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Issues in porting libxml to VMS
Here's a summary of the issues I encountered when building LIBXML under
VMS. There was some VMS support in the version I got, but it was a little
out of date with the result that some newer files had problems.
I present this list "as is" to hopefully act as a guide to anyone having
problems in the future.
That's it. Good luck!
John A Fotheringham (
October 2001
Updated October 2002 by Craig A Berry (
Installation kit
- File attributes. Having downloaded essentially a Unix distribution, some
of the file attributes weren't correct... especially those in the [.VMS]
subdirectory. In EDT you could see line feeds and carriage returns as
<LF><CR> etc. To correct this use the command
$ set file <filespec> /attr=rfm=stm
This sets the record format to be "stream". Other variants may be used
instead depending on how you got the files onto your system. Files will
look okay in an EDT editor once the attributes are set. Without
this the command file may not run correctly, since it may be interpreted
as a single line.
- VMS-specific files are in a [.VMS] directory. If you've found this file
then you already know this :-) This directory contains
BUILD_LIBXML.COM - a build command file, which I've radically re-worked
CONFIG.VMS - a configuration file to replace config.h
- Don't execute BUILD_LIBXML.COM until you've done all the following
- read these notes
- reviewed the configuration section of BUILD_LIBXML.COM, and in particular
updated the module lists in line with MAKEFILE
- identified the location of the include files, so that you can manually
set the LIBXML logical if need be.
- re-read these notes :-p
instructions for all these steps are below.
- the file [.vms]config.vms is used in lieu of a Configure-generated config.h.
This file contains a number of define statements that identify the software
options required under VMS
- The include files are in a [.INCLUDE.LIBXML] subdirectory. You need
a logical "libxml" to point to this so that include statements of the
#include <libxml/parser.h>
will work correctly. The source files are mostly two levels above this
directory, although there are some .h files there as well.
- The command file BUILD_LIBXML.COM will do the following
- setup some logicals
- set def to the source directory
- compile modules and place them into a LIBXML.OLB library
- compile and link a number of self-test programs
- compile and link a number of utilities and test programs
- set def back to the original directory (i.e. if it fails you might not be
where you started :-)
before running this command file review the configuration segment at
the top. In particular compare the lists of modules with those in the
most recent version of the Unix MAKEFILE. Instructions are contained
in the command file itself.
The command file will attempt to set two logicals
- xml_srcdir. The directory containing the source files
- libxml. The include file directory.
It attempts this by looking for modules globals.c and globals.h in
nearby directories. If this logic fails, you'll need to manually define
these logicals.
The TRIO package
- A sub-package TRIO is used to provide some functions not naturally available
under VMS. These include support for infinite and undefined numbers,
and specialised print functions like "snprintf"
I had to make several changes to trionan.c in discussion with the author
(hopefully these are now included in the distro, so I won't list them here)
To build this software we need to add
to the compile command for xpath.c and trio.c, and to any main program
that uses this functionality. BUILD_LIBXML.COM should do this for you.
- to build in trio support you need the define WITH_TRIO to be set. This
is done by default for VMS in xmlversion.h
Compiler and linker errors
- the DEC C compiler may produce a number of warnings when compiling the
C code. These include
- Implicit function warnings. These indicate functions whose type is
not defined in a .h file. This will probably only happen if your
configuration is not correct (e.g. for "snprintf" if you haven't
edited xmlversion.h to set WITH_TRIO
- uninitialised variables. Not usually a problem. You can solve this
by editing the code to initialise the variables affected
Changes made to the codebase
- I changed all dummy declarations in trio.c to be
va_list dummy = NULL;
to prevent compiler whinge in TRIO.C about uninitialised variables
- I had to add the following to nanoftp.c
#if defined(VMS) || defined(__VMS)
#define SOCKLEN_T unsigned int
This matches similar lines already added to nanohttp.c
- Several variables and function names exceed the 31 character limit
of the VMS linker. The solution adopted has been to use the
/NAMES=SHORTENED compiler option, which requires DEC/Compaq C 5.7
or later. For a complete list of the names that needed shortening
and the short names generated by the compiler, see [.vms]config.vms.