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Problem Report 0329 Details

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    Problem Report Number 0329
    Submitter's Classification Specification problem
    State Resolved
    Resolution Permanent Interpretation (PIN)
    Problem Resolution ID PIN.X.0045
    Raised 1994-10-11 08:00
    Updated 2003-03-13 08:00
    Published 1994-10-27 08:00
    Product Standard Internationalised System Calls and Libraries (XPG4)
    Certification Program The Open Brand certification program
    Test Suite VSX4 version 4.3.4
    Test Identification ANSI.os/genuts/system_X 50, 51, 59
    Specification System Interfaces and Headers Issue 4
    Location in Spec See Problem Text
    Problem Summary PIN4.045 These testcases make one crucial assumption that cannot be expected to work on every platform. The assumption is that a SIGALRM signal will be delivered to the parent in the middle of a system() funct...
    Problem Text
    These testcases make one crucial assumption that cannot be expected to
    work on every platform. The assumption is that a SIGALRM signal will
    be delivered to the parent in the middle of a system() function call.

    Our implementation blocks all blockable signals during the a call to
    the system() function so a SIGALRM signal will not arrive until after
    the command being executed has completed. In these tests, the SIGALRM
    signal handlers verify that:

    - (test 50) SIGINT and SIGCONT are ignored - they do not appear
    to be ignored because the system() function has already
    restored their actions.

    - (test 51) SIGCHLD is blocked - it does not appear to be
    blocked because the system() function has already restored
    the signal mask

    - (test 59) system() returns an error if the handler does the wait()
    for the child before the system() function has the chance to do
    so - the signal handler receives an ECHILD error because the
    system() function already performed the wait()

    Since a SIGALRM handler has no chance to gain control until after the
    wait() completes for the system() function, these tests cannot be
    expected to work.
    Test Output
    ************************************************************************

    /tset/ANSI.os/genuts/system_X/T.system_X 50 Failed

    Test Description:
    When a SIGINT or SIGQUIT signal is raised for a process during the
    execution of a call to system(), (while system() is awaiting a
    termination status from the command interpreter) then the SIGINT or
    SIGQUIT signal is ignored.
    Not tested in XPG3 mode.

    Test Strategy:
    CREATE a child process.
    SETUP signal catcher for SIGALRM
    SET alarm time to 5 seconds
    CALL system(cmd), where command executes a sleep()
    SIGNAL catcher will
    EXAMINE signal settings using sigaction()
    VERIFY that SIGINT and SIGQUIT were set to be ignored

    Test Information:
    system() did not ignore SIGINT
    system() did not ignore SIGQUIT

    ************************************************************************

    /tset/ANSI.os/genuts/system_X/T.system_X 51 Failed

    Test Description:
    When a call to system() is awaiting a termination status from the
    command interpreter, then it blocks the SIGCHLD signal.
    Not tested in XPG3 mode.

    Test Strategy:
    CREATE a child process.
    SETUP signal catcher for SIGALRM
    SET alarm time to 5 seconds
    CALL system(cmd), where command executes a sleep()
    SIGNAL catcher will
    EXAMINE signal mask using sigprocmask()
    VERIFY that SIGCHLD was blocked using sigismember()

    Test Information:
    system() did not block SIGCHLD

    ************************************************************************

    /tset/ANSI.os/genuts/system_X/T.system_X 59 Unresolved

    Test Description:
    When the termination status for the command language interpreter
    cannot be obtained, then a call to system() returns -1 and sets errno
    to indicate the error.
    Not tested in XPG3 mode.

    Test Information:
    wait() failed - errno 115 (ECHILD)

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    The XPG states that during the call to the system() function the SIGINT
    and SIGQUIT signals are ignored and the SIGCHLD signal is blocked. There
    is no mention of changes to the disposition of other signals and it could
    be considered that the specification allows these signals to be blocked on
    entry to any call as long as they are unblocked before the call returns.
    An alternative reading of the specification of system() is that it only
    allows the changes to the signal disposition as stated in the description.

    I believe that the first of these alternatives is the correct interpretation
    and that a permanent interpretation should be granted.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Permanent Interpretation (PIN)
    Review Conclusion
    A Permanent Interpretation is granted.

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