1 02/06/84  pl1_io_
 2 
 3 The pl1_io_ subroutine is a collection of utility functions for
 4 extracting information about PL/I files that is not available within
 5 the language itself.
 6 
 7 
 8 Entry points in pl1_io_:
 9    (List is generated by the help command)
10 
11 
12 :Entry:  error_code:  02/06/84 pl1_io_$error_code
13 
14 
15 Function: returns the last nonzero status code encountered by PL/I I/O
16 while performing file operations.  This is a standard Multics status
17 code and describes the most recent error more specifically than the
18 PL/I condition which is raised after an error.
19 
20 
21 Syntax:
22 declare pl1_io_$error_code entry (file) returns (fixed bin(35));
23 code = pl1_io_$error_code (file_variable);
24 
25 
26 Arguments:
27 file_variable
28    is a PL/I file value.  (Input)
29 code
30    is the last nonzero status code associated with the file.  (Output)
31 
32 
33 Notes:  The specific values returned by this function are subject to
34 change.  See "Handling Unusual Occurrences" in the Programmer's
35 Reference Manual.
36 
37 
38 :Entry:  get_iocb_ptr:  02/06/84 pl1_io_$get_iocb_ptr
39 
40 
41 Function: returns the I/O control block pointer for the Multics I/O
42 System switch associated with an open PL/I file.  This pointer may be
43 used to perform control and modes operations upon the switch
44 associated with that file.
45 
46 
47 Syntax:
48 declare pl1_io_$get_iocb_ptr entry (file) returns (ptr);
49 iocb_ptr = pl1_io_$get_iocb_ptr (file_variable);
50 
51 
52 Arguments:
53 file_variable
54    is a PL/I file value.  (Input)
55 iocb_ptr
56    is a pointer to the I/O control block for the file.  (Output)
57 
58 
59 Notes:  Performing explicit operations via the Multics I/O System upon
60 switches in use by PL/I I/O is potentially dangerous unless care is
61 taken that certain conventions are observed.  No calls should be made
62 that affect the data in the PL/I data set being accessed, the
63 positioning of the data set, or the status or interpretation of any I/O
64 operations that may be in progress.  In general, this limits such calls
65 to those which obtain status information.