ANDROID: sdcardfs: Switch to internal case insensitive compare

There were still a few places where we called into a case
insensitive lookup that was not defined by sdcardfs.
Moving them all to the same place will allow us to switch
the implementation in the future.

Additionally, the check in fixup_perms_recursive did not
take into account the length of both strings, causing
extraneous matches when the name we were looking for was
a prefix of the child name.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Change-Id: I45ce768cd782cb4ea1ae183772781387c590ecc2

4 files changed, 11 insertions, 13 deletions

diff --git a/fs/sdcardfs/dentry.c b/fs/sdcardfs/dentry.c
index e6f8e9edf8a9..64494a50e250 100644
--- a/fs/sdcardfs/dentry.c
+++ b/fs/sdcardfs/dentry.c
@@ -82,11 +82,7 @@ static int sdcardfs_d_revalidate(struct dentry *dentry, unsigned int flags)
 		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 	}
 
-	if (dentry->d_name.len != lower_dentry->d_name.len) {
-		__d_drop(dentry);
-		err = 0;
-	} else if (strncasecmp(dentry->d_name.name, lower_dentry->d_name.name,
-				dentry->d_name.len) != 0) {
+	if (!qstr_case_eq(&dentry->d_name, &lower_dentry->d_name)) {
 		__d_drop(dentry);
 		err = 0;
 	}
@@ -166,7 +162,7 @@ static int sdcardfs_cmp_ci(const struct dentry *parent,
 	}
 	*/
 	if (name->len == len) {
-		if (strncasecmp(name->name, str, len) == 0)
+		if (str_n_case_eq(name->name, str, len))
 			return 0;
 	}
 	return 1;
diff --git a/fs/sdcardfs/derived_perm.c b/fs/sdcardfs/derived_perm.c
index c0d5a9d72bde..925692f0d20c 100644
--- a/fs/sdcardfs/derived_perm.c
+++ b/fs/sdcardfs/derived_perm.c
@@ -282,7 +282,7 @@ static void __fixup_perms_recursive(struct dentry *dentry, struct limit_search *
 	if (needs_fixup(info->perm)) {
 		list_for_each_entry(child, &dentry->d_subdirs, d_child) {
 			spin_lock_nested(&child->d_lock, depth + 1);
-			if (!(limit->flags & BY_NAME) || !strncasecmp(child->d_name.name, limit->name, limit->length)) {
+			if (!(limit->flags & BY_NAME) || qstr_case_eq(&child->d_name, &limit->name)) {
 				if (d_inode(child)) {
 					get_derived_permission(dentry, child);
 					fixup_tmp_permissions(d_inode(child));
diff --git a/fs/sdcardfs/packagelist.c b/fs/sdcardfs/packagelist.c
index 56d643f4a9ee..68f8f4571615 100644
--- a/fs/sdcardfs/packagelist.c
+++ b/fs/sdcardfs/packagelist.c
@@ -251,8 +251,7 @@ static void fixup_all_perms_name(const struct qstr *key)
 	struct sdcardfs_sb_info *sbinfo;
 	struct limit_search limit = {
 		.flags = BY_NAME,
-		.name = key->name,
-		.length = key->len,
+		.name = QSTR_INIT(key->name, key->len),
 	};
 	list_for_each_entry(sbinfo, &sdcardfs_super_list, list) {
 		if (sbinfo_has_sdcard_magic(sbinfo))
@@ -265,8 +264,7 @@ static void fixup_all_perms_name_userid(const struct qstr *key, userid_t userid)
 	struct sdcardfs_sb_info *sbinfo;
 	struct limit_search limit = {
 		.flags = BY_NAME | BY_USERID,
-		.name = key->name,
-		.length = key->len,
+		.name = QSTR_INIT(key->name, key->len),
 		.userid = userid,
 	};
 	list_for_each_entry(sbinfo, &sdcardfs_super_list, list) {
diff --git a/fs/sdcardfs/sdcardfs.h b/fs/sdcardfs/sdcardfs.h
index 042f989f0bea..0778eb063b63 100644
--- a/fs/sdcardfs/sdcardfs.h
+++ b/fs/sdcardfs/sdcardfs.h
@@ -470,8 +470,7 @@ extern void packagelist_exit(void);
 #define BY_USERID	(1 << 1)
 struct limit_search {
 	unsigned int flags;
-	const char *name;
-	size_t length;
+	struct qstr name;
 	userid_t userid;
 };
 
@@ -612,6 +611,11 @@ static inline bool str_case_eq(const char *s1, const char *s2)
 	return !strcasecmp(s1, s2);
 }
 
+static inline bool str_n_case_eq(const char *s1, const char *s2, size_t len)
+{
+	return !strncasecmp(s1, s2, len);
+}
+
 static inline bool qstr_case_eq(const struct qstr *q1, const struct qstr *q2)
 {
 	return q1->len == q2->len && str_case_eq(q1->name, q2->name);