Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/rtc_base/strings/string_builder.cc

@@ -0,0 +1,141 @@
+/*
+ *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "rtc_base/strings/string_builder.h"
+
+#include <stdarg.h>
+
+#include <cstdio>
+#include <cstring>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_minmax.h"
+
+namespace rtc {
+
+SimpleStringBuilder::SimpleStringBuilder(rtc::ArrayView<char> buffer)
+    : buffer_(buffer) {
+  buffer_[0] = '\0';
+  RTC_DCHECK(IsConsistent());
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(const char* str) {
+  return Append(str, strlen(str));
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(char ch) {
+  return Append(&ch, 1);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(const std::string& str) {
+  return Append(str.c_str(), str.length());
+}
+
+// Numeric conversion routines.
+//
+// We use std::[v]snprintf instead of std::to_string because:
+// * std::to_string relies on the current locale for formatting purposes,
+//   and therefore concurrent calls to std::to_string from multiple threads
+//   may result in partial serialization of calls
+// * snprintf allows us to print the number directly into our buffer.
+// * avoid allocating a std::string (potential heap alloc).
+// TODO(tommi): Switch to std::to_chars in C++17.
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(int i) {
+  return AppendFormat("%d", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(unsigned i) {
+  return AppendFormat("%u", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(long i) {  // NOLINT
+  return AppendFormat("%ld", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(long long i) {  // NOLINT
+  return AppendFormat("%lld", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(
+    unsigned long i) {  // NOLINT
+  return AppendFormat("%lu", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(
+    unsigned long long i) {  // NOLINT
+  return AppendFormat("%llu", i);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(float f) {
+  return AppendFormat("%g", f);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(double f) {
+  return AppendFormat("%g", f);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::operator<<(long double f) {
+  return AppendFormat("%Lg", f);
+}
+
+SimpleStringBuilder& SimpleStringBuilder::AppendFormat(const char* fmt, ...) {
+  va_list args;
+  va_start(args, fmt);
+  const int len =
+      std::vsnprintf(&buffer_[size_], buffer_.size() - size_, fmt, args);
+  if (len >= 0) {
+    const size_t chars_added = rtc::SafeMin(len, buffer_.size() - 1 - size_);
+    size_ += chars_added;
+    RTC_DCHECK_EQ(len, chars_added) << "Buffer size was insufficient";
+  } else {
+    // This should never happen, but we're paranoid, so re-write the
+    // terminator in case vsnprintf() overwrote it.
+    RTC_NOTREACHED();
+    buffer_[size_] = '\0';
+  }
+  va_end(args);
+  RTC_DCHECK(IsConsistent());
+  return *this;
+}
+
+SimpleStringBuilder& SimpleStringBuilder::Append(const char* str,
+                                                 size_t length) {
+  RTC_DCHECK_LT(size_ + length, buffer_.size())
+      << "Buffer size was insufficient";
+  const size_t chars_added = rtc::SafeMin(length, buffer_.size() - size_ - 1);
+  memcpy(&buffer_[size_], str, chars_added);
+  size_ += chars_added;
+  buffer_[size_] = '\0';
+  RTC_DCHECK(IsConsistent());
+  return *this;
+}
+
+StringBuilder& StringBuilder::AppendFormat(const char* fmt, ...) {
+  va_list args, copy;
+  va_start(args, fmt);
+  va_copy(copy, args);
+  const int predicted_length = std::vsnprintf(nullptr, 0, fmt, copy);
+  va_end(copy);
+
+  RTC_DCHECK_GE(predicted_length, 0);
+  if (predicted_length > 0) {
+    const size_t size = str_.size();
+    str_.resize(size + predicted_length);
+    // Pass "+ 1" to vsnprintf to include space for the '\0'.
+    const int actual_length =
+        std::vsnprintf(&str_[size], predicted_length + 1, fmt, args);
+    RTC_DCHECK_GE(actual_length, 0);
+  }
+  va_end(args);
+  return *this;
+}
+
+}  // namespace rtc