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