1#include "shgetc.h"
2
3/* The shcnt field stores the number of bytes read so far, offset by
4 * the value of buf-rpos at the last function call (__shlim or __shgetc),
5 * so that between calls the inline shcnt macro can add rpos-buf to get
6 * the actual count. */
7
8void __shlim(FILE *f, off_t lim)
9{
10 f->shlim = lim;
11 f->shcnt = f->buf - f->rpos;
12 /* If lim is nonzero, rend must be a valid pointer. */
13 if (lim && f->rend - f->rpos > lim)
14 f->shend = f->rpos + lim;
15 else
16 f->shend = f->rend;
17}
18
19int __shgetc(FILE *f)
20{
21 int c;
22 off_t cnt = shcnt(f);
23 if (f->shlim && cnt >= f->shlim || (c=__uflow(f)) < 0) {
24 f->shcnt = f->buf - f->rpos + cnt;
25 f->shend = f->rpos;
26 f->shlim = -1;
27 return EOF;
28 }
29 cnt++;
30 if (f->shlim && f->rend - f->rpos > f->shlim - cnt)
31 f->shend = f->rpos + (f->shlim - cnt);
32 else
33 f->shend = f->rend;
34 f->shcnt = f->buf - f->rpos + cnt;
35 if (f->rpos <= f->buf) f->rpos[-1] = c;
36 return c;
37}