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Fix FD_ISSET issue by replacing pselect with ppoll
The issue `IO Exception: select reports ready to read, but our fd isn't in the list, this shouldn't happen!, file /tmp/drf-deps-vendornpgsoe22/serial/src/impl/unix.cc, line 516.` is due to the use of FD_ISSET required by select/pselect. The provided solution is to use ppoll instead of pselect.
This commit is contained in:
medjo
parent
683e12d2f6
commit
c7230c4f47
100
src/impl/unix.cc
Executable file → Normal file
100
src/impl/unix.cc
Executable file → Normal file
@ -23,9 +23,10 @@
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# include <linux/serial.h>
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#endif
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#include <sys/select.h>
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#include <sys/time.h>
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#include <time.h>
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#include <signal.h>
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#include <poll.h>
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#ifdef __MACH__
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#include <AvailabilityMacros.h>
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#include <mach/clock.h>
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@ -435,7 +436,7 @@ Serial::SerialImpl::reconfigurePort ()
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// http://www.unixwiz.net/techtips/termios-vmin-vtime.html
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// this basically sets the read call up to be a polling read,
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// but we are using select to ensure there is data available
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// but we are using poll to ensure there is data available
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// to read before each call, so we should never needlessly poll
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options.c_cc[VMIN] = 0;
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options.c_cc[VTIME] = 0;
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@ -494,15 +495,13 @@ Serial::SerialImpl::available ()
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bool
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Serial::SerialImpl::waitReadable (uint32_t timeout)
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{
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// Setup a select call to block for serial data or a timeout
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fd_set readfds;
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FD_ZERO (&readfds);
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FD_SET (fd_, &readfds);
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// Setup a poll call to block for serial data or a timeout
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timespec timeout_ts (timespec_from_ms (timeout));
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int r = pselect (fd_ + 1, &readfds, NULL, NULL, &timeout_ts, NULL);
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struct pollfd fds[] = {fd_, POLLIN, 0};
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int r = ppoll (fds, 1, &timeout_ts, NULL);
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if (r < 0) {
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// Select was interrupted
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// poll was interrupted
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if (errno == EINTR) {
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return false;
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}
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@ -513,11 +512,6 @@ Serial::SerialImpl::waitReadable (uint32_t timeout)
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if (r == 0) {
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return false;
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}
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// This shouldn't happen, if r > 0 our fd has to be in the list!
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if (!FD_ISSET (fd_, &readfds)) {
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THROW (IOException, "select reports ready to read, but our fd isn't"
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" in the list, this shouldn't happen!");
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}
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// Data available to read.
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return true;
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}
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@ -526,7 +520,8 @@ void
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Serial::SerialImpl::waitByteTimes (size_t count)
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{
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timespec wait_time = { 0, static_cast<long>(byte_time_ns_ * count)};
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pselect (0, NULL, NULL, NULL, &wait_time, NULL);
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struct pollfd fds[] = {-1, 0, 0};
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int r = ppoll (fds, 0, &wait_time, NULL);
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}
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size_t
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@ -557,7 +552,7 @@ Serial::SerialImpl::read (uint8_t *buf, size_t size)
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// Timed out
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break;
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}
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// Timeout for the next select is whichever is less of the remaining
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// Timeout for the next poll is whichever is less of the remaining
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// total read timeout and the inter-byte timeout.
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uint32_t timeout = std::min(static_cast<uint32_t> (timeout_remaining_ms),
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timeout_.inter_byte_timeout);
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@ -573,10 +568,10 @@ Serial::SerialImpl::read (uint8_t *buf, size_t size)
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}
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}
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// This should be non-blocking returning only what is available now
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// Then returning so that select can block again.
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// Then returning so that poll can block again.
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ssize_t bytes_read_now =
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::read (fd_, buf + bytes_read, size - bytes_read);
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// read should always return some data as select reported it was
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// read should always return some data as poll reported it was
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// ready to read when we get to this point.
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if (bytes_read_now < 1) {
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// Disconnected devices, at least on Linux, show the
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@ -633,16 +628,13 @@ Serial::SerialImpl::write (const uint8_t *data, size_t length)
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timespec timeout(timespec_from_ms(timeout_remaining_ms));
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FD_ZERO (&writefds);
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FD_SET (fd_, &writefds);
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struct pollfd fds[] = {fd_, POLLOUT, 0};
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int r = ppoll (fds, 1, &timeout, NULL);
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// Do the select
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int r = pselect (fd_ + 1, NULL, &writefds, NULL, &timeout, NULL);
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// Figure out what happened by looking at select's response 'r'
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// Figure out what happened by looking at ppoll's response 'r'
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/** Error **/
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if (r < 0) {
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// Select was interrupted, try again
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// poll was interrupted, try again
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if (errno == EINTR) {
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continue;
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}
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@ -655,40 +647,34 @@ Serial::SerialImpl::write (const uint8_t *data, size_t length)
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}
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/** Port ready to write **/
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if (r > 0) {
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// Make sure our file descriptor is in the ready to write list
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if (FD_ISSET (fd_, &writefds)) {
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// This will write some
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ssize_t bytes_written_now =
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::write (fd_, data + bytes_written, length - bytes_written);
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// write should always return some data as select reported it was
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// ready to write when we get to this point.
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if (bytes_written_now < 1) {
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// Disconnected devices, at least on Linux, show the
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// behavior that they are always ready to write immediately
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// but writing returns nothing.
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throw SerialException ("device reports readiness to write but "
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"returned no data (device disconnected?)");
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}
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// Update bytes_written
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bytes_written += static_cast<size_t> (bytes_written_now);
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// If bytes_written == size then we have written everything we need to
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if (bytes_written == length) {
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break;
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}
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// If bytes_written < size then we have more to write
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if (bytes_written < length) {
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continue;
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}
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// If bytes_written > size then we have over written, which shouldn't happen
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if (bytes_written > length) {
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throw SerialException ("write over wrote, too many bytes where "
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"written, this shouldn't happen, might be "
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"a logical error!");
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}
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// This will write some
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ssize_t bytes_written_now =
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::write (fd_, data + bytes_written, length - bytes_written);
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// write should always return some data as poll reported it was
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// ready to write when we get to this point.
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if (bytes_written_now < 1) {
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// Disconnected devices, at least on Linux, show the
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// behavior that they are always ready to write immediately
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// but writing returns nothing.
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throw SerialException ("device reports readiness to write but "
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"returned no data (device disconnected?)");
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}
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// Update bytes_written
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bytes_written += static_cast<size_t> (bytes_written_now);
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// If bytes_written == size then we have written everything we need to
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if (bytes_written == length) {
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break;
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}
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// If bytes_written < size then we have more to write
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if (bytes_written < length) {
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continue;
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}
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// If bytes_written > size then we have over written, which shouldn't happen
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if (bytes_written > length) {
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throw SerialException ("write over wrote, too many bytes where "
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"written, this shouldn't happen, might be "
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"a logical error!");
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}
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// This shouldn't happen, if r > 0 our fd has to be in the list!
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THROW (IOException, "select reports ready to write, but our fd isn't"
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" in the list, this shouldn't happen!");
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}
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}
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return bytes_written;
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