Jelmer Vernooij > Parse-Pidl > pidl


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pidl - IDL Compiler written in Perl


pidl --help pidl [--outputdir[=OUTNAME]] [--parse-idl-tree] [--dump-idl-tree] [--dump-ndr-tree] [--ndr-header[=OUTPUT]] [--header[=OUTPUT]] [--ejs[=OUTPUT]] [--swig[=OUTPUT]] [--uint-enums] [--ndr-parser[=OUTPUT]] [--client] [--server] [--dcom-proxy] [--com-header] [--warn-compat] [--quiet] [--verbose] [--template] [--eth-parser[=OUTPUT]] [--diff] [--dump-idl] [<idlfile>.idl]...


pidl is an IDL compiler written in Perl that aims to be somewhat compatible with the midl compiler. IDL stands for "Interface Definition Language".

pidl can generate stubs for DCE/RPC server code, DCE/RPC client code and ethereal dissectors for DCE/RPC traffic.

IDL compilers like pidl take a description of an interface as their input and use it to generate C (though support for other languages may be added later) code that can use these interfaces, pretty print data sent using these interfaces, or even generate ethereal dissectors that can parse data sent over the wire by these interfaces.

pidl takes IDL files in the same format as is used by midl, converts it to a .pidl file (which contains pidl's internal representation of the interface) and can then generate whatever output you need. .pidl files should be used for debugging purposes only. Write your interface definitions in .idl format.

The goal of pidl is to implement a IDL compiler that can be used while developing the RPC subsystem in Samba (for both marshalling/unmarshalling and debugging purposes).



Show list of available options.

--outputdir OUTNAME

Write output files to the specified directory. Defaults to the current directory.


Read internal tree structure from input files rather then assuming they contain IDL.


Generate a new IDL file. File will be named OUTNAME.idl.


Generate a C header file for the specified interface. Filename defaults to OUTNAME.h.


Generate a C header file with the prototypes for the NDR parsers. Filename defaults to ndr_OUTNAME.h.


Generate a C file containing NDR parsers. Filename defaults to ndr_OUTNAME.c.


Generate boilerplate for the RPC server that implements the interface. Filename defaults to ndr_OUTNAME_s.c.


Generate stubs for a RPC server that implements the interface. Output will be written to stdout.


Generate an Ethereal dissector (in C) for the interface. Filename defaults to packet-dcerpc-OUTNAME.c.

Pidl will read additional data from an ethereal conformance file if present. Such a file should have the same location as the IDL file but with the extension cnf rather then idl. See below for details on the format of this file.


Parse an IDL file, generate a new IDL file based on the internal data structures and see if there are any differences with the original IDL file. Useful for debugging pidl.


Tell pidl to dump the internal tree representation of an IDL file the to disk. Useful for debugging pidl.


Tell pidl to dump the internal NDR information tree it generated from the IDL file to disk. Useful for debugging pidl.


IDL files are always preprocessed using the C preprocessor.

Pretty much everything in an interface (the interface itself, functions, parameters) can have attributes (or properties whatever name you give them). Attributes always prepend the element they apply to and are surrounded by square brackets ([]). Multiple attributes are separated by comma's; arguments to attributes are specified between parentheses.

See the section COMPATIBILITY for the list of attributes that pidl supports.

C-style comments can be used.


A conformant array is one with that ends in [*] or []. The strange things about conformant arrays are that they can only appear as the last element of a structure (unless there is a pointer to the conformant array, of course) and the array size appears before the structure itself on the wire.

So, in this example:

        typedef struct {
                long abc;
                long count;     
                long foo;
                [size_is(count)] long s[*];
        } Struct1;

it appears like this:

        [size_is] [abc] [count] [foo] [s...]

the first [size_is] field is the allocation size of the array, and occurs before the array elements and even before the structure alignment.

Note that size_is() can refer to a constant, but that doesn't change the wire representation. It does not make the array a fixed array.

midl.exe would write the above array as the following C header:

   typedef struct {
                long abc;
                long count;     
                long foo;
                long s[1];
        } Struct1;

pidl takes a different approach, and writes it like this:

    typedef struct {
                long abc;
                long count;     
                long foo;
                long *s;
        } Struct1;


A varying array looks like this:

        typedef struct {
                long abc;
                long count;     
                long foo;
                [size_is(count)] long *s;
        } Struct1;

This will look like this on the wire:

        [abc] [count] [foo] [PTR_s]    [count] [s...]


A fixed array looks like this:

    typedef struct {
            long s[10];
    } Struct1;

The NDR representation looks just like 10 separate long declarations. The array size is not encoded on the wire.

pidl also supports "inline" arrays, which are not part of the IDL/NDR standard. These are declared like this:

    typedef struct {
            uint32 foo;
            uint32 count;
            uint32 bar;
            long s[count];
    } Struct1;

This appears like this:

        [foo] [count] [bar] [s...]

