Merge pull request #97 from joshtriplett/remove-more-generated-files
Remove more generated files
This commit is contained in:
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doc/libffi.info
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doc/libffi.info
@@ -1,618 +0,0 @@
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This is libffi.info, produced by makeinfo version 5.1 from libffi.texi.
|
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|
||||
This manual is for Libffi, a portable foreign-function interface
|
||||
library.
|
||||
|
||||
Copyright (C) 2008, 2010, 2011 Red Hat, Inc.
|
||||
|
||||
Permission is granted to copy, distribute and/or modify this
|
||||
document under the terms of the GNU General Public License as
|
||||
published by the Free Software Foundation; either version 2, or (at
|
||||
your option) any later version. A copy of the license is included
|
||||
in the section entitled "GNU General Public License".
|
||||
|
||||
INFO-DIR-SECTION Development
|
||||
START-INFO-DIR-ENTRY
|
||||
* libffi: (libffi). Portable foreign-function interface library.
|
||||
END-INFO-DIR-ENTRY
|
||||
|
||||
|
||||
File: libffi.info, Node: Top, Next: Introduction, Up: (dir)
|
||||
|
||||
libffi
|
||||
******
|
||||
|
||||
This manual is for Libffi, a portable foreign-function interface
|
||||
library.
|
||||
|
||||
Copyright (C) 2008, 2010, 2011 Red Hat, Inc.
|
||||
|
||||
Permission is granted to copy, distribute and/or modify this
|
||||
document under the terms of the GNU General Public License as
|
||||
published by the Free Software Foundation; either version 2, or (at
|
||||
your option) any later version. A copy of the license is included
|
||||
in the section entitled "GNU General Public License".
|
||||
|
||||
* Menu:
|
||||
|
||||
* Introduction:: What is libffi?
|
||||
* Using libffi:: How to use libffi.
|
||||
* Missing Features:: Things libffi can't do.
|
||||
* Index:: Index.
|
||||
|
||||
|
||||
File: libffi.info, Node: Introduction, Next: Using libffi, Prev: Top, Up: Top
|
||||
|
||||
1 What is libffi?
|
||||
*****************
|
||||
|
||||
Compilers for high level languages generate code that follow certain
|
||||
conventions. These conventions are necessary, in part, for separate
|
||||
compilation to work. One such convention is the "calling convention".
|
||||
The calling convention is a set of assumptions made by the compiler
|
||||
about where function arguments will be found on entry to a function. A
|
||||
calling convention also specifies where the return value for a function
|
||||
is found. The calling convention is also sometimes called the "ABI" or
|
||||
"Application Binary Interface".
|
||||
|
||||
Some programs may not know at the time of compilation what arguments
|
||||
are to be passed to a function. For instance, an interpreter may be
|
||||
told at run-time about the number and types of arguments used to call a
|
||||
given function. 'Libffi' can be used in such programs to provide a
|
||||
bridge from the interpreter program to compiled code.
|
||||
|
||||
The 'libffi' library provides a portable, high level programming
|
||||
interface to various calling conventions. This allows a programmer to
|
||||
call any function specified by a call interface description at run time.
|
||||
|
||||
FFI stands for Foreign Function Interface. A foreign function
|
||||
interface is the popular name for the interface that allows code written
|
||||
in one language to call code written in another language. The 'libffi'
|
||||
library really only provides the lowest, machine dependent layer of a
|
||||
fully featured foreign function interface. A layer must exist above
|
||||
'libffi' that handles type conversions for values passed between the two
|
||||
languages.
|
||||
|
||||
|
||||
File: libffi.info, Node: Using libffi, Next: Missing Features, Prev: Introduction, Up: Top
|
||||
|
||||
2 Using libffi
|
||||
**************
|
||||
|
||||
* Menu:
|
||||
|
||||
* The Basics:: The basic libffi API.
|
||||
* Simple Example:: A simple example.
|
||||
* Types:: libffi type descriptions.
|
||||
* Multiple ABIs:: Different passing styles on one platform.
|
||||
* The Closure API:: Writing a generic function.
|
||||
* Closure Example:: A closure example.
|
||||
|
||||
|
||||
File: libffi.info, Node: The Basics, Next: Simple Example, Up: Using libffi
|
||||
|
||||
2.1 The Basics
|
||||
==============
|
||||
|
||||
'Libffi' assumes that you have a pointer to the function you wish to
|
||||
call and that you know the number and types of arguments to pass it, as
|
||||
well as the return type of the function.
