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Problem Report 0250 Details

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    Problem Report Number 0250
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Test Suite Deficiency (TSD)
    Problem Resolution ID TSD.X.0250
    Raised 1996-01-12 08:00
    Updated 2003-03-13 08:00
    Published 1996-01-19 08:00
    Product Standard Internationalised System Calls and Libraries (XPG4)
    Certification Program The Open Brand certification program
    Test Suite VSX4 version 4.3.5
    Test Identification ANSI.os/genuts/free 1
    Linked Problem Reports TSD4.176, (in, old, system)
    Problem Summary TSD4.250 This waiver was granted with TSD4.125 under VSX4.2.4, TSD4.176 under VSX4.3.2 and the failure still occurs under VSX4.3.5. A new TSD is been requested. The strategy in test 1 seems flawed based on the...
    Problem Text

    ***********************************************************************
    This waiver was granted with TSD4.125 under VSX4.2.4, TSD4.176 under
    VSX4.3.2 and the failure still occurs under VSX4.3.5. A new TSD is
    been requested.
    ***********************************************************************
    The strategy in test 1 seems flawed based on the XPG4 and ANSI C
    specifications. The basic assumption that the same memory area is
    allocated on the subsequent malloc() after a free(), is not specified
    in XPG4 or ANSI. This assumption would require that an implementation
    follow a specified algorithm for allocation of memory. Since no such
    algorithm is specified by XPG4 or ANSI, the assumption made in the
    test strategy is in error.

    The algorithm/strategy used in our implementation is based on our
    performance analysis and advanced algorithms for memory allocation
    and dispersement. When smaller blocks are free'd, they are coalesced
    into larger blocks, effectively removing the "individuality" of the
    smaller block. Therefore, acquiring the exact same memory region in
    a subsequent malloc is not guaranteed.

    The following test program successfully demonstrates that our
    implementation does indeed make free'd memory "availabe for further
    allocation". Please feel free to review this test program.

    In general, there needs to be a way to test the functionality as
    specified for free(), without infringing on the ability of an
    implementation to utilize unique algorithms for memory allocation.
    ***********************************************************************

    Test Output

    ************************************************************************
    /tset/ANSI.os/genuts/free/T.free 1 Failed

    Test Description:
    free() frees the block pointed to by ptr and makes it available for
    further allocation.
    Posix Ref: Component FREE Assertion 8.1-04(A)

    Test Strategy:
    CREATE child process
    CHILD process will
    CALL malloc() to allocate 20 bytes
    CALL free() to free the area of memory just allocated
    REPEAT 1000 times:
    CALL malloc() to allocate 20 bytes
    CHECK whether area of memory just allocated overlaps area
    previously freed
    VERIFY that an overlap was found

    Test Information:
    failed to reuse freed memory in next 1000 malloc() calls
    ***********************************************************************

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    It is recognised that the test strategy may not work on implementations
    with advanced memory allocation algorithms. A waiver is recommended on
    the grounds of a Test Suite Deficiency.

    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.

    Problem Reporting System Options:

     

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