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Message-ID: <20240403033607.GE2576@sol.localdomain>
Date: Tue, 2 Apr 2024 20:36:07 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: Eugen Hristev <eugen.hristev@...labora.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
jaegeuk@...nel.org, chao@...nel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel@...labora.com, viro@...iv.linux.org.uk, brauner@...nel.org,
jack@...e.cz, krisman@...e.de,
Gabriel Krisman Bertazi <krisman@...labora.com>
Subject: Re: [PATCH v15 3/9] libfs: Introduce case-insensitive string
comparison helper
On Tue, Apr 02, 2024 at 06:48:36PM +0300, Eugen Hristev wrote:
> +int generic_ci_match(const struct inode *parent,
> + const struct qstr *name,
> + const struct qstr *folded_name,
> + const u8 *de_name, u32 de_name_len)
> +{
> + const struct super_block *sb = parent->i_sb;
> + const struct unicode_map *um = sb->s_encoding;
> + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
> + struct qstr dirent = QSTR_INIT(de_name, de_name_len);
> + int res = 0, match = 0;
> +
> + if (IS_ENCRYPTED(parent)) {
> + const struct fscrypt_str encrypted_name =
> + FSTR_INIT((u8 *) de_name, de_name_len);
> +
> + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent)))
> + return -EINVAL;
> +
> + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
> + if (!decrypted_name.name)
> + return -ENOMEM;
> + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name,
> + &decrypted_name);
> + if (res < 0)
> + goto out;
> + dirent.name = decrypted_name.name;
> + dirent.len = decrypted_name.len;
> + }
> +
> + /*
> + * Attempt a case-sensitive match first. It is cheaper and
> + * should cover most lookups, including all the sane
> + * applications that expect a case-sensitive filesystem.
> + */
> + if (folded_name->name) {
> + if (dirent.len == folded_name->len &&
> + !memcmp(folded_name->name, dirent.name, dirent.len)) {
> + match = 1;
> + goto out;
> + }
> + res = utf8_strncasecmp_folded(um, folded_name, &dirent);
> + } else {
> + if (dirent.len == name->len &&
> + !memcmp(name->name, dirent.name, dirent.len) &&
> + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) {
> + match = 1;
> + goto out;
> + }
> + res = utf8_strncasecmp(um, name, &dirent);
> + }
The 'match' variable is unnecessary because setting res=0 achieves the same
effect.
- Eric
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