procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
Generate a private key (priv.pem):
$ openssl genrsa -out priv.pem 2048
Generate 2 self-signed certificates from this key (pub.pem, pub-other.pem):
$ openssl req -new -x509 -key priv.pem -nodes -sha256 -days 9000 \
-out pub.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'
$ openssl req -new -x509 -key priv.pem -nodes -sha256 -days 9000 \
-out pub-other.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'
Now generate an expired certificate by turning back the system time:
$ faketime 2016-01-01T00:00:00Z \
openssl req -new -x509 -key priv.pem -nodes -sha256 -days 1 \
-out pub-expired.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'
Generate a certificate not yet active by advancing the system time:
$ faketime 2030-01-1T00:00:00Z \
openssl req -new -x509 -key priv.pem -nodes -sha256 -days 1 \
-out pub-not-yet.pem -batch -subj '/CN=localhost/emailAddress=hg@localhost/'
Generate a passphrase protected client certificate private key:
$ openssl genrsa -aes256 -passout pass:1234 -out client-key.pem 2048
Create a copy of the private key without a passphrase:
$ openssl rsa -in client-key.pem -passin pass:1234 -out client-key-decrypted.pem
Create a CSR and sign the key using the server keypair:
$ printf '.\n.\n.\n.\n.\n.\nhg-client@localhost\n.\n.\n' | \
openssl req -new -key client-key.pem -passin pass:1234 -out client-csr.pem
$ openssl x509 -req -days 9000 -in client-csr.pem -CA pub.pem -CAkey priv.pem \
-set_serial 01 -out client-cert.pem
When replacing the certificates, references to certificate fingerprints will
need to be updated in test files.
Fingerprints for certs can be obtained by running:
$ openssl x509 -in pub.pem -noout -sha1 -fingerprint
$ openssl x509 -in pub.pem -noout -sha256 -fingerprint