Revert "Remove deprecated ByteBufferReader and ByteBufferWriter functions"

This reverts commit e0e03ba73a0859924a55c4dfa4ce20ff80820f0b.

Reason for revert: Speculative rollback (breaks WebKit Linux Leak)

Original change's description:
> Remove deprecated ByteBufferReader and ByteBufferWriter functions
>
> This completes the conversion of ByteBufferReader and ByteBufferWriter
> to uint8_t.
>
> No-Try: True
> Bug: webrtc:15661
> Change-Id: I4152a8a4fd2462282d4107b3c2eed19acc8b29b0
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/331640
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#41403}

Bug: webrtc:15661, chromium:1513059
Change-Id: I3938b8209f5cc1596307deadac157a8f6c2b2253
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/331940
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41411}

api/transport/stun.cc

@@ -587,7 +587,7 @@ bool StunMessage::AddFingerprint() {
 
 bool StunMessage::Read(ByteBufferReader* buf) {
   // Keep a copy of the buffer data around for later verification.
-  buffer_.assign(reinterpret_cast<const char*>(buf->Data()), buf->Length());
+  buffer_.assign(buf->Data(), buf->Length());
 
   if (!buf->ReadUInt16(&type_)) {
     return false;

p2p/base/pseudo_tcp.cc

@@ -1213,7 +1213,7 @@ void PseudoTcp::parseOptions(const char* data, uint32_t len) {
 
     // Content of this option.
     if (opt_len <= buf.Length()) {
-      applyOption(kind, reinterpret_cast<const char*>(buf.Data()), opt_len);
+      applyOption(kind, buf.Data(), opt_len);
       buf.Consume(opt_len);
     } else {
       RTC_LOG(LS_ERROR) << "Invalid option length received.";

rtc_base/byte_buffer.cc

@@ -139,6 +139,10 @@ bool ByteBufferReader::ReadBytes(rtc::ArrayView<uint8_t> val) {
   return ReadBytes(val.data(), val.size());
 }
 
+bool ByteBufferReader::ReadBytes(char* val, size_t len) {
+  return ReadBytes(reinterpret_cast<uint8_t*>(val), len);
+}
+
 // Private function supporting the other Read* functions.
 bool ByteBufferReader::ReadBytes(uint8_t* val, size_t len) {
   if (len > Length()) {

rtc_base/byte_buffer.h

@@ -100,6 +100,12 @@ class ByteBufferWriterT {
   void WriteBytes(const uint8_t* val, size_t len) {
     WriteBytesInternal(reinterpret_cast<const value_type*>(val), len);
   }
+  // For backwards compatibility: Write an array of char
+  // TODO(bugs.webrtc.org/15665): Remove when users converted
+  [[deprecated("Use WriteString")]] void WriteBytes(const char* val,
+                                                    size_t len) {
+    WriteBytesInternal(reinterpret_cast<const value_type*>(val), len);
+  }
 
   // Reserves the given number of bytes and returns a value_type* that can be
   // written into. Useful for functions that require a value_type* buffer and
@@ -157,10 +163,14 @@ class ByteBufferReader {
   ByteBufferReader(const ByteBufferReader&) = delete;
   ByteBufferReader& operator=(const ByteBufferReader&) = delete;
 
-  const uint8_t* Data() const { return bytes_ + start_; }
+  // Returns start of unprocessed data.
+  // TODO(bugs.webrtc.org/15661): Deprecate and remove.
+  const char* Data() const {
+    return reinterpret_cast<const char*>(bytes_ + start_);
+  }
   // Returns number of unprocessed bytes.
   size_t Length() const { return end_ - start_; }
-  // Returns a view of the unprocessed data. Does not move current position.
+  // Returns a view of the unprocessed data.
   rtc::ArrayView<const uint8_t> DataView() const {
     return rtc::ArrayView<const uint8_t>(bytes_ + start_, end_ - start_);
   }
@@ -173,8 +183,11 @@ class ByteBufferReader {
   bool ReadUInt32(uint32_t* val);
   bool ReadUInt64(uint64_t* val);
   bool ReadUVarint(uint64_t* val);
-  // Copies the val.size() next bytes into val.data().
   bool ReadBytes(rtc::ArrayView<uint8_t> val);
+  // For backwards compatibility.
+  // TODO(bugs.webrtc.org/15661): Deprecate and remove.
+  [[deprecated("Read using ArrayView")]] bool ReadBytes(char* val, size_t len);
+
   // Appends next `len` bytes from the buffer to `val`. Returns false
   // if there is less than `len` bytes left.
   bool ReadString(std::string* val, size_t len);

rtc_base/server_socket_adapters.cc

@@ -75,9 +75,7 @@ void AsyncSocksProxyServerSocket::ProcessInput(char* data, size_t* len) {
 
   // Consume parsed data
   *len = response.Length();
-  if (response.Length() > 0) {
+  memmove(data, response.Data(), *len);
-    memmove(data, response.DataView().data(), *len);
-  }
 }
 
 void AsyncSocksProxyServerSocket::DirectSend(const ByteBufferWriter& buf) {