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>
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@ -200,6 +200,7 @@ static inline const char *kbasename(const char *path)
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void fortify_panic(const char *name) __noreturn __cold;
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void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter");
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void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter");
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void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter");
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void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter");
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#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
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@ -395,4 +396,33 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q)
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#endif
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/**
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* memcpy_and_pad - Copy one buffer to another with padding
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* @dest: Where to copy to
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* @dest_len: The destination buffer size
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* @src: Where to copy from
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* @count: The number of bytes to copy
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* @pad: Character to use for padding if space is left in destination.
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*/
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__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len,
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const void *src, size_t count, int pad)
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{
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size_t dest_size = __builtin_object_size(dest, 0);
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size_t src_size = __builtin_object_size(src, 0);
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if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) {
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if (dest_size < dest_len && dest_size < count)
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__write_overflow();
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else if (src_size < dest_len && src_size < count)
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__read_overflow3();
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}
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if (dest_size < dest_len)
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fortify_panic(__func__);
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if (dest_len > count) {
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memcpy(dest, src, count);
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memset(dest + count, pad, dest_len - count);
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} else
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memcpy(dest, src, dest_len);
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}
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#endif /* _LINUX_STRING_H_ */
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