mercurial/dummycert.pem

worker: avoid potential partial write of pickled data

Previously, the code wrote the pickled data using os.write(). However,
os.write() can write less bytes than passed to it. To trigger the problem, the
pickled data had to be larger than 2147479552 bytes on my system.

Instead, open a file object and pass it to pickle.dump(). This also has the
advantage that it doesn’t buffer the whole pickled data in memory.

Note that the opened file must be buffered because pickle doesn’t support
unbuffered streams because unbuffered streams’ write() method might write less
bytes than passed to it (like os.write()) but pickle.dump() relies on that all
bytes are written (see https://github.com/python/cpython/issues/93050).

The side effect of using a file object and a with statement is that wfd is
explicitly closed now while it seems like before it was implicitly closed by
process exit.

A dummy certificate that will make OS X 10.6+ Python use the system CA
certificate store:

-----BEGIN CERTIFICATE-----
MIIBIzCBzgIJANjmj39sb3FmMA0GCSqGSIb3DQEBBQUAMBkxFzAVBgNVBAMTDmhn
LmV4YW1wbGUuY29tMB4XDTE0MDgzMDA4NDU1OVoXDTE0MDgyOTA4NDU1OVowGTEX
MBUGA1UEAxMOaGcuZXhhbXBsZS5jb20wXDANBgkqhkiG9w0BAQEFAANLADBIAkEA
mh/ZySGlcq0ALNLmA1gZqt61HruywPrRk6WyrLJRgt+X7OP9FFlEfl2tzHfzqvmK
CtSQoPINWOdAJMekBYFgKQIDAQABMA0GCSqGSIb3DQEBBQUAA0EAF9h49LkSqJ6a
IlpogZuUHtihXeKZBsiktVIDlDccYsNy0RSh9XxUfhk+XMLw8jBlYvcltSXdJ7We
aKdQRekuMQ==
-----END CERTIFICATE-----

This certificate was generated to be syntactically valid but never be usable;
it expired before it became valid.

Created as:

  $ cat > cn.conf << EOT
  > [req]
  > distinguished_name = req_distinguished_name
  > [req_distinguished_name]
  > commonName = Common Name
  > commonName_default = no.example.com
  > EOT
  $ openssl req -nodes -new -x509 -keyout /dev/null \
  >   -out dummycert.pem -days -1 -config cn.conf -subj '/CN=hg.example.com'

To verify the content of this certificate:

  $ openssl x509 -in dummycert.pem -noout -text
  Certificate:
      Data:
          Version: 1 (0x0)
          Serial Number: 15629337334278746470 (0xd8e68f7f6c6f7166)
      Signature Algorithm: sha1WithRSAEncryption
          Issuer: CN=hg.example.com
          Validity
              Not Before: Aug 30 08:45:59 2014 GMT
              Not After : Aug 29 08:45:59 2014 GMT
          Subject: CN=hg.example.com
          Subject Public Key Info:
              Public Key Algorithm: rsaEncryption
                  Public-Key: (512 bit)
                  Modulus:
                      00:9a:1f:d9:c9:21:a5:72:ad:00:2c:d2:e6:03:58:
                      19:aa:de:b5:1e:bb:b2:c0:fa:d1:93:a5:b2:ac:b2:
                      51:82:df:97:ec:e3:fd:14:59:44:7e:5d:ad:cc:77:
                      f3:aa:f9:8a:0a:d4:90:a0:f2:0d:58:e7:40:24:c7:
                      a4:05:81:60:29
                  Exponent: 65537 (0x10001)
      Signature Algorithm: sha1WithRSAEncryption
           17:d8:78:f4:b9:12:a8:9e:9a:22:5a:68:81:9b:94:1e:d8:a1:
           5d:e2:99:06:c8:a4:b5:52:03:94:37:1c:62:c3:72:d1:14:a1:
           f5:7c:54:7e:19:3e:5c:c2:f0:f2:30:65:62:f7:25:b5:25:dd:
           27:b5:9e:68:a7:50:45:e9:2e:31