Trailing-Edge
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PDP-10 Archives
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SRI_NIC_PERM_FS_1_19910112
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kcc-4/lib/usys/bufpos.c
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/*
* BUFPOS - skip through buffer figuring out physical file position
*
* Copyright (C) 1986 by Ian Macky, SRI International
*/
/* This routine is not a system call. It is used ONLY by STDIO's ftell()
** which cheats. Eventually some better mechanism should be developed and
** this routine flushed. --KLH
*/
#include "c-env.h"
#include "sys/usysio.h"
#include "sys/usysig.h"
long _bufpos(fd, n)
int fd, n;
{
char *p;
int c, ufx, position;
USYS_BEG();
if (fd < 0 || fd >= OPEN_MAX || !(ufx = _uioufx[fd]) ||
n < 0 || n > UIO_BUFSIZ)
USYS_RET(-1);
if (!(p = _uiopbuf[ufx]) || !(_uioflgs[ufx] & _UIO_CONVERTED))
USYS_RET(n); /* no buffer! */
position = 0;
c = *p;
while (n--) {
position++;
if (c == '\r') {
if ((c = *++p) == '\n') position++;
else continue;
}
c = *++p;
}
USYS_RET(position);
}