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Problem Report 1435 Details

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Report 1435 Actions

    Problem Report Number 1435
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Test Suite Deficiency (TSD)
    Problem Resolution ID TSD.X.0717
    Raised 1970-01-01 08:00
    Updated 2003-03-13 08:00
    Published 1996-01-16 08:00
    Product Standard Internationalised System Calls and Libraries Extended (UNIX 95)
    Certification Program The Open Brand certification program
    Test Suite VSU version 4.0.2
    Test Identification CAPIbase/writev 58
    Problem Summary TSD4U.00098 This test may fail on implmentations where setpgrp() does not create a new session (VSU_SETPGRP_CREATES_SESSION is false).
    Problem Text
    This test may fail on implmentations where setpgrp() does not create
    a new session (VSU_SETPGRP_CREATES_SESSION is false).

    Consequently, the writev() function is not returning an error after
    the process is orphaned. Instead, the call returns successfully.

    We believe that the cause of the writev58 failure is due to a programming
    error in the fwritev58.c test module. The test routine was calling setpgrp()
    which was failing. This failure was not spotted because it was not enclosed in
    the usual error trapping wrapper. setpgrp() was failing with error EPERM
    due to the caller already being a process group leader. This usual practice
    to avoid this error is to first fork and then have the child call setpgrp()
    so that it's process id is different to it's inherited process group id. Once
    this fork was placed into the test routine it worked as expected and the
    test passed.

    Further, the function setpgrp() was added to XPG4 because it was defined in
    the SVID. The SVID states what setpgrp() will return upon success, but is
    silent about what it returns upon failure. The SVID got translated into
    the XPG4 as:

    DESCRIPTION
    If the calling process is not already a session
    leader, setpgrp() sets the process group ID of the
    calling process to the process ID of the calling
    process. If setpgrp() creates a new session, then
    the new session has no controlling terminal.

    The setpgrp() function has no effect when the
    calling process is a session leader.

    RETURN VALUE
    Upon successful completion, setpgrp() returns the
    new process group ID.

    ERRORS
    No errors are defined.

    The test did not check for an error because no error is defined. However,
    the XPG4 states "If the calling process is not already a session leader ...",
    and "Upon successful completion...". What, pray tell, does it do if the
    process is already a session leader? What if the completion is not successful?

    So, what is missing from the equation? Well, if one reads the SVID
    (rather than the XPG4), one will notice that there is a statement:

    The function setpgrp() will be phased out in favor of the function
    setsid() and has moved to Level 2 effective September 30, 1989.
    -------

    "Level 2" means it is obsolete.

    So looking a the XPG4 definition of setsid():

    DESCRIPTION
    The setsid() function creates a new session, if the
    calling process is not a process group leader. Upon
    return the calling process will be the session
    leader of this new session, will be the process
    group leader of a new process group, and will have
    no controlling terminal. The process group ID of
    the calling process will be set equal to the process
    ID of the calling process. The calling process will
    be the only process in the new process group and the
    only process in the new session.

    RETURN VALUE
    Upon successful completion, setsid() returns the
    value of the process group ID of the calling
    process. Otherwise it returns (pid_t)-1 and sets
    errno to indicate the error.

    ERRORS
    The setsid() function will fail if:

    [EPERM] The calling process is already a
    process group leader, or the process
    group ID of a process other than the
    calling process matches the process
    ID of the calling process.

    The function setsid() has been in the X/Open Portability Guide since
    XPG3, and *it* was added to align with POSIX! The test should not be
    using setpgrp(), because it has an implied error condition but no error
    return defined!! It should be using setsid() and checking the error
    return!!!

    Test Output

    TEST PURPOSE #58
    EIO in errno and return -1 on a call to ssize_t
    writev(int fildes, const struct iovec *iov, int
    iovcnt) when the process is a member of a background
    process group and is attempting to write to its
    controlling terminal, TOSTOP is set, the process is
    neither ignoring nor blocking the SIGTTOU signal, and
    the process is orphaned.
    PREP: Allocate and initialize I/O buffers
    PREP: Open master side of pseudo terminal
    PREP: Open slave side as controlling terminal
    PREP: Set TOSTOP
    PREP: fork() a child
    PREP: fork() a child of the child
    PREP: Put process in background
    PREP: Wait to become orphan
    PREP: Catch SIGTTOU
    TEST: Call writev()
    TEST: writev() returns -1 with EIO set
    ERROR: writev() returned 8192 with errno = 0(0 - No error), expected -1
    with
    errno = EIO
    PREP: Let first child die so second is orphan
    58 FAIL

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    We agree this is a test suite deficiency in the test
    suite version(s) listed.

    Although this fails for the same reason as TSD4U.00027, the failure
    point is different. The default openctl() function provided in the
    user-defined capi_user directory does not detect the failure of the
    setpgrp() function as in TSD4U.00027, where the openctl() function
    contained an additional ioctl() call that fails.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Test Suite Deficiency (TSD)
    Review Conclusion
    This is an agreed Test Suite Deficiency.

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