From 7bbdee6cc402253a43f94b38f071a4ce794179f3 Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Fri, 2 Jun 2023 11:43:46 +0300
Subject: [PATCH] Kernel: Symlinks are now working

We still have to implement loop or depth detection
---
 kernel/include/kernel/FS/VirtualFileSystem.h |  4 +-
 kernel/kernel/FS/VirtualFileSystem.cpp       | 69 +++++++++++++-------
 kernel/kernel/Process.cpp                    |  4 +-
 kernel/kernel/Shell.cpp                      |  1 +
 4 files changed, 49 insertions(+), 29 deletions(-)

diff --git a/kernel/include/kernel/FS/VirtualFileSystem.h b/kernel/include/kernel/FS/VirtualFileSystem.h
index c2e815d2..a97586e3 100644
--- a/kernel/include/kernel/FS/VirtualFileSystem.h
+++ b/kernel/include/kernel/FS/VirtualFileSystem.h
@@ -25,7 +25,7 @@ namespace Kernel
 			BAN::RefPtr<Inode> inode;
 			BAN::String canonical_path;
 		};
-		BAN::ErrorOr<File> file_from_absolute_path(BAN::StringView, bool follow_links);
+		BAN::ErrorOr<File> file_from_absolute_path(BAN::StringView, bool follow_link);
 
 	private:
 		VirtualFileSystem() = default;
@@ -39,7 +39,7 @@ namespace Kernel
 		MountPoint* mount_from_root_inode(BAN::RefPtr<Inode>);
 
 	private:
-		RecursiveSpinLock				m_lock;
+		SpinLock						m_lock;
 		FileSystem*						m_root_fs = nullptr;
 		BAN::Vector<MountPoint>			m_mount_points;
 	};
diff --git a/kernel/kernel/FS/VirtualFileSystem.cpp b/kernel/kernel/FS/VirtualFileSystem.cpp
index e4b85242..86bcbb2f 100644
--- a/kernel/kernel/FS/VirtualFileSystem.cpp
+++ b/kernel/kernel/FS/VirtualFileSystem.cpp
@@ -82,7 +82,7 @@ namespace Kernel
 		return nullptr;
 	}
 
-	BAN::ErrorOr<VirtualFileSystem::File> VirtualFileSystem::file_from_absolute_path(BAN::StringView path, bool follow_links)
+	BAN::ErrorOr<VirtualFileSystem::File> VirtualFileSystem::file_from_absolute_path(BAN::StringView path, bool follow_link)
 	{
 		LockGuard _(m_lock);
 
@@ -93,13 +93,22 @@ namespace Kernel
 
 		BAN::String canonical_path;
 
-		const auto path_parts = TRY(path.split('/'));
+		BAN::Vector<BAN::String> path_parts;
 
-		for (auto path_part : path_parts)
 		{
+			auto temp = TRY(path.split('/'));
+			for (size_t i = 0; i < temp.size(); i++)
+				TRY(path_parts.push_back(temp[temp.size() - i - 1]));
+		}
+
+		while (!path_parts.empty())
+		{
+			const auto& path_part = path_parts.back();
+			auto orig = inode;
+
 			if (path_part.empty() || path_part == "."sv)
 			{
-				continue;
+
 			}
 			else if (path_part == ".."sv)
 			{
@@ -119,32 +128,42 @@ namespace Kernel
 			else
 			{
 				inode = TRY(inode->read_directory_inode(path_part));
-				TRY(canonical_path.push_back('/'));
-				TRY(canonical_path.append(path_part));
 
 				if (auto* mount_point = mount_from_host_inode(inode))
 					inode = mount_point->target->root_inode();
 
-				if (follow_links && inode->mode().iflnk())
+				TRY(canonical_path.push_back('/'));
+				TRY(canonical_path.append(path_part));
+			}
+
+			path_parts.pop_back();
+
+			if (inode->mode().iflnk() && (follow_link || !path_parts.empty()))
+			{
+				auto target = TRY(inode->link_target());
+				if (target.empty())
+					return BAN::Error::from_errno(ENOENT);
+				
+				if (target.front() == '/')
 				{
-					auto target = TRY(inode->link_target());
-					if (target.empty())
-						return BAN::Error::from_errno(ENOENT);
-					if (target.front() == '/')
-					{
-						File file = TRY(file_from_absolute_path(target, follow_links));
-						inode = file.inode;
-						canonical_path = BAN::move(file.canonical_path);
-					}
-					else
-					{
-						while (canonical_path.back() != '/')
-							canonical_path.pop_back();
-						TRY(canonical_path.append(target));
-						File file = TRY(file_from_absolute_path(canonical_path, follow_links));
-						inode = file.inode;
-						canonical_path = BAN::move(file.canonical_path);
-					}
+					inode = root_inode();
+					canonical_path.clear();
+
+					auto temp = TRY(target.sv().split('/'));
+					for (size_t i = 0; i < temp.size(); i++)
+						TRY(path_parts.emplace_back(temp[temp.size() - i - 1]));
+				}
+				else
+				{
+					inode = orig;
+
+					while (canonical_path.back() != '/')
+						canonical_path.pop_back();
+					canonical_path.pop_back();
+
+					auto new_parts = TRY(target.sv().split('/'));
+					for (size_t i = 0; i < new_parts.size(); i++)
+						TRY(path_parts.emplace_back(new_parts[new_parts.size() - i - 1]));
 				}
 			}
 		}
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 1f2060ae..2a88dc11 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -296,7 +296,7 @@ namespace Kernel
 
 	BAN::ErrorOr<int> Process::open(BAN::StringView path, int flags)
 	{
-		if (flags & ~O_RDWR)
+		if (flags & ~(O_RDONLY | O_WRONLY | O_NOFOLLOW))
 			return BAN::Error::from_errno(ENOTSUP);
 
 		BAN::String absolute_path = TRY(absolute_path_of(path));
@@ -468,7 +468,7 @@ namespace Kernel
 
 	BAN::ErrorOr<void> Process::stat(BAN::StringView path, struct stat* out)
 	{
-		int fd = TRY(open(path, O_RDONLY));
+		int fd = TRY(open(path, O_RDONLY | O_NOFOLLOW));
 		auto ret = fstat(fd, out);
 		MUST(close(fd));
 		return ret;
diff --git a/kernel/kernel/Shell.cpp b/kernel/kernel/Shell.cpp
index 78a926a2..5e8a3e39 100644
--- a/kernel/kernel/Shell.cpp
+++ b/kernel/kernel/Shell.cpp
@@ -41,6 +41,7 @@ namespace Kernel
 			mode.ifdir() ? 'd' :
 			mode.ifblk() ? 'b' :
 			mode.ifchr() ? 'c' :
+			mode.iflnk() ? 'l' :
 							'-';
 
 		buffer[1] = (mode.mode & Inode::Mode::IRUSR) ? 'r' : '-';