From b75970958e8b97fc2f2ecf982634a33bb9dbb31a Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Sun, 1 Jun 2025 05:06:47 +0300
Subject: [PATCH] Kernel/LibC: Implement unlinkat

---
 kernel/include/kernel/Process.h                |  2 +-
 kernel/kernel/Process.cpp                      | 11 +++++++++--
 userspace/libraries/LibC/include/sys/syscall.h |  2 +-
 userspace/libraries/LibC/unistd.cpp            |  9 +++++++--
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index cb83f003..44999608 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -107,7 +107,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_access(const char* path, int amode);
 		BAN::ErrorOr<long> sys_create_dir(const char*, mode_t);
 		BAN::ErrorOr<long> sys_hardlinkat(int fd1, const char* path1, int fd2, const char* path2, int flag);
-		BAN::ErrorOr<long> sys_unlink(const char*);
+		BAN::ErrorOr<long> sys_unlinkat(int fd, const char* path, int flag);
 		BAN::ErrorOr<long> sys_readlinkat(int fd, const char* path, char* buffer, size_t bufsize);
 
 		BAN::ErrorOr<long> sys_symlinkat(const char* path1, int fd, const char* path2);
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 7df76edd..54d9810b 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -1158,12 +1158,19 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<long> Process::sys_unlink(const char* path)
+	BAN::ErrorOr<long> Process::sys_unlinkat(int fd, const char* path, int flag)
 	{
+		if (flag && flag != AT_REMOVEDIR)
+			return BAN::Error::from_errno(EINVAL);
+
 		LockGuard _(m_process_lock);
 		TRY(validate_string_access(path));
 
-		auto [parent, file_name] = TRY(find_parent_file(AT_FDCWD, path, O_WRONLY));
+		auto [parent, file_name] = TRY(find_parent_file(fd, path, O_WRONLY));
+
+		if (TRY(parent.inode->find_inode(file_name))->mode().ifdir() != (flag == AT_REMOVEDIR))
+			return BAN::Error::from_errno(flag ? EPERM : ENOTDIR);
+
 		TRY(parent.inode->unlink(file_name));
 
 		return 0;
diff --git a/userspace/libraries/LibC/include/sys/syscall.h b/userspace/libraries/LibC/include/sys/syscall.h
index c8cf2e93..7a15417c 100644
--- a/userspace/libraries/LibC/include/sys/syscall.h
+++ b/userspace/libraries/LibC/include/sys/syscall.h
@@ -56,7 +56,7 @@ __BEGIN_DECLS
 	O(SYS_POWEROFF,			poweroff)		\
 	O(SYS_FCHMODAT,			fchmodat)		\
 	O(SYS_CREATE_DIR,		create_dir)		\
-	O(SYS_UNLINK,			unlink) 		\
+	O(SYS_UNLINKAT,			unlinkat) 		\
 	O(SYS_READLINKAT,		readlinkat)		\
 	O(SYS_MSYNC,			msync)			\
 	O(SYS_PREAD,			pread)			\
diff --git a/userspace/libraries/LibC/unistd.cpp b/userspace/libraries/LibC/unistd.cpp
index 6560b78b..48f21720 100644
--- a/userspace/libraries/LibC/unistd.cpp
+++ b/userspace/libraries/LibC/unistd.cpp
@@ -518,12 +518,17 @@ int fdatasync(int fildes)
 
 int unlink(const char* path)
 {
-	return syscall(SYS_UNLINK, path);
+	return unlinkat(AT_FDCWD, path, 0);
+}
+
+int unlinkat(int fd, const char* path, int flag)
+{
+	return syscall(SYS_UNLINKAT, fd, path, flag);
 }
 
 int rmdir(const char* path)
 {
-	return syscall(SYS_UNLINK, path);
+	return unlinkat(AT_FDCWD, path, AT_REMOVEDIR);
 }
 
 char* optarg = nullptr;