|
||||
|
||||
The first thing you must do is create an 'ffi_cif' object that
|
||||
matches the signature of the function you wish to call. This is a
|
||||
separate step because it is common to make multiple calls using a single
|
||||
'ffi_cif'. The "cif" in 'ffi_cif' stands for Call InterFace. To
|
||||
prepare a call interface object, use the function 'ffi_prep_cif'.
|
||||
|
||||
-- Function: ffi_status ffi_prep_cif (ffi_cif *CIF, ffi_abi ABI,
|
||||
unsigned int NARGS, ffi_type *RTYPE, ffi_type **ARGTYPES)
|
||||
This initializes CIF according to the given parameters.
|
||||
|
||||
ABI is the ABI to use; normally 'FFI_DEFAULT_ABI' is what you want.
|
||||
*note Multiple ABIs:: for more information.
|
||||
|
||||
NARGS is the number of arguments that this function accepts.
|
||||
|
||||
RTYPE is a pointer to an 'ffi_type' structure that describes the
|
||||
return type of the function. *Note Types::.
|
||||
|
||||
ARGTYPES is a vector of 'ffi_type' pointers. ARGTYPES must have
|
||||
NARGS elements. If NARGS is 0, this argument is ignored.
|
||||
|
||||
'ffi_prep_cif' returns a 'libffi' status code, of type
|
||||
'ffi_status'. This will be either 'FFI_OK' if everything worked
|
||||
properly; 'FFI_BAD_TYPEDEF' if one of the 'ffi_type' objects is
|
||||
incorrect; or 'FFI_BAD_ABI' if the ABI parameter is invalid.
|
||||
|
||||
If the function being called is variadic (varargs) then
|
||||
'ffi_prep_cif_var' must be used instead of 'ffi_prep_cif'.
|
||||
|
||||
-- Function: ffi_status ffi_prep_cif_var (ffi_cif *CIF, ffi_abi varabi,
|
||||
unsigned int NFIXEDARGS, unsigned int varntotalargs, ffi_type
|
||||
*RTYPE, ffi_type **ARGTYPES)
|
||||
This initializes CIF according to the given parameters for a call
|
||||
to a variadic function. In general it's operation is the same as
|
||||
for 'ffi_prep_cif' except that:
|
||||
|
||||
NFIXEDARGS is the number of fixed arguments, prior to any variadic
|
||||
arguments. It must be greater than zero.
|
||||
|
||||
NTOTALARGS the total number of arguments, including variadic and
|
||||
fixed arguments.
|
||||
|
||||
Note that, different cif's must be prepped for calls to the same
|
||||
function when different numbers of arguments are passed.
|
||||
|
||||
Also note that a call to 'ffi_prep_cif_var' with
|
||||
NFIXEDARGS=NOTOTALARGS is NOT equivalent to a call to
|
||||
'ffi_prep_cif'.
|
||||
|
||||
To call a function using an initialized 'ffi_cif', use the 'ffi_call'
|
||||
function:
|
||||
|
||||
-- Function: void ffi_call (ffi_cif *CIF, void *FN, void *RVALUE, void
|
||||
**AVALUES)
|
||||
This calls the function FN according to the description given in
|
||||
CIF. CIF must have already been prepared using 'ffi_prep_cif'.
|
||||
|
||||
RVALUE is a pointer to a chunk of memory that will hold the result
|
||||
of the function call. This must be large enough to hold the
|
||||
result, no smaller than the system register size (generally 32 or
|
||||
64 bits), and must be suitably aligned; it is the caller's
|
||||
responsibility to ensure this. If CIF declares that the function
|
||||
returns 'void' (using 'ffi_type_void'), then RVALUE is ignored.
|
||||
|
||||
AVALUES is a vector of 'void *' pointers that point to the memory
|
||||
locations holding the argument values for a call. If CIF declares
|
||||
that the function has no arguments (i.e., NARGS was 0), then
|
||||
AVALUES is ignored. Note that argument values may be modified by
|
||||
the callee (for instance, structs passed by value); the burden of
|
||||
copying pass-by-value arguments is placed on the caller.
|
||||
|
||||
|
||||
File: libffi.info, Node: Simple Example, Next: Types, Prev: The Basics, Up: Using libffi
|
||||
|
||||
2.2 Simple Example
|
||||
==================
|
||||
|
||||
Here is a trivial example that calls 'puts' a few times.
