Fix the case where the browser livelocks if we cannot open a file.

If one tries to upload a file that one doesn't have read access to,
the browser livelocks. It tries to read from the file, gets nothing
but spins forever because it knows that it hasn't finished reading.

To address this, firstly we add a check at stat() time to make sure
that we can read the file. However, this doesn't take care of the case
where the access() call was incorrect, or the permissions have changed
under us. In this case, we replace the missing file with NULs.

BUG=30850

Review URL: http://codereview.chromium.org/541022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@42152 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 8 deletions

diff --git a/net/base/file_stream_posix.cc b/net/base/file_stream_posix.cc
index a4c5b3c..e947a6e 100644
--- a/net/base/file_stream_posix.cc
+++ b/net/base/file_stream_posix.cc
@@ -298,13 +298,8 @@ FileStream::FileStream()
 }
 
 FileStream::FileStream(base::PlatformFile file, int flags)
-    : file_(file),
-      open_flags_(flags) {
-  // If the file handle is opened with base::PLATFORM_FILE_ASYNC, we need to
-  // make sure we will perform asynchronous File IO to it.
-  if (flags & base::PLATFORM_FILE_ASYNC) {
-    async_context_.reset(new AsyncContext());
-  }
+    : file_(base::kInvalidPlatformFileValue) {
+  Open(file, flags);
 }
 
 FileStream::~FileStream() {
@@ -323,6 +318,12 @@ void FileStream::Close() {
   }
 }
 
+void FileStream::Release() {
+  // Abort any existing asynchronous operations.
+  async_context_.reset();
+  file_ = base::kInvalidPlatformFileValue;
+}
+
 int FileStream::Open(const FilePath& path, int open_flags) {
   if (IsOpen()) {
     DLOG(FATAL) << "File is already open!";
@@ -344,6 +345,21 @@ int FileStream::Open(const FilePath& path, int open_flags) {
   return OK;
 }
 
+int FileStream::Open(base::PlatformFile file, int open_flags) {
+  if (IsOpen()) {
+    DLOG(FATAL) << "File is already open!";
+    return ERR_UNEXPECTED;
+  }
+
+  open_flags_ = open_flags;
+  file_ = file;
+
+  if (open_flags & base::PLATFORM_FILE_ASYNC)
+    async_context_.reset(new AsyncContext());
+
+  return OK;
+}
+
 bool FileStream::IsOpen() const {
   return file_ != base::kInvalidPlatformFileValue;
 }
@@ -445,7 +461,7 @@ int64 FileStream::Truncate(int64 bytes) {
   if (!IsOpen())
     return ERR_UNEXPECTED;
 
-  // We better be open for reading.
+  // We better be open for writing.
   DCHECK(open_flags_ & base::PLATFORM_FILE_WRITE);
 
   // Seek to the position to truncate from.