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Text File | 2002-08-05 | 17.4 KB | 645 lines

=head1 XSBuilder - Autogenerating XS-glue Code O'Reilly OpenSource Convention 2002 Gerald Richter ecos gmbh http://www.ecos.de =head1 XSBuilder - What is it? =head2 It's purpose is to automaticly generate a Perl interface to C Code =head2 Solves the problem, that the Perl interface is not always uptodate with the C interface =head2 Saves a lot of Copy&Paste work =head2 Systematical changes have to be done only once For example changes in the memory management of strings. =head2 Is part of mod_perl 2.0 build system Most code is developed by Doug MacEachern. Additionaly I have =over =item abstracted the code from mod_perl so it's useable for any C code =item added new features like callbacks and the ability to parse comments =item Replaced C::Scan with a Parse::RecDescent to be platform and compiler independend =back Goal is to replace the current mod_perl XS generation code with XSBuilder =head2 Inline versus XSBuilder =over =item Inline: embed C-Code into Perl =item XSBuilder: Create interface for existing C-libraries/applicationen =back =head1 XSBuilder - What does it do? =head2 Create Perl functions/methods for every C function The function can be assigned to different packages, also automaticly by inspecting the first parameter =head2 Create a Perl class for every C structure Every element of structure becomes a Perl method to get/set it's value. The object can be either a scalar reference (used by mod_perl) or a reference to a hash (use by Embperl), which allows to store extra data by the Perl code into this hash. =head2 Create glue code to handle callbacks There several sorts of callback, not all are implemented right now =head2 Create Perl constant subs Coming soon... =head1 XSBuilder - How does it work? =head2 Parse the C header files Extract =over =item Functions, their arguments and return types =item Structures and it's members =item Constants =item Callbacks =back and create four tables which contains the results =head2 Create the XS code Input is =over =item The source tables =item Mapfiles which contains the mapping from C to Perl =item Addtional C and Perl code that can be used to customize the interface =back Output is =over =item The XS files (one form every generated class) =item Makefile.PL for every class =item pm files =back =head1 Parse the source =head2 Create your own ParseSource class and override methods... package Apache::DAV::ParseSource; use strict; use vars qw{@ISA $VERSION} ; use ExtUtils::XSBuilder::ParseSource ; @ISA = ('ExtUtils::XSBuilder::ParseSource') ; $VERSION = '0.01'; my $dav_dir = 'C:\perl\msrc\cvs\mod_dav' ; my $ap_dir = 'c:\programme\apache group\apache' ; # ============================================================================ sub find_includes { my $self = shift; return $self->{includes} if $self->{includes}; my @includes = ("$ap_dir/include/ap_alloc.h", "$dav_dir/mod_dav.h") ; return $self->{includes} = $self -> sort_includes (\@includes) ; } # ============================================================================ sub package { 'Apache::DAV' } # ============================================================================ sub preprocess { my $self = shift ; $_[0] =~ s/(?:API_EXPORT)(?:_NONSTD)?\s*$\s*(.*?)\s*$/$1/g ; } 1; =head2 ...run it use FindBin ; use lib ($FindBin::Bin) ; require ParseSource ; Apache::DAV::ParseSource -> run ; =head2 ...and you get C:\perl\msrc\davint>perl xsbuilder\source_scan.pl Will use mod_dav in C:\perl\msrc\cvs\mod_dav Will use Apache in c:\programme\apache group\apache Initialize parser scan c:\programme\apache group\apache/include/ap_alloc.h ... constant: APACHE_ALLOC_H func: ap_init_alloc func: ap_cleanup_alloc func: ap_make_sub_pool func: ap_destroy_pool constant: ap_pool_join func: ap_pool_join func: ap_find_pool func: ap_pool_is_ancestor func: ap_clear_pool func: ap_cleanup_for_exec func: ap_palloc func: ap_pcalloc