genode/repos/os/include/ram_fs/node.h

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File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
/*
* \brief File-system node
* \author Norman Feske
* \date 2012-04-11
*/
/*
* Copyright (C) 2012-2015 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__RAM_FS__NODE_H_
#define _INCLUDE__RAM_FS__NODE_H_
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
/* Genode includes */
#include <file_system/listener.h>
#include <file_system/node.h>
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
#include <util/list.h>
namespace File_system {
using namespace Genode;
class Node;
}
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
class File_system::Node : public Node_base, public List<Node>::Element
{
public:
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
typedef char Name[128];
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
private:
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
int _ref_count;
Name _name;
unsigned long const _inode;
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
/**
* Generate unique inode number
*/
static unsigned long _unique_inode()
{
static unsigned long inode_count;
return ++inode_count;
}
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
public:
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
Node()
: _ref_count(0), _inode(_unique_inode())
{ _name[0] = 0; }
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
unsigned long inode() const { return _inode; }
char const *name() const { return _name; }
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
/**
* Assign name
*/
void name(char const *name) { strncpy(_name, name, sizeof(_name)); }
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
virtual size_t read(char *dst, size_t len, seek_off_t) = 0;
virtual size_t write(char const *src, size_t len, seek_off_t) = 0;
};
File-system interface, ram_fs, libc-fs This patch introduces the file-system-session interface, provides an implementation of this interface in the form of an in-memory file system, and enables the libc to use the new file-system facility. The new interface resides in 'os/include/file_system_session/'. It uses synchronous RPC calls for functions referring to directory and meta-data handling. For transferring payload from/to files, the packet-stream interface is used. I envision that the asynchronous design of the packet-stream interface fits well will the block-session interface. Compared to Unix-like file-system APIs, Genode's file-system session interface is much simpler. In particular, it does not support per-file permissions. On Genode, we facilitate binding policy (such as write-permission) is sessions rather than individual file objects. As a reference implementation of the new interface, there is the new 'ram_fs' service at 'os/src/server/ram_fs'. It stores sparse files in memory. At the startup, 'ram_fs' is able to populate the file-system content with directories and ROM modules as specified in its configuration. To enable libc-using programs to access the new file-system interface, there is the new libc plugin at 'libports/src/lib/libc-fs'. Using this plugin, files stored on a native Genode file system can be accessed using the traditional POSIX file API. To see how the three parts described above fit together, the test case at 'libports/run/libc_fs' can be taken as reference. It reuses the original 'libc_ffat' test to exercise several file operations on a RAM file-system using the libc API. :Known limitations: The current state should be regarded as work in progress. In particular the error handling is not complete yet. Not all of the session functions return the proper exceptions in the event of an error. I plan to successively refine the interface while advancing the file-system implementations. Also the support for truncating files and symlink handling are not yet implemented. Furthermore, there is much room for optimization, in particular for the handling of directory entries. Currently, we communicate only one dir entry at a time, which is bad when traversing large trees. However, I decided to focus on functionality first and defer optimizations (such as batching dir entries) to a later stage. The current implementation does not handle file modification times at all, which may be a severe limitation for tools that depend on this information such as GNU make. Support for time will be added after we have revisited Genode's timer-session interface (issue #1). Fixes #54 Fixes #171
2012-04-11 13:46:33 +00:00
#endif /* _INCLUDE__RAM_FS__NODE_H_ */