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71 lines
1.5 KiB
71 lines
1.5 KiB
/* This is file FSEEK.C */
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/* This file may have been modified by DJ Delorie (Jan 1991). If so,
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** these modifications are Coyright (C) 1991 DJ Delorie, 24 Kirsten Ave,
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** Rochester NH, 03867-2954, USA.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)fseek.c 5.3 (Berkeley) 3/9/86";
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#endif LIBC_SCCS and not lint
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/*
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* Seek for standard library. Coordinates with buffering.
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*/
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#include <stdio.h>
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#ifdef linux
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#include <unistd.h>
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#endif
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int
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fseek(register FILE *iop, long offset, int ptrname)
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{
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register resync, c;
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long p = -1; /* can't happen? */
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iop->_flag &= ~_IOEOF;
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if (iop->_flag&_IOREAD) {
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if (ptrname<2 && iop->_base &&
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!(iop->_flag&_IONBF)) {
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c = iop->_cnt;
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p = offset;
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if (ptrname==0) {
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long curpos = lseek(fileno(iop), 0L, 1);
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if (curpos == -1)
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return (-1);
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p += c - curpos;
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} else
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offset -= c;
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if(!(iop->_flag&_IORW) && c>0&&p<=c
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&& p>=iop->_base-iop->_ptr){
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iop->_ptr += (int)p;
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iop->_cnt -= (int)p;
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return(0);
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}
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resync = offset&01;
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} else
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resync = 0;
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if (iop->_flag & _IORW) {
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iop->_ptr = iop->_base;
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iop->_flag &= ~_IOREAD;
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resync = 0;
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}
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p = lseek(fileno(iop), offset-resync, ptrname);
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iop->_cnt = 0;
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if (resync && p != -1)
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if (getc(iop) == EOF)
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p = -1;
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}
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else if (iop->_flag & (_IOWRT|_IORW)) {
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p = fflush(iop);
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if (iop->_flag & _IORW) {
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iop->_cnt = 0;
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iop->_flag &= ~_IOWRT;
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iop->_ptr = iop->_base;
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}
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return(lseek(fileno(iop), offset, ptrname) == -1 || p == EOF ?
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-1 : 0);
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}
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return(p==-1?-1:0);
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}
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