Guardian Procedure Calls Reference Manual

Returned Value
INT
A file-system error code that indicates the outcome of the call.
FILE_READ64_ procedure was passed a filenum for an unstructured open of the primary partition of an
enhanced key-sequenced file. For more information on enhanced key-sequenced files, see the Enscribe
Programmer's Guide
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• The address of a parameter refers to the selectable segment area but no selectable segment is in use at
the time of the call.
• The address of a parameter is extended, but it is an absolute address and the caller is not privileged.
Considerations
• EpTAL callers must set toggle
EpTAL callers must set the toggle _64BIT_CALLS before sourcing the FILE_READ64_ procedure
section from EXTDECS.
• Familiar semantics
Unless otherwise described, the semantic behavior of FILE_READ64_ is the same as that of
READX.
• Waited FILE_READ64_
If a waited FILE_READ64_ is executed, the count-read parameter indicates the number of
bytes actually read.
• Nowait FILE_READ64_
If a nowait FILE_READ64_ is executed, the count-read parameter has no meaning and can
be omitted. The count of the number of bytes read is obtained through the
count-transferred parameter of the FILE_AWAITIO64_ procedure or the count-transferred
field of the completion-info parameter of the call to FILE_COMPLETEL_ when the I/O
operation completes.
If a nowait FILE_READ64_ is executed, then the operation must be completed by calling either
FILE_AWAITIO64_ or FILE_COMPLETEL_.
WARNING! When using nowait file I/O, data corruption might occur if the read buffer is
modified before either FILE_AWAITIO64_ or FILE_COMPLETEL_ completes the call. The buffer
space must not be freed or reused while the I/O is in progress.
It is possible to initiate concurrent nowait read operations that share the same data buffer. To
do this successfully with files opened by FILE_OPEN_, you must use SETMODE function 72 to
cause the system to use an intermediate buffer in the process file segment (PFS) for I/O transfers.
With files opened by OPEN, a PFS buffer is used by default.
• FILE_READ64_ from process files
The action for a FILE_READ64_ of a process file is the same as that for a FILE_WRITEREAD64_
with zero write-count.
• FILE_READ64_ call when default locking mode is in effect
If the default locking mode is in effect when a call to FILE_READ64_ is made to a locked file,
but the filenum of the locked file differs from the filenum in the call, the caller of
FILE_READ64_ is suspended and queued in the "locking" queue behind other processes
attempting to lock or read the file or record.
FILE_READ64_ Procedure 477