undef _POSIX_SOURCE 25#endif 26 27#include <fcntl.h> 28 29#include "port_after.h" 30 31int 32__ftruncate(int fd, long wantsize) { 33 long cursize; 34 35 /* determine current file size */ 36 if ((cursize = lseek(fd, 0L, 2)) == -1) 37 return (-1); 38 39 /* maybe lengthen... */ 40 if (cursize < wantsize) { 41 if (lseek(fd, wantsize - 1, 0) == -1 || 42 write(fd, "", 1) == -1) { 43 return (-1); 44 } 45 return (0); 46 } 47 48 /* maybe shorten... */ 49 if (wantsize < cursize) { 50 struct flock fl; 51 52 fl.l_whence = 0; 53 fl.l_len = 0; 54 fl.l_start = wantsize; 55 fl.l_type = F_WRLCK; 56 return (fcntl(fd, F_FREESP, &fl)); 57 } 58 return (0); 59} 60#endif 61 62#ifndef OWN_FTRUNCATE 63int __bindcompat_ftruncate; 64#endif 65