jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Leon Albrecht <leon.a@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Checked.h>
8#include <Kernel/FileSystem/Inode.h>
9#include <Kernel/FileSystem/InodeFile.h>
10#include <Kernel/FileSystem/OpenFileDescription.h>
11#include <Kernel/Process.h>
12
13namespace Kernel {
14
15// https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_fallocate.html
16ErrorOr<FlatPtr> Process::sys$posix_fallocate(int fd, Userspace<off_t const*> userspace_offset, Userspace<off_t const*> userspace_length)
17{
18 VERIFY_NO_PROCESS_BIG_LOCK(this);
19 TRY(require_promise(Pledge::stdio));
20
21 // [EINVAL] The len argument is less than zero, or the offset argument is less than zero, or the underlying file system does not support this operation.
22 auto offset = TRY(copy_typed_from_user(userspace_offset));
23 if (offset < 0)
24 return EINVAL;
25 auto length = TRY(copy_typed_from_user(userspace_length));
26 if (length <= 0)
27 return EINVAL;
28
29 Checked<size_t> checked_size { length };
30 checked_size += offset;
31 // FIXME: Return EFBIG if offset+length > FileSizeMax
32 if (checked_size.has_overflow())
33 return EFBIG;
34
35 auto description = TRY(open_file_description(fd));
36
37 // [EBADF] The fd argument references a file that was opened without write permission.
38 if (!description->is_writable())
39 return EBADF;
40
41 // [ESPIPE] The fd argument is associated with a pipe or FIFO.
42 if (description->is_fifo())
43 return ESPIPE;
44
45 // [ENODEV] The fd argument does not refer to a regular file.
46 if (!description->file().is_regular_file())
47 return ENODEV;
48
49 VERIFY(description->file().is_inode());
50
51 auto& file = static_cast<InodeFile&>(description->file());
52 if (file.inode().size() >= checked_size.value())
53 return 0;
54
55 // Note: truncate essentially calls resize in the inodes implementation
56 // while resize is not a standard member of an inode, so we just call
57 // truncate instead
58 TRY(file.inode().truncate(checked_size.value()));
59
60 // FIXME: EINTR: A signal was caught during execution.
61 return 0;
62}
63
64}