Sortix 1.1dev ports manual
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H2XS(1) | Perl Programmers Reference Guide | H2XS(1) |
NAME
h2xs - convert .h C header files to Perl extensionsSYNOPSIS
h2xs [OPTIONS ...] [headerfile ... [extra_libraries]] h2xs -h|-?|--helpDESCRIPTION
h2xs builds a Perl extension from C header files. The extension will include functions which can be used to retrieve the value of any #define statement which was in the C header files. The module_name will be used for the name of the extension. If module_name is not supplied then the name of the first header file will be used, with the first character capitalized. If the extension might need extra libraries, they should be included here. The extension Makefile.PL will take care of checking whether the libraries actually exist and how they should be loaded. The extra libraries should be specified in the form -lm -lposix, etc, just as on the cc command line. By default, the Makefile.PL will search through the library path determined by Configure. That path can be augmented by including arguments of the form -L/another/library/path in the extra-libraries argument. In spite of its name, h2xs may also be used to create a skeleton pure Perl module. See the -X option.OPTIONS
- -A, --omit-autoload
- Omit all autoload facilities. This is the same as -c but also removes the "use AutoLoader" statement from the .pm file.
- -B, --beta-version
- Use an alpha/beta style version number. Causes version number to be "0.00_01" unless -v is specified.
- -C, --omit-changes
- Omits creation of the Changes file, and adds a HISTORY section to the POD template.
- -F, --cpp-flags=addflags
- Additional flags to specify to C preprocessor when scanning header for function declarations. Writes these options in the generated Makefile.PL too.
- -M, --func-mask=regular expression
- selects functions/macros to process.
- -O, --overwrite-ok
- Allows a pre-existing extension directory to be overwritten.
- -P, --omit-pod
- Omit the autogenerated stub POD section.
- -X, --omit-XS
- Omit the XS portion. Used to generate a skeleton pure Perl module. "-c" and "-f" are implicitly enabled.
- -a, --gen-accessors
- Generate an accessor method for each element of structs and
unions. The generated methods are named after the element name; will
return the current value of the element if called without additional
arguments; and will set the element to the supplied value (and return the
new value) if called with an additional argument. Embedded structures and
unions are returned as a pointer rather than the complete structure, to
facilitate chained calls.
- -b, --compat-version=version
- Generates a .pm file which is backwards compatible with the
specified perl version.
- no use of 'our' (uses 'use vars' instead)
- no 'use warnings'
- -c, --omit-constant
- Omit "constant()" from the .xs file and corresponding specialised "AUTOLOAD" from the .pm file.
- -d, --debugging
- Turn on debugging messages.
- -e, --omit-enums=[regular expression]
- If regular expression is not given, skip all
constants that are defined in a C enumeration. Otherwise skip only those
constants that are defined in an enum whose name matches regular
expression.
h2xs -e -n Module::Foo foo.h
h2xs -n Module::Foo -e foo.h
- -f, --force
- Allows an extension to be created for a header even if that header is not found in standard include directories.
- -g, --global
- Include code for safely storing static data in the .xs file. Extensions that do no make use of static data can ignore this option.
- -h, -?, --help
- Print the usage, help and version for this h2xs and exit.
- -k, --omit-const-func
- For function arguments declared as "const", omit the const attribute in the generated XS code.
- -m, --gen-tied-var
- Experimental: for each variable declared in the header file(s), declare a perl variable of the same name magically tied to the C variable.
- -n, --name=module_name
- Specifies a name to be used for the extension, e.g., -n RPC::DCE
- -o, --opaque-re=regular expression
- Use "opaque" data type for the C types matched by
the regular expression, even if these types are
"typedef"-equivalent to types from typemaps. Should not be used
without -x.
- -p, --remove-prefix=prefix
- Specify a prefix which should be removed from the Perl function names, e.g., -p sec_rgy_ This sets up the XS PREFIX keyword and removes the prefix from functions that are autoloaded via the "constant()" mechanism.
- -s, --const-subs=sub1,sub2
- Create a perl subroutine for the specified macros rather than autoload with the constant() subroutine. These macros are assumed to have a return type of char *, e.g., -s sec_rgy_wildcard_name,sec_rgy_wildcard_sid.
- -t, --default-type=type
- Specify the internal type that the constant() mechanism uses for macros. The default is IV (signed integer). Currently all macros found during the header scanning process will be assumed to have this type. Future versions of "h2xs" may gain the ability to make educated guesses.
- --use-new-tests
- When --compat-version (-b) is present the generated tests will use "Test::More" rather than "Test" which is the default for versions before 5.6.2. "Test::More" will be added to PREREQ_PM in the generated "Makefile.PL".
- --use-old-tests
- Will force the generation of test code that uses the older "Test" module.
- --skip-exporter
- Do not use "Exporter" and/or export any symbol.
- --skip-ppport
- Do not use "Devel::PPPort": no portability to older version.
- --skip-autoloader
- Do not use the module "AutoLoader"; but keep the constant() function and "sub AUTOLOAD" for constants.
- --skip-strict
- Do not use the pragma "strict".
- --skip-warnings
- Do not use the pragma "warnings".
