From 6a1e1d788b6d9104a42449bb0b8f50815bcc109d Mon Sep 17 00:00:00 2001
From: ShirkNeko <109797057+ShirkNeko@users.noreply.github.com>
Date: Thu, 23 Oct 2025 22:16:06 +0800
Subject: [PATCH] kernel: sulog: Simplify code using vfs_truncate

---
 kernel/kernel_compat.c | 36 ------------------------------------
 kernel/kernel_compat.h |  4 ----
 kernel/sulog.c         | 37 ++++---------------------------------
 kernel/sulog.h         |  1 -
 4 files changed, 4 insertions(+), 74 deletions(-)

diff --git a/kernel/kernel_compat.c b/kernel/kernel_compat.c
index 961c7c19..c49ac125 100644
--- a/kernel/kernel_compat.c
+++ b/kernel/kernel_compat.c
@@ -93,39 +93,3 @@ long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 	return strncpy_from_user_nofault(dst, unsafe_addr, count);
 }
 
-int ksu_vfs_unlink(struct inode *dir, struct dentry *dentry)
-{
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 6, 0)
-    struct inode *delegated_inode = NULL;
-    return vfs_unlink(&nop_mnt_idmap, dir, dentry, &delegated_inode);
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 12, 0)
-    struct inode *delegated_inode = NULL;
-    return vfs_unlink(&init_user_ns, dir, dentry, &delegated_inode);
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
-    struct inode *delegated_inode = NULL;
-    return vfs_unlink(dir, dentry, &delegated_inode);
-#else
-    return vfs_unlink(dir, dentry);
-#endif
-}
-
-int ksu_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-                   struct inode *new_dir, struct dentry *new_dentry)
-{
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 12, 0)
-    struct renamedata rd = {
-        .old_dir = old_dir,
-        .old_dentry = old_dentry,
-        .new_dir = new_dir,
-        .new_dentry = new_dentry,
-        .delegated_inode = NULL,
-        .flags = 0,
-    };
-    return vfs_rename(&rd);
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
-    struct inode *delegated_inode = NULL;
-    return vfs_rename(old_dir, old_dentry, new_dir, new_dentry, &delegated_inode, 0);
-#else
-    return vfs_rename(old_dir, old_dentry, new_dir, new_dentry);
-#endif
-}
diff --git a/kernel/kernel_compat.h b/kernel/kernel_compat.h
index 9952e35a..11ee9023 100644
--- a/kernel/kernel_compat.h
+++ b/kernel/kernel_compat.h
@@ -94,8 +94,4 @@ static long ksu_copy_from_user_retry(void *to,
 	return copy_from_user(to, from, count);
 }
 
-extern int ksu_vfs_unlink(struct inode *dir, struct dentry *dentry);
-extern int ksu_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-                   struct inode *new_dir, struct dentry *new_dentry);
-
 #endif
diff --git a/kernel/sulog.c b/kernel/sulog.c
index e8b552eb..d54862ac 100644
--- a/kernel/sulog.c
+++ b/kernel/sulog.c
@@ -135,40 +135,11 @@ static void sulog_work_handler(struct work_struct *work)
 	}
 	
 	if (fp->f_inode->i_size > SULOG_MAX_SIZE) {
-		pr_info("sulog: rotating log file, size: %lld\n", fp->f_inode->i_size);
-		filp_close(fp, 0);
-		
-		struct path old_path;
-		if (!kern_path(SULOG_OLD_PATH, 0, &old_path)) {
-			ksu_vfs_unlink(old_path.dentry->d_parent->d_inode, old_path.dentry);
-			path_put(&old_path);
+		pr_info("sulog: log file exceeds maximum size, clearing...\n");
+		if (vfs_truncate(&fp->f_path, 0)) {
+			pr_err("sulog: failed to truncate log file\n");
 		}
-		
-		struct path current_path, parent_path;
-		if (!kern_path(SULOG_PATH, 0, &current_path)) {
-			parent_path = current_path;
-			path_get(&parent_path);
-			parent_path.dentry = current_path.dentry->d_parent;
-			
-			struct dentry *old_dentry = lookup_one_len("sulog.log.old", 
-				parent_path.dentry, strlen("sulog.log.old"));
-			if (!IS_ERR(old_dentry)) {
-				ksu_vfs_rename(parent_path.dentry->d_inode, current_path.dentry,
-                          parent_path.dentry->d_inode, old_dentry);
-				dput(old_dentry);
-			}
-			path_put(&current_path);
-			path_put(&parent_path);
-		}
-		
-		fp = ksu_filp_open_compat(SULOG_PATH, O_WRONLY | O_CREAT | O_EXCL, 0640);
-		if (IS_ERR(fp)) {
-			pr_err("sulog: failed to create new log file: %ld\n", PTR_ERR(fp));
-			goto cleanup;
-		}
-		
-		const char *rotate_msg = "=== Log file rotated, old log saved as sulog.log.old ===\n";
-		ksu_kernel_write_compat(fp, rotate_msg, strlen(rotate_msg), &pos);
+		pos = 0;
 	} else {
 		pos = fp->f_inode->i_size;
 	}
diff --git a/kernel/sulog.h b/kernel/sulog.h
index 5be99957..459b04af 100644
--- a/kernel/sulog.h
+++ b/kernel/sulog.h
@@ -6,7 +6,6 @@
 extern struct timezone sys_tz;
 
 #define SULOG_PATH "/data/adb/ksu/log/sulog.log"
-#define SULOG_OLD_PATH "/data/adb/ksu/log/sulog.log.old"
 #define SULOG_MAX_SIZE (128 * 1024 * 1024) // 128MB
 #define SULOG_ENTRY_MAX_LEN 512
 #define SULOG_COMM_LEN 256