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Problem Report 1928 Details

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Report 1928 Actions

    Problem Report Number 1928
    Submitter's Classification Test Suite problem
    State Resolved
    Resolution Rejected (REJ)
    Problem Resolution ID REJ.X.0564
    Raised 2000-10-23 08:00
    Updated 2003-03-13 08:00
    Published null
    Product Standard Internationalised System Calls and Libraries Extended V2 (UNIX 98)
    Certification Program The Open Brand certification program
    Test Suite VSX4 version 4.4.5
    Test Identification POSIX.os/files/fstat 1
    Problem Summary PG5R.007 In this case test is expecting that when we write to one end of pipe (fd[1]) time stamps on the other end (fd[0]) be updated. According to the CAE specification Issue 5: volume 1 page 34, "However, si...
    Problem Text

    In this case test is expecting that when we write to one end
    of pipe (fd[1]) time stamps on the other end (fd[0]) be
    updated.

    According to the CAE specification Issue 5: volume 1 page 34,

    "However, since pipes may be STREAMS-based, a STREAM can be a
    full-duplex connection between two processes"

    When pipes are full-duplex you cannot have a single shared stat
    structure because that design would imply a single buffer exists
    for the pipe.

    So, when specification states that streams based pipes are
    full-duplex, it is not correct for the tests to expect what
    amounts to half-duplex behavior in both design and implementation.

    Also, we think that the behaviour expected by VSX4 tests is not
    specified in the specification and request for a waiver.

    Test Output

    ************************************************************************
    /tset/POSIX.os/files/fstat/T.fstat 1 Failed

    Test Description:
    A call to fstat() stores information about the file associated with
    the named file descriptor in the area pointed to by buf and returns
    a value of zero.
    Posix Ref: Component FSTAT Assertion 5.6.2.2-04(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-05(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-06(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-07(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-08(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-09(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-10(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-11(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-12(A)
    Posix Ref: Component FSTAT Assertion 5.6.2.2-13(A)

    Test Strategy:
    CHECK st_dev, st_ino, S_ISREG(st_mode), st_size, st_atime, st_mtime
    and st_ctime for a regular file as follows:
    CREATE file using crfile() - (genlib)
    OBTAIN time using time()
    SLEEP for 2 seconds using sleep()
    WRITE data to file using write()
    CLOSE file descriptor using close()
    OBTAIN time using time()
    SLEEP for 1 second using sleep()
    OBTAIN file status information for "." and ".." using stat()
    OPEN file using open() with a time out
    OBTAIN file status information for test file using fstat()
    VERIFY that fstat() returned 0
    VERIFY that st_dev is the same as for "." and ".."
    VERIFY that st_ino is different from "." and ".."
    VERIFY that file is a regular file using S_ISREG()
    VERIFY that st_size is the same as the number of bytes written to
    the file
    VERIFY that st_atime is set to the value when time() was first
    called
    VERIFY that st_mtime and st_ctime are set to the value when time()
    was subsequently called
    UNLINK file
    CHECK st_mode permission bits as follows:
    CREATE file using crfile() - (genlib)
    FOR each portable file nane with each of the file modes and it's
    complement:
    CHANGE the mode of the current portable filename using chmod()
    with the current file mode
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that st_mode is the same as the current mode
    UNLINK file
    CHECK st_uid and st_gid as follows:
    CREATE child process using cppair()
    CREATE subprogram using execve passing as parameters: the
    Program name, the file name, the group and user ids for vsxg1 and vsx1
    CREATE file using creat() with read, write and execute
    permissions for user, group and others owned by user vsx1 and
    group vsxg1
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that st_uid and st_gid are set to vsx1 and vsxg1
    CHECK st_nlink as follows:
    CREATE file using crfile() - (genlib)
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that the number of links to the file is one
    LINK to file using link()
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that the number of links to the file is two
    CLOSE file descriptor using close()
    UNLINK file
    CHECK that S_ISDIR(st_mode) refers to a directory as follows:
    CREATE directory using crdir()
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that file is a directory using S_ISDIR()
    WHEN not testing the XNFS specification:
    CHECK that S_ISFIFO(st_mode) refers to a FIFO as follows:
    CREATE FIFO using mkfifo()
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that file is a directory using S_ISFIFO()
    WHEN not testing the XNFS specification:
    CHECK st_size, st_atime, st_mtime and st_ctime as follows:
    CREATE pipe using pipe()
    CALL fstat() to force timestamp update
    OBTAIN time using time()
    SLEEP for 2 seconds using sleep()
    WRITE data to file using write()
    CALL fstat() to force timestamp update
    OBTAIN time using time()
    SLEEP for 1 second using sleep()
    OBTAIN file status information using fstat()
    VERIFY that fstat() returned 0 and errno was not set
    VERIFY that st_atime is set to the value when time() was first
    called
    VERIFY that st_mtime is set to the value when time() was
    subsequently called
    VERIFY that st_ctime is set to the value when time() was
    subsequently called
    CLOSE both file descriptors using close()

    Test Information:
    fstat() on pipe set st_mtime incorrectly: expected 971125622,
    observed 971125620
    fstat() on pipe set st_ctime incorrectly: expected 971125622,
    observed 971125620

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

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    The behaviour expected by the test is definitely required by the
    specification. It derives from the definition of "pipe" in XBD5:

    "An object accessed by one of the pair of file descriptors created
    by the pipe() function. Once created, the file descriptors can be
    used to manipulate it, and it behaves identically to a FIFO special
    file when accessed in this way."

    together with the definition of "file times update" in XBD5:

    "Each file has three associated time values that are updated when
    file data has been accessed, file data has been modified, or file
    status has been changed, respectively. These values are returned in
    the file characteristics structure, as described in <sys/stat.h>."

    Since FIFOs are "files", they have "three associated time values",
    and these same three values are returned by calling stat() on the
    file name or by calling fstat() on any fd that is open to the FIFO,
    regardless of whether the fd was opened for reading or writing.

    The definition of "pipe" requires that the pair of fd's returned by
    pipe() behave identically to a pair of fd's open for reading and
    writing, respectively, to a FIFO. Since an fstat() on the FIFO's
    reading fd and an fstat() on the FIFO's writing fd return the same
    timestamps (the "three associated time values"), the same must be
    true for the pipe's reading fd and writing fd, as the test expects.

    The quoted definition of "pipe" was in POSIX.1-1988 and has remained
    unchanged in all the specifications derived from it. Implementations
    with STREAMS-based pipes had to comply with this definition during
    the several years before STREAMS were added to XSH, and so there was
    no reason to change the specification at that time to allow a
    different behaviour for STREAMS-based pipes. (Anyway, would any
    vendors have wanted to be only UNIX95 compliant, and not POSIX.1
    and XPG4 compliant?)

    If the claim that "when pipes are full-duplex you cannot have a single
    shared stat structure" is true, then perhaps the many existing
    implementations that have STREAMS-based pipes and that pass this
    test have some internal mechanism whereby the relevant timestamps in
    both of the stat structures are marked for update when the pipe is
    read or written. That is just speculation, but whatever means they
    use, the point is that the problem of how to make STREAMS-based pipes
    have POSIX-conforming timestamps was solved some ten or more years ago.

    It is recommended that this request is refused.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Rejected (REJ)
    Review Conclusion
    This request is refused.

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