From 9453287a6b41b27ae0c97b79fafa0a7850ea4240 Mon Sep 17 00:00:00 2001
From: Christian Helmuth <christian.helmuth@genode-labs.com>
Date: Thu, 30 Jul 2020 16:34:16 +0200
Subject: [PATCH] libc: move current working directory into kernel

---
 .../libports/src/lib/libc/file_operations.cc  | 17 +++++++--
 repos/libports/src/lib/libc/internal/cwd.h    | 35 +++++++++++++++++++
 repos/libports/src/lib/libc/internal/init.h   |  2 ++
 repos/libports/src/lib/libc/internal/kernel.h | 11 +++++-
 repos/libports/src/lib/libc/kernel.cc         |  3 +-
 5 files changed, 64 insertions(+), 4 deletions(-)
 create mode 100644 repos/libports/src/lib/libc/internal/cwd.h

diff --git a/repos/libports/src/lib/libc/file_operations.cc b/repos/libports/src/lib/libc/file_operations.cc
index 697c5b8e0a..07b5fd51d5 100644
--- a/repos/libports/src/lib/libc/file_operations.cc
+++ b/repos/libports/src/lib/libc/file_operations.cc
@@ -43,6 +43,8 @@ extern "C" {
 #include <internal/mem_alloc.h>
 #include <internal/mmap_registry.h>
 #include <internal/errno.h>
+#include <internal/init.h>
+#include <internal/cwd.h>
 
 using namespace Libc;
 
@@ -61,6 +63,14 @@ Libc::Mmap_registry *Libc::mmap_registry()
 }
 
 
+static Cwd *_cwd_ptr;
+
+void Libc::init_file_operations(Cwd &cwd)
+{
+	_cwd_ptr = &cwd;
+}
+
+
 /***************
  ** Utilities **
  ***************/
@@ -70,8 +80,11 @@ Libc::Mmap_registry *Libc::mmap_registry()
  */
 static Absolute_path &cwd()
 {
-	static Absolute_path _cwd("/");
-	return _cwd;
+	struct Missing_call_of_init_file_operations : Exception { };
+	if (!_cwd_ptr)
+		throw Missing_call_of_init_file_operations();
+
+	return _cwd_ptr->cwd();
 }
 
 /**
diff --git a/repos/libports/src/lib/libc/internal/cwd.h b/repos/libports/src/lib/libc/internal/cwd.h
new file mode 100644
index 0000000000..928fb22d90
--- /dev/null
+++ b/repos/libports/src/lib/libc/internal/cwd.h
@@ -0,0 +1,35 @@
+/*
+ * \brief  Interface for access to current working directory
+ * \author Christian Helmuth
+ * \date   2020-07-20
+ */
+
+/*
+ * Copyright (C) 2020 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _LIBC__INTERNAL__CWD_H_
+#define _LIBC__INTERNAL__CWD_H_
+
+/* libc-internal includes */
+#include <internal/types.h>
+#include <libc-plugin/plugin.h>
+
+namespace Libc {
+
+	/**
+	 * Interface to resume all user contexts
+	 */
+	struct Cwd : Interface
+	{
+		/**
+		 * Provide access to current working directory (modifiable)
+		 */
+		virtual Absolute_path &cwd() = 0;
+	};
+}
+
+#endif /* _LIBC__INTERNAL__CWD_H_ */
diff --git a/repos/libports/src/lib/libc/internal/init.h b/repos/libports/src/lib/libc/internal/init.h
index 5e50f0c466..856ce4cdf2 100644
--- a/repos/libports/src/lib/libc/internal/init.h
+++ b/repos/libports/src/lib/libc/internal/init.h
@@ -39,6 +39,7 @@ namespace Libc {
 	struct Signal;
 	struct File_descriptor_allocator;
 	struct Timer_accessor;
+	struct Cwd;
 
 	/**
 	 * Support for shared libraries
@@ -64,6 +65,7 @@ namespace Libc {
 	 * Virtual file system
 	 */
 	void init_vfs_plugin(Suspend &);
+	void init_file_operations(Cwd &);
 
 	/**
 	 * Select support
diff --git a/repos/libports/src/lib/libc/internal/kernel.h b/repos/libports/src/lib/libc/internal/kernel.h
index 30b428523e..ec2a399ce6 100644
--- a/repos/libports/src/lib/libc/internal/kernel.h
+++ b/repos/libports/src/lib/libc/internal/kernel.h
@@ -41,6 +41,7 @@
 #include <internal/signal.h>
 #include <internal/monitor.h>
 #include <internal/pthread.h>
+#include <internal/cwd.h>
 
 namespace Libc {
 	class Kernel;
@@ -107,7 +108,8 @@ struct Libc::Kernel final : Vfs::Io_response_handler,
                             Select,
                             Kernel_routine_scheduler,
                             Current_time,
-                            Watch
+                            Watch,
+                            Cwd
 {
 	private:
 
@@ -286,6 +288,8 @@ struct Libc::Kernel final : Vfs::Io_response_handler,
 
 		Constructible<Clone_connection> _clone_connection { };
 
+		Absolute_path _cwd { "/" };
+
 		struct Resumer
 		{
 			GENODE_RPC(Rpc_resume, void, resume);
@@ -658,6 +662,11 @@ struct Libc::Kernel final : Vfs::Io_response_handler,
 				? watch_handle : nullptr;
 		}
 
+		/**
+		 * Cwd interface
+		 */
+		Absolute_path &cwd() { return _cwd; }
+
 
 		/****************************************
 		 ** Vfs::Io_response_handler interface **
diff --git a/repos/libports/src/lib/libc/kernel.cc b/repos/libports/src/lib/libc/kernel.cc
index 600d206592..3a8c2ca250 100644
--- a/repos/libports/src/lib/libc/kernel.cc
+++ b/repos/libports/src/lib/libc/kernel.cc
@@ -168,7 +168,7 @@ void Libc::Kernel::_init_file_descriptors()
 		typedef String<Vfs::MAX_PATH_LEN> Path;
 
 		if (node.has_attribute("cwd"))
-			chdir(node.attribute_value("cwd", Path()).string());
+			_cwd.import(node.attribute_value("cwd", Path()).string(), _cwd.base());
 
 		init_fd(node, "stdin",  0, O_RDONLY);
 		init_fd(node, "stdout", 1, O_WRONLY);
@@ -418,6 +418,7 @@ Libc::Kernel::Kernel(Genode::Env &env, Genode::Allocator &heap)
 	init_plugin(*this);
 	init_sleep(*this);
 	init_vfs_plugin(*this);
+	init_file_operations(*this);
 	init_time(*this, _rtc_path, *this);
 	init_select(*this, *this, *this, _signal);
 	init_socket_fs(*this);