kernel_samsung_a53x/include/linux/stddef.h

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2024-06-15 21:02:09 +02:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_STDDEF_H
#define _LINUX_STDDEF_H
#include <uapi/linux/stddef.h>
#undef NULL
#define NULL ((void *)0)
enum {
false = 0,
true = 1
};
#undef offsetof
#ifdef __compiler_offsetof
#define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER)
#else
#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER)
#endif
/**
* sizeof_field(TYPE, MEMBER)
*
* @TYPE: The structure containing the field of interest
* @MEMBER: The field to return the size of
*/
#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
/**
* offsetofend(TYPE, MEMBER)
*
* @TYPE: The type of the structure
* @MEMBER: The member within the structure to get the end offset of
*/
#define offsetofend(TYPE, MEMBER) \
(offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))
/**
* struct_group() - Wrap a set of declarations in a mirrored struct
*
* @NAME: The identifier name of the mirrored sub-struct
* @MEMBERS: The member declarations for the mirrored structs
*
* Used to create an anonymous union of two structs with identical
* layout and size: one anonymous and one named. The former can be
* used normally without sub-struct naming, and the latter can be
* used to reason about the start, end, and size of the group of
* struct members.
*/
#define struct_group(NAME, MEMBERS...) \
__struct_group(/* no tag */, NAME, /* no attrs */, MEMBERS)
/**
* struct_group_attr() - Create a struct_group() with trailing attributes
*
* @NAME: The identifier name of the mirrored sub-struct
* @ATTRS: Any struct attributes to apply
* @MEMBERS: The member declarations for the mirrored structs
*
* Used to create an anonymous union of two structs with identical
* layout and size: one anonymous and one named. The former can be
* used normally without sub-struct naming, and the latter can be
* used to reason about the start, end, and size of the group of
* struct members. Includes structure attributes argument.
*/
#define struct_group_attr(NAME, ATTRS, MEMBERS...) \
__struct_group(/* no tag */, NAME, ATTRS, MEMBERS)
/**
* struct_group_tagged() - Create a struct_group with a reusable tag
*
* @TAG: The tag name for the named sub-struct
* @NAME: The identifier name of the mirrored sub-struct
* @MEMBERS: The member declarations for the mirrored structs
*
* Used to create an anonymous union of two structs with identical
* layout and size: one anonymous and one named. The former can be
* used normally without sub-struct naming, and the latter can be
* used to reason about the start, end, and size of the group of
* struct members. Includes struct tag argument for the named copy,
* so the specified layout can be reused later.
*/
#define struct_group_tagged(TAG, NAME, MEMBERS...) \
__struct_group(TAG, NAME, /* no attrs */, MEMBERS)
stddef: Introduce DECLARE_FLEX_ARRAY() helper commit 3080ea5553cc909b000d1f1d964a9041962f2c5b upstream. There are many places where kernel code wants to have several different typed trailing flexible arrays. This would normally be done with multiple flexible arrays in a union, but since GCC and Clang don't (on the surface) allow this, there have been many open-coded workarounds, usually involving neighboring 0-element arrays at the end of a structure. For example, instead of something like this: struct thing { ... union { struct type1 foo[]; struct type2 bar[]; }; }; code works around the compiler with: struct thing { ... struct type1 foo[0]; struct type2 bar[]; }; Another case is when a flexible array is wanted as the single member within a struct (which itself is usually in a union). For example, this would be worked around as: union many { ... struct { struct type3 baz[0]; }; }; These kinds of work-arounds cause problems with size checks against such zero-element arrays (for example when building with -Warray-bounds and -Wzero-length-bounds, and with the coming FORTIFY_SOURCE improvements), so they must all be converted to "real" flexible arrays, avoiding warnings like this: fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree': fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds] 209 | anode->btree.u.internal[0].down = cpu_to_le32(a); | ~~~~~~~~~~~~~~~~~~~~~~~^~~ In file included from fs/hpfs/hpfs_fn.h:26, from fs/hpfs/anode.c:10: fs/hpfs/hpfs.h:412:32: note: while referencing 'internal' 412 | struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving | ^~~~~~~~ drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg': drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds] 360 | tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22, from drivers/net/can/usb/etas_es58x/es58x_fd.c:17: drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg' 231 | u8 raw_msg[0]; | ^~~~~~~ However, it _is_ entirely possible to have one or more flexible arrays in a struct or union: it just has to be in another struct. And since it cannot be alone in a struct, such a struct must have at least 1 other named member -- but that member can be zero sized. Wrap all this nonsense into the new DECLARE_FLEX_ARRAY() in support of having flexible arrays in unions (or alone in a struct). As with struct_group(), since this is needed in UAPI headers as well, implement the core there, with a non-UAPI wrapper. Additionally update kernel-doc to understand its existence. https://github.com/KSPP/linux/issues/137 Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-26 20:31:42 +01:00
/**
* DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
*
* @TYPE: The type of each flexible array element
* @NAME: The name of the flexible array member
*
* In order to have a flexible array member in a union or alone in a
* struct, it needs to be wrapped in an anonymous struct with at least 1
* named member, but that member can be empty.
*/
#define DECLARE_FLEX_ARRAY(TYPE, NAME) \
__DECLARE_FLEX_ARRAY(TYPE, NAME)
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#endif