HP OpenVMS Systems

C, RMS I/O, and sharable images?

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The Question is:

 
Is there any limitation to RMS I/O from a shared image?
 
I have a program (in c) that works correctly when linked with /image. This
program has a main() that calls a (soon to be global) routine that calls
printf().
 
These same printf() calls don't work when that source is linked with /share
and a linker options file that names the above mentioned global entry point.
 
 
The caller of LIB$FIND_IMAGE_SYMBOL (?) might be loading the image from EXEC
mode.
I didn't write the loader, and I have no access to its source.
 
I've tried fprintf to stderr, but no luck.
I've redirected stdout to a file, but no joy.
 
 

The Answer is :

 
  You will first need to determine what processor mode the application
  is operating in -- most standard language run-time libraries and even
  the OpenVMS system run-time libraries are not supported for inner-mode
  operations.
 
  Applications executing in inner processor modes will usually use only
  OpenVMS system services and/or entry points directly in the OpenVMS
  executive -- while a subset of the C run-time library is available to
  inner mode code in recent OpenVMS Alpha releases, this is not the
  default C run-time and it requires an explicitly and deliberately
  different linking procedure.  (See the OpenVMS Alpha device driver
  documentation for details of the kernel-mode C run-time interface.)
 
  The standard C (user-mode) run-time library routines require explicit
  initialization when not used with a C main program -- please see the
  details of the VAXC$CRTL_INIT call included in the C documentation.
 
  There are a large number of (user-mode) shareable images written in
  C, and a cookbook for the creation of a shareable image is included
  in the Ask The Wizard area -- these (user-mode) shareable images do
  work just fine...  A full source example of a C shareable image is
  included in topic 2486 here in Ask The Wizard, including a call to
  lib$find_image_symbol to activate the shareable image, and the use
  of printf from within the shareable image.
 

  

     

     
answer written or last revised on ( 1-DEC-1999 )
     
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