Re: Calling an ILE C Routine from ILE RPG (V7R2)

Just as a further follow up.

Null termination (Options *String) is needed for _both_ the char parms. The C function uses strlen() to determine string length and that in turn relies on null termination.

On May 22, 2020, at 8:49 AM, Nathan Andelin <nandelin@xxxxxxxxx> wrote:

I also wondered about options(*string).

One more thing I noticed in the C source code for pw_rand() is a 4th
parameter, a pointer to a character buffer named "remove". That parameter
appears to be missing in the RPG prototype. That could cause a pointer
exception.

Pointer exceptions are often the hardest to figure out.


On Fri, May 22, 2020 at 6:44 AM Jon Paris <jon.paris@xxxxxxxxxxxxxx> wrote:

The only possibility I can think of is that the C code is expecting a null
terminated string. i.e. one ending in x'00'.

Add Options(*String) to the proto of the 70 char field and the pass
%TrimR(PW_BUFF) as the parm.

OK - I won't nag about free form declarations but MOVE ?

On May 22, 2020, at 5:34 AM, Patrik Schindler <poc@xxxxxxxxxx> wrote:

Hello,

I've ported https://github.com/tytso/pwgen to the CL environment (not

PASE!), for easy generation of random characters. and calling the resulting
*PGM runs fine.

There's one function (pw_rand) I want to call from RPG, by linking

(binding) all (necessary) *MODULE objects from pwgen together with the
RPGLE module containing the mainline to one *PGM. I'm *not* talking about a
service program.

The C prototype is: void pw_rand(char *buf, int size, int pw_flags);

What I expect it to do: I pass a struct predetermined by the existing C

code, stating I want to create a 64 char password with the password flags
3. The password buffer is apparently preallocated by RPG (see debug output
below), since it's filled with *BLANKs. The function runs and places a
(most likely zero-teminated) string into the buffer: 64 bytes password, 1
byte '00'X. I made the buffer a bit larger to be on the safe side. I also
looked up proper field sizes in IBM documentation and that seems correct.

That's what I did in positional RPG:

DPW_BUF S 70A
DPW_SIZE S 10I 0
DPW_FLAGS S 10I 0
*
DPW_RAND PR EXTPROC('pw_rand')
D PW_BUF 70A
D PW_SIZE 10I 0 VALUE
D PW_FLAGS 10I 0 VALUE
*----------------
C MOVE 64 PW_SIZE
C MOVE 3 PW_FLAGS
C CALLP PW_RAND ( PW_BUF : PW_SIZE : PW_FLAGS )

( I hope, my MUA will not mess up with the formatting.)

Compiles and links fine, but when I try to run the call, the application

crashes with MCH 3601 (Pointer not set for location referenced.). I read
some articles in the net about it but I can't find out where or what I do
wrong.

Debug:

PW_BUF CHAR(70) '

'

VALUE IN HEX

'40404040404040404040404040404040404040404040404040404040404040404040404040404040'X

41

'404040404040404040404040404040404040404040404040404040404040'X

PW_FLAGS ZONED(1,0) 3. 'F3'X
PW_SIZE ZONED(2,0) 64. 'F6F4'X

Help greatly appreciated! Please refrain from "do it with RPG free",

because I don't want to open yet another task on my already big stack.
(Learning free is on my list, for a later point in time.)

:wq! PoC

PGP-Key: DDD3 4ABF 6413 38DE - https://www.pocnet.net/poc-key.asc

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