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#include <unistd.h>
#include <sys/time.h>
#include <errno.h>
#include "io_internal.h"
#ifdef __MINGW32__
#include <stdio.h>
#endif
void io_wantread_really(int64 d, io_entry* e);
int64 io_canread() {
io_entry* e;
#if defined(HAVE_SIGIO)
/* We promise that the user can call io_canread() and read, and
* the user uses io_tryread or calls io_eagain_read to signal if
* there is no more data to read. That means if the user does not
* call io_eagain_read, we need to know which fd it was so we can
* keep it in the alternative queue. */
if (alt_curread!=-1) {
e=iarray_get(&io_fds,alt_curread);
e->next_read=alt_firstread;
alt_firstread=alt_curread;
alt_curread=-1;
}
#endif
if (first_readable==-1)
#if defined(HAVE_SIGIO)
{
if (alt_firstread>=0 && (e=iarray_get(&io_fds,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=iarray_get(&io_fds,first_readable);
if (!e) break;
r=first_readable;
first_readable=e->next_read;
e->next_read=-1;
debug_printf(("io_canread: dequeue %lld from normal read queue (next is %ld)\n",r,first_readable));
if (e->closed) {
/* The fd was previously closed, but there were still open events on it.
* To prevent race conditions, we did not actually close the fd
* but only marked it as closed, so we can skip this event here */
continue;
}
#ifdef __MINGW32__
// printf("event on %d: wr %d rq %d aq %d\n",(int)r,e->wantread,e->readqueued,e->acceptqueued);
#endif
if (e->wantread &&
#ifdef __MINGW32__
(e->canread || e->acceptqueued==1 || e->readqueued==1)
#else
e->canread
#endif
) {
#if defined(HAVE_SIGIO)
#if 0
/* this code violates an invariant that the other code has, namely
* that e->next_read is -1 once the fd is dequeued. */
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));
#else
alt_curread=r;
#endif
if (io_waitmode!=_SIGIO)
#endif
e->canread=0;
if (!e->kernelwantread)
io_wantread_really(r,e);
return r;
}
}
return -1;
}