From cd5164d38dae8e3990295754bfc736135086c2af Mon Sep 17 00:00:00 2001
From: JW Wang <jwwang@mozilla.com>
Date: Thu, 2 Nov 2017 14:26:24 +0800
Subject: [PATCH] Bug 1415766. P1 - we never pass anything other than
 NS_SEEK_SET to Seek(). r=bechen,gerald

MozReview-Commit-ID: AgvapCwwSpr

--HG--
extra : rebase_source : 2ba05b44f228c3d9a9440202c024abbd5487282f
extra : intermediate-source : f2ec0fec7c544171e7567beed322349dfb8e59a8
extra : source : 8e34a87b250f800897a761d2ccd408959007d02b
---
 dom/media/MediaCache.cpp | 30 +++++-------------------------
 dom/media/MediaCache.h   |  4 +---
 2 files changed, 6 insertions(+), 28 deletions(-)

diff --git a/dom/media/MediaCache.cpp b/dom/media/MediaCache.cpp
index d1a7e9f4679e..7e027a3628a8 100644
--- a/dom/media/MediaCache.cpp
+++ b/dom/media/MediaCache.cpp
@@ -25,7 +25,6 @@
 #include "nsContentUtils.h"
 #include "nsIObserverService.h"
 #include "nsIPrincipal.h"
-#include "nsISeekableStream.h"
 #include "nsPrintfCString.h"
 #include "nsProxyRelease.h"
 #include "nsThreadUtils.h"
@@ -2414,41 +2413,22 @@ MediaCacheStream::SetPlaybackRate(uint32_t aBytesPerSecond)
 }
 
 nsresult
-MediaCacheStream::Seek(int32_t aWhence, int64_t aOffset)
+MediaCacheStream::Seek(int64_t aOffset)
 {
   NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
 
   ReentrantMonitorAutoEnter mon(mMediaCache->GetReentrantMonitor());
-  if (mClosed)
-    return NS_ERROR_FAILURE;
-
-  int64_t oldOffset = mStreamOffset;
-  int64_t newOffset = mStreamOffset;
-  switch (aWhence) {
-  case PR_SEEK_END:
-    if (mStreamLength < 0)
-      return NS_ERROR_FAILURE;
-    newOffset = mStreamLength + aOffset;
-    break;
-  case PR_SEEK_CUR:
-    newOffset += aOffset;
-    break;
-  case PR_SEEK_SET:
-    newOffset = aOffset;
-    break;
-  default:
-    NS_ERROR("Unknown whence");
+  if (mClosed) {
     return NS_ERROR_FAILURE;
   }
-
+  int64_t oldOffset = mStreamOffset;
+  int64_t newOffset = aOffset;
   if (!IsOffsetAllowed(newOffset)) {
     return NS_ERROR_FAILURE;
   }
   mStreamOffset = newOffset;
-
   LOG("Stream %p Seek to %" PRId64, this, mStreamOffset);
   mMediaCache->NoteSeek(this, oldOffset);
-
   mMediaCache->QueueUpdate();
   return NS_OK;
 }
@@ -2669,7 +2649,7 @@ MediaCacheStream::ReadAt(int64_t aOffset, char* aBuffer,
   NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
 
   ReentrantMonitorAutoEnter mon(mMediaCache->GetReentrantMonitor());
-  nsresult rv = Seek(nsISeekableStream::NS_SEEK_SET, aOffset);
+  nsresult rv = Seek(aOffset);
   if (NS_FAILED(rv)) return rv;
   return Read(aBuffer, aCount, aBytes);
 }
diff --git a/dom/media/MediaCache.h b/dom/media/MediaCache.h
index 7d830ce42c31..68d8d1ecf462 100644
--- a/dom/media/MediaCache.h
+++ b/dom/media/MediaCache.h
@@ -339,9 +339,7 @@ public:
   // These methods must be called on a different thread from the main
   // thread. They should always be called on the same thread for a given
   // stream.
-  // This can fail when aWhence is NS_SEEK_END and no stream length
-  // is known.
-  nsresult Seek(int32_t aWhence, int64_t aOffset);
+  nsresult Seek(int64_t aOffset);
   int64_t Tell();
   // *aBytes gets the number of bytes that were actually read. This can
   // be less than aCount. If the first byte of data is not in the cache,