Use spans in chrome_pdf::DocumentLoaderImpl::SaveBuffer().

Replace a pointer/size pair with a span.

Change-Id: I1773fc3a65464eb891db7324eef1be8e5791928c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4214272
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1100137}

pdf/loader/document_loader_impl.cc

@@ -11,6 +11,7 @@
 #include <utility>
 
 #include "base/check_op.h"
+#include "base/containers/span.h"
 #include "base/feature_list.h"
 #include "base/functional/bind.h"
 #include "base/functional/callback.h"
@@ -317,7 +318,7 @@ void DocumentLoaderImpl::DidRead(int32_t result) {
     DCHECK(!chunk_.chunk_data);
     chunk_.chunk_index = chunk_stream_.GetChunkIndex(start_pos);
   }
-  if (!SaveBuffer(buffer_.data(), result)) {
+  if (!SaveBuffer(result)) {
     return ReadMore();
   }
   if (IsDocumentComplete())
@@ -325,18 +326,19 @@ void DocumentLoaderImpl::DidRead(int32_t result) {
   return ContinueDownload();
 }
 
-bool DocumentLoaderImpl::SaveBuffer(char* input, uint32_t input_size) {
+bool DocumentLoaderImpl::SaveBuffer(uint32_t input_size) {
   const uint32_t document_size = GetDocumentSize();
   bytes_received_ += input_size;
   bool chunk_saved = false;
   bool loading_pending_request = pending_requests_.Contains(chunk_.chunk_index);
-  while (input_size > 0) {
+  auto input = base::make_span(buffer_).first(input_size);
+  while (!input.empty()) {
     if (chunk_.data_size == 0)
       chunk_.chunk_data = std::make_unique<DataStream::ChunkData>();
 
     const size_t new_chunk_data_len =
-        std::min(DataStream::kChunkSize - chunk_.data_size, size_t{input_size});
-    memcpy(chunk_.chunk_data->data() + chunk_.data_size, input,
+        std::min(DataStream::kChunkSize - chunk_.data_size, input.size());
+    memcpy(chunk_.chunk_data->data() + chunk_.data_size, input.data(),
            new_chunk_data_len);
     chunk_.data_size += new_chunk_data_len;
     if (chunk_.data_size == DataStream::kChunkSize ||
@@ -347,8 +349,7 @@ bool DocumentLoaderImpl::SaveBuffer(char* input, uint32_t input_size) {
       chunk_saved = true;
     }
 
-    input += new_chunk_data_len;
-    input_size -= new_chunk_data_len;
+    input = input.subspan(new_chunk_data_len);
   }
 
   client_->OnNewDataReceived();

pdf/loader/document_loader_impl.h

@@ -71,7 +71,7 @@ class DocumentLoaderImpl : public DocumentLoader {
   // Called when we complete server request.
   void ReadComplete();
 
-  bool SaveBuffer(char* input, uint32_t input_size);
+  bool SaveBuffer(uint32_t input_size);
   void SaveChunkData();
 
   uint32_t EndOfCurrentChunk() const;