[Info-vax] Non-portable code

[VAXman- at SendSpamHere.ORG]

In article <hi1u2a$s9s$1 at news-01.bur.connect.com.au>, "Richard Maher" <maher_rj at hotspamnotmail.com> writes:
>Hi Marc,
>
><VAXman- @SendSpamHere.ORG> wrote in message
>news:00A971CB.1A391FDB at SendSpamHere.ORG...
>> In article <mn.2d1b7da1fb0d0bdb.104627 at brutele.be>, Marc Van Dyck
><marc.vandyck at brutele.be> writes:
>> >G'd evening to all...
>> >
>> >I have a program on my systems, that was written in the VAX ages,
>> >and that I use to display which version of layered products, tools,
>> >etc,
>> >are installed. It simply extracts from the image headers the version
>> >info that has been put there by the linker, with the IDENT clause of
>> >the link options file.
>> >
>> >Here is an extract of the code that does it (Pascal) :
>> >
>> >RESET ( f ) ;
>> >buffer := f^ ;
>> >CLOSE ( f ) ;
>> >
>> >addr := IADDRESS (buffer) +
>> >        buffer[EIHD$L_IMGIDOFF+1]::$UBYTE +
>> >        EIHI$T_IMGID ;
>> >image_id.LENGTH := 0 ;
>> >
>> >LIB$MOVC3 ( word_integer_length := 1 ,
>> >            source := %IMMED addr ,
>> >            destination := image_id.LENGTH ) ;
>> >addr := addr + 1 ;
>> >STR$COPY_R ( destination_string := image_id.BODY ,
>> >             word_integer_source_length := image_id.LENGTH ,
>> >             source_string_address := %IMMED addr ) ;
>> >
>> >(Assuming that f is an executable image file and image_id the place for
>> >the info that I want to obtain)
>> >
>> >EIHD$L_IMGIDOFF and EIHI$T_IMGID are declared as [EXTERNAL,VALUE]
>> >variables and resolved at link time by inserting a .STB file (don't
>> >remember which one, I'm at home here) in the link options file.
>> >
>> >This works perfectly well on VAX and Alpha. On Itanium, it compiles
>> >but either gives false results, or even ACCVIOes (I suppose that it
>> >happens when what I read in buffer[EIHD$L_IMGIDOFF+1] is absurdly
>> >high).
>> >
>> >So, a few questions :
>> >
>> >For Integrity images, is the method I used above still valid - but with
>> >wrong offsets - or am I completely screwed up ? If positive, what are
>> >the offsets that I should use ? If not, how should I do ? Is it
>> >documented somewhere ?
>>
>> This will NOT work on IA64.  You need too study ELF.
>>
>>
>> >If the offsets EIHD$L_IMGIDOFF and EIHI$T_IMGID are wrong on Integrity,
>> >why is it possible that the program compiled and linked with no problem
>> >at all ? I would have expected that those either have the correct
>> >value,
>> >or do not exist at all, in which case the link would have failed. Where
>> >am I wrong ?
>>
>> They're not wrong.  The image format was NOT devised by DEC/Compaq/HP and
>> VMS engineering.  The chose to go with ELF.  Check $ELFDEF in STARLET.MLB
>>
>>
>> >If I need to have code differences between the VAX/AXP and the I64
>> >version, do I need to have two separate source files, or does Pascal
>> >provide some way of conditional compiling ?
>>
>> Pascal specific questions are best left to John Reagan.  I've done
>> what you are seeking to do in Macro32 with a common source file.
>>
>>
>> >Many thanks in advance for your help. This is the first time I
>> >encouter code which is not source-compatible between the 3 VMS
>> >hardware architectures...
>>
>> You haven't looked very hard! :)
>>
>> -- 
>> VAXman- A Bored Certified VMS Kernel Mode Hacker
>VAXman(at)TMESIS(dot)ORG
>>
>>   http://www.quirkfactory.com/popart/asskey/eqn2.png
>>
>>   "Well my son, life is like a beanstalk, isn't it?"
>
>Not sure if it helps but Tim Sneddon (pretty sure it was him?) put me onto
>the DCL Symbol populating functionality with Analyze/Image.
>
>I'd include the bit from our KITINSTAL.COM (IA64) but I can't get there at
>the moment as the IP Address regime is all over the place with
>Browser\OS\Hardware versioning Tests :-(
>
>Anyway, IIRC at least for us it was the mut's nuts.

ANALYZE/IMAGE on the Itanium *WILL* create DCL symbols with the information
he is seeking but it's not very practical from within a program.  I'm not a
fan of SPAWNing a process to run a DCL command(s) to access information and
there would be more than just SPAWNing to run ANALYZE/IMAGE as the symbols
it would create would be visible only in the subprocess.

Reading the image file itself to garner the information isn't difficult but
it's not as simple or straighforward as 'twas in days of VAX and Alpha yore
to locate it.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

  http://www.quirkfactory.com/popart/asskey/eqn2.png
  
  "Well my son, life is like a beanstalk, isn't it?"