Kernel: Rewrite directory listing so it can be integrated to libc

kernel/include/kernel/API/DirectoryEntry.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <dirent.h>
+
+namespace Kernel::API
+{
+
+	struct DirectoryEntry
+	{
+		size_t rec_len { 0 };
+		struct dirent dirent;
+		DirectoryEntry* next() const { return (DirectoryEntry*)((uintptr_t)this + rec_len); }
+	};
+	
+	struct DirectoryEntryList
+	{
+		size_t entry_count { 0 };
+		DirectoryEntry array[];
+	};
+
+}

kernel/include/kernel/DeviceManager.h

@@ -34,7 +34,7 @@ namespace Kernel
 		virtual BAN::StringView name() const override { return "device-manager"; }
 
 		virtual BAN::ErrorOr<BAN::RefPtr<Inode>> read_directory_inode(BAN::StringView) override;
-		virtual BAN::ErrorOr<BAN::Vector<BAN::String>> read_directory_entries(size_t) override;
+		virtual BAN::ErrorOr<void> read_next_directory_entries(off_t, DirectoryEntryList*, size_t) override;
 
 	private:
 		DeviceManager() = default;

kernel/include/kernel/FS/Ext2.h

@@ -141,7 +141,7 @@ namespace Kernel
 
 		virtual BAN::ErrorOr<BAN::String> link_target() override;
 		
-		virtual BAN::ErrorOr<BAN::Vector<BAN::String>> read_directory_entries(size_t) override;
+		virtual BAN::ErrorOr<void> read_next_directory_entries(off_t, DirectoryEntryList*, size_t) override;
 		virtual BAN::ErrorOr<BAN::RefPtr<Inode>> read_directory_inode(BAN::StringView) override;
 
 		virtual BAN::ErrorOr<size_t> read(size_t, void*, size_t) override;

kernel/include/kernel/FS/Inode.h

@@ -5,12 +5,16 @@
 #include <BAN/StringView.h>
 #include <BAN/Vector.h>
 
+#include <kernel/API/DirectoryEntry.h>
+
 #include <sys/types.h>
 #include <time.h>
 
 namespace Kernel
 {
 
+	using namespace API;
+
 	class Inode : public BAN::RefCounted<Inode>
 	{
 	public:
@@ -75,7 +79,7 @@ namespace Kernel
 		virtual BAN::ErrorOr<BAN::String> link_target() { ASSERT_NOT_REACHED(); }
 
 		virtual BAN::ErrorOr<BAN::RefPtr<Inode>> read_directory_inode(BAN::StringView)				{ if (!mode().ifdir()) return BAN::Error::from_errno(ENOTDIR); ASSERT_NOT_REACHED(); }
-		virtual BAN::ErrorOr<BAN::Vector<BAN::String>> read_directory_entries(size_t)  { if (!mode().ifdir()) return BAN::Error::from_errno(ENOTDIR); ASSERT_NOT_REACHED(); }
+		virtual BAN::ErrorOr<void> read_next_directory_entries(off_t, DirectoryEntryList*, size_t)	{ if (!mode().ifdir()) return BAN::Error::from_errno(ENOTDIR); ASSERT_NOT_REACHED(); }
 
 		virtual BAN::ErrorOr<size_t> read(size_t, void*, size_t)		{ if (mode().ifdir()) return BAN::Error::from_errno(EISDIR); ASSERT_NOT_REACHED(); }
 		virtual BAN::ErrorOr<size_t> write(size_t, const void*, size_t)	{ if (mode().ifdir()) return BAN::Error::from_errno(EISDIR); ASSERT_NOT_REACHED(); }

kernel/include/kernel/Process.h

@@ -71,7 +71,7 @@ namespace Kernel
 
 		BAN::ErrorOr<void> mount(BAN::StringView source, BAN::StringView target);
 
-		BAN::ErrorOr<BAN::Vector<BAN::String>> read_directory_entries(int);
+		BAN::ErrorOr<void> read_next_directory_entries(int fd, DirectoryEntryList* buffer, size_t buffer_size);
 
