jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <Kernel/Debug.h>
8#include <Kernel/FileSystem/OpenFileDescription.h>
9#include <Kernel/PerformanceManager.h>
10#include <Kernel/Process.h>
11
12namespace Kernel {
13
14using BlockFlags = Thread::FileBlocker::BlockFlags;
15
16static ErrorOr<NonnullRefPtr<OpenFileDescription>> open_readable_file_description(auto& fds, int fd)
17{
18 auto description = TRY(fds.with_shared([&](auto& fds) { return fds.open_file_description(fd); }));
19 if (!description->is_readable())
20 return EBADF;
21 if (description->is_directory())
22 return EISDIR;
23 return description;
24}
25
26static ErrorOr<void> check_blocked_read(OpenFileDescription* description)
27{
28 if (description->is_blocking()) {
29 if (!description->can_read()) {
30 auto unblock_flags = BlockFlags::None;
31 if (Thread::current()->block<Thread::ReadBlocker>({}, *description, unblock_flags).was_interrupted())
32 return EINTR;
33 if (!has_flag(unblock_flags, BlockFlags::Read))
34 return EAGAIN;
35 // TODO: handle exceptions in unblock_flags
36 }
37 }
38 return {};
39}
40
41ErrorOr<FlatPtr> Process::sys$readv(int fd, Userspace<const struct iovec*> iov, int iov_count)
42{
43 VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
44 TRY(require_promise(Pledge::stdio));
45 if (iov_count < 0)
46 return EINVAL;
47
48 if (iov_count > IOV_MAX)
49 return EFAULT;
50
51 u64 total_length = 0;
52 Vector<iovec, 32> vecs;
53 TRY(vecs.try_resize(iov_count));
54 TRY(copy_n_from_user(vecs.data(), iov, iov_count));
55 for (auto& vec : vecs) {
56 total_length += vec.iov_len;
57 if (total_length > NumericLimits<i32>::max())
58 return EINVAL;
59 }
60
61 auto description = TRY(open_readable_file_description(fds(), fd));
62
63 int nread = 0;
64 for (auto& vec : vecs) {
65 TRY(check_blocked_read(description));
66 auto buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)vec.iov_base, vec.iov_len));
67 auto nread_here = TRY(description->read(buffer, vec.iov_len));
68 nread += nread_here;
69 }
70
71 return nread;
72}
73
74ErrorOr<FlatPtr> Process::sys$read(int fd, Userspace<u8*> buffer, size_t size)
75{
76 auto const start_timestamp = TimeManagement::the().uptime_ms();
77 auto result = read_impl(fd, buffer, size);
78
79 if (Thread::current()->is_profiling_suppressed())
80 return result;
81
82 auto description = TRY(open_readable_file_description(fds(), fd));
83 PerformanceManager::add_read_event(*Thread::current(), fd, size, description, start_timestamp, result);
84
85 return result;
86}
87
88ErrorOr<FlatPtr> Process::read_impl(int fd, Userspace<u8*> buffer, size_t size)
89{
90 VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
91 TRY(require_promise(Pledge::stdio));
92 if (size == 0)
93 return 0;
94 if (size > NumericLimits<ssize_t>::max())
95 return EINVAL;
96 dbgln_if(IO_DEBUG, "sys$read({}, {}, {})", fd, buffer.ptr(), size);
97 auto description = TRY(open_readable_file_description(fds(), fd));
98
99 TRY(check_blocked_read(description));
100 auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
101 return TRY(description->read(user_buffer, size));
102}
103
104// NOTE: The offset is passed by pointer because off_t is 64bit,
105// hence it can't be passed by register on 32bit platforms.
106ErrorOr<FlatPtr> Process::sys$pread(int fd, Userspace<u8*> buffer, size_t size, Userspace<off_t const*> userspace_offset)
107{
108 VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
109 TRY(require_promise(Pledge::stdio));
110 if (size == 0)
111 return 0;
112 if (size > NumericLimits<ssize_t>::max())
113 return EINVAL;
114 auto offset = TRY(copy_typed_from_user(userspace_offset));
115 if (offset < 0)
116 return EINVAL;
117 dbgln_if(IO_DEBUG, "sys$pread({}, {}, {}, {})", fd, buffer.ptr(), size, offset);
118 auto description = TRY(open_readable_file_description(fds(), fd));
119 if (!description->file().is_seekable())
120 return EINVAL;
121 TRY(check_blocked_read(description));
122 auto user_buffer = TRY(UserOrKernelBuffer::for_user_buffer(buffer, size));
123 return TRY(description->read(user_buffer, offset, size));
124}
125
126}