forked from lix-project/lix
* Handle a subtle race condition: the client closing the socket
between the last worker read/write and the enabling of the signal handler.
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parent
3ed9e4ad9b
commit
a9f9241054
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@ -76,7 +76,34 @@ static void startWork()
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canSendStderr = true;
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/* Handle client death asynchronously. */
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signal(SIGIO, sigioHandler);
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if (signal(SIGIO, sigioHandler) == SIG_ERR)
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throw SysError("setting handler for SIGIO");
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/* Of course, there is a race condition here: the socket could
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have closed between when we last read from / wrote to it, and
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between the time we set the handler for SIGIO. In that case we
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won't get the signal. So do a non-blocking select() to find
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out if any input is available on the socket. If there is, it
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has to be the 0-byte read that indicates that the socket has
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closed. */
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struct timeval timeout;
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timeout.tv_sec = timeout.tv_usec = 0;
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fd_set fds;
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FD_ZERO(&fds);
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FD_SET(STDIN_FILENO, &fds);
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if (select(STDIN_FILENO + 1, &fds, 0, 0, &timeout) == -1)
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throw SysError("select()");
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if (FD_ISSET(STDIN_FILENO, &fds)) {
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char c;
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if (read(STDIN_FILENO, &c, 1) != 0)
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throw Error("EOF expected (protocol error?)");
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_isInterrupted = 1;
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checkInterrupt();
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}
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}
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@ -87,7 +114,8 @@ static void stopWork()
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/* Stop handling async client death; we're going to a state where
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we're either sending or receiving from the client, so we'll be
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notified of client death anyway. */
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signal(SIGIO, SIG_IGN);
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if (signal(SIGIO, SIG_IGN) == SIG_ERR)
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throw SysError("ignoring SIGIO");
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canSendStderr = false;
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writeInt(STDERR_LAST, *_to);
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