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To-do list for xgawk enhancements:
Done:
- Add AWKLIBPATH with default pointing to ${libexecdir}/$PACKAGE/$VERSION
- Change default shared library extension from ".so" to ".$shlibext"
- Patch build infrastructure so that the current code in the
extension subdirectory gets built and installed into the default $AWKLIBPATH
location.
- Implement @load
- Patch ERRNO handling to create a simple API for use by extensions:
extern void update_ERRNO_int(int)
enum errno_translate { TRANSLATE, DONT_TRANSLATE };
extern void update_ERRNO_string(const char *string, enum errno_translate);
extern void unset_ERRNO(void);
- Add valgrind-noleak target.
- Fix minor bug in fork extension, and add wait function.
- Patch filefuncs extension to read symbolic links more robustly.
- Add shared library tests.
To do (not necessarily in this order):
- Enhance extension/fork.c waitpid to allow the caller to specify the options.
And add an optional array argument to wait and waitpid in which to return
exit status information.
- Maybe add more shared library tests.
- Figure out how to support xgawk on platforms such as Cygwin where a DLL
cannot be linked with unresolved references. There are currently 3
possible solutions:
1. Restructure gawk as a stub calling into a shared library.
2. Move a subset of gawk interfaces into a shared library that can be
called by extensions.
3. Change the interface between gawk and extensions so that gawk will
pass a pointer to a structure into dlload that contains the addresses
of all variables and functions to which the extension may need access.
- Enable default ".awk" search in io.c:find_source(). The simple change
is to add this code inline in io.c:
#ifndef DEFAULT_FILETYPE
#define DEFAULT_FILETYPE ".awk"
#endif
- Fix lint complaints about shared library functions being called without
having been defined. For example, try:
gawk --lint -lordchr 'BEGIN {print chr(65)}'
gawk: warning: function `chr' called but never defined
A
In ext.c, make_builtin needs to call awkgram.y:func_use. If done naively,
I think this would result in complaints about shared library functions
defined but not used. So there should probably be an enhancement to func_use
and ftable to indicate if it's a shared library function.
- Develop a libgawk shared library for use by extensions. In particular,
a few existing extensions use a hash API for mapping string handles to
structures. In xgawk, we had this API inside array.c, but it probably
belongs in a separate libgawk shared library:
typedef struct _strhash strhash;
extern strhash *strhash_create P((size_t min_table_size));
/* Find an entry in the hash table. If it is not found, the insert_if_missing
argument indicates whether a new entry should be created. The caller
may set the "data" field to any desired value. If it is a new entry,
"data" will be initialized to NULL. */
extern strhash_entry *strhash_get P((strhash *, const char *s, size_t len,
int insert_if_missing));
typedef void (*strhash_delete_func)(void *data, void *opaque,
strhash *, strhash_entry *);
extern int strhash_delete P((strhash *, const char *s, size_t len,
strhash_delete_func, void *opaque));
extern void strhash_destroy P((strhash *, strhash_delete_func, void *opaque));
- Running "make install" should install the new libgawk shared library
as well as header files needed to build extensions under /usr/include/gawk.
The extensions include "awk.h", and that pulls in the following headers
(according to gcc -M) :
awk.h config.h custom.h gettext.h mbsupport.h protos.h getopt.h \
regex.h dfa.h
Most likely, most of this is not required. Arnold has suggested
creating a smaller header to define the public interface for use by shared
libraries. One could imagine having "awk-ext.h" that is included by "awk.h".
Separate projects for major standalone extensions. Where should these
be hosted?
- Time. This defines sleep and gettimeofday. This one is quite trivial,
and I propose that it be included in the mainline gawk distro.
- XML
- PostgreSQL
- GD
- MPFR. Is this still useful if MPFR support will be integrated into gawk?
Possible changes requiring (further) discussion:
- Change from dlopen to using the libltdl library (i.e. lt_dlopen).
This may support more platforms.
- Implement namespaces. Arnold suggested the following in an email:
- Extend the definition of an 'identifier' to include "." as a valid character
although an identifier can't start with it.
- Extension libraries install functions and global variables with names
that have a "." in them: XML.parse(), XML.name, whatever.
- Awk code can read/write such variables and call such functions, but they
cannot define such functions
function XML.foo() { .. } # error
or create a variable with such a name if it doesn't exist. This would
be a run-time error, not a parse-time error.
- This last rule may be too restrictive.
I don't want to get into fancy rules a la perl and file-scope visibility
etc, I'd like to keep things simple. But how we design this is going
to be very important.
- Include a sample rpm spec file in a new packaging subdirectory.
- Patch lexer for @include and @load to make quotes optional.
- Add a -i (--include) option.
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