| // Copyright 2019 The Pigweed Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| // use this file except in compliance with the License. You may obtain a copy of |
| // the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| // License for the specific language governing permissions and limitations under |
| // the License. |
| |
| #include "pw_string/format.h" |
| |
| #include <cstdio> |
| |
| namespace pw::string { |
| |
| StatusWithSize Format(span<char> buffer, const char* format, ...) { |
| va_list args; |
| va_start(args, format); |
| const StatusWithSize result = FormatVaList(buffer, format, args); |
| va_end(args); |
| |
| return result; |
| } |
| |
| StatusWithSize FormatVaList(span<char> buffer, |
| const char* format, |
| va_list args) { |
| if (buffer.empty()) { |
| return StatusWithSize::ResourceExhausted(); |
| } |
| |
| const int result = std::vsnprintf(buffer.data(), buffer.size(), format, args); |
| |
| // If an error occurred, the number of characters written is unknown. |
| // Discard any output by terminating the buffer. |
| if (result < 0) { |
| buffer[0] = '\0'; |
| return StatusWithSize::InvalidArgument(); |
| } |
| |
| // If result >= buffer.size(), the output was truncated and null-terminated. |
| if (static_cast<unsigned>(result) >= buffer.size()) { |
| return StatusWithSize::ResourceExhausted(buffer.size() - 1); |
| } |
| |
| return StatusWithSize(result); |
| } |
| |
| } // namespace pw::string |