Kernel/LibC: Implement rename{,at}

kernel/include/kernel/FS/Ext2/Inode.h

@@ -37,6 +37,7 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> create_file_impl(BAN::StringView, mode_t, uid_t, gid_t) override;
 		virtual BAN::ErrorOr<void> create_directory_impl(BAN::StringView, mode_t, uid_t, gid_t) override;
 		virtual BAN::ErrorOr<void> link_inode_impl(BAN::StringView, BAN::RefPtr<Inode>) override;
+		virtual BAN::ErrorOr<void> rename_inode_impl(BAN::RefPtr<Inode>, BAN::StringView, BAN::StringView) override;
 		virtual BAN::ErrorOr<void> unlink_impl(BAN::StringView) override;
 
 		virtual BAN::ErrorOr<BAN::String> link_target_impl() override;
@@ -64,6 +65,7 @@ namespace Kernel
 		BAN::ErrorOr<BAN::Optional<uint32_t>> fs_block_of_data_block_index(uint32_t data_block_index);
 
 		BAN::ErrorOr<void> link_inode_to_directory(Ext2Inode&, BAN::StringView name);
+		BAN::ErrorOr<void> remove_inode_from_directory(BAN::StringView name, bool cleanup_directory);
 		BAN::ErrorOr<bool> is_directory_empty();
 
 		BAN::ErrorOr<void> cleanup_indirect_block(uint32_t block, uint32_t depth);

kernel/include/kernel/FS/Inode.h

@@ -97,6 +97,7 @@ namespace Kernel
 		BAN::ErrorOr<void> create_file(BAN::StringView, mode_t, uid_t, gid_t);
 		BAN::ErrorOr<void> create_directory(BAN::StringView, mode_t, uid_t, gid_t);
 		BAN::ErrorOr<void> link_inode(BAN::StringView, BAN::RefPtr<Inode>);
+		BAN::ErrorOr<void> rename_inode(BAN::RefPtr<Inode>, BAN::StringView, BAN::StringView);
 		BAN::ErrorOr<void> unlink(BAN::StringView);
 
 		// Link API
@@ -144,6 +145,7 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> create_file_impl(BAN::StringView, mode_t, uid_t, gid_t)					{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<void> create_directory_impl(BAN::StringView, mode_t, uid_t, gid_t)				{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<void> link_inode_impl(BAN::StringView, BAN::RefPtr<Inode>)						{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<void> rename_inode_impl(BAN::RefPtr<Inode>, BAN::StringView, BAN::StringView)	{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<void> unlink_impl(BAN::StringView)												{ return BAN::Error::from_errno(ENOTSUP); }
 
 		// Link API
@@ -187,7 +189,7 @@ namespace Kernel
 		friend class Epoll;
 		friend class FileBackedRegion;
 		friend class OpenFileDescriptorSet;
-		friend class SharedFileData;
+		friend struct SharedFileData;
 		friend class TTY;
 	};
 

kernel/include/kernel/FS/TmpFS/Inode.h

@@ -157,6 +157,7 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> create_file_impl(BAN::StringView, mode_t, uid_t, gid_t) override final;
 		virtual BAN::ErrorOr<void> create_directory_impl(BAN::StringView, mode_t, uid_t, gid_t) override final;
 		virtual BAN::ErrorOr<void> link_inode_impl(BAN::StringView, BAN::RefPtr<Inode>) override final;
+		virtual BAN::ErrorOr<void> rename_inode_impl(BAN::RefPtr<Inode>, BAN::StringView, BAN::StringView) override final;
 		virtual BAN::ErrorOr<void> unlink_impl(BAN::StringView) override;
 
 		virtual bool can_read_impl() const override { return false; }
@@ -168,6 +169,8 @@ namespace Kernel
 		template<TmpFuncs::for_each_valid_entry_callback F>
 		void for_each_valid_entry(F callback);
 
+		BAN::ErrorOr<void> unlink_inode(BAN::StringView, bool cleanup);
+
 		friend class TmpInode;
 	};
 

kernel/include/kernel/Process.h

@@ -109,9 +109,9 @@ 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_renameat(int oldfd, const char* old, int newfd, const char* _new);
 		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);
 
 		BAN::ErrorOr<long> sys_flock(int fd, int op);

kernel/kernel/FS/Ext2/Inode.cpp

@@ -2,6 +2,7 @@
 #include <BAN/ScopeGuard.h>
 #include <kernel/FS/Ext2/FileSystem.h>
 #include <kernel/FS/Ext2/Inode.h>
+#include <kernel/Lock/LockGuard.h>
 #include <kernel/Timer/Timer.h>
 