 		BAN::ErrorOr<BAN::String> working_directory() const;
 		BAN::ErrorOr<void> set_working_directory(BAN::StringView);

kernel/kernel/DeviceManager.cpp

@@ -114,19 +114,49 @@ namespace Kernel
 		return BAN::Error::from_errno(ENOENT);
 	}
 
-	BAN::ErrorOr<BAN::Vector<BAN::String>> DeviceManager::read_directory_entries(size_t index)
+	BAN::ErrorOr<void> DeviceManager::read_next_directory_entries(off_t offset, DirectoryEntryList* list, size_t list_size)
 	{
-		BAN::Vector<BAN::String> result;
+		if (offset != 0)
-		if (index > 0)
+		{
-			return result;
+			list->entry_count = 0;
+			return {};
+		}
 
 		LockGuard _(m_lock);
-		TRY(result.reserve(m_devices.size() + 2));
+
-		MUST(result.emplace_back("."sv));
+		size_t needed_size = sizeof(DirectoryEntryList);
-		MUST(result.emplace_back(".."sv));
+		needed_size += sizeof(DirectoryEntry) + 2;
+		needed_size += sizeof(DirectoryEntry) + 3;
 		for (Device* device : m_devices)
-			MUST(result.emplace_back(device->name()));
+			needed_size += sizeof(DirectoryEntry) + device->name().size() + 1;
-		return result;
+		if (needed_size > list_size)
+			return BAN::Error::from_errno(EINVAL);
+
+		DirectoryEntry* ptr = list->array;
+
+		ptr->dirent.d_ino = ino();
+		ptr->rec_len = sizeof(DirectoryEntry) + 2;
+		memcpy(ptr->dirent.d_name, ".", 2);
+		ptr = ptr->next();
+
+		ptr->dirent.d_ino = 69; // FIXME: store parent inode number when we implement proper RAM fs
+		ptr->rec_len = sizeof(DirectoryEntry) + 3;
+		memcpy(ptr->dirent.d_name, "..", 3);
+		ptr = ptr->next();
+
+		for (Device* device : m_devices)
+		{
+			ptr->dirent.d_ino = device->ino();
+			ptr->rec_len = sizeof(DirectoryEntry) + device->name().size() + 1;
+			memcpy(ptr->dirent.d_name, device->name().data(), device->name().size());
+			ptr->dirent.d_name[device->name().size()] = '\0';
+
+			ptr = ptr->next();
+		}
+
+		list->entry_count = m_devices.size() + 2;
+
+		return {};
 	}
 
 

kernel/kernel/FS/Ext2.cpp

@@ -291,24 +291,48 @@ namespace Kernel
 		return n_read;
 	}
 
-	BAN::ErrorOr<BAN::Vector<BAN::String>> Ext2Inode::read_directory_entries(size_t index)
+	BAN::ErrorOr<void> Ext2Inode::read_next_directory_entries(off_t offset, DirectoryEntryList* list, size_t list_size)
 	{
 		if (!mode().ifdir())
 			return BAN::Error::from_errno(ENOTDIR);
 		
 		uint32_t data_block_count = blocks();
-		if (index >= data_block_count)
+		if (offset >= data_block_count)
-			return BAN::Vector<BAN::String>();
+		{
+			list->entry_count = 0;
+			return {};
+		}
 
 		uint32_t block_size = blksize();
-		uint32_t block_index = TRY(data_block_index(index));
+		uint32_t block_index = TRY(data_block_index(offset));
 
 		BAN::Vector<uint8_t> block_buffer;
 		TRY(block_buffer.resize(block_size));
 
 		m_fs.read_block(block_index, block_buffer.span());
 
