create-native-map(1)
NAME
create-native-map - C/C# Mapping Creator
SYNOPSIS
create-native-map [OPTIONS]* ASSEMBLY-FILE-NAME OUPUT-PREFIX
OPTIONS
--autoconf-header=HEADER
HEADER is a header file name in the syntax typically used with
the C #include statement, e.g. #include <stdio.h> or #include
"local.h" .
An Autoconf-formatted macro is generated from the include name,
and a #include directive is wrapped within a #ifdef block for
the Autoconf macro within the generated .c file.
For example, --autoconf-header=<stdio.h> would generate the
code:
#ifndef HAVE_STDIO_H
#include <stdio.h>
#endif /* ndef HAVE_STDIO_H */
--autoconf-member=MEMBER
Specify that any access to MEMBER should be wrapped within a
#ifdef HAVE_MEMBER block. MEMBER can be either a field-name or
a class-name . field-name combination.
For example, given the C# declaration:
[Mono.Unix.Native.Map ("struct dirent")]
struct Dirent {
public long d_off;
}
then --autoconf-member=d_off would generate the code similar to:
int
ToDirent (struct dirent *from, struct Dirent *to)
{
#ifdef HAVE_STRUCT_DIRENT_D_OFF
to->d_off = from->d_off;
#endif /* ndef HAVE_STRUCT_DIRENT_D_OFF */
}
--exclude-native-symbol=SYMBOL
SYMBOL is a [DllImport] -marked method that should not have a
prototype generated for it.
--impl-header=HEADER
Insert a #include statement within the generated .c file for
HEADER .
For example, --impl-header=<stdlib.h> generates
#include <stdlib.h>
--impl-macro=MACRO
Insert a #define statement within the generated .c file. MACRO
can contain a = to separate the macro name from the macro value.
For example, --impl-macro=FOO=42 generates
#define FOO 42
--library=LIBRARY
Create prototypes for [DllImport] -marked methods which
reference the native library LIBRARY into the generated .h file.
--public-header=HEADER
Insert a #include statement within the generated .h file for
HEADER .
For example, --public-header=<stdlib.h> generates
#include <stdlib.h>
--public-macro=MACRO
Insert a #define statement within the generated .h file. MACRO
can contain a = to separate the macro name from the macro value.
For example, --public-macro=FOO=42 generates
#define FOO 42
--rename-member=FROM=TO
This is used when FROM is a C macro, and thus must be altered in
order to be used sanely. All generated references to the
managed representation will use TO instead of FROM .
For example, given the C# declaration:
[Mono.Unix.Native.Map ("struct stat")]
struct Stat {
public long st_atime;
}
and the argument --rename-member=st_atime=st_atime_ , the
generated .h file would contain:
struct Stat {
gint64 st_atime_;
};
(note the altered field name), while the generated .c file would
contain:
ToStat (struct stat *from, struct Stat *to)
{
to->st_atime_ = from->st_atime;
}
--rename-namespace=FROM=TO
By default, the C "namespace" (symbol prefix) is the C#
namespace; types within the C# namespace Mono.Unix.Native would
be in the C "namespace" Mono_Unix_Native . Use --rename-
namespace to modify the default, e.g. --rename-
namespace=Mono.Unix.Native=Mono_Posix .
DESCRIPTION
create-native-map is a program for a specific scenario: keeping code
which is tightly coupled between C and C# in sync with each other,
based upon the C# types.
Platform Invoke is only useful if the managed code knows the exact
types and layout of all unmanaged structures it uses. This is usually
the case on Windows, but it is not the case on Unix. For example,
struct stat makes use of types with sizes that will vary from platform
to platform (or even based on the compiler macros defined!). For
example, off_t is usually a signed 32-bit integer on ILP32 platforms,
but may be a signed 64-bit integer on LP64 platforms, but may also be a
64-bit signed integer on ILP32 platforms if the _FILE_OFFSET_BITS macro
has the value 64. In short, everything is flexible within Unix, and
managed code can't deal with such flexibility.
Thus, the niche for create-native-map : assume a fixed ABI that managed
code can target, and generate code to "thunk" the managed
representations to the corresponding native representations. This
needs to be done for everything that can vary between platforms and
compiler flags, from enumeration values ( SIGBUS has the value 10 on
FreeBSD but 7 on Linux) to structure members (how big is off_t ?).
create-native-map will inspect ASSEMBLY-FILE-NAME and output the
following files:
OUTPUT-PREFIX.h
Contains enumeration values, class and structure
declarations, delegate declarations, and [DllImport]
-marked methods (from the library specified by --library
) within the assembly ASSEMBLY-FILE-NAME .
OUTPUT-PREFIX.c
Contains the implementation of enumeration and structure
conversion functions.
OUTPUT-PREFIX.cs
Contains a partial class NativeConvert containing
enumeration translation methods.
