getname_maybe_null() - the third variant of pathname copy-in

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Semantics used by statx(2) (and later *xattrat(2)): without AT_EMPTY_PATH
it's standard getname() (i.e. ERR_PTR(-ENOENT) on empty string,
ERR_PTR(-EFAULT) on NULL), with AT_EMPTY_PATH both empty string and
NULL are accepted.

Calling conventions: getname_maybe_null(user_pointer, flags) returns
	* pointer to struct filename when non-empty string had been
successfully read
	* ERR_PTR(...) on error
	* NULL if an empty string or NULL pointer had been given
with AT_EMPTY_PATH in the flags argument.

It tries to avoid allocation in the last case; it's not always
able to do so, in which case the temporary struct filename instance
is freed and NULL returned anyway.

Fast path is inlined.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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This commit is contained in:

Al Viro 2024-10-07 23:08:34 -04:00

parent 5b313bcb6e

commit e896474fe4

3 changed files with 37 additions and 31 deletions

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30

fs/namei.c

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28

fs/stat.c

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10

include/linux/fs.h

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