-		BAN::Vector<BAN::String> entries;
+		// First determine if we have big enough list
+		{
+			const uint8_t* block_buffer_end = block_buffer.data() + block_size;
+			const uint8_t* entry_addr = block_buffer.data();
+
+			size_t needed_size = sizeof(DirectoryEntryList);
+			while (entry_addr < block_buffer_end)
+			{
+				auto& entry = *(Ext2::LinkedDirectoryEntry*)entry_addr;
+				if (entry.inode)
+					needed_size += sizeof(DirectoryEntry) + entry.name_len + 1;
+				entry_addr += entry.rec_len;
+			}
+
+			if (needed_size > list_size)
+				return BAN::Error::from_errno(EINVAL);
+		}
+
+		// Second fill the list
+		{
+			DirectoryEntry* ptr = list->array;
+			list->entry_count = 0;
 
 			const uint8_t* block_buffer_end = block_buffer.data() + block_size;
 			const uint8_t* entry_addr = block_buffer.data();
@@ -316,11 +340,20 @@ namespace Kernel
 			{
 				auto& entry = *(Ext2::LinkedDirectoryEntry*)entry_addr;
 				if (entry.inode)
-				TRY(entries.emplace_back(BAN::StringView(entry.name, entry.name_len)));
+				{
+					ptr->dirent.d_ino = entry.inode;
+					ptr->rec_len = sizeof(DirectoryEntry) + entry.name_len + 1;
+					memcpy(ptr->dirent.d_name, entry.name, entry.name_len);
+					ptr->dirent.d_name[entry.name_len] = '\0';
+
+					ptr = ptr->next();
+					list->entry_count++;
+				}
 				entry_addr += entry.rec_len;
 			}
+		}
 
-		return entries;
+		return {};
 	}
 
 	BAN::ErrorOr<void> Ext2Inode::create_file(BAN::StringView name, mode_t mode)

kernel/kernel/Process.cpp

@@ -629,8 +629,7 @@ namespace Kernel
 		return ret;
 	}
 
-	// FIXME: This whole API has to be rewritten
+	BAN::ErrorOr<void> Process::read_next_directory_entries(int fd, DirectoryEntryList* list, size_t list_size)
-	BAN::ErrorOr<BAN::Vector<BAN::String>> Process::read_directory_entries(int fd)
 	{
 		OpenFileDescription open_fd_copy;
 
@@ -640,7 +639,7 @@ namespace Kernel
 			open_fd_copy = open_file_description(fd);
 		}
 
-		auto result = TRY(open_fd_copy.inode->read_directory_entries(open_fd_copy.offset));
+		TRY(open_fd_copy.inode->read_next_directory_entries(open_fd_copy.offset, list, list_size));
 
 		{
 			LockGuard _(m_lock);
@@ -648,7 +647,7 @@ namespace Kernel
 			open_file_description(fd).offset = open_fd_copy.offset + 1;
 		}
 
-		return result;
+		return {};
 	}
 
 	BAN::ErrorOr<BAN::String> Process::working_directory() const

kernel/kernel/Shell.cpp

@@ -516,12 +516,20 @@ argument_done:
 
 			BAN::Vector<BAN::String> all_entries;
 
-			BAN::Vector<BAN::String> entries;
+			DirectoryEntryList* directory_list = (DirectoryEntryList*)kmalloc(4096);
-			while (!(entries = TRY(Process::current().read_directory_entries(fd))).empty())
+			if (directory_list == nullptr)
+				return BAN::Error::from_errno(ENOMEM);
+			while (true)
 			{
-				TRY(all_entries.reserve(all_entries.size() + entries.size()));
+				TRY(Process::current().read_next_directory_entries(fd, directory_list, 4096));
-				for (auto& entry : entries)
+				if (directory_list->entry_count == 0)
-					TRY(all_entries.push_back(entry));
+					break;
+				DirectoryEntry* current = directory_list->array;
+				for (size_t i = 0; i < directory_list->entry_count; i++)
+				{
+					TRY(all_entries.emplace_back(current->dirent.d_name));
+					current = current->next();
+				}
 			}
 
 			BAN::String entry_prefix;