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Commit 01f33c33 authored by Martin Wilck's avatar Martin Wilck Committed by Sagi Grimberg
Browse files

string.h: add memcpy_and_pad() 



This helper function is useful for the nvme subsystem, and maybe
others.

Note: the warnings reported by the kbuild test robot for this patch
are actually generated by the use of CONFIG_PROFILE_ALL_BRANCHES
together with __FORTIFY_INLINE.

Signed-off-by: default avatarMartin Wilck <mwilck@suse.com>
Reviewed-by: default avatarSagi Grimberg <sagi@grimbeg.me>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 48fa362b

include/linux/string.h

+30 −0
Original line number Diff line number Diff line
@@ -200,6 +200,7 @@ static inline const char *kbasename(const char *path) 
void fortify_panic(const char *name) __noreturn __cold;

void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter");

void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter");

void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter");

void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter");



#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
@@ -395,4 +396,33 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q) 


#endif



/**

 * memcpy_and_pad - Copy one buffer to another with padding

 * @dest: Where to copy to

 * @dest_len: The destination buffer size

 * @src: Where to copy from

 * @count: The number of bytes to copy

 * @pad: Character to use for padding if space is left in destination.

 */

__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len,

				     const void *src, size_t count, int pad)

{

	size_t dest_size = __builtin_object_size(dest, 0);

	size_t src_size = __builtin_object_size(src, 0);



	if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) {

		if (dest_size < dest_len && dest_size < count)

			__write_overflow();

		else if (src_size < dest_len && src_size < count)

			__read_overflow3();

	}

	if (dest_size < dest_len)

		fortify_panic(__func__);

	if (dest_len > count) {

		memcpy(dest, src, count);

		memset(dest + count, pad,  dest_len - count);

	} else

		memcpy(dest, src, dest_len);

}



#endif /* _LINUX_STRING_H_ */