* Delete the chroot directory automatically.

* Removed some debug messages.
This commit is contained in:
Eelco Dolstra 2007-10-27 16:06:38 +00:00
parent 9397cd30c8
commit dc6f373842
5 changed files with 80 additions and 19 deletions

View file

@ -116,6 +116,9 @@
limited form of caching. This is used by
<command>nix-channel</command> to prevent unnecessary downloads when
the channel hasnt changed.</para></listitem>
<listitem><para>TODO: chroot support.</para></listitem>
</itemizedlist>

View file

@ -135,6 +135,44 @@
#build-users-group =
### Option `build-use-chroot'
#
# If set to `true', builds will be performed in a chroot environment,
# i.e., the build will be isolated from the normal file system
# hierarchy and will only see the Nix store, the temporary build
# directory, and the directories configured with the
# `build-chroot-dirs' option (such as /proc and /dev). This is useful
# to prevent undeclared dependencies on files in directories such as
# /usr/bin.
#
# The use of a chroot requires that Nix is run as root (but you can
# still use the "build users" feature to perform builds under
# different users than root). Currently, chroot builds only work on
# Linux because Nix uses "bind mounts" to make the Nix store and other
# directories available inside the chroot.
#
# The default is `false'.
#
# Example:
# build-use-chroot = true
#build-use-chroot = false
### Option `build-chroot-dirs'
#
# When builds are performed in a chroot environment, Nix will mount
# (using `mount --bind' on Linux) some directories from the normal
# file system hierarchy inside the chroot. These are the Nix store,
# the temporary build directory (usually /tmp/nix-<pid>-<number>) and
# the directories listed here. The default is "/dev /proc". Files
# in /dev (such as /dev/null) are needed by many builds, and some
# files in /proc may also be needed occasionally.
#
# Example:
# build-use-chroot = /dev /proc /bin
#build-chroot-dirs = /dev /proc
### Option `system'
#
# This option specifies the canonical Nix system name of the current

View file

@ -586,7 +586,8 @@ void deletePathWrapped(const Path & path)
#include <sys/mount.h>
/* Helper class for automatically unmounting bind-mounts in chroots. */
/* Helper RAII class for automatically unmounting bind-mounts in
chroots. */
struct BindMount
{
Path source, target;
@ -612,7 +613,7 @@ struct BindMount
void bind(const Path & source, const Path & target)
{
printMsg(lvlError, format("bind mounting `%1%' to `%2%'") % source % target);
debug(format("bind mounting `%1%' to `%2%'") % source % target);
this->source = source;
this->target = target;
@ -626,7 +627,8 @@ struct BindMount
void unbind()
{
if (source == "") return;
printMsg(lvlError, format("umount `%1%'") % target);
debug(format("unmount bind-mount `%1%'") % target);
/* Urgh. Unmount sometimes doesn't succeed right away because
the mount point is still busy. It shouldn't be, because
@ -644,16 +646,18 @@ struct BindMount
sleep(1);
}
else
throw SysError(format("unmounting `%1%' failed") % target);
throw SysError(format("unmounting bind-mount `%1%' failed") % target);
}
/* Get rid of the directories for the mount point created in
bind(). */
for (Paths::reverse_iterator i = created.rbegin(); i != created.rend(); ++i) {
printMsg(lvlError, format("delete `%1%'") % *i);
debug(format("deleting `%1%'") % *i);
if (remove(i->c_str()) == -1)
throw SysError(format("cannot unlink `%1%'") % *i);
}
source = "";
}
};
@ -704,11 +708,14 @@ private:
/* Whether we're currently doing a chroot build. */
bool useChroot;
/* A RAII object to delete the chroot directory. */
boost::shared_ptr<AutoDelete> autoDelChroot;
/* In chroot builds, the list of bind mounts currently active.
The destructor of BindMount will cause the binds to be
unmounted. */
list<boost::shared_ptr<BindMount> > bindMounts;
typedef void (DerivationGoal::*GoalState)();
GoalState state;
@ -797,18 +804,11 @@ DerivationGoal::~DerivationGoal()
/* Careful: we should never ever throw an exception from a
destructor. */
try {
printMsg(lvlError, "DESTROY");
killChild();
deleteTmpDir(false);
} catch (...) {
ignoreException();
}
try {
//sleep(1);
bindMounts.clear();
} catch (...) {
ignoreException();
}
}
@ -1646,7 +1646,27 @@ void DerivationGoal::startBuilder()
Path tmpRootDir;
if (useChroot) {
tmpRootDir = createTempDir();
/* Create a temporary directory in which we set up the chroot
environment using bind-mounts.
!!! Big danger here: since we're doing this in /tmp, there
is a risk that the admin does something like "rm -rf
/tmp/chroot-nix-*" to clean up aborted builds, and if some
of the bind-mounts are still active, then "rm -rf" will
happily recurse into those mount points (thereby deleting,
say, /nix/store). Ideally, tmpRootDir should be created in
some special location (maybe in /nix/var/nix) where Nix
takes care of unmounting / deleting old chroots
automatically. */
tmpRootDir = createTempDir("", "chroot-nix");
/* Clean up the chroot directory automatically, but don't
recurse; that would be very very bad if the unmount of a
bind-mount fails. Instead BindMount::unbind() unmounts and
deletes exactly those directories that it created to
produce the mount point, so that after all the BindMount
destructors have run, tmpRootDir should be empty. */
autoDelChroot = boost::shared_ptr<AutoDelete>(new AutoDelete(tmpRootDir, false));
printMsg(lvlChatty, format("setting up chroot environment in `%1%'") % tmpRootDir);

View file

@ -318,19 +318,19 @@ void makePathReadOnly(const Path & path)
}
static Path tempName(const Path & tmpRoot)
static Path tempName(const Path & tmpRoot, const Path & prefix)
{
static int counter = 0;
Path tmpRoot2 = canonPath(tmpRoot.empty() ? getEnv("TMPDIR", "/tmp") : tmpRoot, true);
return (format("%1%/nix-%2%-%3%") % tmpRoot2 % getpid() % counter++).str();
return (format("%1%/%2%-%3%-%4%") % tmpRoot2 % prefix % getpid() % counter++).str();
}
Path createTempDir(const Path & tmpRoot)
Path createTempDir(const Path & tmpRoot, const Path & prefix)
{
while (1) {
checkInterrupt();
Path tmpDir = tempName(tmpRoot);
Path tmpDir = tempName(tmpRoot, prefix);
if (mkdir(tmpDir.c_str(), 0777) == 0) {
/* Explicitly set the group of the directory. This is to
work around around problems caused by BSD's group

View file

@ -70,7 +70,7 @@ void deletePath(const Path & path, unsigned long long & bytesFreed);
void makePathReadOnly(const Path & path);
/* Create a temporary directory. */
Path createTempDir(const Path & tmpRoot = "");
Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix");
/* Create a directory and all its parents, if necessary. Returns the
list of created directories, in order of creation. */