MPE/iX Intrinsics Reference Manual (32650-90875)

232 Chapter6
Command Definitions (FLUSHLOG-GETUSERMODE)
FOPEN
Bits Value/Meaning
12.4 Access type
Indicates the type of access intended for the file. This option
restricts/allows minimal use of file system intrinsics.
The following bit settings are valid:
0000 Allows read access only, if the file's security provisions
specify read access. FWRITE, FUPDATE, and FWRITEDIR
intrinsic calls cannot reference this file. The end-of-file
(EOF) is not changed; the record pointer starts at 0.
0001 Allows write access only, if the file's security provisions
allow write access. (This only applies if the file is not open
with shared access, otherwise you are given a “0010”
access) Any data written in the file prior to the current
FOPEN request is deleted. FREAD, FREADSEEK, FUPDATE,
and FREADDIR intrinsic calls cannot reference this file.
The EOF is set to 0; the record pointer starts at 0. On
magnetic tape an EOF is written when the file is closed
even if no data is written.
0010 Allows write-save access only, if the file's security
provisions allow write access. Previous data in the file is
not deleted. FREAD, FREADSEEK, FUPDATE, and FREADDIR
intrinsic calls cannot reference this file. The EOF is not
changed; the record pointer starts at 0. Therefore, data is
overwritten if a call to FWRITE is made. The system
changes this value to append for message files.
0011 Allows append access only if the file's security provisions
allow either append or write access. FREAD, FREADDIR,
FREADSEEK, FUPDATE, FSPACE, FPOINT, and FWRITEDIR
intrinsic calls cannot reference this file. Data written by
the FWRITE intrinsic is appended to the EOF, thereby
extending the EOF. When a file is opened for append
access, it is impossible to overwrite data in the file. For
disk files, the EOF is updated after each FWRITE call.
Therefore, data cannot be overwritten.
0100 Allows read/write (I/O) access only if the file's security
provisions allows both read and write access. If both read
and write access are not allowed, the access type specified
in the security provisions ( read or write) is allowed. Any
file intrinsic except FUPDATE can be called for this file. The
EOF is not changed; the record pointer starts at 0. This
option is not valid for message files.
0101 Allows update access only if the file's security provisions
allows both read and write access. If both read and write
access are not allowed, the access type specified in the
security provisions (read or write) is allowed. All file