fix: BIO_set_retry_write when BIO_CTRL_FLUSH to allow writer returns WouldBlock on flush#118
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kornelski merged 1 commit intocloudflare:masterfrom Jan 20, 2026
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…WouldBlock on flush
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Does this require upstream boringssl to fix the status too? openssl/openssl@bcbc7d6 |
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No. You can try if the test can pass. |
kornelski
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Jan 20, 2026
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A fix for rust-openssl can be found at rust-openssl/rust-openssl#1922
This PR fixes a BIO_flush related issue. According to openssl doc(link):
BIO_flush(), because it can write data may return 0 or -1 indicating that the call should be retried later in a similar manner to BIO_write(). The BIO_should_retry() call should be used and appropriate action taken is the call fails.
We have to call BIO_set_retry_write on retriable_error like WouldBlock. Otherwise, when the flush returns WouldBlock, it will fail.
Since we usually wrap openssl with a TcpStream, there is no buffer inside and flush always returns Ok(()), this issue is not obvious. However, if users use a buffered io, the flush support will be essential.