build-fhs-{chroot,user}env: expose sockets in /tmp

pkgs/build-support/build-fhs-chrootenv/init.sh.in

@@ -3,7 +3,7 @@
 chrootenvDest=/run/chrootenv/@name@
 
 # Create some mount points for stuff that must be bind mounted
-mkdir -p $chrootenvDest/{nix/store,dev,proc,sys,host-etc,home,var,run}
+mkdir -p $chrootenvDest/{nix/store,dev,proc,sys,host-etc,host-tmp,home,var,run}
 
 # Symlink the software that should be part of the chroot system profile
 for i in @chrootEnv@/*

pkgs/build-support/build-fhs-chrootenv/mount.sh.in

@@ -22,5 +22,13 @@ mount --rbind /run $chrootenvDest/run
 # Bind mount the host system's /etc
 mount --bind /etc $chrootenvDest/host-etc
 
+# Bind mount the host system's /tmp
+mount --bind /tmp $chrootenvDest/host-tmp
+
 # Bind mount /tmp
 mount --bind /tmp/chrootenv-@name@ $chrootenvDest/tmp
+
+# Expose sockets in /tmp
+for i in /tmp/.*-unix; do
+  ln -s "/host-tmp/$(basename "$i")" "$chrootenvDest/$i"
+done

pkgs/build-support/build-fhs-chrootenv/umount.sh.in

@@ -3,4 +3,4 @@
 chrootenvDest=/run/chrootenv/@name@
 
 # Unmount all (r)bind mounts
-umount -l $chrootenvDest/{dev/pts,dev/shm,dev,nix/store,proc,sys,host-etc,home,var,tmp,run}
+umount -l $chrootenvDest/{dev/pts,dev/shm,dev,nix/store,proc,sys,host-etc,host-tmp,home,var,tmp,run}

pkgs/build-support/build-fhs-userenv/chroot-user.rb

@@ -7,6 +7,7 @@ mounts = [ ['/nix/store', nil],
            ['/proc', nil],
            ['/sys', nil],
            ['/etc', 'host-etc'],
+           ['/tmp', 'host-tmp'],
            ['/home', nil],
            ['/var', nil],
            ['/run', nil],

pkgs/build-support/build-fhs-userenv/default.nix

@@ -10,6 +10,11 @@ let
   '';
 
   init = writeText "init" ''
+           # Expose sockets in /tmp
+           for i in /host-tmp/.*-unix; do
+             ln -s "$i" "/tmp/$(basename "$i")"
+           done
+
            [ -d "$1" ] && [ -r "$1" ] && cd "$1"
            shift
            exec "${runScript}" "$@"