genode/repos/libports/src/lib/libc/internal/vfs_plugin.h

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/*
* \brief Libc plugin for using a process-local virtual file system
* \author Norman Feske
* \author Emery Hemingway
* \author Christian Helmuth
* \date 2014-04-09
*/
/*
* Copyright (C) 2014-2019 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__VFS_PLUGIN_H_
#define _LIBC__INTERNAL__VFS_PLUGIN_H_
/* Genode includes */
#include <libc/component.h>
#include <vfs/file_system.h>
/* libc includes */
#include <fcntl.h>
#include <unistd.h>
/* libc plugin interface */
#include <libc-plugin/plugin.h>
#include <libc-plugin/fd_alloc.h>
/* libc-internal includes */
#include <internal/errno.h>
namespace Libc { class Vfs_plugin; }
class Libc::Vfs_plugin : public Libc::Plugin
{
private:
Genode::Allocator &_alloc;
Vfs::File_system &_root_dir;
Vfs::Io_response_handler &_response_handler;
/**
* Sync a handle and propagate errors
*/
int _vfs_sync(Vfs::Vfs_handle&);
VFS: nonblocking interface The VFS library can be used in single-threaded or multi-threaded environments and depending on that, signals are handled by the same thread which uses the VFS library or possibly by a different thread. If a VFS plugin needs to block to wait for a signal, there is currently no way which works reliably in both environments. For this reason, this commit makes the interface of the VFS library nonblocking, similar to the File_system session interface. The most important changes are: - Directories are created and opened with the 'opendir()' function and the directory entries are read with the recently introduced 'queue_read()' and 'complete_read()' functions. - Symbolic links are created and opened with the 'openlink()' function and the link target is read with the 'queue_read()' and 'complete_read()' functions and written with the 'write()' function. - The 'write()' function does not wait for signals anymore. This can have the effect that data written by a VFS library user has not been processed by a file system server yet when the library user asks for the size of the file or closes it (both done with RPC functions at the file system server). For this reason, a user of the VFS library should request synchronization before calling 'stat()' or 'close()'. To make sure that a file system server has processed all write request packets which a client submitted before the synchronization request, synchronization is now requested at the file system server with a synchronization packet instead of an RPC function. Because of this change, the synchronization interface of the VFS library is now split into 'queue_sync()' and 'complete_sync()' functions. Fixes #2399
2017-08-15 20:51:53 +02:00
public:
Vfs_plugin(Libc::Env &env,
Genode::Allocator &alloc,
Vfs::Io_response_handler &handler)
:
_alloc(alloc), _root_dir(env.vfs()), _response_handler(handler)
{ }
~Vfs_plugin() final { }
bool root_dir_has_dirents() const { return _root_dir.num_dirent("/") > 0; }
bool supports_access(const char *, int) override { return true; }
bool supports_mkdir(const char *, mode_t) override { return true; }
bool supports_open(const char *, int) override { return true; }
bool supports_poll() override { return true; }
bool supports_readlink(const char *, char *, ::size_t) override { return true; }
bool supports_rename(const char *, const char *) override { return true; }
bool supports_rmdir(const char *) override { return true; }
bool supports_stat(const char *) override { return true; }
bool supports_symlink(const char *, const char *) override { return true; }
bool supports_unlink(const char *) override { return true; }
bool supports_mmap() override { return true; }
bool supports_select(int nfds,
fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct timeval *timeout) override;
Libc::File_descriptor *open(const char *, int, int libc_fd);
Libc::File_descriptor *open(const char *path, int flags) override
{
return open(path, flags, Libc::ANY_FD);
}
int access(char const *, int) override;
int close(Libc::File_descriptor *) override;
int dup2(Libc::File_descriptor *, Libc::File_descriptor *) override;
int fcntl(Libc::File_descriptor *, int, long) override;
int fstat(Libc::File_descriptor *, struct stat *) override;
int fstatfs(Libc::File_descriptor *, struct statfs *) override;
int fsync(Libc::File_descriptor *fd) override;
int ftruncate(Libc::File_descriptor *, ::off_t) override;
ssize_t getdirentries(Libc::File_descriptor *, char *, ::size_t , ::off_t *) override;
int ioctl(Libc::File_descriptor *, int , char *) override;
::off_t lseek(Libc::File_descriptor *fd, ::off_t offset, int whence) override;
int mkdir(const char *, mode_t) override;
bool poll(File_descriptor &fdo, struct pollfd &pfd) override;
ssize_t read(Libc::File_descriptor *, void *, ::size_t) override;
ssize_t readlink(const char *, char *, ::size_t) override;
int rename(const char *, const char *) override;
int rmdir(const char *) override;
int stat(const char *, struct stat *) override;
int symlink(const char *, const char *) override;
int unlink(const char *) override;
ssize_t write(Libc::File_descriptor *, const void *, ::size_t ) override;
void *mmap(void *, ::size_t, int, int, Libc::File_descriptor *, ::off_t) override;
int munmap(void *, ::size_t) override;
int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout) override;
};
#endif /* _LIBC__INTERNAL__VFS_PLUGIN_H_ */