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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: Martin Wilck <mwilck@suse.com>
Reviewed-by: Sagi Grimberg <sagi@grimbeg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Martin Wilck 2017-08-14 22:12:38 +02:00 committed by Sagi Grimberg
parent 48fa362b6c
commit 01f33c336e
1 changed files with 30 additions and 0 deletions
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30
include/linux/string.h
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@ -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_ */