This manual is for Libffi, a portable foreign-function interface
library.
- Copyright (C) 2008, 2010 Red Hat, Inc.
+ 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
This manual is for Libffi, a portable foreign-function interface
library.
- Copyright (C) 2008, 2010 Red Hat, Inc.
+ 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
want. *note Multiple ABIs:: for more information.
NARGS is the number of arguments that this function accepts.
- `libffi' does not yet handle varargs functions; see *note Missing
- Features:: for more information.
RTYPE is a pointer to an `ffi_type' structure that describes the
return type of the function. *Note Types::.
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:
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.
+ 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.
\1f
File: libffi.info, Node: Simple Example, Next: Types, Prev: The Basics, Up: Using libffi
describe the structure to `libffi' by creating a new `ffi_type' object
for it.
- -- ffi_type:
+ -- 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.
`libffi' is missing a few features. We welcome patches to add support
for these.
- * There is no support for calling varargs functions. This may work
- on some platforms, depending on how the ABI is defined, but it is
- not reliable.
+ * Variadic closures.
* There is no support for bit fields in structures.
* The "raw" API is undocumented.
+ Note that variadic support is very new and tested on a relatively
+small number of platforms.
+
\1f
File: libffi.info, Node: Index, Prev: Missing Features, Up: Top
\0\b[index\0\b]
* Menu:
-* : Structures. (line 12)
* ABI: Introduction. (line 13)
* Application Binary Interface: Introduction. (line 13)
* calling convention: Introduction. (line 13)
* closure API: The Closure API. (line 13)
* closures: The Closure API. (line 13)
* FFI: Introduction. (line 31)
-* ffi_call: The Basics. (line 41)
-* ffi_closure_alloca: The Closure API. (line 19)
+* ffi_call: The Basics. (line 63)
+* ffi_closure_alloc: The Closure API. (line 19)
* ffi_closure_free: The Closure API. (line 26)
* FFI_CLOSURES: The Closure API. (line 13)
* ffi_prep_cif: The Basics. (line 16)
+* ffi_prep_cif_var: The Basics. (line 39)
* ffi_prep_closure_loc: The Closure API. (line 34)
* ffi_status <1>: The Closure API. (line 37)
* ffi_status: The Basics. (line 18)
* ffi_type_void: Primitive Types. (line 10)
* Foreign Function Interface: Introduction. (line 31)
* void <1>: The Closure API. (line 20)
-* void: The Basics. (line 43)
+* void: The Basics. (line 65)
\1f
Tag Table:
-Node: Top\7f706
-Node: Introduction\7f1448
-Node: Using libffi\7f3084
-Node: The Basics\7f3570
-Node: Simple Example\7f6177
-Node: Types\7f7204
-Node: Primitive Types\7f7487
-Node: Structures\7f9307
-Node: Type Example\7f10167
-Node: Multiple ABIs\7f11390
-Node: The Closure API\7f11761
-Node: Closure Example\7f14705
-Node: Missing Features\7f16264
-Node: Index\7f16757
+Node: Top\7f712
+Node: Introduction\7f1460
+Node: Using libffi\7f3096
+Node: The Basics\7f3582
+Node: Simple Example\7f7224
+Node: Types\7f8251
+Node: Primitive Types\7f8534
+Node: Structures\7f10354
+Node: Type Example\7f11224
+Node: Multiple ABIs\7f12447
+Node: The Closure API\7f12818
+Node: Closure Example\7f15762
+Node: Missing Features\7f17321
+Node: Index\7f17774
\1f
End Tag Table
projects / python / commitdiff