func: ap_pstrdup func: ap_pstrndup func: ap_pstrcat func: ap_pvsprintf valuefield: ap_pool * : pool valuefield: int : elt_size valuefield: int : nelts valuefield: int : nalloc valuefield: char * : elts struct: (type=array_header) ... =head2 The result is stored in four tables =over =item xsbuilder/tables/Apache/DAV/FuntionTable.pm Contains all function, it arguments and comments =item xsbuilder/tables/Apache/DAV/ConstantTable.pm Contains all constants =item xsbuilder/tables/Apache/DAV/StructureTable.pm Contains all structures, it's members and their comments =item xsbuilder/tables/Apache/DAV/CallbackTable.pm Contains all callback function definitions =back =head1 Create the map files =head2 Mapfiles are used to tell XSBuilder how C datatypes, structures and function aruments should be mapped into Perl ones. =head2 Create your own WrapXS class and override methods package Apache::DAV::WrapXS ; use strict; use vars qw{@ISA $VERSION} ; use ExtUtils::XSBuilder::WrapXS ; @ISA = ('ExtUtils::XSBuilder::WrapXS') ; $VERSION = '0.01'; # ============================================================================ sub new_parsesource { [ Apache::DAV::ParseSource->new ] } # ============================================================================ sub my_xs_prefix { 'davxs_' } # ============================================================================ sub h_filename_prefix { 'moddav_xs_' } # ============================================================================ sub xs_includes { my $self = shift ; my $i = $self -> SUPER::xs_includes ; my @i = grep (!/ap_alloc/, @$i) ; return \@i ; } =head2 XSBuilder can create/update initial maps for you use FindBin ; use lib ($FindBin::Bin) ; require ParseSource ; require WrapXS ; Apache::DAV::WrapXS->checkmaps (' '); =head2 run it C:\perl\msrc\davint>perl xsbuilder\xs_check.pl Will use mod_dav in C:\perl\msrc\cvs\mod_dav Will use Apache in c:\programme\apache group\apache Parse xsbuilder\maps/_types.map... WARNING: No *_function.map file found in xsbuilder\maps WARNING: No *_callback.map file found in xsbuilder\maps WARNING: No *_structure.map file found in xsbuilder\maps Write xsbuilder\maps/new_function.map... Write xsbuilder\maps/new_callback.map... Write xsbuilder\maps/new_structure.map... Write xsbuilder\maps/new_type.map... =head2 Now we have four map files =over 4 =item new_types.map Contains the mapping from C type to Perl classes =item new_functions.map Contains the mapping form C functions to Perl functions. Can be used to reorder arguments, tell XSBuilder which arguments are actualy return values and in which Perl package the function will be created. =item new_structures.map Contains the mapping from C structures to Perl classes and defines for which members a access methods should be created. You can also specify if you want a C<new> method for the class. =item new_callbacks.map Contains the mapping form C callback functions to Perl callback functions. Can be used to reorder arguments, tell XSBuilder which arguments are actualy return values and in which Perl package the function will be created. =back It's a good idea to rename the prefix from C<new_> to something unique, here we use C<dav> Everytime you rerun checkmaps, XSBuilder will create new_* files with the items that are not already part of the other maps. =head2 Next step is to customize the maps... =head1 type map =head2 autogenerated dav_type.map DIR | FILE | HANDLE | array_header | dav_buffer | dav_dyn_context | dav_dyn_hooks | dav_dyn_module | dav_dyn_provider | dav_error | dav_get_props_result | dav_hooks_liveprop | dav_hooks_locks | dav_hooks_repository | dav_if_header | dav_if_state_type | ... =head2 Add Perl classes struct array_header | Apache::Array struct dav_buffer | struct dav_datum | Apache::DAV::Datum struct dav_dyn_context | Apache::DAV::DynContext struct dav_dyn_hooks | Apache::DAV::DynHooks struct dav_dyn_module | Apache::DAV::DynModule struct dav_dyn_provider | Apache::DAV::DynProvider struct dav_error | Apache::DAV::Error struct dav_get_props_result | Apache::DAV::PropsResult struct dav_hooks_db | Apache::DAV::HooksDb struct dav_hooks_liveprop | Apache::DAV::HooksLiveprop struct dav_hooks_locks | Apache::DAV::HooksLocks struct dav_hooks_repository | Apache::DAV::HooksRepository struct dav_hooks_vsn | struct dav_if_header | Apache::DAV::IfHeader struct dav_if_state_list | Apache::DAV::StateList ... struct pool | Apache::Pool struct request_rec | Apache:: struct server_rec | Apache::Server ... Defines the mapping from C datatypes to Perl datatypes and classes and tells XSBuilder which datatype are (like) structures =head1 function map Function map defines the mapping from C functions arguments to Perl arguments =over =item Tell XSBuilder where to place functions and which prefix to strip MODULE=Apache::DAV PACKAGE=guess PREFIX=dav_ =item Simple entries in the function map will be mapped 1:1 from C to Perl dav_add_response dav_buffer_append dav_buffer_init dav_buffer_place dav_buffer_place_mem dav_check_bufsize dav_close_propdb dav_collect_liveprop_uris dav_dyn_module_add dav_empty_elem ... =item The following map file entry tells XSBuilder that the value of C<res_p> should be returned dav_get_resource | | r, <res_p The C function int dav_get_resource(request_rec *r, dav_resource **res_p) ; How to call it from Perl # get a sub request of the actual document $subr = $r -> lookup_uri($uri); # get a mod_dav resource object my ($err, $resource) = $subr->get_resource; =item You can let XSBuilder insert your custom code, for the interface If you call C<get_props> from Perl C<glue_dav_get_props> will be called, which can adjust the arguments and return types as necessary. The actual code for C<glue_dav_get_props> will be taken from separate include file. dav_get_props | glue_ dav_get_allprops | glue_ xsinclude\Apache\DAV\PropResult\Apache__DAV__PropResults.h dav_get_props_result * dav_glue_get_props(dav_propdb * db, dav_xml_doc *doc) { dav_get_props_result * result = (dav_get_props_result *)ap_palloc (db -> p, sizeof (dav_get_props_result)) ; *result = dav_get_props(db, doc) ; return result ; } =item Arguments can be replaced MODULE=Apache::Array PACKAGE=Apache::Array PREFIX=ap_ ap_make_array | ap_make_array(r->pool, nelts, elt_size) | request_rec *:r, nelts, elt_size ap_make_array requires a pool a it's first parameter, we pass the request_rec from Perl and XSBuilder will take the pool from the request_rec. =back =head1 structure map MALLOC=strdup:$dest = ($type)strdup($src) FREE=strdup:free($src) <dav_xml_elem> name ns lang first_cdata following_cdata parent next first_child attr last_child ns_scope propid provider ns_map new </dav_xml_elem> MALLOC=strdup:$dest = ($type)ap_pstrdup(obj -> pool, $src) <array_header> pool elt_size nelts nalloc elts private </array_header> =head2 Create a accessor functions for every element and, if requested, a new method $setprop = Apache::DAV::XMLElem -> new ({name => 'prop'}) ; $elem = Apache::DAV::XMLElem -> new ({name => $name, ns => $namespaces}) ; $setprop -> first_child($elem) ; $first = $setprop -> first_child ; =head2 some datatypes, like strings, requires dynamic allocated memory From _types.map,which conatins a set of standard types int | IV int * | UNDEFINED unsigned int | UV signed int | IV long | IV long int | IV unsigned long | UV unsigned | UV char * | PV | | | strdup const char * | PV | | | strdup const char ** | UNDEFINED char const * | PV | | | strdup unsigned char * | PV | | | strdup const unsigned char * | PV | | | strdup ... =head1 callback maps Callback maps have the same options a function maps # dav_hooks_db -> open dav_error *(*)(pool * p,const dav_resource * resource,int ro,dav_db * * pdb) | p, resource, ro=0, <pdb # dav_hooks_lock -> has_locks dav_error *(*)(dav_lockdb * lockdb,const dav_resource * resource,int * locks_present) =head1 Generate the XS files use FindBin ; use lib ($FindBin::Bin) ; require ParseSource ; require WrapXS ; Apache::DAV::WrapXS->run; =head2 ...and run... C:\perl\msrc\davint>perl xsbuilder\xs_generate.pl Will use mod_dav in C:\perl\msrc\cvs\mod_dav Will use Apache in c:\programme\apache group\apache Parse xsbuilder\maps/_types.map... Parse xsbuilder\maps/dav_type.map... mkdir xs writing...xs//typemap Parse xsbuilder\maps/dav_functions.map... WARNING: Cannot map type int(*)(void * ,const char * ,const char * ) for function ap_table_do WARNING: Cannot map type dav_buffer * for function dav_buffer_append WARNING: Cannot map type dav_buffer * for function dav_buffer_init WARNING: Cannot map type dav_buffer * for function dav_buffer_place WARNING: Cannot map type dav_buffer * for function dav_buffer_place_mem WARNING: Cannot map type dav_buffer * for function dav_check_bufsize WARNING: Cannot map return type int * for function dav_collect_liveprop_uris WARNING: Cannot map type dav_resource * * for function dav_ensure_resource_writable WARNING: Cannot map type dav_buffer * for function dav_lock_get_activelock WARNING: Cannot map type dav_buffer * for function dav_set_bufsize WARNING: Cannot map type int * for function dav_xml2text struct array_header... Parse xsbuilder\maps/dav_structure.map... elt_size... nelts... nalloc... elts... struct dav_buffer... struct dav_datum... dptr... dsize... struct dav_dyn_context... =head1 Makefile.PL =head2 We need create a top level Makefile.PL use ExtUtils::MakeMaker (); my $apdir = '/path/to/apache'; my $davdir = '/path/to/moddav'; %MMARGS = ( 'INC' => "-I\"$davdir\" -I\"$apdir/include\" -I\"$apdir/os/unix\" -I\"$dir/xs\" -I\"$dir/xsinclude\"", ) ; open FH, ">xs/mmargs.pl" or die "Cannot open xs/mmargs.pl ($!)" ; print FH Data::Dumper -> Dump ([\%MMARGS], ['MMARGS']) ; close FH ; ExtUtils::MakeMaker::WriteMakefile( 'NAME' => 'Apache::DAV', 'VERSION' => '0.13', %MMARGS, ); =head2 Makefile.PL's for all class are generated automaticly C:\perl\msrc\davint>perl Makefile.PL Will use Apache in c:\programme\apache group\apache Will use mod_dav in C:\perl\msrc\cvs\mod_dav Checking if your kit is complete... Looks good Writing Makefile for Apache::Array Writing Makefile for Apache::DAV::Datum Writing Makefile for Apache::DAV::DynContext Writing Makefile for Apache::DAV::DynHooks Writing Makefile for Apache::DAV::DynModule Writing Makefile for Apache::DAV::DynProvider Writing Makefile for Apache::DAV::Error Writing Makefile for Apache::DAV::HooksDb Writing Makefile for Apache::DAV::HooksLiveprop Writing Makefile for Apache::DAV::HooksLocks Writing Makefile for Apache::DAV::HooksRepository Writing Makefile for Apache::DAV::IfHeader Writing Makefile for Apache::DAV::Lock Writing Makefile for Apache::DAV::LockDB Writing Makefile for Apache::DAV::LockTokenList Writing Makefile for Apache::DAV::LockupResult Writing Makefile for Apache::DAV::PropCtx Writing Makefile for Apache::DAV::PropsResult Writing Makefile for Apache::DAV::Resource Writing Makefile for Apache::DAV::Response Writing Makefile for Apache::DAV::StateList Writing Makefile for Apache::DAV::Text Writing Makefile for Apache::DAV::TextHeader Writing Makefile for Apache::DAV::WalkerCtx Writing Makefile for Apache::DAV::XMLAttr Writing Makefile for Apache::DAV::XMLDoc Writing Makefile for Apache::DAV::XMLElem Writing Makefile for Apache::DAV Writing Makefile for Apache::TableEntry Writing Makefile for Apache Writing Makefile for WrapXS Writing Makefile for Apache::DAV =head2 and now compile... =head1 How does it go on... =head2 Generating documentation XSBuilder already extracts source comments for functions and structures. It also parses doxygen comments, which are used in Apache 2.0. Lyle Brooks has started on automaticly createing POD files from this information. =head2 Improving callbacks Callbacks are the main area that needs improvement. =head2 Bring it back to mod_perl 2.0 =head2 First version will be released just after the conference to CPAN =head2 Any feedback and help appreciated =head2 Questions?