|
||||
|
||||
#include <stdio.h>
|
||||
#include <ffi.h>
|
||||
|
||||
int main()
|
||||
{
|
||||
ffi_cif cif;
|
||||
ffi_type *args[1];
|
||||
void *values[1];
|
||||
char *s;
|
||||
ffi_arg rc;
|
||||
|
||||
/* Initialize the argument info vectors */
|
||||
args[0] = &ffi_type_pointer;
|
||||
values[0] = &s;
|
||||
|
||||
/* Initialize the cif */
|
||||
if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1,
|
||||
&ffi_type_sint, args) == FFI_OK)
|
||||
{
|
||||
s = "Hello World!";
|
||||
ffi_call(&cif, puts, &rc, values);
|
||||
/* rc now holds the result of the call to puts */
|
||||
|
||||
/* values holds a pointer to the function's arg, so to
|
||||
call puts() again all we need to do is change the
|
||||
value of s */
|
||||
s = "This is cool!";
|
||||
ffi_call(&cif, puts, &rc, values);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
File: libffi.info, Node: Types, Next: Multiple ABIs, Prev: Simple Example, Up: Using libffi
|
||||
|
||||
2.3 Types
|
||||
=========
|
||||
|
||||
* Menu:
|
||||
|
||||
* Primitive Types:: Built-in types.
|
||||
* Structures:: Structure types.
|
||||
* Type Example:: Structure type example.
|
||||
|
||||
|
||||
File: libffi.info, Node: Primitive Types, Next: Structures, Up: Types
|
||||
|
||||
2.3.1 Primitive Types
|
||||
---------------------
|
||||
|
||||
'Libffi' provides a number of built-in type descriptors that can be used
|
||||
to describe argument and return types:
|
||||
|
||||
'ffi_type_void'
|
||||
The type 'void'. This cannot be used for argument types, only for
|
||||
return values.
|
||||
|
||||
'ffi_type_uint8'
|
||||
An unsigned, 8-bit integer type.
|
||||
|
||||
'ffi_type_sint8'
|
||||
A signed, 8-bit integer type.
|
||||
|
||||
'ffi_type_uint16'
|
||||
An unsigned, 16-bit integer type.
|
||||
|
||||
'ffi_type_sint16'
|
||||
A signed, 16-bit integer type.
|
||||
|
||||
'ffi_type_uint32'
|
||||
An unsigned, 32-bit integer type.
|
||||
|
||||
'ffi_type_sint32'
|
||||
A signed, 32-bit integer type.
|
||||
|
||||
'ffi_type_uint64'
|
||||
An unsigned, 64-bit integer type.
|
||||
|
||||
'ffi_type_sint64'
|
||||
A signed, 64-bit integer type.
|
||||
|
||||
'ffi_type_float'
|
||||
The C 'float' type.
|
||||
|
||||
'ffi_type_double'
|
||||
The C 'double' type.
|
||||
|
||||
'ffi_type_uchar'
|
||||
The C 'unsigned char' type.
|
||||
|
||||
'ffi_type_schar'
|
||||
The C 'signed char' type. (Note that there is not an exact
|
||||
equivalent to the C 'char' type in 'libffi'; ordinarily you should
|
||||
either use 'ffi_type_schar' or 'ffi_type_uchar' depending on
|
||||
whether 'char' is signed.)
|
||||
|
||||
'ffi_type_ushort'
|
||||
The C 'unsigned short' type.
|
||||
|
||||
'ffi_type_sshort'
|
||||
The C 'short' type.
|
||||
|
||||
'ffi_type_uint'
|
||||
The C 'unsigned int' type.
|
||||
|
||||
'ffi_type_sint'
|
||||
The C 'int' type.
|
||||
|
||||
'ffi_type_ulong'
|
||||
The C 'unsigned long' type.
|
||||
|
||||
'ffi_type_slong'
|
||||
The C 'long' type.
|
||||
|
||||
'ffi_type_longdouble'
|
||||
On platforms that have a C 'long double' type, this is defined. On
|
||||
other platforms, it is not.
|
||||
|
||||
'ffi_type_pointer'
|
||||
A generic 'void *' pointer. You should use this for all pointers,
|
||||
regardless of their real type.
|
||||
|
||||
Each of these is of type 'ffi_type', so you must take the address
|
||||
when passing to 'ffi_prep_cif'.
|
||||
|
||||
|
||||
File: libffi.info, Node: Structures, Next: Type Example, Prev: Primitive Types, Up: Types
|
||||
|
||||
2.3.2 Structures
|
||||
----------------
|
||||
|
||||
Although 'libffi' has no special support for unions or bit-fields, it is
|
||||
perfectly happy passing structures back and forth. You must first
|
||||
describe the structure to 'libffi' by creating a new 'ffi_type' object
|
||||
for it.
