blob: 57dea10f2bb01f65da2a386ea82a91f64ba73bf3 [file] [log] [blame]
// 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
// 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);
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.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