What Unix service would get called from printf? I was curious, so I
wrote a simple program:
---
#include <stdlib.h>
#include <stdio.h>
#define _POSIX_SOURCE
#include <unistd.h>
#pragma linkage(callqdb,OS_NOSTACK)
#pragma map(callqdb, "BPX1QDB")
void callqdb(int * rv,
int * rc,
int * rsn
);
void main(int args, char **argv, char **env)
{
int rv, rc, rsn;
char buffer[80];
rv = rc = rsn = 0;
callqdb(&rv, &rc, &rsn);
printf("before printf: rv = %08X, rc = %08X, rsn = %08X\n",
rv, rc, rsn);
rv = rc = rsn = 0;
callqdb(&rv, &rc, &rsn);
printf("after printf: rv = %08X, rc = %08X, rsn = %08X\n",
rv, rc, rsn);
rc = getcwd(buffer, 80);
printf("rc = %08X, cwd = %s\n", rc, buffer);
rv = rc = rsn = 0;
callqdb(&rv, &rc, &rsn);
printf("after getcwd: rv = %08X, rc = %08X, rsn = %08X\n",
rv, rc, rsn);
}
---
The output shows that the dub only occured after the getcwd() call:
---
before printf: rv = 00000008, rc = 00000000, rsn = 00000000
after printf: rv = 00000008, rc = 00000000, rsn = 00000000
rc = 2187E2FC, cwd = /u/sasdtp
after getcwd: rv = 00000001, rc = 00000000, rsn = 00000000
---
In article
<of50d25821.e29d6e03-on802580dd.004f2c48-802580dd.004f8...@notes.na.collabserv.com>
you wrote:
> I understood the original question to be how to avoid OMVS and you almost
> certainly need OMVS for printf. For Metal C I wrote my own printf subset
> that calls WTO - you at least have varargs.
> Cheers,
> Dave Griffiths
> z/OS Developer
> IBM United Kingdom Limited, Hursley Park, Winchester, SO21 2JN, UK
>
> From: David Crayford <[email protected]>
> To: [email protected]
> Date: 08/03/2017 13:52
> Subject: Re: Which C library functions imply dub?
> Sent by: IBM Mainframe Discussion List <[email protected]>
> On 8/03/2017 9:15 PM, David Griffiths1 wrote:
> > Hi, not sure of the definitive answer but you can probably take a guess
> by
> > comparing with the Metal C library. By definition Metal C calls don't
> > require access to the unix kernel. In fact if you don't want to connect
> to
> > OMVS why not use Metal C anyway?
> That's a no-brainer! For a simple example how about just being able to
> use printf().
> > Cheers,
> >
> > Dave Griffiths
> > z/OS Developer
> > IBM United Kingdom Limited, Hursley Park, Winchester, SO21 2JN, UK
> >
> >
> >
> >
> >
> > From: Charles Mills <[email protected]>
> > To: [email protected]
> > Date: 08/03/2017 02:30
> > Subject: Which C library functions imply dub?
> > Sent by: IBM Mainframe Discussion List <[email protected]>
> >
> >
> >
> > X-posted from a thread on MVS-OE
> >
> >
> >
> > How would I determine which standard C library functions imply or cause
> a
> > dub? (Other than by trying them without an OMVS segment and seeing if
> they
> > blow up?) Is this documented somewhere? I guess another way of phrasing
> > the
> > question is "how would I determine which standard C library functions
> are
> > 'UNIX functions'?"
> >
> >
> >
> > Do most of them? Surely not strlen()? Does fopen()? Only if you
> reference
> > a
> > UNIX file as opposed to //DD:FOO?
> >
> >
> >
> > Charles
--
Don Poitras - SAS Development - SAS Institute Inc. - SAS Campus Drive
[email protected] (919) 531-5637 Cary, NC 27513
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