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;
}
- 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