From 957df0893271fd2eac5a353d8480850fed3b6e25 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Wed, 14 Aug 2024 13:21:33 +0300
Subject: [PATCH] Kernel: root command line option can be specified as an UUID

Format is the same as in linux
root=UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

This makes it easier to boot when computer has multiple disks installed
---
 kernel/include/kernel/Storage/Partition.h |  3 ++
 kernel/kernel/FS/VirtualFileSystem.cpp    | 58 ++++++++++++++++++++---
 kernel/kernel/Storage/Partition.cpp       |  1 +
 3 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/kernel/include/kernel/Storage/Partition.h b/kernel/include/kernel/Storage/Partition.h
index aec7c5ec..a2ec014b 100644
--- a/kernel/include/kernel/Storage/Partition.h
+++ b/kernel/include/kernel/Storage/Partition.h
@@ -25,6 +25,8 @@ namespace Kernel
 
 		virtual BAN::StringView name() const override { return m_name; }
 
+		BAN::StringView uuid() const { return m_guid_string; }
+
 	private:
 		Partition(BAN::RefPtr<BlockDevice>, const BAN::GUID&, const BAN::GUID&, uint64_t, uint64_t, uint64_t, const char*, uint32_t, BAN::StringView);
 
@@ -32,6 +34,7 @@ namespace Kernel
 		BAN::RefPtr<BlockDevice> m_device;
 		const BAN::GUID m_type;
 		const BAN::GUID m_guid;
+		const BAN::String m_guid_string;
 		const uint64_t m_first_block;
 		const uint64_t m_last_block;
 		const uint64_t m_attributes;
diff --git a/kernel/kernel/FS/VirtualFileSystem.cpp b/kernel/kernel/FS/VirtualFileSystem.cpp
index 8c1181f5..c89eabaf 100644
--- a/kernel/kernel/FS/VirtualFileSystem.cpp
+++ b/kernel/kernel/FS/VirtualFileSystem.cpp
@@ -5,6 +5,8 @@
 #include <kernel/FS/TmpFS/FileSystem.h>
 #include <kernel/FS/VirtualFileSystem.h>
 #include <kernel/Lock/LockGuard.h>
+#include <kernel/Storage/Partition.h>
+
 #include <fcntl.h>
 
 namespace Kernel
@@ -17,13 +19,57 @@ namespace Kernel
 		ASSERT(!s_instance);
 		s_instance = MUST(BAN::RefPtr<VirtualFileSystem>::create());
 
-		ASSERT(root_path.size() >= 5 && root_path.substring(0, 5) == "/dev/"_sv);;
-		root_path = root_path.substring(5);
+		BAN::RefPtr<BlockDevice> root_device;
+		if (root_path.size() >= 5 && root_path.substring(0, 5) == "UUID="_sv)
+		{
+			auto uuid = root_path.substring(5);
+			if (uuid.size() != 36)
+				panic("Invalid UUID specified for root '{}'", uuid);
 
-		auto root_inode = MUST(DevFileSystem::get().root_inode()->find_inode(root_path));
-		if (!root_inode->mode().ifblk())
-			Kernel::panic("Specified root '/dev/{}' does not name a block device", root_path);
-		s_instance->m_root_fs = MUST(FileSystem::from_block_device(static_cast<BlockDevice*>(root_inode.ptr())));
+			BAN::RefPtr<Partition> root_partition;
+			DevFileSystem::get().for_each_inode(
+				[&root_partition, uuid](BAN::RefPtr<Inode> inode) -> BAN::Iteration
+				{
+					if (!inode->is_device())
+						return BAN::Iteration::Continue;
+					if (!static_cast<Device*>(inode.ptr())->is_partition())
+						return BAN::Iteration::Continue;
+					auto* partition = static_cast<Partition*>(inode.ptr());
+					dprintln("compare '{}' vs '{}'", partition->uuid(), uuid);
+					if (partition->uuid() != uuid)
+						return BAN::Iteration::Continue;
+					dprintln("FOUND");
+					root_partition = partition;
+					return BAN::Iteration::Break;
+				}
+			);
+			if (!root_partition)
+				panic("Could not find partition with UUID '{}'", uuid);
+			root_device = root_partition;
+		}
+		else if (root_path.size() >= 5 && root_path.substring(0, 5) == "/dev/"_sv)
+		{
+			auto device_name = root_path.substring(5);
+
+			auto device_result = DevFileSystem::get().root_inode()->find_inode(device_name);
+			if (device_result.is_error())
+				panic("Could not open root device '{}': {}", root_path, device_result.error());
+
+			auto device_inode = device_result.release_value();
+			if (!device_inode->mode().ifblk())
+				panic("Root inode '{}' is not an block device", root_path);
+
+			root_device = static_cast<BlockDevice*>(device_inode.ptr());
+		}
+		else
+		{
+			panic("Unknown root path format '{}' specified", root_path);
+		}
+
+		auto filesystem_result = FileSystem::from_block_device(root_device);
+		if (filesystem_result.is_error())
+			panic("Could not create filesystem from '{}': {}", root_path, filesystem_result.error());
+		s_instance->m_root_fs = filesystem_result.release_value();
 
 		Credentials root_creds { 0, 0, 0, 0 };
 		MUST(s_instance->mount(root_creds, &DevFileSystem::get(), "/dev"_sv));
diff --git a/kernel/kernel/Storage/Partition.cpp b/kernel/kernel/Storage/Partition.cpp
index 54e343e1..e74104fc 100644
--- a/kernel/kernel/Storage/Partition.cpp
+++ b/kernel/kernel/Storage/Partition.cpp
@@ -18,6 +18,7 @@ namespace Kernel
 		, m_device(device)
 		, m_type(type)
 		, m_guid(guid)
+		, m_guid_string(MUST(guid.to_string()))
 		, m_first_block(first_block)
 		, m_last_block(last_block)
 		, m_attributes(attr)