Revert 42152 - 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

TBR=vandebo@chromium.org
Review URL: http://codereview.chromium.org/1145004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@42154 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 20 insertions, 30 deletions

diff --git a/net/base/upload_data_stream.cc b/net/base/upload_data_stream.cc
index 8c964f4..21f4ce8 100644
--- a/net/base/upload_data_stream.cc
+++ b/net/base/upload_data_stream.cc
@@ -10,7 +10,7 @@
 
 namespace net {
 
-UploadDataStream::UploadDataStream(UploadData* data)
+UploadDataStream::UploadDataStream(const UploadData* data)
     : data_(data),
       buf_(new IOBuffer(kBufSize)),
       buf_len_(0),
@@ -66,19 +66,18 @@ void UploadDataStream::FillBuf() {
     } else {
       DCHECK(element.type() == UploadData::TYPE_FILE);
 
-      if (element.file_range_length() == 0) {
-        // If we failed to open the file, then the length is set to zero. The
-        // length used when calculating the POST size was also zero. This
-        // matches the behaviour of Mozilla.
-        next_element_remaining_ = 0;
-      } else {
-        if (!next_element_stream_.IsOpen()) {
-          // We ignore the return value of Open becuase we've already checked
-          // !IsOpen, above.
-          int flags = base::PLATFORM_FILE_READ |
-                      base::PLATFORM_FILE_WRITE;
-          next_element_stream_.Open(element.platform_file(), flags);
-
+      if (!next_element_stream_.IsOpen()) {
+        int flags = base::PLATFORM_FILE_OPEN |
+                    base::PLATFORM_FILE_READ;
+        int rv = next_element_stream_.Open(element.file_path(), flags);
+        // If the file does not exist, that's technically okay.. we'll just
+        // upload an empty file.  This is for consistency with Mozilla.
+        DLOG_IF(WARNING, rv != OK) << "Failed to open \""
+                                   << element.file_path().value()
+                                   << "\" for reading: " << rv;
+
+        next_element_remaining_ = 0;  // Default to reading nothing.
+        if (rv == OK) {
           uint64 offset = element.file_range_offset();
           if (offset && next_element_stream_.Seek(FROM_BEGIN, offset) < 0) {
             DLOG(WARNING) << "Failed to seek \"" << element.file_path().value()
@@ -90,18 +89,11 @@ void UploadDataStream::FillBuf() {
       }
 
       int rv = 0;
-      if (next_element_remaining_ > 0) {
-        int count =
-            static_cast<int>(std::min(next_element_remaining_,
-                                      static_cast<uint64>(size_remaining)));
-        rv = next_element_stream_.Read(buf_->data() + buf_len_, count, NULL);
-        if (rv < 1) {
-          // If the file was truncated between the time that we opened it and
-          // now, or if we got an error on reading, then we pad with NULs.
-          memset(buf_->data() + buf_len_, 0, count);
-          rv = count;
-        }
-
+      int count = static_cast<int>(std::min(
+          static_cast<uint64>(size_remaining), next_element_remaining_));
+      if (count > 0 &&
+          (rv = next_element_stream_.Read(buf_->data() + buf_len_,
+                                          count, NULL)) > 0) {
         buf_len_ += rv;
         next_element_remaining_ -= rv;
       } else {
@@ -112,14 +104,12 @@ void UploadDataStream::FillBuf() {
     if (advance_to_next_element) {
       ++next_element_;
       next_element_offset_ = 0;
-      next_element_stream_.Release();
+      next_element_stream_.Close();
     }
   }
 
-  if (next_element_ == end && !buf_len_) {
+  if (next_element_ == end && !buf_len_)
     eof_ = true;
-    data_->CloseFiles();
-  }
 }
 
 }  // namespace net