From c423164066a4566eee78ba3db09321ccfd051cc7 Mon Sep 17 00:00:00 2001
From: Bananymous <bananymousosq@gmail.com>
Date: Sun, 11 Jun 2023 00:19:20 +0300
Subject: [PATCH] LibC: Implement basic dirent functionality

We don't currently support seeking
---
 libc/CMakeLists.txt   |  1 +
 libc/dirent.cpp       | 92 +++++++++++++++++++++++++++++++++++++++++++
 libc/include/dirent.h |  4 +-
 3 files changed, 95 insertions(+), 2 deletions(-)
 create mode 100644 libc/dirent.cpp

diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 8717a5c627..f7ba67e087 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -5,6 +5,7 @@ project(libc CXX ASM)
 set(LIBC_SOURCES
 	assert.cpp
 	ctype.cpp
+	dirent.cpp
 	fcntl.cpp
 	printf_impl.cpp
 	stdio.cpp
diff --git a/libc/dirent.cpp b/libc/dirent.cpp
new file mode 100644
index 0000000000..16f9f6ede1
--- /dev/null
+++ b/libc/dirent.cpp
@@ -0,0 +1,92 @@
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <kernel/API/DirectoryEntry.h>
+
+struct __DIR
+{
+	int fd { -1 };
+	size_t entry_index { 0 };
+	Kernel::API::DirectoryEntry* current { nullptr };
+
+	size_t buffer_size { 0 };
+	Kernel::API::DirectoryEntryList buffer[];
+};
+
+int closedir(DIR* dirp)
+{
+	if (dirp == nullptr || dirp->fd == -1)
+	{
+		errno = EBADF;
+		return -1;
+	}
+	
+	close(dirp->fd);
+	dirp->fd = -1;
+	free(dirp);
+
+	return 0;
+}
+
+int dirfd(DIR* dirp)
+{
+	if (dirp == nullptr || dirp->fd == -1)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	return dirp->fd;
+}
+
+DIR* fdopendir(int fd)
+{
+	DIR* dirp = (DIR*)malloc(sizeof(DIR) + 4096);
+	if (dirp == nullptr)
+		return nullptr;
+
+	dirp->fd = fd;
+	dirp->current = nullptr;
+	dirp->buffer_size = 4096;
+
+	return dirp;
+}
+
+DIR* opendir(const char* dirname)
+{
+	int fd = open(dirname, O_SEARCH);
+	if (fd == -1)
+		return nullptr;
+	return fdopendir(fd);
+}
+
+struct dirent* readdir(DIR* dirp)
+{
+	if (dirp == nullptr || dirp->fd == -1)
+	{
+		errno = EBADF;
+		return nullptr;
+	}
+
+	dirp->entry_index++;
+	if (dirp->current && dirp->entry_index < dirp->buffer->entry_count)
+	{
+		dirp->current = dirp->current->next();
+		return &dirp->current->dirent;
+	}
+
+	if (syscall(SYS_READ_DIR_ENTRIES, dirp->fd, dirp->buffer, dirp->buffer_size) == -1)
+		return nullptr;
+
+	if (dirp->buffer->entry_count == 0)
+		return nullptr;
+
+	dirp->entry_index = 0;
+	dirp->current = dirp->buffer->array;
+
+	return &dirp->current->dirent;
+}
diff --git a/libc/include/dirent.h b/libc/include/dirent.h
index dbb4af0c0c..1ea2f25397 100644
--- a/libc/include/dirent.h
+++ b/libc/include/dirent.h
@@ -10,8 +10,8 @@ __BEGIN_DECLS
 #define __need_ino_t
 #include <sys/types.h>
 
-struct DIR;
-typedef struct DIR DIR;
+struct __DIR;
+typedef struct __DIR DIR;
 
 struct dirent
 {