Handle invalid CFStrings in GetHFSDecomposedForm()

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/logging.h"
@@ skipping 1174 matching lines @@
       return (codepoint1 < codepoint2) ? -1 : 1;
     if (codepoint1 == 0) {
       DCHECK_EQ(index1, length1);
       DCHECK_EQ(index2, length2);
       return 0;
     }
   }
 }
 
 StringType FilePath::GetHFSDecomposedForm(StringPieceType string) {
+  StringType result;
   ScopedCFTypeRef<CFStringRef> cfstring(
       CFStringCreateWithBytesNoCopy(
           NULL,
           reinterpret_cast<const UInt8*>(string.data()),
           string.length(),
           kCFStringEncodingUTF8,
           false,
           kCFAllocatorNull));
-  // Query the maximum length needed to store the result. In most cases this
-  // will overestimate the required space. The return value also already
-  // includes the space needed for a terminating 0.
-  CFIndex length = CFStringGetMaximumSizeOfFileSystemRepresentation(cfstring);
-  DCHECK_GT(length, 0);  // should be at least 1 for the 0-terminator.
-  // Reserve enough space for CFStringGetFileSystemRepresentation to write into.
-  // Also set the length to the maximum so that we can shrink it later.
-  // (Increasing rather than decreasing it would clobber the string contents!)
-  StringType result;
-  result.reserve(length);
-  result.resize(length - 1);
-  Boolean success = CFStringGetFileSystemRepresentation(cfstring,
-                                                        &result[0],
-                                                        length);
-  if (success) {
-    // Reduce result.length() to actual string length.
-    result.resize(strlen(result.c_str()));
-  } else {
-    // An error occurred -> clear result.
-    result.clear();
+  if (cfstring) {
+    // Query the maximum length needed to store the result. In most cases this
+    // will overestimate the required space. The return value also already
+    // includes the space needed for a terminating 0.
+    CFIndex length = CFStringGetMaximumSizeOfFileSystemRepresentation(cfstring);
+    DCHECK_GT(length, 0);  // should be at least 1 for the 0-terminator.
+    // Reserve enough space for CFStringGetFileSystemRepresentation to write
+    // into. Also set the length to the maximum so that we can shrink it later.
+    // (Increasing rather than decreasing it would clobber the string contents!)
+    result.reserve(length);
+    result.resize(length - 1);
+    Boolean success = CFStringGetFileSystemRepresentation(cfstring,
+                                                          &result[0],
+                                                          length);
+    if (success) {
+      // Reduce result.length() to actual string length.
+      result.resize(strlen(result.c_str()));
+    } else {
+      // An error occurred -> clear result.
+      result.clear();
+    }
   }
   return result;
 }
 
 int FilePath::CompareIgnoreCase(StringPieceType string1,
                                 StringPieceType string2) {
   // Quick checks for empty strings - these speed things up a bit and make the
   // following code cleaner.
   if (string1.empty())
     return string2.empty() ? 0 : -1;
@@ skipping 88 matching lines @@
 #endif
 }
 
 #if defined(OS_ANDROID)
 bool FilePath::IsContentUri() const {
   return StartsWith(path_, "content://", base::CompareCase::INSENSITIVE_ASCII);
 }
 #endif
 
 }  // namespace base