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As a follow-up to #46543, this adds a dedicated function to compute the size of the buffer needed to encode data using Base64 instead of calling the encode function with nullptr. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide] and the [C++, Objective-C, Java style guides]. - [ ] I listed at least one issue that this PR fixes in the description above. - [x] I added new tests to check the change I am making or feature I am adding, or the PR is [test-exempt]. See [testing the engine] for instructions on writing and running engine tests. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I signed the [CLA]. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/wiki/Tree-hygiene#overview [Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene [test-exempt]: https://github.com/flutter/flutter/wiki/Tree-hygiene#tests [Flutter Style Guide]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo [C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style [testing the engine]: https://github.com/flutter/flutter/wiki/Testing-the-engine [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/wiki/Chat
60 lines
1.6 KiB
C++
60 lines
1.6 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_SHELL_COMMON_BASE64_H_
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#define FLUTTER_SHELL_COMMON_BASE64_H_
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#include <cstddef>
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namespace flutter {
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struct Base64 {
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public:
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enum class Error {
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kNone,
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kBadPadding,
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kBadChar,
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};
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/**
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Base64 encodes src into dst.
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@param dst a pointer to a buffer large enough to receive the result.
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@return the required length of dst for encoding.
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*/
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static size_t Encode(const void* src, size_t length, void* dst);
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/**
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Returns the length of the buffer that needs to be allocated to encode
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srcDataLength bytes.
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*/
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static size_t EncodedSize(size_t srcDataLength) {
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// Take the floor of division by 3 to find the number of groups that need to
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// be encoded. Each group takes 4 bytes to be represented in base64.
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return ((srcDataLength + 2) / 3) * 4;
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}
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/**
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Base64 decodes src into dst.
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This can be called once with 'dst' nullptr to get the required size,
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then again with an allocated 'dst' pointer to do the actual decoding.
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@param dst nullptr or a pointer to a buffer large enough to receive the
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result
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@param dstLength assigned the length dst is required to be. Must not be
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nullptr.
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*/
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[[nodiscard]] static Error Decode(const void* src,
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size_t srcLength,
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void* dst,
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size_t* dstLength);
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};
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} // namespace flutter
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#endif // FLUTTER_SHELL_COMMON_BASE64_H_
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