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41 lines
1.1 KiB
C

#include <unistd.h>
#include <sys/time.h>
#include <errno.h>
#include "io_internal.h"
int64 io_canread() {
io_entry* e;
if (first_readable==-1)
#ifdef HAVE_SIGIO
{
if (alt_firstread>=0 && (e=array_get(&io_fds,sizeof(io_entry),alt_firstread)) && e->canread) {
debug_printf(("io_canread: normal read queue is empty, swapping in alt read queue (starting with %ld)\n",alt_firstread));
first_readable=alt_firstread;
alt_firstread=-1;
} else
return -1;
}
#else
return -1;
#endif
for (;;) {
int64 r;
e=array_get(&io_fds,sizeof(io_entry),first_readable);
if (!e) break;
r=first_readable;
first_readable=e->next_read;
debug_printf(("io_canread: dequeue %lld from normal read queue (next is %ld)\n",r,first_readable));
if (e->wantread && e->canread) {
#ifdef HAVE_SIGIO
e->next_read=alt_firstread;
alt_firstread=r;
debug_printf(("io_canread: enqueue %ld in alt read queue (next is %ld)\n",alt_firstread,e->next_read));
if (io_waitmode!=_SIGIO)
#endif
e->canread=0;
return r;
}
}
return -1;
}