Add FilePath::FinalExtension() to avoid double extensions (.tar.gz) for file selector

base/files/file_path.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/files/file_path.h"
 
 #include <string.h>
 #include <algorithm>
 
 #include "base/basictypes.h"
@@ skipping 89 matching lines @@
       it != input.end(); ++it) {
     if (!FilePath::IsSeparator(*it))
       return false;
   }
 
   return true;
 }
 
 // Find the position of the '.' that separates the extension from the rest
 // of the file name. The position is relative to BaseName(), not value().
-// This allows a second extension component of up to 4 characters when the
-// rightmost extension component is a common double extension (gz, bz2, Z).
-// For example, foo.tar.gz or foo.tar.Z would have extension components of
-// '.tar.gz' and '.tar.Z' respectively. Returns npos if it can't find an
-// extension.
-StringType::size_type ExtensionSeparatorPosition(const StringType& path) {
+// Returns npos if it can't find an extension.
+StringType::size_type FinalExtensionSeparatorPosition(const StringType& path) {
   // Special case "." and ".."
   if (path == FilePath::kCurrentDirectory || path == FilePath::kParentDirectory)
     return StringType::npos;
 
-  const StringType::size_type last_dot =
-      path.rfind(FilePath::kExtensionSeparator);
+  return path.rfind(FilePath::kExtensionSeparator);
+}
+
+// Same as above, but allow a second extension component of up to 4
+// characters when the rightmost extension component is a common double
+// extension (gz, bz2, Z).  For example, foo.tar.gz or foo.tar.Z would have
+// extension components of '.tar.gz' and '.tar.Z' respectively.
+StringType::size_type ExtensionSeparatorPosition(const StringType& path) {
+  const StringType::size_type last_dot = FinalExtensionSeparatorPosition(path);
 
   // No extension, or the extension is the whole filename.
   if (last_dot == StringType::npos || last_dot == 0U)
     return last_dot;
 
   const StringType::size_type penultimate_dot =
       path.rfind(FilePath::kExtensionSeparator, last_dot - 1);
   const StringType::size_type last_separator =
       path.find_last_of(FilePath::kSeparators, last_dot - 1,
                         FilePath::kSeparatorsLength - 1);
@@ skipping 231 matching lines @@
 
 StringType FilePath::Extension() const {
   FilePath base(BaseName());
   const StringType::size_type dot = ExtensionSeparatorPosition(base.path_);
   if (dot == StringType::npos)
     return StringType();
 
   return base.path_.substr(dot, StringType::npos);
 }
 
+StringType FilePath::FinalExtension() const {
+  FilePath base(BaseName());
+  const StringType::size_type dot = FinalExtensionSeparatorPosition(base.path_);
+  if (dot == StringType::npos)
+    return StringType();
+
+  return base.path_.substr(dot, StringType::npos);
+}
+
 FilePath FilePath::RemoveExtension() const {
   if (Extension().empty())
     return *this;
 
   const StringType::size_type dot = ExtensionSeparatorPosition(path_);
   if (dot == StringType::npos)
     return *this;
 
   return FilePath(path_.substr(0, dot));
 }
 
+FilePath FilePath::RemoveFinalExtension() const {
+  if (FinalExtension().empty())
+    return *this;
+
+  const StringType::size_type dot = FinalExtensionSeparatorPosition(path_);
+  if (dot == StringType::npos)
+    return *this;
+
+  return FilePath(path_.substr(0, dot));
+}
+
 FilePath FilePath::InsertBeforeExtension(const StringType& suffix) const {
   if (suffix.empty())
     return FilePath(path_);
 
   if (IsEmptyOrSpecialCase(BaseName().value()))
     return FilePath();
 
   StringType ext = Extension();
   StringType ret = RemoveExtension().value();
   ret.append(suffix);
@@ skipping 890 matching lines @@
 bool FilePath::IsContentUri() const {
   return StartsWithASCII(path_, "content://", false /*case_sensitive*/);
 }
 #endif
 
 }  // namespace base
 
 void PrintTo(const base::FilePath& path, std::ostream* out) {
   *out << path.value();
 }