annotate mercurial/helptext/urls.txt @ 45095:8e04607023e5

procutil: ensure that procutil.std{out,err}.write() writes all bytes

Python 3 offers different kind of streams and it’s not guaranteed for all of
them that calling write() writes all bytes.

When Python is started in unbuffered mode, sys.std{out,err}.buffer are
instances of io.FileIO, whose write() can write less bytes for
platform-specific reasons (e.g. Linux has a 0x7ffff000 bytes maximum and could
write less if interrupted by a signal; when writing to Windows consoles, it’s
limited to 32767 bytes to avoid the "not enough space" error). This can lead to
silent loss of data, both when using sys.std{out,err}.buffer (which may in fact
not be a buffered stream) and when using the text streams sys.std{out,err}
(I’ve created a CPython bug report for that:
https://bugs.python.org/issue41221).

Python may fix the problem at some point. For now, we implement our own wrapper
for procutil.std{out,err} that calls the raw stream’s write() method until all
bytes have been written. We don’t use sys.std{out,err} for larger writes, so I
think it’s not worth the effort to patch them.

Valid URLs are of the form::

  local/filesystem/path[#revision]
  file://local/filesystem/path[#revision]
  http://[user[:pass]@]host[:port]/[path][#revision]
  https://[user[:pass]@]host[:port]/[path][#revision]
  ssh://[user@]host[:port]/[path][#revision]

Paths in the local filesystem can either point to Mercurial
repositories or to bundle files (as created by :hg:`bundle` or
:hg:`incoming --bundle`). See also :hg:`help paths`.

An optional identifier after # indicates a particular branch, tag, or
changeset to use from the remote repository. See also :hg:`help
revisions`.

Some features, such as pushing to http:// and https:// URLs are only
possible if the feature is explicitly enabled on the remote Mercurial
server.

Note that the security of HTTPS URLs depends on proper configuration of
web.cacerts.

Some notes about using SSH with Mercurial:

- SSH requires an accessible shell account on the destination machine
  and a copy of hg in the remote path or specified with remotecmd.
- path is relative to the remote user's home directory by default. Use
  an extra slash at the start of a path to specify an absolute path::

    ssh://example.com//tmp/repository

- Mercurial doesn't use its own compression via SSH; the right thing
  to do is to configure it in your ~/.ssh/config, e.g.::

    Host *.mylocalnetwork.example.com
      Compression no
    Host *
      Compression yes

  Alternatively specify "ssh -C" as your ssh command in your
  configuration file or with the --ssh command line option.

These URLs can all be stored in your configuration file with path
aliases under the [paths] section like so::

  [paths]
  alias1 = URL1
  alias2 = URL2
  ...

You can then use the alias for any command that uses a URL (for
example :hg:`pull alias1` will be treated as :hg:`pull URL1`).

Two path aliases are special because they are used as defaults when
you do not provide the URL to a command:

default:
  When you create a repository with hg clone, the clone command saves
  the location of the source repository as the new repository's
  'default' path. This is then used when you omit path from push- and
  pull-like commands (including incoming and outgoing).

default-push:
  The push command will look for a path named 'default-push', and
  prefer it over 'default' if both are defined.