linux-ext4 - [PATCH v2] ext4: replace strcpy() with '.' assignment

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Message-Id: <20250518-ext4-strcpy-v2-1-80d316325046@ethancedwards.com>
Date: Sun, 18 May 2025 23:54:21 -0400
From: Ethan Carter Edwards <ethan@...ancedwards.com>
To: Theodore Ts'o <tytso@....edu>, 
 Andreas Dilger <adilger.kernel@...ger.ca>
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-hardening@...r.kernel.org, 
 Ethan Carter Edwards <ethan@...ancedwards.com>
Subject: [PATCH v2] ext4: replace strcpy() with '.' assignment

strcpy() is deprecated; assignment can be used instead which
theoretically/potentially increases speed as a function call is removed.

Straight assignment works because the strings are not null-terminated
which means they don't strictly require a str(s)cpy call.

No functional changes intended.

Link: https://github.com/KSPP/linux/issues/88
Suggested-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Ethan Carter Edwards <ethan@...ancedwards.com>
---
There's an ongoing effort to remove calls to strcpy throughout the
kernel.

Link: https://github.com/KSPP/linux/issues/88
---
Changes in v2:
- completely remove the call to strcpy and replace it with assignment
  off of Theo's suggestion. Thanks.
- Link to v1: https://lore.kernel.org/r/20250518-ext4-strcpy-v1-1-6c8a82ff078f@ethancedwards.com
---
 fs/ext4/inline.c | 4 ++--
 fs/ext4/namei.c  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 2c9b762925c72f2ff5a402b02500370bc1eb0eb1..f3bc8b3904a8a9b55162f002b5bd63a527b290a5 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1314,7 +1314,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 		if (pos == 0) {
 			fake.inode = cpu_to_le32(inode->i_ino);
 			fake.name_len = 1;
-			strcpy(fake.name, ".");
+			fake.name[0] = ".";
 			fake.rec_len = ext4_rec_len_to_disk(
 					  ext4_dir_rec_len(fake.name_len, NULL),
 					  inline_size);
@@ -1324,7 +1324,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 		} else if (pos == EXT4_INLINE_DOTDOT_OFFSET) {
 			fake.inode = cpu_to_le32(parent_ino);
 			fake.name_len = 2;
-			strcpy(fake.name, "..");
+			fake.name[0] = fake.name[1] = ".";
 			fake.rec_len = ext4_rec_len_to_disk(
 					  ext4_dir_rec_len(fake.name_len, NULL),
 					  inline_size);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index e9712e64ec8f04586f5ebcd332431e6af92e4f36..c7d7c46a0b18ae109d30358c157812ac2ded200e 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2926,7 +2926,7 @@ struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
 	de->name_len = 1;
 	de->rec_len = ext4_rec_len_to_disk(ext4_dir_rec_len(de->name_len, NULL),
 					   blocksize);
-	strcpy(de->name, ".");
+	de->name[0] = '.';
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
 
 	de = ext4_next_entry(de, blocksize);
@@ -2940,7 +2940,7 @@ struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
 		de->rec_len = ext4_rec_len_to_disk(
 					ext4_dir_rec_len(de->name_len, NULL),
 					blocksize);
-	strcpy(de->name, "..");
+	de->name[0] = de->name[1] = '.';
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
 
 	return ext4_next_entry(de, blocksize);

---
base-commit: 5723cc3450bccf7f98f227b9723b5c9f6b3af1c5
change-id: 20250518-ext4-strcpy-1545c6f79b51

Best regards,
-- 
Ethan Carter Edwards <ethan@...ancedwards.com>