OUTPUT-PREFIX.xml
Generates ECMA XML documentation stubs for the
enumeration translation methods in OUTPUT-PREFIX.cs .
create-native-map primarily looks for MapAttribute -decorated types,
and makes use of two MapAttribute properties:
NativeType
Contains the corresponding C type. Only useful if
applied to classes, structures, and fields.
SuppressFlags
When specified on an enumeration member of a [Flags]
-decorated enumeration type, disables the normal code
generator support for bit-masking enumeration types.
This is useful when bitmask and non-bitmask information
is stored within the same type, and bitmask checking
shouldn't be used for the non-bitmask values. Example:
Mono.Unix.Native.FilePermissions.S_IFREG , which is not a
bitmask value, while most of FilePermissions consists of
bitmask values ( FilePermissions.S_IRUSR ,
FilePermissions.S_IWUSR , etc.).
The MapAttribute attribute can be specified on classes, structures,
delegates, fields, and enumerations.
Delegates
Code generation for delegates ignores the
MapAttribute.NativeType property, and generates a function
pointer typedef that best matches the delegate declaration into
the .h file.
For example,
namespace Foo {
[Map]
delegate string MyCallback (string s);
}
generates the typedef :
typedef char* (*Foo_MyCallback) (const char *s);
Classes and Structures
A [Map] -decorated class or structure will get a C structure
declaration within the .h file:
[Map]
struct Foo {
public int i;
}
becomes
struct Foo {
public int i;
};
If the MapAttribute.NativeType property is set, then conversion
functions will be declared within the .h file and created within
the .c file:
namespace Foo {
[Map ("struct stat")]
struct Stat {
public uint st_uid;
}
}
becomes
/* The .h file */
struct Foo_Stat {
unsigned int st_uid;
};
int
Foo_FromStat (struct Foo_Stat *from, struct stat *to);
int
Foo_ToStat (struct stat *to, sxtruct Foo_Stat *to);
/* The .c file */
int
Foo_FromStat (struct Foo_Stat *from, struct stat *to)
{
memset (to, 0, sizeof(*to);
to->st_uid = from->st_uid;
return 0;
}
int
Foo_ToStat (struct stat *to, sxtruct Foo_Stat *to)
{
memset (to, 0, sizeof(*to);
to->st_uid = from->st_uid;
return 0;
}
For classes, the conversion functions will only copy fields
declared in the class itself. Fields declared in parent classes
will not be copied. (This is because create-native-map does not
know how the inheritance is implemented in C. Therefore copying
fields from parent classes is left to the caller of the
conversion functions.)
Fields If a field (1) has the MapAttribute attribute, and (2) has the
MapAttribute.NativeType property set, then the specified native
type will be used for overflow checking. For example:
namespace Foo {
[Map ("struct stat")]
struct Stat {
[Map ("off_t")] public long st_size;
}
}
generates
/* The .h file */
struct Foo_Stat {
gint64 st_size;
};
int
Foo_FromStat (struct Foo_Stat *from, struct stat *to);
int
Foo_ToStat (struct stat *to, sxtruct Foo_Stat *to);
/* The .c file */
int
Foo_FromStat (struct Foo_Stat *from, struct stat *to)
{
_cnm_return_val_if_overflow (off_t, from->st_size, -1);
memset (to, 0, sizeof(*to);
to->st_size = from->st_size;
return 0;
}
int
Foo_ToStat (struct stat *to, sxtruct Foo_Stat *to)
{
_cnm_return_val_if_overflow (gint64, from->st_size, -1);
memset (to, 0, sizeof(*to);
to->st_size = from->st_size;
return 0;
}
This is useful for better error checking within the conversion
functions. MapAttribute.NativeType is required for this as
there is no other way to know what the native type is (without
parsing the system header files...).
Enumerations
Generates a C enumeration and macros for each of the members
within the enumeration. To and From functions are also declared
in the .h file and implemented in the .c file.
For example,
namespace Foo {
[Map]
enum Errno {
EINVAL
}
}
would generate the following in the .h file:
enum Foo_Errno {
Foo_Errno_EINVAL = 0,
#define Foo_Errno_EINVAL Foo_Errno_EINVAL
};
int Foo_FromErrno (int from, int *to);
int Foo_ToErrno (int from, int *to);
and generates the following in the the .c file:
int
Foo_FromErrno (int from, int *to)
{
*to = 0;
if (from == Foo_Errno_EPERM)
#ifdef EINVAL
{*to = EINVAL;}
#else
{errno = EINVAL; return -1;}
#endif
return 0;
}
int
Foo_ToErrno (int from, int *to)
{
*to = 0;
#ifdef EINVAL
if (from == EINVAL)
{*to = Foo_Errno_EPERM; return 0;}
#endif
return -1;
}
Different code will be generated if the managed enum is a
[Flags] -decorated enumeration (to account for bitwise flags),
but this is the basic idea.
MAILING LISTS
Visit http://lists.ximian.com/mailman/listinfo/mono-devel-list for details.
WEB SITE
Visit http://www.mono-project.com for details
create-native-map(1)
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