1 // Copyright 2019 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "mojo/public/cpp/system/file_data_source.h"
6
7 #include <algorithm>
8 #include <limits>
9
10 namespace mojo {
11
12 namespace {
13
CalculateEndOffset(base::File * file,MojoResult * result)14 uint64_t CalculateEndOffset(base::File* file, MojoResult* result) {
15 if (!file->IsValid())
16 return 0u;
17 int64_t length = file->GetLength();
18 if (length < 0) {
19 *result =
20 FileDataSource::ConvertFileErrorToMojoResult(file->GetLastFileError());
21 return 0u;
22 }
23 return length;
24 }
25
26 } // namespace
27
28 // static
ConvertFileErrorToMojoResult(base::File::Error error)29 MojoResult FileDataSource::ConvertFileErrorToMojoResult(
30 base::File::Error error) {
31 switch (error) {
32 case base::File::FILE_OK:
33 return MOJO_RESULT_OK;
34 case base::File::FILE_ERROR_NOT_FOUND:
35 return MOJO_RESULT_NOT_FOUND;
36 case base::File::FILE_ERROR_SECURITY:
37 case base::File::FILE_ERROR_ACCESS_DENIED:
38 return MOJO_RESULT_PERMISSION_DENIED;
39 case base::File::FILE_ERROR_TOO_MANY_OPENED:
40 case base::File::FILE_ERROR_NO_MEMORY:
41 return MOJO_RESULT_RESOURCE_EXHAUSTED;
42 case base::File::FILE_ERROR_ABORT:
43 return MOJO_RESULT_ABORTED;
44 default:
45 return MOJO_RESULT_UNKNOWN;
46 }
47 }
48
FileDataSource(base::File file)49 FileDataSource::FileDataSource(base::File file)
50 : file_(std::move(file)),
51 error_(ConvertFileErrorToMojoResult(file_.error_details())),
52 start_offset_(0u),
53 end_offset_(CalculateEndOffset(&file_, &error_)) {}
54
55 FileDataSource::~FileDataSource() = default;
56
SetRange(uint64_t start,uint64_t end)57 void FileDataSource::SetRange(uint64_t start, uint64_t end) {
58 if (start > end) {
59 start_offset_ = 0;
60 end_offset_ = 0;
61 if (error_ == MOJO_RESULT_OK)
62 error_ = MOJO_RESULT_INVALID_ARGUMENT;
63 } else {
64 start_offset_ = start;
65 end_offset_ = end;
66 }
67 }
68
GetLength() const69 uint64_t FileDataSource::GetLength() const {
70 return end_offset_ - start_offset_;
71 }
72
Read(uint64_t offset,base::span<char> buffer)73 DataPipeProducer::DataSource::ReadResult FileDataSource::Read(
74 uint64_t offset,
75 base::span<char> buffer) {
76 ReadResult result;
77 if (error_ != MOJO_RESULT_OK)
78 result.result = error_;
79 else if (GetLength() < offset)
80 result.result = MOJO_RESULT_INVALID_ARGUMENT;
81
82 uint64_t readable_size = GetLength() - offset;
83 uint64_t read_size =
84 std::min(static_cast<uint64_t>(std::numeric_limits<int>::max()),
85 std::min(static_cast<uint64_t>(buffer.size()), readable_size));
86 // |read_offset| should not overflow if 'GetLength() < offset' is true.
87 // Otherwise, MOJO_RESULT_INVALID_ARGUMENT should be already set.
88 uint64_t read_offset = start_offset_ + offset;
89 if (read_offset > std::numeric_limits<int64_t>::max())
90 result.result = MOJO_RESULT_INVALID_ARGUMENT;
91
92 if (result.result != MOJO_RESULT_OK)
93 return result;
94
95 int bytes_read =
96 file_.Read(static_cast<int64_t>(read_offset), buffer.data(), read_size);
97 if (bytes_read < 0) {
98 result.bytes_read = 0;
99 result.result = ConvertFileErrorToMojoResult(file_.GetLastFileError());
100 } else {
101 result.bytes_read = bytes_read;
102 }
103 return result;
104 }
105
106 } // namespace mojo
107