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unicode: Recreate utf8_parse_version()

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All filesystems that currently support UTF-8 casefold can fetch the
UTF-8 version from the filesystem metadata stored on disk. They can get
the data stored and directly match it to a integer, so they can skip the
string parsing step, which motivated the removal of this function in the
first place.

However, for tmpfs, the only way to tell the kernel which UTF-8 version
we are about to use is via mount options, using a string. Re-introduce
utf8_parse_version() to be used by tmpfs.

This version differs from the original by skipping the intermediate step
of copying the version string to an auxiliary string before calling
match_token(). This versions calls match_token() in the argument string.
The paramenters are simpler now as well.

utf8_parse_version() was created by 9d53690f0d ("unicode: implement
higher level API for string handling") and later removed by 49bd03cc7e
("unicode: pass a UNICODE_AGE() tripple to utf8_load").

Signed-off-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20241021-tonyk-tmpfs-v8-4-f443d5814194@igalia.com
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
André Almeida 2024-10-21 13:37:20 -03:00 committed by Christian Brauner
parent 04dad6c6d3
commit 142fa60f61
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2 changed files with 28 additions and 0 deletions
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26
fs/unicode/utf8-core.c
View File

@ -214,3 +214,29 @@ void utf8_unload(struct unicode_map *um)
}
EXPORT_SYMBOL(utf8_unload);
/**
* utf8_parse_version - Parse a UTF-8 version number from a string
*
* @version: input string
*
* Returns the parsed version on success, negative code on error
*/
int utf8_parse_version(char *version)
{
substring_t args[3];
unsigned int maj, min, rev;
static const struct match_token token[] = {
{1, "%d.%d.%d"},
{0, NULL}
};
if (match_token(version, token, args) != 1)
return -EINVAL;
if (match_int(&args[0], &maj) || match_int(&args[1], &min) ||
match_int(&args[2], &rev))
return -EINVAL;
return UNICODE_AGE(maj, min, rev);
}
EXPORT_SYMBOL(utf8_parse_version);

2
include/linux/unicode.h
View File

@ -78,4 +78,6 @@ int utf8_casefold_hash(const struct unicode_map *um, const void *salt,
struct unicode_map *utf8_load(unsigned int version);
void utf8_unload(struct unicode_map *um);
int utf8_parse_version(char *version);
#endif /* _LINUX_UNICODE_H */