kernel: Separate and modularize the user data scanner scan function

kernel/user_data_scanner.h

@@ -0,0 +1,86 @@
+#ifndef _KSU_USER_DATA_SCANNER_H_
+#define _KSU_USER_DATA_SCANNER_H_
+
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+
+#define USER_DATA_BASE_PATH "/data/user_de"
+#define PRIMARY_USER_PATH "/data/user_de/0"
+#define DATA_PATH_LEN 384 // 384 is enough for /data/user_de/{userid}/<package> and /data/app/<package>/base.apk
+#define MAX_SUPPORTED_USERS 32 // Supports up to 32 users
+#define SMALL_BUFFER_SIZE 64
+#define SCHEDULE_INTERVAL 100
+
+// https://docs.kernel.org/filesystems/porting.html
+// filldir_t (readdir callbacks) calling conventions have changed. Instead of returning 0 or -E... it returns bool now. false means "no more" (as -E... used to) and true - "keep going" (as 0 in old calling conventions). Rationale: callers never looked at specific -E... values anyway. -> iterate_shared() instances require no changes at all, all filldir_t ones in the tree converted.
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 1, 0)
+#define FILLDIR_RETURN_TYPE bool
+#define FILLDIR_ACTOR_CONTINUE true
+#define FILLDIR_ACTOR_STOP false
+#else
+#define FILLDIR_RETURN_TYPE int
+#define FILLDIR_ACTOR_CONTINUE 0
+#define FILLDIR_ACTOR_STOP -EINVAL
+#endif
+
+// Global work buffer to avoid stack allocation
+struct work_buffers {
+	char path_buffer[DATA_PATH_LEN];
+	char package_buffer[KSU_MAX_PACKAGE_NAME];
+	char small_buffer[SMALL_BUFFER_SIZE];
+	uid_t user_ids_buffer[MAX_SUPPORTED_USERS];
+};
+
+struct work_buffers *get_work_buffer(void);
+
+struct uid_data {
+	struct list_head list;
+	u32 uid;
+	char package[KSU_MAX_PACKAGE_NAME];
+	uid_t user_id;
+};
+
+struct deferred_path_info {
+	struct list_head list;
+	char path[DATA_PATH_LEN];
+	char package_name[KSU_MAX_PACKAGE_NAME];
+	uid_t user_id;
+};
+
+struct user_scan_ctx {
+	struct list_head *deferred_paths;
+	uid_t user_id;
+	size_t pkg_count;
+	size_t error_count;
+	struct work_buffers *work_buf;
+	size_t processed_count;
+};
+
+struct user_dir_ctx {
+	struct dir_context ctx;
+	struct user_scan_ctx *scan_ctx;
+};
+
+struct user_id_ctx {
+	struct dir_context ctx;
+	uid_t *user_ids;
+	size_t count;
+	size_t max_count;
+	size_t processed_count;
+};
+
+int scan_user_data_for_uids(struct list_head *uid_list, bool scan_all_users);
+FILLDIR_RETURN_TYPE scan_user_packages(struct dir_context *ctx, const char *name,
+				       int namelen, loff_t off, u64 ino, unsigned int d_type);
+FILLDIR_RETURN_TYPE collect_user_ids(struct dir_context *ctx, const char *name,
+				     int namelen, loff_t off, u64 ino, unsigned int d_type);
+static int process_deferred_paths(struct list_head *deferred_paths, struct list_head *uid_list);
+static int scan_primary_user_apps(struct list_head *uid_list, size_t *pkg_count, 
+				   size_t *error_count, struct work_buffers *work_buf);
+static int get_all_active_users(struct work_buffers *work_buf, size_t *found_count);
+static int scan_secondary_users_apps(struct list_head *uid_list, struct work_buffers *work_buf, 
+				      size_t user_count, size_t *total_pkg_count, 
+				      size_t *total_error_count);
+
+#endif /* _KSU_USER_DATA_SCANNER_H_ */