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#include <poll.h>
#include <inttypes.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#define P_READ (0)
#define P_WRITE (1)
/*
* Generic (posix) implelentation of signals, using pipes.
* 64bit version, packing two ints into a pointer.
* This version requires that you use -fno-strict-aliasing
* since it's doing evil pointer casting.
*/
dnbd3_signal_t* signal_new()
{
int fds[2];
if ( pipe( fds ) == -1 ) return NULL;
fcntl( fds[P_READ], F_SETFL, O_NONBLOCK );
fcntl( fds[P_WRITE], F_SETFL, O_NONBLOCK );
return (dnbd3_signal_t*)*((uintptr_t*)fds);
}
dnbd3_signal_t* signal_newBlocking()
{
int fds[2];
if ( pipe( fds ) == -1 ) return NULL;
return (dnbd3_signal_t*)*((uintptr_t*)fds);
}
int signal_call(const dnbd3_signal_t* const signal)
{
if ( signal == NULL ) return SIGNAL_ERROR;
static char one = 1;
const int* fds = (int*)&signal;
// Write one byte on every call, so the number of bytes read will
// match the number of events
return write( fds[P_WRITE], &one, 1 ) > 0 ? SIGNAL_OK : SIGNAL_ERROR;
}
int signal_wait(const dnbd3_signal_t* const signal, int timeoutMs)
{
if ( signal == NULL ) return SIGNAL_ERROR;
const int* fds = (int*)&signal;
struct pollfd ps = {
.fd = fds[P_READ],
.events = POLLIN
};
int ret = poll( &ps, 1, timeoutMs );
if ( ret == 0 ) return SIGNAL_TIMEOUT;
if ( ret == -1 ) return SIGNAL_ERROR;
if ( ps.revents & ( POLLERR | POLLNVAL ) ) return SIGNAL_ERROR;
return signal_clear( signal );
}
int signal_clear(const dnbd3_signal_t* const signal)
{
if ( signal == NULL ) return SIGNAL_ERROR;
char throwaway[100];
const int* fds = (int*)&signal;
ssize_t ret, total = 0;
do {
ret = read( fds[P_READ], throwaway, sizeof throwaway );
if ( ret < 0 ) {
if ( errno == EAGAIN ) return total;
return SIGNAL_ERROR;
}
total += ret;
} while ( (size_t)ret == sizeof throwaway );
return (int)total;
}
void signal_close(const dnbd3_signal_t* const signal)
{
const int* fds = (int*)&signal;
close( fds[P_READ] );
close( fds[P_WRITE] );
}
int signal_getWaitFd(const dnbd3_signal_t* const signal)
{
if ( signal == NULL ) return -1;
const int* fds = (int*)&signal;
return fds[P_READ];
}
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