exfat currently unconditionally strips trailing periods '.' when performing path lookup. This is done intentionally, loosely following Windows behaviour and specifications which state: #exFAT The concatenated file name has the same set of illegal characters as other FAT-based file systems (see Table 31). #FAT ... Leading and trailing spaces in a long name are ignored. Leading and embedded periods are allowed in a name and are stored in the long name. Trailing periods are ignored. Note: Leading and trailing space ' ' characters are currently retained by Linux kernel exfat, in conflict with the above specification. Some implementations, such as fuse-exfat, don't perform path trailer removal. When mounting images which contain trailing-dot paths, these paths are unreachable, e.g.: + mount.exfat-fuse /dev/zram0 /mnt/test/ FUSE exfat 1.3.0 + cd /mnt/test/ + touch fuse_created_dots... ' fuse_created_spaces ' + ls -l total 0 -rwxrwxrwx 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces ' -rwxrwxrwx 1 root 0 0 Aug 18 09:45 fuse_created_dots... + cd / + umount /mnt/test/ + mount -t exfat /dev/zram0 /mnt/test + cd /mnt/test + ls -l ls: cannot access 'fuse_created_dots...': No such file or directory total 0 -rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces ' -????????? ? ? ? ? ? fuse_created_dots... + touch kexfat_created_dots... ' kexfat_created_spaces ' + ls -l ls: cannot access 'fuse_created_dots...': No such file or directory total 0 -rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces ' -rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' kexfat_created_spaces ' -????????? ? ? ? ? ? fuse_created_dots... -rwxr-xr-x 1 root 0 0 Aug 18 09:45 kexfat_created_dots + cd / + umount /mnt/test/ With this change, the "keeptail" mount option can be used to access paths with trailing periods. E.g. continuing from the previous example: + mount -t exfat -o keeptail /dev/zram0 /mnt/test + cd /mnt/test + ls -l total 0 -rwxr-xr-x 1 root 0 0 Aug 18 10:32 ' fuse_created_spaces ' -rwxr-xr-x 1 root 0 0 Aug 18 10:32 ' kexfat_created_spaces ' -rwxr-xr-x 1 root 0 0 Aug 18 10:32 fuse_created_dots... -rwxr-xr-x 1 root 0 0 Aug 18 10:32 kexfat_created_dots Link: https://bugzilla.suse.com/show_bug.cgi?id=1188964 Link: https://lore.kernel.org/linux-fsdevel/003b01d755e4$31fb0d80$95f12880$@samsung.com/ Link: https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification#773-filename-field Suggested-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: David Disseldorp <ddiss@xxxxxxx> --- fs/exfat/namei.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c index 24b41103d1cc..e49455ce6da2 100644 --- a/fs/exfat/namei.c +++ b/fs/exfat/namei.c @@ -65,11 +65,14 @@ static int exfat_d_revalidate(struct dentry *dentry, unsigned int flags) return ret; } -/* returns the length of a struct qstr, ignoring trailing dots */ -static unsigned int exfat_striptail_len(unsigned int len, const char *name) +/* returns the length of a struct qstr, possibly ignoring trailing dots */ +static unsigned int exfat_striptail_len(struct super_block *sb, + unsigned int len, const char *name) { - while (len && name[len - 1] == '.') - len--; + if (!EXFAT_SB(sb)->options.keeptail) { + while (len && name[len - 1] == '.') + len--; + } return len; } @@ -83,7 +86,7 @@ static int exfat_d_hash(const struct dentry *dentry, struct qstr *qstr) struct super_block *sb = dentry->d_sb; struct nls_table *t = EXFAT_SB(sb)->nls_io; const unsigned char *name = qstr->name; - unsigned int len = exfat_striptail_len(qstr->len, qstr->name); + unsigned int len = exfat_striptail_len(sb, qstr->len, qstr->name); unsigned long hash = init_name_hash(dentry); int i, charlen; wchar_t c; @@ -104,8 +107,8 @@ static int exfat_d_cmp(const struct dentry *dentry, unsigned int len, { struct super_block *sb = dentry->d_sb; struct nls_table *t = EXFAT_SB(sb)->nls_io; - unsigned int alen = exfat_striptail_len(name->len, name->name); - unsigned int blen = exfat_striptail_len(len, str); + unsigned int alen = exfat_striptail_len(sb, name->len, name->name); + unsigned int blen = exfat_striptail_len(sb, len, str); wchar_t c1, c2; int charlen, i; @@ -136,7 +139,7 @@ static int exfat_utf8_d_hash(const struct dentry *dentry, struct qstr *qstr) { struct super_block *sb = dentry->d_sb; const unsigned char *name = qstr->name; - unsigned int len = exfat_striptail_len(qstr->len, qstr->name); + unsigned int len = exfat_striptail_len(sb, qstr->len, qstr->name); unsigned long hash = init_name_hash(dentry); int i, charlen; unicode_t u; @@ -161,8 +164,8 @@ static int exfat_utf8_d_cmp(const struct dentry *dentry, unsigned int len, const char *str, const struct qstr *name) { struct super_block *sb = dentry->d_sb; - unsigned int alen = exfat_striptail_len(name->len, name->name); - unsigned int blen = exfat_striptail_len(len, str); + unsigned int alen = exfat_striptail_len(sb, name->len, name->name); + unsigned int blen = exfat_striptail_len(sb, len, str); unicode_t u_a, u_b; int charlen, i; @@ -419,7 +422,7 @@ static int __exfat_resolve_path(struct inode *inode, const unsigned char *path, struct exfat_inode_info *ei = EXFAT_I(inode); /* strip all trailing periods */ - namelen = exfat_striptail_len(strlen(path), path); + namelen = exfat_striptail_len(sb, strlen(path), path); if (!namelen) return -ENOENT; -- 2.31.1