|
||||
|
||||
-- Data type: ffi_type
|
||||
The 'ffi_type' has the following members:
|
||||
'size_t size'
|
||||
This is set by 'libffi'; you should initialize it to zero.
|
||||
|
||||
'unsigned short alignment'
|
||||
This is set by 'libffi'; you should initialize it to zero.
|
||||
|
||||
'unsigned short type'
|
||||
For a structure, this should be set to 'FFI_TYPE_STRUCT'.
|
||||
|
||||
'ffi_type **elements'
|
||||
This is a 'NULL'-terminated array of pointers to 'ffi_type'
|
||||
objects. There is one element per field of the struct.
|
||||
|
||||
|
||||
File: libffi.info, Node: Type Example, Prev: Structures, Up: Types
|
||||
|
||||
2.3.3 Type Example
|
||||
------------------
|
||||
|
||||
The following example initializes a 'ffi_type' object representing the
|
||||
'tm' struct from Linux's 'time.h'.
|
||||
|
||||
Here is how the struct is defined:
|
||||
|
||||
struct tm {
|
||||
int tm_sec;
|
||||
int tm_min;
|
||||
int tm_hour;
|
||||
int tm_mday;
|
||||
int tm_mon;
|
||||
int tm_year;
|
||||
int tm_wday;
|
||||
int tm_yday;
|
||||
int tm_isdst;
|
||||
/* Those are for future use. */
|
||||
long int __tm_gmtoff__;
|
||||
__const char *__tm_zone__;
|
||||
};
|
||||
|
||||
Here is the corresponding code to describe this struct to 'libffi':
|
||||
|
||||
{
|
||||
ffi_type tm_type;
|
||||
ffi_type *tm_type_elements[12];
|
||||
int i;
|
||||
|
||||
tm_type.size = tm_type.alignment = 0;
|
||||
tm_type.type = FFI_TYPE_STRUCT;
|
||||
tm_type.elements = &tm_type_elements;
|
||||
|
||||
for (i = 0; i < 9; i++)
|
||||
tm_type_elements[i] = &ffi_type_sint;
|
||||
|
||||
tm_type_elements[9] = &ffi_type_slong;
|
||||
tm_type_elements[10] = &ffi_type_pointer;
|
||||
tm_type_elements[11] = NULL;
|
||||
|
||||
/* tm_type can now be used to represent tm argument types and
|
||||
return types for ffi_prep_cif() */
|
||||
}
|
||||
|
||||
|
||||
File: libffi.info, Node: Multiple ABIs, Next: The Closure API, Prev: Types, Up: Using libffi
|
||||
|
||||
2.4 Multiple ABIs
|
||||
=================
|
||||
|
||||
A given platform may provide multiple different ABIs at once. For
|
||||
instance, the x86 platform has both 'stdcall' and 'fastcall' functions.
|
||||
|
||||
'libffi' provides some support for this. However, this is
|
||||
necessarily platform-specific.
|
||||
|
||||
|
||||
File: libffi.info, Node: The Closure API, Next: Closure Example, Prev: Multiple ABIs, Up: Using libffi
|
||||
|
||||
2.5 The Closure API
|
||||
===================
|
||||
|
||||
'libffi' also provides a way to write a generic function - a function
|
||||
that can accept and decode any combination of arguments. This can be
|
||||
useful when writing an interpreter, or to provide wrappers for arbitrary
|
||||
functions.
|
||||
|
||||
This facility is called the "closure API". Closures are not supported
|
||||
on all platforms; you can check the 'FFI_CLOSURES' define to determine
|
||||
whether they are supported on the current platform.
|
||||
|
||||
Because closures work by assembling a tiny function at runtime, they
|
||||
require special allocation on platforms that have a non-executable heap.
|
||||
Memory management for closures is handled by a pair of functions:
|
||||
|
||||
-- Function: void *ffi_closure_alloc (size_t SIZE, void **CODE)
|
||||
Allocate a chunk of memory holding SIZE bytes. This returns a
|
||||
pointer to the writable address, and sets *CODE to the
|
||||
corresponding executable address.
|
||||
|
||||
SIZE should be sufficient to hold a 'ffi_closure' object.
|
||||
|
||||
-- Function: void ffi_closure_free (void *WRITABLE)
|
||||
Free memory allocated using 'ffi_closure_alloc'. The argument is
|
||||
the writable address that was returned.
|
||||
|
||||
Once you have allocated the memory for a closure, you must construct
|
||||
a 'ffi_cif' describing the function call. Finally you can prepare the
|
||||
closure function:
|
||||
|
||||
-- Function: ffi_status ffi_prep_closure_loc (ffi_closure *CLOSURE,
|
||||
ffi_cif *CIF, void (*FUN) (ffi_cif *CIF, void *RET, void
|
||||
**ARGS, void *USER_DATA), void *USER_DATA, void *CODELOC)
|
||||
Prepare a closure function.
