51 lines
1020 B
C
51 lines
1020 B
C
/*
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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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extern long lseek();
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extern int fflush();
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int
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fseek(iop, offset, ptrname)
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register FILE *iop;
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long offset;
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int ptrname;
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{
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register int c;
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long p;
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iop->_flag &= ~_IOEOF;
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if(iop->_flag & _IOREAD) {
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if(ptrname < 2 && iop->_base && !(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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p += (long)c-lseek(fileno(iop), 0L, 1);
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else
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offset -= (long)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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}
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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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}
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p = lseek(fileno(iop), offset, ptrname);
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iop->_cnt = 0;
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} else if(iop->_flag & (_IOWRT | _IORW)) {
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(void) 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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p = lseek(fileno(iop), offset, ptrname);
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}
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return((p == -1)? -1: 0);
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}
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