Dataloader/MP Reference Manual

Creating a Customized Version of DataLoader/MP
DataLoader/MP Reference Manual—424148-003
5-20
Sequential I/O
Name must be null-terminated and must contain either a Guardian file name or an OSS
file name. If Name contains any “/” characters, DataLoader/MP treats it as an OSS file
name. If Name does not contain any “/” characters, DataLoader/MP treats it as a
Guardian file name and the usual default volume rules apply.
OSS files are treated as if they were Guardian unstructured files. No interpretation may
be specified for an OSS file. Any modifier that can be used with a Guardian
unstructured file may be used with an OSS file.
The file is opened for either read or write access, depending upon AccessMode. If the
string pointed to by AccessMode is an uppercase or lowercase letter r, the file is
opened for read access. If the string pointed to by AccessMode is an uppercase or
lowercase letter w, the file is opened for write access. This string must be
null-terminated.
The value returned by this procedure is a positive integer, referred to in
DataLoader/MP as FileNum, that is used to identify this open in all subsequent calls
to DataLoader/MP sequential I/O procedures. FileNum is not the same as the
Guardian file number.
File number -1 means the file specified by the -I= parameter (not standard input). File
number -2 means the file specified by the -O= parameter (not standard output). They
are used for DTLRead and DTLWrite procedures only.
There are no error returns. Any errors are handled by DataLoader/MP.
DTLRead
This procedure reads a record up to MaxLen bytes from the file FileNum and places
those bytes into the buffer pointed to by Buf.
The syntax for this procedure follows:
If FileNum is -1, this procedure reads from the file specified in the -I= parameter.
The value returned by this procedure is the actual number of bytes read with a value of
-1 indicating EOF.
There are no error returns. Any errors are handled by DataLoader/MP.
DTLWrite
This procedure writes up to Len bytes from the buffer pointed to by Buf to the file
FileNum.
The syntax for this procedure follows:
long DTLRead( short FileNum, char* Buf, long MaxLen );
long DTLWrite( short FileNum, char* Buf, long Len );