Fix gst error handling#20801
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alalek merged 2 commits intoopencv:3.4from Oct 8, 2021
JonasVautherin:fix-gst-error-handling
Merged
Fix gst error handling#20801alalek merged 2 commits intoopencv:3.4from JonasVautherin:fix-gst-error-handling
alalek merged 2 commits intoopencv:3.4from
JonasVautherin:fix-gst-error-handling
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* Use the return value instead of the error, which gives no guarantee of being NULL in case of error * Test err pointer before accessing it * Remove unreachable code
JonasVautherin
commented
Oct 3, 2021
| GSafePtr<GError> err; | ||
| uridecodebin.attach(gst_parse_launch(filename, err.getRef())); | ||
| if (err) | ||
| if (!uridecodebin) |
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This is the actual bug: nothing guarantees that err will be NULL if gst_parse_launch fails. But uridecodebin will be NULL for sure in case of failure.
JonasVautherin
commented
Oct 3, 2021
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| if (manualpipeline) | ||
| { | ||
| if (err) |
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This code is at best unreachable (if we reach this line, it means that manualpipeline is true, and hence it means that gst_parse_launch above did not fail), and at worst it triggers an error because gst_parse_launch does not guarantee err to be NULL if it succeeds.
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Our "bad" tests are fails and hangs with that change.
alalek
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Oct 8, 2021
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Thank you 👍
To be merged without fix in writer.
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@alalek: similar to #20796. I think I have found a case where somebody had an issue with one of those bugs: https://stackoverflow.com/questions/61394756/how-to-use-opencv-videowriter-with-gstreamer 🙂
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Patch to opencv_extra has the same branch name.