 #include <sys/stat.h>
@@ -585,6 +586,37 @@ done:
 		return {};
 	}
 
+	BAN::ErrorOr<void> Ext2Inode::rename_inode_impl(BAN::RefPtr<Inode> old_parent, BAN::StringView old_name, BAN::StringView new_name)
+	{
+		ASSERT(this->mode().ifdir());
+		ASSERT(old_parent->mode().ifdir());
+		ASSERT(&m_fs == old_parent->filesystem());
+
+		auto* ext2_parent = static_cast<Ext2Inode*>(old_parent.ptr());
+
+		// FIXME: possible deadlock :)
+		LockGuard _(ext2_parent->m_mutex);
+
+		auto old_inode = TRY(ext2_parent->find_inode_impl(old_name));
+		auto* ext2_inode = static_cast<Ext2Inode*>(old_inode.ptr());
+
+		if (auto replace_or_error = find_inode_impl(new_name); replace_or_error.is_error())
+		{
+			if (replace_or_error.error().get_error_code() != ENOENT)
+				return replace_or_error.release_error();
+		}
+		else
+		{
+			TRY(unlink_impl(new_name));
+		}
+
+		TRY(link_inode_to_directory(*ext2_inode, new_name));
+
+		TRY(ext2_parent->remove_inode_from_directory(old_name, false));
+
+		return {};
+	}
+
 	BAN::ErrorOr<void> Ext2Inode::link_inode_to_directory(Ext2Inode& inode, BAN::StringView name)
 	{
 		if (!this->mode().ifdir())
@@ -778,7 +810,7 @@ needs_new_block:
 		return {};
 	}
 
-	BAN::ErrorOr<void> Ext2Inode::unlink_impl(BAN::StringView name)
+	BAN::ErrorOr<void> Ext2Inode::remove_inode_from_directory(BAN::StringView name, bool cleanup_directory)
 	{
 		ASSERT(mode().ifdir());
 		if (m_inode.flags & Ext2::Enum::INDEX_FL)
@@ -802,7 +834,7 @@ needs_new_block:
 				if (entry.inode && name == BAN::StringView(entry.name, entry.name_len))
 				{
 					auto inode = TRY(Ext2Inode::create(m_fs, entry.inode));
-					if (inode->mode().ifdir())
+					if (cleanup_directory && inode->mode().ifdir())
 					{
 						if (!TRY(inode->is_directory_empty()))
 							return BAN::Error::from_errno(ENOTEMPTY);
@@ -836,6 +868,12 @@ needs_new_block:
 		return {};
 	}
 
+	BAN::ErrorOr<void> Ext2Inode::unlink_impl(BAN::StringView name)
+	{
+		TRY(remove_inode_from_directory(name, true));
+		return {};
+	}
+
 	BAN::ErrorOr<uint32_t> Ext2Inode::allocate_new_block_to_indirect_block(uint32_t& block, uint32_t index, uint32_t depth)
 	{
 		const uint32_t inode_blocks_per_fs_block = blksize() / 512;

kernel/kernel/FS/Inode.cpp

@@ -114,6 +114,20 @@ namespace Kernel
 		return link_inode_impl(name, inode);
 	}
 
+	BAN::ErrorOr<void> Inode::rename_inode(BAN::RefPtr<Inode> old_parent, BAN::StringView old_name, BAN::StringView new_name)
+	{
+		LockGuard _(m_mutex);
+		if (!this->mode().ifdir())
+			return BAN::Error::from_errno(ENOTDIR);
+		if (!old_parent->mode().ifdir())
+			return BAN::Error::from_errno(ENOTDIR);
+		if (this->filesystem() != old_parent->filesystem())
+			return BAN::Error::from_errno(EXDEV);
+		if (auto* fs = filesystem(); fs && (fs->flag() & ST_RDONLY))
+			return BAN::Error::from_errno(EROFS);
+		return rename_inode_impl(old_parent, old_name, new_name);
+	}
+
 	BAN::ErrorOr<void> Inode::unlink(BAN::StringView name)
 	{
 		LockGuard _(m_mutex);

