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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#pragma once
28
29#include <AK/NonnullRefPtr.h>
30#include <AK/RefCounted.h>
31#include <AK/String.h>
32#include <AK/Types.h>
33#include <Kernel/Forward.h>
34#include <Kernel/KResult.h>
35#include <Kernel/UnixTypes.h>
36#include <LibBareMetal/Memory/VirtualAddress.h>
37
38namespace Kernel {
39
40// File is the base class for anything that can be referenced by a FileDescription.
41//
42// The most important functions in File are:
43//
44// read() and write()
45// - Implement reading and writing.
46// - Return the number of bytes read/written, OR a negative error code.
47//
48// can_read() and can_write()
49//
50// - Used to implement blocking I/O, and the select() and poll() syscalls.
51// - Return true if read() or write() would succeed, respectively.
52// - Note that can_read() should return true in EOF conditions,
53// and a subsequent call to read() should return 0.
54//
55// ioctl()
56//
57// - Optional. If unimplemented, ioctl() on this File will fail with -ENOTTY.
58// - Can be overridden in subclasses to implement arbitrary functionality.
59// - Subclasses should take care to validate incoming addresses before dereferencing.
60//
61// mmap()
62//
63// - Optional. If unimplemented, mmap() on this File will fail with -ENODEV.
64// - Called by mmap() when userspace wants to memory-map this File somewhere.
65// - Should create a Region in the Process and return it if successful.
66
67class File : public RefCounted<File> {
68public:
69 virtual ~File();
70
71 virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options);
72 virtual void close();
73
74 virtual bool can_read(const FileDescription&) const = 0;
75 virtual bool can_write(const FileDescription&) const = 0;
76
77 virtual ssize_t read(FileDescription&, u8*, ssize_t) = 0;
78 virtual ssize_t write(FileDescription&, const u8*, ssize_t) = 0;
79 virtual int ioctl(FileDescription&, unsigned request, unsigned arg);
80 virtual KResultOr<Region*> mmap(Process&, FileDescription&, VirtualAddress preferred_vaddr, size_t offset, size_t size, int prot, bool shared);
81
82 virtual String absolute_path(const FileDescription&) const = 0;
83
84 virtual KResult truncate(u64) { return KResult(-EINVAL); }
85 virtual KResult chown(uid_t, gid_t) { return KResult(-EBADF); }
86 virtual KResult chmod(mode_t) { return KResult(-EBADF); }
87
88 virtual const char* class_name() const = 0;
89
90 virtual bool is_seekable() const { return false; }
91
92 virtual bool is_inode() const { return false; }
93 virtual bool is_fifo() const { return false; }
94 virtual bool is_device() const { return false; }
95 virtual bool is_tty() const { return false; }
96 virtual bool is_master_pty() const { return false; }
97 virtual bool is_block_device() const { return false; }
98 virtual bool is_character_device() const { return false; }
99 virtual bool is_socket() const { return false; }
100
101protected:
102 File();
103};
104
105}