python/src/Modules/_ctypes/libffi_osx/ffi.c

/* -----------------------------------------------------------------------
   prep_cif.c - Copyright (c) 1996, 1998  Red Hat, Inc.

   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   ``Software''), to deal in the Software without restriction, including
   without limitation the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions:

   The above copyright notice and this permission notice shall be included
   in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   IN NO EVENT SHALL CYGNUS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR
   OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   OTHER DEALINGS IN THE SOFTWARE.
   ----------------------------------------------------------------------- */

#include <ffi.h>
#include <ffi_common.h>

#include <stdbool.h>
#include <stdlib.h>

/* Round up to FFI_SIZEOF_ARG. */
#define STACK_ARG_SIZE(x) ALIGN(x, FFI_SIZEOF_ARG)

/* Perform machine independent initialization of aggregate type
   specifications. */

static ffi_status
initialize_aggregate(
/*@out@*/	ffi_type*	arg)
{
/*@-usedef@*/

	if (arg == NULL || arg->elements == NULL ||
		arg->size != 0 || arg->alignment != 0)
		return FFI_BAD_TYPEDEF;

	ffi_type**	ptr = &(arg->elements[0]);

	while ((*ptr) != NULL)
	{
		if (((*ptr)->size == 0) && (initialize_aggregate(*ptr) != FFI_OK))
			return FFI_BAD_TYPEDEF;

		/* Perform a sanity check on the argument type */
		FFI_ASSERT_VALID_TYPE(*ptr);

#ifdef POWERPC_DARWIN
		int curalign = (*ptr)->alignment;

		if (ptr != &(arg->elements[0]))
		{
			if (curalign > 4 && curalign != 16)
				curalign = 4;
		}

		arg->size		= ALIGN(arg->size, curalign);
		arg->size		+= (*ptr)->size;
		arg->alignment	= (arg->alignment > curalign) ? 
			arg->alignment : curalign;
#else
		arg->size		= ALIGN(arg->size, (*ptr)->alignment);
		arg->size		+= (*ptr)->size;
		arg->alignment	= (arg->alignment > (*ptr)->alignment) ? 
			arg->alignment : (*ptr)->alignment;
#endif

		ptr++;
    }

  /* Structure size includes tail padding.  This is important for
     structures that fit in one register on ABIs like the PowerPC64
     Linux ABI that right justify small structs in a register.
     It's also needed for nested structure layout, for example
     struct A { long a; char b; }; struct B { struct A x; char y; };
     should find y at an offset of 2*sizeof(long) and result in a
     total size of 3*sizeof(long).  */
	arg->size = ALIGN(arg->size, arg->alignment);

	if (arg->size == 0)
		return FFI_BAD_TYPEDEF;

	return FFI_OK;

/*@=usedef@*/
}

#ifndef __CRIS__
/* The CRIS ABI specifies structure elements to have byte
   alignment only, so it completely overrides this functions,
   which assumes "natural" alignment and padding.  */

/* Perform machine independent ffi_cif preparation, then call
   machine dependent routine. */

#if defined(X86_DARWIN)

static inline bool
struct_on_stack(
	int	size)
{
	if (size > 8)
		return true;

	/* This is not what the ABI says, but is what is really implemented */
	switch (size)
	{
		case 1:
		case 2:
		case 4:
		case 8:
			return false;

		default:
			return true;
	}
}

#endif	// defined(X86_DARWIN)

// Arguments' ffi_type->alignment must be nonzero.
ffi_status
ffi_prep_cif(
/*@out@*/ /*@partial@*/	ffi_cif*		cif, 
						ffi_abi			abi,
						unsigned int	nargs, 
/*@dependent@*/ /*@out@*/ /*@partial@*/ ffi_type*	rtype, 
/*@dependent@*/			ffi_type**		atypes)
{
	if (cif == NULL)
		return FFI_BAD_TYPEDEF;

	if (abi <= FFI_FIRST_ABI || abi > FFI_DEFAULT_ABI)
		return FFI_BAD_ABI;

	unsigned int	bytes	= 0;
	unsigned int	i;
	ffi_type**		ptr;

	cif->abi = abi;
	cif->arg_types = atypes;
	cif->nargs = nargs;
	cif->rtype = rtype;
	cif->flags = 0;

	/* Initialize the return type if necessary */
	/*@-usedef@*/
	if ((cif->rtype->size == 0) && (initialize_aggregate(cif->rtype) != FFI_OK))
		return FFI_BAD_TYPEDEF;
	/*@=usedef@*/

	/* Perform a sanity check on the return type */
	FFI_ASSERT_VALID_TYPE(cif->rtype);

	/* x86-64 and s390 stack space allocation is handled in prep_machdep.  */
#if !defined M68K && !defined __x86_64__ && !defined S390 && !defined PA
	/* Make space for the return structure pointer */
	if (cif->rtype->type == FFI_TYPE_STRUCT
#ifdef SPARC
		&& (cif->abi != FFI_V9 || cif->rtype->size > 32)
#endif
#ifdef X86_DARWIN
		&& (struct_on_stack(cif->rtype->size))
#endif
		)
		bytes = STACK_ARG_SIZE(sizeof(void*));
#endif

	for (ptr = cif->arg_types, i = cif->nargs; i > 0; i--, ptr++)
	{
		/* Initialize any uninitialized aggregate type definitions */
		if (((*ptr)->size == 0) && (initialize_aggregate((*ptr)) != FFI_OK))
			return FFI_BAD_TYPEDEF;

		if ((*ptr)->alignment == 0)
			return FFI_BAD_TYPEDEF;

		/* Perform a sanity check on the argument type, do this 
		check after the initialization.  */
		FFI_ASSERT_VALID_TYPE(*ptr);

#if defined(X86_DARWIN)
		{
			int align = (*ptr)->alignment;

			if (align > 4)
				align = 4;

			if ((align - 1) & bytes)
				bytes = ALIGN(bytes, align);

			bytes += STACK_ARG_SIZE((*ptr)->size);
		}
#elif !defined __x86_64__ && !defined S390 && !defined PA
#ifdef SPARC
		if (((*ptr)->type == FFI_TYPE_STRUCT
			&& ((*ptr)->size > 16 || cif->abi != FFI_V9))
			|| ((*ptr)->type == FFI_TYPE_LONGDOUBLE
			&& cif->abi != FFI_V9))
				bytes += sizeof(void*);
		else
#endif
		{
			/* Add any padding if necessary */
			if (((*ptr)->alignment - 1) & bytes)
				bytes = ALIGN(bytes, (*ptr)->alignment);

			bytes += STACK_ARG_SIZE((*ptr)->size);
		}
#endif
	}

	cif->bytes = bytes;

	/* Perform machine dependent cif processing */
	return ffi_prep_cif_machdep(cif);
}
#endif /* not __CRIS__ */