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Problem Report 1587 Details

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Report 1587 Actions

    Problem Report Number 1587
    Submitter's Classification Specification problem
    State Resolved
    Resolution Permanent Interpretation (PIN)
    Problem Resolution ID PIN.X.0144
    Raised 1995-11-03 08:00
    Updated 2003-03-13 08:00
    Published 1995-11-13 08:00
    Product Standard Internationalised System Calls and Libraries Extended (UNIX 95)
    Certification Program The Open Brand certification program
    Test Suite VSU version 4.1.0
    Test Identification CAPI.os/ioprim/select 21 22
    Specification System Interfaces and Libraries Issue 4 Version 2
    Location in Spec See Problem Text
    Problem Summary PIN4U.00010 select should not fail if called with nfds == FD_SETSIZE.
    Problem Text
    We feel that there is a problem with the description of the
    select() function as described below:

    In the <sys/time.h> description, you find this statement:

    "FD_SETSIZE
    Maximum number of file descriptors in an fd_set structure."

    We understand this as the "number" of file descriptors we can use,
    indicating a "range" of file descriptors from 0 to FD_SETSIZE-1 since
    0 is a valid file or socket descriptor.

    In the select() DESCRIPTION, you find the statement:

    "The nfds argument specifies the range of file descriptors to be
    tested. The select() function tests file descriptors in the range
    of 0 to nfds-1."

    It is clear from the text that if nfds == FD_SETSIZE, the test
    should go from 0 to FD_SETSIZE-1.

    This point is further enforced by the following statement found in
    the 7th paragraph of the DESCRIPTION:

    "For each file descriptor less than nfds, the corresponding
    bit will be set on successful completion if it was set on
    input and the associated condition is true for that descriptor."

    However, the select() ERRORS section states

    "EINVAL The nfds argument is less than 0, or greater than or equal
    to FD_SETSIZE."

    We believe this contradicts 1 and 2 above. Since nfds is the
    number of file descriptors to test (range from 0 to nfds-1) and
    FD_SETSIZE is defined as the maximum number of file descriptors in an
    fd_set structure (indicating file descriptors 0 thru FD_SETSIZE-1 are
    available), then we need be able to specify FD_SETSIZE as the nfds
    value so that file descriptors in the range 0 to FD_SETSIZE-1 are
    tested.

    Also note that the BSD documentation for select() says exactly
    what XPG4 says, "greater than or equal to", but the BSD
    supplemental documentation [Advanced 43.BSD IPC Tutorial] say
    that select(FD_SETSIZE, X, Y, Z, foo) should work! But the
    4.3BSD IPC Tutorial has sample code that uses FD_SETSIZE as the
    first argument.

    We think that 3. above should read:

    "EINVAL The nfds argument is less than or equal to 0, or greater
    than FD_SETSIZE."

    Test Output
    10|2060 /tset/CAPIbase/fselect/fselect21 19:29:57|TC Start, scenario ref
    15|2042 1.10 1|TCM Start
    400|2042 21 1 19:30:00|IC Start
    200|2042 1 19:30:00|TP Start
    520|2042 1 93782048 1 1|SPEC1170TESTSUITE CASE 21
    520|2042 1 93782048 1 2|A call to int select(int nfds, fd_set *readfds,
    520|2042 1 93782048 1 3|*writefds, fd_set *exceptfds, const struct timev
    520|2042 1 93782048 1 4|*timeout) when a timeout is specified shall not
    520|2042 1 93782048 1 5|any pending timers setup by alarm(), ualarm() or
    520|2042 1 93782048 1 6|setitimer().
    520|2042 1 130613270 1 1|PREP: Create fifo
    520|2042 1 130613270 1 2|PREP: Find FIFO buffer size
    520|2042 1 130613270 1 3|PREP: Insure O_NONBLOCK is set
    520|2042 1 130613270 1 4|PREP: Fill FIFO
    520|2042 1 130613270 1 5|PREP: writefds references write end of fifo
    520|2042 1 130613270 1 6|PREP: Set up to catch the SIGALRM signal
    520|2042 1 130613270 1 7|PREP: Set up SIGALRM using ualarm
    520|2042 1 130613270 1 8|PREP: Call select with no events pending to for
    ut
    520|2042 1 130613270 1 9|ERROR: select failed, errno = 121(EINVAL - Inva
    220|2043 1 1 19:30:11|FAIL
    410|2043 22 1 19:30:11|IC End
    80|2061 0 19:30:12|TC End
    10|2061 /tset/CAPIbase/fselect/fselect22 19:30:08|TC Start, scenario ref
    15|2043 1.10 1|TCM Start
    400|2043 22 1 19:30:11|IC Start
    200|2043 1 19:30:11|TP Start
    520|2043 1 93847584 1 1|SPEC1170TESTSUITE CASE 22
    520|2043 1 93847584 1 2|EBADF in errno and return -1 on a call to int
    520|2043 1 93847584 1 3|select(int nfds, fd_set *readfds, fd_set *writef
    520|2043 1 93847584 1 4|fd_set *exceptfds, const struct timeval *timeout
    520|2043 1 93847584 1 5|one or more of the file descriptor sets specify
    520|2043 1 93847584 1 6|descriptor that is not a valid open file descrip
    520|2043 1 130744342 1 1|PREP: Create temporary file
    520|2043 1 130744342 1 2|PREP: Close file to get invalid file descriptor
    520|2043 1 130744342 1 3|CLEANUP: Remove temporary file
    520|2043 1 130744342 1 4|TEST: Call to select on readfds returns -1
    520|2043 1 130744342 1 5|TEST: EBADF in errno
    520|2043 1 130744342 1 6|ERROR: select set errno to 121(EINVAL - Invalid
    220|2043 1 1 19:30:11|FAIL
    410|2043 22 1 19:30:11|IC End
    80|2061 0 19:30:12|TC End

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    A permanent interpretation is recommended.

    VSU currently tests the behavior recommended above.

    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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