|
||||
|
||||
CLOSURE is the address of a 'ffi_closure' object; this is the
|
||||
writable address returned by 'ffi_closure_alloc'.
|
||||
|
||||
CIF is the 'ffi_cif' describing the function parameters.
|
||||
|
||||
USER_DATA is an arbitrary datum that is passed, uninterpreted, to
|
||||
your closure function.
|
||||
|
||||
CODELOC is the executable address returned by 'ffi_closure_alloc'.
|
||||
|
||||
FUN is the function which will be called when the closure is
|
||||
invoked. It is called with the arguments:
|
||||
CIF
|
||||
The 'ffi_cif' passed to 'ffi_prep_closure_loc'.
|
||||
|
||||
RET
|
||||
A pointer to the memory used for the function's return value.
|
||||
FUN must fill this, unless the function is declared as
|
||||
returning 'void'.
|
||||
|
||||
ARGS
|
||||
A vector of pointers to memory holding the arguments to the
|
||||
function.
|
||||
|
||||
USER_DATA
|
||||
The same USER_DATA that was passed to 'ffi_prep_closure_loc'.
|
||||
|
||||
'ffi_prep_closure_loc' will return 'FFI_OK' if everything went ok,
|
||||
and something else on error.
|
||||
|
||||
After calling 'ffi_prep_closure_loc', you can cast CODELOC to the
|
||||
appropriate pointer-to-function type.
|
||||
|
||||
You may see old code referring to 'ffi_prep_closure'. This function
|
||||
is deprecated, as it cannot handle the need for separate writable and
|
||||
executable addresses.
|
||||
|
||||
|
||||
File: libffi.info, Node: Closure Example, Prev: The Closure API, Up: Using libffi
|
||||
|
||||
2.6 Closure Example
|
||||
===================
|
||||
|
||||
A trivial example that creates a new 'puts' by binding 'fputs' with
|
||||
'stdin'.
|
||||
|
||||
#include <stdio.h>
|
||||
#include <ffi.h>
|
||||
|
||||
/* Acts like puts with the file given at time of enclosure. */
|
||||
void puts_binding(ffi_cif *cif, void *ret, void* args[],
|
||||
void *stream)
|
||||
{
|
||||
*(ffi_arg *)ret = fputs(*(char **)args[0], (FILE *)stream);
|
||||
}
|
||||
|
||||
typedef int (*puts_t)(char *);
|
||||
|
||||
int main()
|
||||
{
|
||||
ffi_cif cif;
|
||||
ffi_type *args[1];
|
||||
ffi_closure *closure;
|
||||
|
||||
void *bound_puts;
|
||||
int rc;
|
||||
|
||||
/* Allocate closure and bound_puts */
|
||||
closure = ffi_closure_alloc(sizeof(ffi_closure), &bound_puts);
|
||||
|
||||
if (closure)
|
||||
{
|
||||
/* Initialize the argument info vectors */
|
||||
args[0] = &ffi_type_pointer;
|
||||
|
||||
/* Initialize the cif */
|
||||
if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1,
|
||||
&ffi_type_sint, args) == FFI_OK)
|
||||
{
|
||||
/* Initialize the closure, setting stream to stdout */
|
||||
if (ffi_prep_closure_loc(closure, &cif, puts_binding,
|
||||
stdout, bound_puts) == FFI_OK)
|
||||
{
|
||||
rc = ((puts_t)bound_puts)("Hello World!");
|
||||
/* rc now holds the result of the call to fputs */
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/* Deallocate both closure, and bound_puts */
|
||||
ffi_closure_free(closure);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
File: libffi.info, Node: Missing Features, Next: Index, Prev: Using libffi, Up: Top
|
||||
|
||||
3 Missing Features
|
||||
******************
|
||||
|
||||
'libffi' is missing a few features. We welcome patches to add support
|
||||
for these.
|
||||
|
||||
* Variadic closures.
|
||||
|
||||
* There is no support for bit fields in structures.
|
||||
|
||||
* The closure API is
|
||||
|
||||
* The "raw" API is undocumented.
|
||||
|
||||
Note that variadic support is very new and tested on a relatively
|
||||
small number of platforms.
|
||||
|
||||
|
||||
File: libffi.info, Node: Index, Prev: Missing Features, Up: Top
|
||||
|
||||
Index
|
||||
*****
|
||||
|
||||
| ||||