asf: fix GUID reading on big endian platforms #2694
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Setting the initial parts (data1_, data2_, data3_) from the bytes directly using memcpy() means that they will be interpreted depending on the platform endianness. For example, the initial 4 bytes of the ASF header are 0x30, 0x26, 0xB2, 0x75, which will be read as 0x3026B275 on big endian platforms, never matching the actual GUID (0x75B22630), which is always specified in little endian format. Hence, when reading a GUID from data, make sure to turn the GUID parts to little endian. This fixes the reading of ASF files on big endian platforms. Fixes commit bed8d3d
Codecov Report
@@ Coverage Diff @@
## main #2694 +/- ##
==========================================
- Coverage 63.91% 63.89% -0.02%
==========================================
Files 103 103
Lines 22314 22318 +4
Branches 10800 10801 +1
==========================================
Hits 14261 14261
- Misses 5828 5831 +3
- Partials 2225 2226 +1
|
|
sounds like this fixes #2597 can you confirm? |
neheb
reviewed
Jul 16, 2023
| @@ -55,6 +55,11 @@ AsfVideo::GUIDTag::GUIDTag(const uint8_t* bytes) { | |||
| memcpy(&data2_, bytes + DWORD, WORD); | |||
| memcpy(&data3_, bytes + DWORD + WORD, WORD); | |||
| std::copy(bytes + QWORD, bytes + 2 * QWORD, data4_.begin()); | |||
| if (isBigEndianPlatform()) { | |||
There was a problem hiding this comment.
In other places where I've seen this pattern, a variable gets set to isBigEndianPlatform() and byteSwap gets called as:
data1_ = byteSwap(data1_, bSwap);
data2_ = byteSwap(data2_, bSwap);
data3_ = byteSwap(data3_, bSwap);
|
It does fix the linked issue. Just tested. |
I don't have a big-endian 64bit mips system, however the fix worked fine on a s390x system. |
neheb
approved these changes
Jul 17, 2023
|
@Mergifyio backport 0.28.x |
✅ Backports have been created
|
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Setting the initial parts (
data1_,data2_,data3_) from the bytes directly usingmemcpy()means that they will be interpreted depending on the platform endianness. For example, the initial 4 bytes of the ASF header are0x30,0x26,0xB2,0x75, which will be read as0x3026B275on big endian platofrms, never matching the actual GUID (0x75B22630), which is always specified in little endian format.Hence, when reading a GUID from data, make sure to turn the GUID parts to little endian. This fixes the reading of ASF files on big endian platforms.
Fixes commit bed8d3d