make_chroot: clobber existing /etc/mtab

If our sdk has an /etc/mtab file already, then clobber it.  This fixes
build problems where chromeos-base now installs /etc/mtab for us, but
the sdk build isn't expecting it leading to the error:

INFO    cros_sdk:make_chroot: Running init_setup()...
ln: creating symbolic link `/b/cbuild/new-sdk-chroot/etc/mtab': File exists
Running ['/b/cbuild/src/scripts/sdk_lib/make_chroot.sh', '--stage3_path',
	'/b/cbuild/built-sdk.tar.xz', '--chroot', '/b/cbuild/new-sdk-chroot',
	'--cache_dir', '/b/cbuild/.cache', '--nousepkg'] failed!

BUG=None
TEST=`cros_sdk --chroot foo` still works

Change-Id: I539cf329e93e28534e6ff00577ce415d76918b85
Reviewed-on: https://gerrit.chromium.org/gerrit/43641
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Remove a warning when $HOME is on NFS

If ~/.subversion doesn't exist, the code didn't run, but if it existed
there is no reason to re-create it, nor is it necessary to change its
permissions since they are inherited by the bind mount source.
However user_mkdir was trying to run chown as root which does not work
over NFS with root_squash or krb-nfs.
Therefore, the un-needed call to user_mkdir is removed.
(this is an issue because cros_sdk  --replace does call this code path
multiple times).

BUG=None
TEST=Built the chroot, and the permission denied on 'install' went away.
Change-Id: I01e9a7baf51a99a96d790c9613e26e652379e6df
Reviewed-on: https://gerrit.chromium.org/gerrit/44880
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Marc MERLIN <merlin@chromium.org>
Tested-by: Marc MERLIN <merlin@chromium.org>
Fix 'too many levels of symbolic links' error.

In an Ubuntu Precise chroot on the Chromebook Pixel, /run/shm is a
symbolic link to /dev/shm, so bind-mounting /run/shm to /dev/shm
is really bind-mounting /dev/shm to itself, which causes a 'too many
levels of symbolic links' error. To fix this, we check for a symbolic
link prior to running this command.

BUG=none
TEST=cros_sdk no longer prints errors on Chromebook Pixel
Change-Id: Ib46cde2b4a0e00b69bd187488967e445b228ae80
Reviewed-on: https://gerrit.chromium.org/gerrit/45048
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
Add capability to chroot to use proxies for git:// urls

This patch installs "socat" and a proxy gateway script into
the chroot so that git can use a proxy to access "git://"
protocol urls.  This is needed when performing builds from
behind a firewall that requires a proxy.  The script reads
the proxy environment variables all_proxy (SOCKS),
https_proxy (CONNECT), and http_proxy (CONNECT), in order of
preference, and supports no_proxy as a whitelist of target
hosts that must NOT go through the proxy.

This also updates enter_chroot.sh to automatically use this
script as GIT_PROXY_COMMAND when it sees the proxy
environment variables set.

The "socat" program is added to hard-host-depends as a
separate patch.  That handles socat installation in case of
building a chroot from scratch or upgrading.

The proxy-gw script is installed in the src/scripts/bin
directory which can be stably referenced within the chroot
as /mnt/host/source/src/scripts/bin/.  The
"/mnt/host/source" portion of this path is obtained from the
CHROOT_TRUNK_DIR environment variable which is set to a
suitable value by preexisting logic in common.sh.

This change became necessary to unbreak builds behind
proxies with the recent addition of two ebuilds using
egit.eclass with repositories using git:// URLs.

Original patch by Paul Drews <paul.drews@intel.com>;
modified version by Josh Triplett <josh@joshtriplett.org>.

CQ-DEPENDS=I1b01bce6f3e6a562b87f748e61508d142af576d9
BUG=none
TEST=git clone git://nv-tegra.nvidia.com/tools/cbootimage.git

Change-Id: Ic7fc917d1aa24f408bef6f102b6458114dded694
Reviewed-on: https://gerrit.chromium.org/gerrit/41659
Tested-by: paul drews <paul.drews@intel.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: paul drews <paul.drews@intel.com>
enter_chroot: handle /var/lock->/run/lock symlinks

Newer Gentoo builds have moved to /run which means /var/lock is a symlink
to /run/lock.  But since that is an absolute symlink, it points outside of
the chroot which doesn't work for us.  Use a stable path unrelated to the
chroot instead, but only with newer chroots.

We no longer have to worry about backwards compat because the code that
used to rely on this lock file (running sync processes) was punted a long
time ago.

BUG=chromium:218085
TEST=`cbuildbot chromiumos-sdk` passes

Change-Id: I38c6848dfb86386849050d7ccf3f90cbbe8e0e81
Reviewed-on: https://gerrit.chromium.org/gerrit/46231
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Use rbind for ChromeOS source directory

I use a mount at src/build/images to stop image builds from repeatedly
filling up my SSD. The chroot needs to respect this.

TEST=cros_sdk
BUG=none

Change-Id: I5c7a26c3b4f263bd683d3a897e6edccb83187bda
Reviewed-on: https://gerrit.chromium.org/gerrit/47178
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Tested-by: Michael Spang <spang@chromium.org>
enter_chroot: bind mount /dev/pts

All devpts mounts are actually shared, even if you do:
	mount -t devpts none /dev/pts
	mount -t devpts none /mnt/foo
	mount -t devpts none /mnt/asdfasdf
These all provide the same data.

This is problematic because most distros mount their host devpts like so:
	mount -t devpts devpts /dev/pts -o mode=620,gid=5

But when cros_sdk runs, it uses:
	mount -t devpts none /dev/pts

We aren't specifying a mode/gid, so it ends up using the defaults, and
this resets the host devpts mount as well.

Since we've already assumed that the system has devpts available, it's
fine to also assume that the system has it mounted at /dev/pts and we
can simply bind mount it.

BUG=None
TEST=`cros_sdk` no longer messes up host perms on /dev/pts

Change-Id: Ib594fc5e47707f296d97ac1edce32659ed2b2273
Reviewed-on: https://gerrit.chromium.org/gerrit/48018
Reviewed-by: Steev Klimaszewski <threeway@gmail.com>
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
enter_chroot: speed up entering by backgrounding locale generation

Half of the current time is spent on calling locale-gen even when there is
nothing to be done (all locales already generated).  Throw it into the bg
to unblock the main thread.

BUG=None
TEST=`cros_sdk` still works
TEST=`LANG=et_EE.UTF-8 cros_sdk` generates the new locale in the background

Change-Id: Ibe9a07bec60a59cab1cf4230358f7f8ff5b21c2e
Reviewed-on: https://gerrit.chromium.org/gerrit/58041
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Merge pull request #33 from marineam/sdk-mounts

SDK script updates