Add FileReaderInterface. Move StringFileWriter to StringFile and

util/file/string_file.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // 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
 //
 //     http://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 "util/file/string_file_writer.h"
+#include "util/file/string_file.h"
 
 #include <string.h>
 
+#include <algorithm>
+#include <limits>
+
 #include "base/logging.h"
 #include "base/numerics/safe_math.h"
 #include "util/numeric/safe_assignment.h"
 
 namespace crashpad {
 
-StringFileWriter::StringFileWriter() : string_(), offset_(0) {
+StringFile::StringFile() : string_(), offset_(0) {
 }
 
-StringFileWriter::~StringFileWriter() {
+StringFile::~StringFile() {
 }
 
-void StringFileWriter::Reset() {
+void StringFile::SetString(const std::string& string) {
+  CHECK_LE(string.size(),
+           implicit_cast<size_t>(std::numeric_limits<ssize_t>::max()));
+  string_ = string;
+  offset_ = 0;
+}
+
+void StringFile::Reset() {
   string_.clear();
   offset_ = 0;
 }
 
-bool StringFileWriter::Write(const void* data, size_t size) {
+ssize_t StringFile::Read(void* data, size_t size) {
   DCHECK(offset_.IsValid());
 
   const size_t offset = offset_.ValueOrDie();
+  if (offset >= string_.size()) {
+    return 0;
+  }
+
+  const size_t nread = std::min(size, string_.size() - offset);
+
+  base::CheckedNumeric<ssize_t> new_offset = offset_;
+  new_offset += nread;
+  if (!new_offset.IsValid()) {
+    LOG(ERROR) << "Read(): file too large";
+    return -1;
+  }
+
+  memcpy(data, &string_[offset], nread);
+  offset_ = new_offset;
+
+  return nread;
+}
+
+bool StringFile::Write(const void* data, size_t size) {
+  DCHECK(offset_.IsValid());
+
+  const size_t offset = offset_.ValueOrDie();
   if (offset > string_.size()) {
     string_.resize(offset);
   }
 
   base::CheckedNumeric<ssize_t> new_offset = offset_;
   new_offset += size;
   if (!new_offset.IsValid()) {
     LOG(ERROR) << "Write(): file too large";
     return false;
   }
 
   string_.replace(offset, size, reinterpret_cast<const char*>(data), size);
   offset_ = new_offset;
 
   return true;
 }
 
-bool StringFileWriter::WriteIoVec(std::vector<WritableIoVec>* iovecs) {
+bool StringFile::WriteIoVec(std::vector<WritableIoVec>* iovecs) {
   DCHECK(offset_.IsValid());
 
   if (iovecs->empty()) {
     LOG(ERROR) << "WriteIoVec(): no iovecs";
     return false;
   }
 
   // Avoid writing anything at all if it would cause an overflow.
   base::CheckedNumeric<ssize_t> new_offset = offset_;
   for (const WritableIoVec& iov : *iovecs) {
@@ skipping 12 matching lines @@
 
 #ifndef NDEBUG
   // The interface says that |iovecs| is not sacred, so scramble it to make sure
   // that nobody depends on it.
   memset(&(*iovecs)[0], 0xa5, sizeof((*iovecs)[0]) * iovecs->size());
 #endif
 
   return true;
 }
 
-FileOffset StringFileWriter::Seek(FileOffset offset, int whence) {
+FileOffset StringFile::Seek(FileOffset offset, int whence) {
   DCHECK(offset_.IsValid());
 
   size_t base_offset;
 
   switch (whence) {
     case SEEK_SET:
       base_offset = 0;
       break;
 
     case SEEK_CUR:
@@ skipping 28 matching lines @@
                << " invalid for size_t";
     return -1;
   }
 
   offset_ = new_offset_sizet;
 
   return offset_.ValueOrDie();
 }
 
 }  // namespace crashpad