kernel/kernel/FS/TmpFS/Inode.cpp

@@ -669,7 +669,44 @@ namespace Kernel
 		return {};
 	}
 
+	BAN::ErrorOr<void> TmpDirectoryInode::rename_inode_impl(BAN::RefPtr<Inode> old_parent, BAN::StringView old_name, BAN::StringView new_name)
+	{
+		ASSERT(this->mode().ifdir());
+		ASSERT(old_parent->mode().ifdir());
+		ASSERT(&m_fs == old_parent->filesystem());
+
+		auto* tmp_parent = static_cast<TmpDirectoryInode*>(old_parent.ptr());
+
+		// FIXME: possible deadlock :)
+		LockGuard _(tmp_parent->m_mutex);
+
+		auto old_inode = TRY(tmp_parent->find_inode_impl(old_name));
+		auto* tmp_inode = static_cast<TmpInode*>(old_inode.ptr());
+
+		if (auto replace_or_error = find_inode_impl(new_name); replace_or_error.is_error())
+		{
+			if (replace_or_error.error().get_error_code() != ENOENT)
+				return replace_or_error.release_error();
+		}
+		else
+		{
+			TRY(unlink_impl(new_name));
+		}
+
+		TRY(link_inode(*tmp_inode, new_name));
+
+		TRY(tmp_parent->unlink_inode(old_name, false));
+
+		return {};
+	}
+
 	BAN::ErrorOr<void> TmpDirectoryInode::unlink_impl(BAN::StringView name)
+	{
+		TRY(unlink_inode(name, true));
+		return {};
+	}
+
+	BAN::ErrorOr<void> TmpDirectoryInode::unlink_inode(BAN::StringView name, bool cleanup)
 	{
 		ino_t entry_ino = 0;
 
@@ -687,6 +724,7 @@ namespace Kernel
 
 		ASSERT(inode->nlink() > 0);
 
+		if (cleanup)
 			TRY(inode->prepare_unlink());
 		inode->m_inode_info.nlink--;
 

kernel/kernel/Process.cpp

@@ -1302,6 +1302,27 @@ namespace Kernel
 		return 0;
 	}
 
+	BAN::ErrorOr<long> Process::sys_renameat(int oldfd, const char* old, int newfd, const char* _new)
+	{
+		LockGuard _(m_process_lock);
+		if (old != nullptr)
+			TRY(validate_string_access(old));
+		if (_new != nullptr)
+			TRY(validate_string_access(_new));
+
+		auto [old_parent, old_name] = TRY(find_parent_file(oldfd, old, O_WRONLY));
+		if (!old_parent.inode->mode().ifdir())
+			return BAN::Error::from_errno(ENOTDIR);
+
+		auto [new_parent, new_name] = TRY(find_parent_file(newfd, _new, O_WRONLY));
+		if (!new_parent.inode->mode().ifdir())
+			return BAN::Error::from_errno(ENOTDIR);
+
+		TRY(new_parent.inode->rename_inode(old_parent.inode, old_name, new_name));
+
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_unlinkat(int fd, const char* path, int flag)
 	{
 		if (flag && flag != AT_REMOVEDIR)

userspace/libraries/LibC/include/sys/syscall.h

@@ -14,6 +14,7 @@ __BEGIN_DECLS
 	O(SYS_OPENAT,			openat)			\
 	O(SYS_SEEK,				seek)			\
 	O(SYS_TELL,				tell)			\
+	O(SYS_RENAMEAT,			renameat)		\
 	O(SYS_TCGETATTR,		tcgetattr)		\
 	O(SYS_TCSETATTR,		tcsetattr)		\
 	O(SYS_FORK,				fork)			\

userspace/libraries/LibC/stdio.cpp

@@ -820,56 +820,12 @@ int remove(const char* path)
 
 int rename(const char* old, const char* _new)
 {
-	struct stat st;
+	return renameat(AT_FDCWD, old, AT_FDCWD, _new);
-	if (lstat(old, &st) == -1)
+}
-		return -1;
 
-	if (!S_ISREG(st.st_mode))
+int renameat(int oldfd, const char* old, int newfd, const char* _new)
-	{
+{
-		errno = ENOTSUP;
+	return syscall(SYS_RENAMEAT, oldfd, old, newfd, _new);
-		return -1;
-	}
-
-	if (unlink(_new) == -1 && errno != ENOENT)
-		return -1;
-
-	int old_fd = open(old, O_RDWR);
-	int new_fd = open(_new, O_RDWR | O_CREAT | O_EXCL, st.st_mode);
-	if (old_fd == -1 || new_fd == -1)
-		goto error;
-
-	for (;;)
-	{
-		char buffer[512];
-		ssize_t nread = read(old_fd, buffer, sizeof(buffer));
-		if (nread == -1)
-		{
-			unlink(_new);
-			goto error;
-		}
-		if (nread == 0)
-			break;
-
-		if (write(new_fd, buffer, nread) != nread)
-		{
-			unlink(_new);
-			goto error;
-		}
-	}
-
-	close(new_fd);
-	close(old_fd);
-
-	unlink(old);
-
-	return 0;
-
-error:
-	if (old_fd != -1)
-		close(old_fd);
-	if (new_fd != -1)
-		close(new_fd);
-	return -1;
 }
 
 void rewind(FILE* file)