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#include <unistd.h>
#include <sys/time.h>
#include <poll.h>
#include <errno.h>
#include "io_internal.h"
int64 io_tryread(int64 d,char* buf,int64 len) {
long r;
struct itimerval old,new;
struct pollfd p;
io_entry* e=array_get(&io_fds,sizeof(io_entry),d);
if (!e) { errno=EBADF; return -3; }
if (!e->nonblock) {
p.fd=d;
if (p.fd != d) { errno=EBADF; return -3; } /* catch overflow */
p.events=POLLIN;
switch (poll(&p,1,0)) {
case -1: return -3;
case 0: errno=EAGAIN;
e->canread=0;
e->next_read=-1;
return -1;
}
new.it_interval.tv_usec=10000;
new.it_interval.tv_sec=0;
new.it_value.tv_usec=10000;
new.it_value.tv_sec=0;
setitimer(ITIMER_REAL,&new,&old);
}
r=read(d,buf,len);
if (!e->nonblock) {
setitimer(ITIMER_REAL,&old,0);
}
if (r==-1) {
if (errno==EINTR) errno=EAGAIN;
if (errno!=EAGAIN)
r=-3;
}
if (r==-1 || r==0) {
e->canread=0;
#ifdef HAVE_SIGIO
if (d==alt_firstread) {
debug_printf(("io_tryread: dequeueing %ld from alt read queue (next is %ld)\n",d,e->next_read));
alt_firstread=e->next_read;
}
#endif
e->next_read=-1;
}
return r;
}