Fixed arrays are an extension added to support some of the strange embedded structures in security descriptors and spoolss.

This section is by no means complete. See the OpenGroup and MSDN documentation for additional information.


Missing features in pidl

The following MIDL features are not (yet) implemented in pidl or are implemented with an incompatible interface:

Supported attributes

in, out, ref, length_is, switch_is, size_is, uuid, case, default, string, unique, ptr, pointer_default, v1_enum, object, helpstring, range, local, call_as, endpoint, switch_type, progid, coclass, iid_is.

PIDL Specific properties


The [public] property on a structure or union is a pidl extension that forces the generated pull/push functions to be non-static. This allows you to declare types that can be used between modules. If you don't specify [public] then pull/push functions for other than top-level functions are declared static.


The [noprint] property is a pidl extension that allows you to specify that pidl should not generate a ndr_print_*() function for that structure or union. This is used when you wish to define your own print function that prints a structure in a nicer manner. A good example is the use of [noprint] on dom_sid, which allows the pretty-printing of SIDs.


The [value(expression)] property is a pidl extension that allows you to specify the value of a field when it is put on the wire. This allows fields that always have a well-known value to be automatically filled in, thus making the API more programmer friendly. The expression can be any C expression.


The [relative] property can be supplied on a pointer. When it is used it declares the pointer as a spoolss style "relative" pointer, which means it appears on the wire as an offset within the current encapsulating structure. This is not part of normal IDL/NDR, but it is a very useful extension as it avoids the manual encoding of many complex structures.


Specifies that a size of length bytes should be read, followed by a blob of that size, which will be parsed as NDR.


Specify boolean options, mostly used for low-level NDR options. Several options can be specified using the | character. Note that flags are inherited by substructures!


The [nodiscriminant] property on a union means that the usual uint16 discriminent field at the start of the union on the wire is omitted. This is not normally allowed in IDL/NDR, but is used for some spoolss structures.


Specify that the array or string uses the specified charset. If this attribute is specified, pidl will take care of converting the character data from this format to the host format. Commonly used values are UCS2, DOS and UTF8.

Unsupported MIDL properties

aggregatable, appobject, async_uuid, bindable, control, cpp_quote, defaultbind, defaultcollelem, defaultvalue, defaultvtable, dispinterface, displaybind, dual, entry, first_is, helpcontext, helpfile, helpstringcontext, helpstringdll, hidden, idl_module, idl_quote, id, immediatebind, importlib, import, include, includelib, last_is, lcid, licensed, max_is, module, ms_union, no_injected_text, nonbrowsable, noncreatable, nonextensible, odl, oleautomation, optional, pragma, propget, propputref, propput, readonly, requestedit, restricted, retval, source, transmit_as, uidefault, usesgetlasterror, vararg, vi_progid, wire_marshal.


Pidl needs additional data for ethereal output. This data is read from so-called conformance files. This section describes the format of these files.

Conformance files are simple text files with a single command on each line. Empty lines and lines starting with a '#' character are ignored. Arguments to commands are seperated by spaces.

The following commands are currently supported:

TYPE name dissector ft_type base_type mask valsstring alignment

Register new data type with specified name, what dissector function to call and what properties to give header fields for elements of this type.


Suppress emitting a dissect_type function for the specified type

PARAM_VALUE type param

Set parameter to specify to dissector function for given type.

HF_FIELD hf title filter ft_type base_type valsstring mask description

Generate a custom header field with specified properties.

HF_RENAME old_hf_name new_hf_name

Force the use of new_hf_name when the parser generator was going to use old_hf_name.

This can be used in conjunction with HF_FIELD in order to make more then one element use the same filter name.


Remove the specified prefix from all function names (if present).

PROTOCOL longname shortname filtername

Change the short-, long- and filter-name for the current interface in Ethereal.


Change description for the specified header field. `field' is the hf name of the field.

IMPORT dissector code...

Code to insert when generating the specified dissector. @HF@ and @PARAM@ will be substituted.


        # Generating an ethereal parser
        $ ./pidl --eth-parser -- atsvc.idl
        # Generating a TDR parser
        $ ./pidl --tdr-parser --tdr-header --header -- regf.idl


This man page is correct for version 4.0 of the Samba suite.

SEE ALSO ^ yapp(1)


pidl was written by Andrew Tridgell, Stefan Metzmacher, Tim Potter and Jelmer Vernooij.

This manpage was written by Jelmer Vernooij, partially based on the original pidl README by Andrew Tridgell.

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