User setup and erlang installation

A bit fiddly, but this lets us run a realistic erlang install script
from userspace, and then re-enter userspace later without wiping the
installation.

debian/create_environment

@@ -17,14 +17,6 @@ else
     ./get_debootstrap --arch i386 sid "$FRESH" http://deb.debian.org/debian/
 fi
 
-cleanup_mount() {
-    if mountpoint "$1" > /dev/null
-    then
-        echo "Unmounting $1"
-        umount "$1"
-    fi
-}
-
 if test -e "$ROOT"
 then
     echo "Existing installation found at $ROOT, removing."
@@ -35,8 +27,14 @@ echo "Copying $FRESH to $ROOT."
 cp -r "$FRESH" "$ROOT"
 
 echo "Initializing $ROOT."
-mkdir -p "$ROOT/proc"
-mount proc $ROOT/proc -t proc
-mkdir -p "$ROOT/sys"
-mount sysfs $ROOT/sys -t sysfs
 
+./mountpoints
+
+# Don't bother creating a new tmpfs. We don't want to leak files in, and we
+# don't want to waste more RAM on a second tmpfs. The whole thing is
+# temporary, after all.
+chmod 1777 "$ROOT/tmp"
+
+cp -r install_scripts "$ROOT/root"
+
+chroot "$ROOT" /root/install_scripts/user_setup "$@"

debian/destroy_environment

@@ -18,8 +18,10 @@ cleanup_mount() {
 
 if test -e "$ROOT"
 then
-    cleanup_mount "$ROOT/proc"
+    cleanup_mount "$ROOT/dev/pts"
+    cleanup_mount "$ROOT/dev"
     cleanup_mount "$ROOT/sys"
+    cleanup_mount "$ROOT/proc"
     echo "Removing $ROOT"
     rm -r "$ROOT"
 else

debian/enter_environment

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+if test `id -u` -ne 0
+then
+    echo "$0 must be run as root."
+    return
+fi
+
+ROOT=test_environment
+
+if test -e "$ROOT"
+then
+    echo "Using existing environment in $ROOT."
+else
+    ./create_environment
+fi
+
+./mountpoints
+
+chroot "$ROOT" sudo -iu user "$@"

debian/install_scripts/get_erlang_zx

@@ -0,0 +1,3 @@
+#!/bin/sh
+sudo apt install erlang-base
+wget -q https://zxq9.com/projects/zomp/get_zx && bash get_zx

debian/install_scripts/user_setup

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# Noninteractive, so that other scripts can install things with apt.
+export DEBIAN_FRONTEND=noninteractive
+
+# Overwrite locale setting specified before the chroot
+export LANG=C
+export LC_ALL=C
+
+# Install sudo, since most user-facing scripts will use sudo
+apt install sudo
+
+# Add a passwordless sudoer
+useradd -m -s /bin/bash -G sudo user
+passwd -d user
+echo "user ALL=(ALL) NOPASSWD:ALL" > "/etc/sudoers.d/user"
+chmod 0440 "/etc/sudoers.d/user"
+
+# Copy the install scripts into their home directory
+cp -r ~/install_scripts /home/user
+chown -R user:user /home/user/install_scripts
+
+# su to this new user... Or sudo -iu, since we want to pass in arguments too.
+cd /home/user
+sudo -iu user "$@"

debian/mountpoints

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+if test `id -u` -ne 0
+then
+    echo "$0 must be run as root."
+    return
+fi
+
+ROOT=test_environment
+
+check_mount() {
+    if mountpoint "$ROOT$1" > /dev/null
+    then
+        echo "$ROOT$1 already mounted."
+    else
+        mkdir -p "$ROOT$1"
+        mount -o bind "$1" "$ROOT$1"
+    fi
+}
+
+check_mount /proc
+check_mount /sys
+check_mount /dev
+check_mount /dev/pts
+