Don't allow '\0' characters in FilePath.

base/file_path.cc

Index: base/file_path.cc
diff --git a/base/file_path.cc b/base/file_path.cc
index 094c699587d36bd83cb509d5b82e7c5383667d04..ec59ff1e5a020dcf1f5dfb326f1a281f71b19872 100644
--- a/base/file_path.cc
+++ b/base/file_path.cc
@@ -40,6 +40,8 @@ const FilePath::CharType FilePath::kParentDirectory[] = FILE_PATH_LITERAL("..");
 
 const FilePath::CharType FilePath::kExtensionSeparator = FILE_PATH_LITERAL('.');
 
+const FilePath::CharType kStringTerminator = FILE_PATH_LITERAL('\0');
+

[Tom Sepez, 2012/12/20 21:14:34]

Should be in namespace { below.

 typedef FilePath::StringType StringType;
 
 namespace {
@@ -182,6 +184,10 @@ FilePath::FilePath(const FilePath& that) : path_(that.path_) {
 }
 
 FilePath::FilePath(const StringType& path) : path_(path) {
+  // Don't allow '\0' characters in path.

[Tom Sepez, 2012/12/20 21:14:34]

nit: not sure we need this comment. Maybe just add a note to file_path.h that
paths can't contain NULs as a precaution against OS usage.

+  StringType::size_type zero_pos = path_.find(kStringTerminator);
+  if (zero_pos != StringType::npos)
+    path_.erase(zero_pos);

[Tom Sepez, 2012/12/20 21:14:34]

nit: maybe write
   path_.erase(zero_pos, StringType::npos)
to make it clearer?

 }
 
 FilePath::~FilePath() {
@@ -454,7 +460,15 @@ bool FilePath::MatchesExtension(const StringType& extension) const {
 }
 
 FilePath FilePath::Append(const StringType& component) const {
-  DCHECK(!IsPathAbsolute(component));
+  StringType appended(component);

[Tom Sepez, 2012/12/20 21:14:34]

Would be nice to avoid the copy if the NULs not found.

+
+  // Don't allow '\0' characters to be appended.
+  StringType::size_type zero_pos = appended.find(kStringTerminator);
+  if (zero_pos != StringType::npos)
+    appended.erase(zero_pos);
+
+  DCHECK(!IsPathAbsolute(appended));
+
   if (path_.compare(kCurrentDirectory) == 0) {
     // Append normally doesn't do any normalization, but as a special case,
     // when appending to kCurrentDirectory, just return a new path for the
@@ -463,7 +477,7 @@ FilePath FilePath::Append(const StringType& component) const {
     // it's likely in practice to wind up with FilePath objects containing
     // only kCurrentDirectory when calling DirName on a single relative path
     // component.
-    return FilePath(component);
+    return FilePath(appended);
   }
 
   FilePath new_path(path_);
@@ -472,7 +486,7 @@ FilePath FilePath::Append(const StringType& component) const {
   // Don't append a separator if the path is empty (indicating the current
   // directory) or if the path component is empty (indicating nothing to
   // append).
-  if (component.length() > 0 && new_path.path_.length() > 0) {
+  if (appended.length() > 0 && new_path.path_.length() > 0) {
     // Don't append a separator if the path still ends with a trailing
     // separator after stripping (indicating the root directory).
     if (!IsSeparator(new_path.path_[new_path.path_.length() - 1])) {
@@ -483,7 +497,7 @@ FilePath FilePath::Append(const StringType& component) const {
     }
   }
 
-  new_path.path_.append(component);
+  new_path.path_.append(appended);
   return new_path;
 }