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substdi.c
74 lines (62 loc) · 1.31 KB
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substdi.c
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#include "substdio.h"
#include "byte.h"
#include "error.h"
static int oneread(substdio_fn op,int fd,char *buf,int len)
{
int r;
for (;;) {
r = op(fd,buf,len);
if (r == -1) if (errno == error_intr) continue;
return r;
}
}
static int getthis(substdio *s,char *buf,int len)
{
int r;
int q;
r = s->p;
q = r - len;
if (q > 0) { r = len; s->p = q; } else s->p = 0;
byte_copy(buf,r,s->x + s->n);
s->n += r;
return r;
}
int substdio_feed(substdio *s)
{
int r;
int q;
if (s->p) return s->p;
q = s->n;
r = oneread(s->op,s->fd,s->x,q);
if (r <= 0) return r;
s->p = r;
q -= r;
s->n = q;
if (q > 0) /* damn, gotta shift */ byte_copyr(s->x + q,r,s->x);
return r;
}
int substdio_bget(substdio *s,char *buf,int len)
{
int r;
if (s->p > 0) return getthis(s,buf,len);
r = s->n; if (r <= len) return oneread(s->op,s->fd,buf,r);
r = substdio_feed(s); if (r <= 0) return r;
return getthis(s,buf,len);
}
int substdio_get(substdio *s,char *buf,int len)
{
int r;
if (s->p > 0) return getthis(s,buf,len);
if (s->n <= len) return oneread(s->op,s->fd,buf,len);
r = substdio_feed(s); if (r <= 0) return r;
return getthis(s,buf,len);
}
const char *substdio_peek(substdio *s)
{
return s->x + s->n;
}
void substdio_seek(substdio *s,int len)
{
s->n += len;
s->p -= len;
}