Flesh out tool/zsh/mkofs

It now prevents double-mounting.

Also adds vim filetype modelines.

tool/zsh/mkofs

@@ -1 +1,24 @@
-sudo mount -t tmpfs -o size=10G,noatime,nodiratime /dev/shm ${COSMO:-$PWD}/o
+[[ -f /proc/mounts ]] || {
+  echo "mkofs: only supported on linux" >&2
+  return 1
+}
+local o
+if [[ -d "$PWD/o" ]]; then
+  o=$PWD/o
+elif [[ -n "$COSMO" && -d "$COSMO/o" ]]; then
+  o=$COSMO/o
+else
+  echo "mkofs: o/ not found" >&2
+  return 1
+fi
+o=$(realpath "$o")
+cut -d' ' -f2 /proc/mounts | while read -r line; do
+  if [[ "$o" = "$line" ]]; then
+    echo "mkofs: $o already mounted" >&2
+    return 0
+  fi
+done
+( set -x
+  sudo mount -t tmpfs -o size=10G,noatime,nodiratime /dev/shm "$o"
+)
+# vim:ft=zsh

tool/zsh/mmake

@@ -42,3 +42,4 @@ local make=${MAKE:-${COSMOCC:-/opt/cosmocc/current}/bin/make}
 [[ -x $make ]] || make=${COSMO:-$PWD}/build/bootstrap/make.com
 ( set -x
   exec $make $j $flags MODE=$mode $targs )
+# vim:ft=zsh

tool/zsh/nproc

@@ -16,3 +16,4 @@ nproc() {
   echo 2
 }
 nproc
+# vim:ft=zsh