- -v, --version=version
- Specify a version number for this extension. This version number is added to the templates. The default is 0.01, or 0.00_01 if "-B" is specified. The version specified should be numeric.
- -x, --autogen-xsubs
- Automatically generate XSUBs basing on function
declarations in the header file. The package "C::Scan" should be
installed. If this option is specified, the name of the header file may
look like "NAME1,NAME2". In this case NAME1 is used instead of
the specified string, but XSUBs are emitted only for the declarations
included from file NAME2.
EXAMPLES
# Default behavior, extension is Rusers h2xs rpcsvc/rusers # Same, but extension is RUSERS h2xs -n RUSERS rpcsvc/rusers # Extension is rpcsvc::rusers. Still finds <rpcsvc/rusers.h> h2xs rpcsvc::rusers # Extension is ONC::RPC. Still finds <rpcsvc/rusers.h> h2xs -n ONC::RPC rpcsvc/rusers # Without constant() or AUTOLOAD h2xs -c rpcsvc/rusers # Creates templates for an extension named RPC h2xs -cfn RPC # Extension is ONC::RPC. h2xs -cfn ONC::RPC # Extension is a pure Perl module with no XS code. h2xs -X My::Module # Extension is Lib::Foo which works at least with Perl5.005_03. # Constants are created for all #defines and enums h2xs can find # in foo.h. h2xs -b 5.5.3 -n Lib::Foo foo.h # Extension is Lib::Foo which works at least with Perl5.005_03. # Constants are created for all #defines but only for enums # whose names do not start with 'bar_'. h2xs -b 5.5.3 -e '^bar_' -n Lib::Foo foo.h # Makefile.PL will look for library -lrpc in # additional directory /opt/net/lib h2xs rpcsvc/rusers -L/opt/net/lib -lrpc # Extension is DCE::rgynbase # prefix "sec_rgy_" is dropped from perl function names h2xs -n DCE::rgynbase -p sec_rgy_ dce/rgynbase # Extension is DCE::rgynbase # prefix "sec_rgy_" is dropped from perl function names # subroutines are created for sec_rgy_wildcard_name and # sec_rgy_wildcard_sid h2xs -n DCE::rgynbase -p sec_rgy_ \ -s sec_rgy_wildcard_name,sec_rgy_wildcard_sid dce/rgynbase # Make XS without defines in perl.h, but with function declarations # visible from perl.h. Name of the extension is perl1. # When scanning perl.h, define -DEXT=extern -DdEXT= -DINIT(x)= # Extra backslashes below because the string is passed to shell. # Note that a directory with perl header files would # be added automatically to include path. h2xs -xAn perl1 -F "-DEXT=extern -DdEXT= -DINIT\(x\)=" perl.h # Same with function declaration in proto.h as visible from perl.h. h2xs -xAn perl2 perl.h,proto.h # Same but select only functions which match /^av_/ h2xs -M '^av_' -xAn perl2 perl.h,proto.h # Same but treat SV* etc as "opaque" types h2xs -o '^[S]V \*$' -M '^av_' -xAn perl2 perl.h,proto.h
Extension based on .h and .c files
Suppose that you have some C files implementing some functionality, and the corresponding header files. How to create an extension which makes this functionality accessible in Perl? The example below assumes that the header files are interface_simple.h and interface_hairy.h, and you want the perl module be named as "Ext::Ension". If you need some preprocessor directives and/or linking with external libraries, see the flags "-F", "-L" and "-l" in "OPTIONS".- Find the directory name
- Start with a dummy run of h2xs:
h2xs -Afn Ext::Ension
- Copy C files
- Copy your header files and C files to this directory Ext/Ension.
- Create the extension
- Run h2xs, overwriting older autogenerated files:
h2xs -Oxan Ext::Ension interface_simple.h interface_hairy.h
- Archive and test
- As usual, run
cd Ext/Ension perl Makefile.PL make dist make make test
- Hints
- It is important to do "make dist" as early as
possible. This way you can easily merge(1) your changes to
autogenerated files if you decide to edit your ".h" files and
rerun h2xs.
ENVIRONMENT
No environment variables are used.AUTHOR
Larry Wall and othersSEE ALSO
perl, perlxstut, ExtUtils::MakeMaker, and AutoLoader.DIAGNOSTICS
The usual warnings if it cannot read or write the files involved.LIMITATIONS of -x
h2xs would not distinguish whether an argument to a C function which is of the form, say, "int *", is an input, output, or input/output parameter. In particular, argument declarations of the formint foo(n) int *nshould be better rewritten as
int foo(n) int &nif "n" is an input parameter. Additionally, h2xs has no facilities to intuit that a function
int foo(addr,l) char *addr int ltakes a pair of address and length of data at this address, so it is better to rewrite this function as
int foo(sv) SV *addr PREINIT: STRLEN len; char *s; CODE: s = SvPV(sv,len); RETVAL = foo(s, len); OUTPUT: RETVALor alternately
static int my_foo(SV *sv) { STRLEN len; char *s = SvPV(sv,len); return foo(s, len); } MODULE = foo PACKAGE = foo PREFIX = my_ int foo(sv) SV *svSee perlxs and perlxstut for additional details.
2022-03-05 | perl v5.32.0 |