Add static function File::ReadFileToString.

Change-Id: Ib50aea743662376c8c7da82bba4002932da4014c

media/file/file.cc

@@ -4,13 +4,15 @@
 
 #include "media/file/file.h"
 
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
 #include "media/file/local_file.h"
 
 namespace media {
 
 const char* kLocalFilePrefix = "file://";
 
-typedef File* (*FileFactoryFunction)(const char* fname, const char* mode);
+typedef File* (*FileFactoryFunction)(const char* file_name, const char* mode);
 
 struct SupportedTypeInfo {
   const char* type;
@@ -18,30 +20,30 @@ struct SupportedTypeInfo {
   const FileFactoryFunction factory_function;
 };
 
-static File* CreateLocalFile(const char* fname, const char* mode) {
-  return new LocalFile(fname, mode);
+static File* CreateLocalFile(const char* file_name, const char* mode) {
+  return new LocalFile(file_name, mode);
 }
 
 static const SupportedTypeInfo kSupportedTypeInfo[] = {
     { kLocalFilePrefix, strlen(kLocalFilePrefix), &CreateLocalFile },
 };
 
-File* File::Create(const char* fname, const char* mode) {
+File* File::Create(const char* file_name, const char* mode) {
   for (size_t i = 0; i < arraysize(kSupportedTypeInfo); ++i) {
     const SupportedTypeInfo& type_info = kSupportedTypeInfo[i];
-    if (strncmp(type_info.type, fname, type_info.type_length) == 0) {
-      return type_info.factory_function(fname + type_info.type_length, mode);
+    if (strncmp(type_info.type, file_name, type_info.type_length) == 0) {
+      return type_info.factory_function(file_name + type_info.type_length,
+                                        mode);
     }
   }
   // Otherwise we assume it is a local file
-  return CreateLocalFile(fname, mode);
+  return CreateLocalFile(file_name, mode);
 }
 
-File* File::Open(const char* name, const char* mode) {
-  File* file = File::Create(name, mode);
-  if (!file) {
+File* File::Open(const char* file_name, const char* mode) {
+  File* file = File::Create(file_name, mode);
+  if (!file)
     return NULL;
-  }
   if (!file->Open()) {
     delete file;
     return NULL;
@@ -49,16 +51,31 @@ File* File::Open(const char* name, const char* mode) {
   return file;
 }
 
-// Return the file size or -1 on failure.
-// Requires opening and closing the file.
-int64 File::GetFileSize(const char* name) {
-  File* f = File::Open(name, "r");
-  if (!f) {
+int64 File::GetFileSize(const char* file_name) {
+  File* file = File::Open(file_name, "r");
+  if (!file)
     return -1;
-  }
-  int64 res = f->Size();
-  f->Close();
+  int64 res = file->Size();
+  file->Close();
   return res;
 }
 
+bool File::ReadFileToString(const char* file_name, std::string* contents) {
+  DCHECK(contents);
+
+  File* file = File::Open(file_name, "r");
+  if (!file)
+    return false;
+
+  const size_t kBufferSize = 0x40000;  // 256KB.
+  scoped_ptr<char[]> buf(new char[kBufferSize]);
+
+  int64 len;
+  while ((len = file->Read(buf.get(), kBufferSize)) > 0)
+    contents->append(buf.get(), len);
+
+  file->Close();
+  return len == 0;
+}
+
 }  // namespace media

media/file/file.h

@@ -20,7 +20,7 @@ class File {
   // Open the specified file, or return NULL on error.
   // This is actually a file factory method, it opens a proper file, e.g.
   // LocalFile, MemFile automatically based on prefix.
-  static File* Open(const char* name, const char* mode);
+  static File* Open(const char* file_name, const char* mode);
 
   // Flush() and de-allocate resources associated with this file, and
   // delete this File object.  THIS IS THE ONE TRUE WAY TO DEALLOCATE
@@ -65,8 +65,12 @@ class File {
   // ************************************************************
 
   // Returns the size of a file in bytes, and opens and closes the file
-  // in the process. Returns -1 on failure.
-  static int64 GetFileSize(const char* fname);
+  // in the process. Returns a value < 0 on failure.
+  static int64 GetFileSize(const char* file_name);
+
+  // Read the file at |file_name| into |contents|, returning true on success.
+  // |contents| should not be NULL.
+  static bool ReadFileToString(const char* file_name, std::string* contents);
 
  protected:
   explicit File(const std::string& file_name) : file_name_(file_name) {}
@@ -80,7 +84,7 @@ class File {
  private:
   // This is a file factory method, it creates a proper file, e.g.
   // LocalFile, MemFile based on prefix.
-  static File* Create(const char* fname, const char* mode);
+  static File* Create(const char* file_name, const char* mode);
 
   std::string file_name_;
   DISALLOW_COPY_AND_ASSIGN(File);