Problem Report 0019 Details

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    Problem Report Number 0019
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Rejected (REJ)
    Problem Resolution ID REJ.PX.0012
    Raised 2004-06-24 06:29
    Updated 2004-06-30 20:07
    Published 2004-06-30 20:07
    Product Standard 1003.1-2003 System Interfaces
    Certification Program POSIX Certified by IEEE and The Open Group
    Test Suite VSX-PCTS2003 version 1.0B
    Test Identification /tset/POSIX.os/procprim/sigconcept/T.sigconcept 35
    Location in Spec Volume 2, section 2.4.4
    Problem Summary A sigconcept test assumes that stopping a proccess stops reads from
    occuring to its buffers.
    Problem Text Section 2.4.4 states "If the action of the signal is to stop the
    process, the process shall stop until continued or terminated.
    Generation of a SIGCONT signal for the process shall cause the process
    to be continued, and the original function shall continue at the point
    the process was stopped."

    Signal Concept test 35 interpretes this to mean that if a process
    issues a read call which blocks and then process receives a STOP
    signal, a matching write call which would normally fill the read
    buffer an unblock the task has no effect. It does this by testing
    that SIGCONT with a signal handler to the blocked, reading process
    interrupt read() before any data is read.

    Our interpretation allows the write to fill the read buffer. When the
    reading process receives SIGCONT and the function is interrupted, it
    does not return EINTR because data was transferred.

    Analogous situations occur while blocking on open(), fnctl(), and write
    ().
    Test Output /tset/POSIX.os/procprim/sigconcept/T.sigconcept 35 Failed

    Test Description:
    If _POSIX_JOB_CONTROL is defined, when any of the functions fcntl(),
    open(), pause(), read(), sleep(), sigsuspend(), tcdrain(), wait(),
    waitpid(), and write() are stopped by the delivery of a signal whose
    action is to stop the process, the subsequent generation of a SIGCONT
    signal that is being caught by a signal catching function shall cause
    the process to continue after returning from the signal catching
    function with the function reporting that it has been interrupted by
    the SIGCONT signal.
    Posix Ref: Component Signal Concepts Assertion 3.3.1.4-48(C)
    Posix Ref: Component Signal Concepts Assertion 3.3.1.4-49(C:D)

    Test Strategy:
    FOR each of the test functions tcdrain(), fcntl(), sleep(), pause(),
    sigsuspend(), read(), write(), open(), wait(), waitpid():
    IF terminal output is buffered or not testing tcdrain
    FORK a child process
    CHILD process:
    CREATE new process group using setpgid(0,0)
    SET the SIGCONT signal action to signal catching function
    SET the SIGSTOP signal action to SIG_DFL
    IF testing wait() or waitpid()
    FORK a child process which sleeps for 2.5 * WAITTIME
    CALL the test function
    PARENT process:
    SET alarm for time WAITTIME
    WAIT for the child process to obtain the child status
    VERIFY the child process is active
    SEND the SIGSTOP signal to the child process
    SLEEP for WAITTIME
    WAIT for the child process to obtain the child status
    VERIFY the child process stopped
    CALL a variable function dependent on the test function which
    will cause the test function to continue after SIGCONT is
    received
    SEND the SIGCONT signal to the child process
    CHILD process:
    VERIFY that test function returned an error with errno set to
    EINTR
    IF testing wait() or waitpid()
    KILL the child process waited for
    EXIT
    PARENT process:
    WAIT for the child process to obtain the child status
    VERIFY the child process exited

    Test Information:
    function reported no interruption by stopping or SIGCONT signal
    fcntl() returned 0 errno 32, should return -1 errno 4
    function reported no interruption by stopping or SIGCONT signal
    read() returned 1 errno 32, should return -1 errno 4
    function reported no interruption by stopping or SIGCONT signal
    write() returned 1 errno 32, should return -1 errno 4
    function reported no interruption by stopping or SIGCONT signal
    open() returned 9 errno 32, should return -1 errno 4

    Review Information

    Review Type TSMA Review
    Start Date 2004-06-24 06:29
    Last Updated 2004-06-24 18:52
    Completed 2004-06-24 18:52
    Status Complete
    Review Recommendation Rejected (REJ)
    Review Response This test does appear to be too strict in its testing of read() and
    write(). These functions do not always indicate an EINTR error when
    interrupted, and the test should allow for that. However, the same does
    not apply to fcntl() and open().

    XSH6 section 2.4.4 Signal Effects on Other Functions states:

    "Signals affect the behavior of certain functions defined by this volume
    of IEEE Std 1003.1-2001 if delivered to a process while it is executing
    such a function. [...] If the action of the signal is to invoke a
    signal-catching function, the signal-catching function shall be invoked;
    in this case the original function is said to be ``interrupted'' by the
    signal. If the signal-catching function executes a return statement, the
    behavior of the interrupted function shall be as described individually
    for that function"

    Since, as indicated by the submitter, a SIGCONT causes the process to
    continue "at the point the process was stopped", and in the test the
    process was stopped while executing the open() or fcntl() function, this
    means the SIGCONT signal is delivered to the process "while it is
    executing" open() or fcntl() respectively, and the above text from 2.4.4
    therefore applies to this delivery of this SIGCONT signal.

    The behaviour described individually for open() and fcntl() when
    interrupted is to indicate an EINTR error, and therefore the test is
    right to expect EINTR in those cases.

    Review Type SA Review
    Start Date 2004-06-24 17:52
    Last Updated 2004-06-30 20:07
    Completed 2004-06-30 20:07
    Status Complete
    Review Resolution Rejected (REJ)
    Review Conclusion The case for a waiver has not been made for all four
    interfaces cited. It is agreed that the tests are too strict
    for the read() and write() cases (see the TSMA response)
    and a waiver could be requested separately for those.
    However fcntl() and open() are expected to return EINTR in this case.
    This request is rejected.

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