catalyst-auto: add a preclean option to trim temp files

This makes it easier to cronjob things w/out needing manual cleanup
from time to time by people.

tools/catalyst-auto

@@ -24,6 +24,7 @@ config_files=()
 verbose=0
 keep_tmpdir=0
 testing=0
+preclean=0
 
 # Set pipefail so that run_cmd returns the right value in $?
 set -o pipefail
@@ -41,6 +42,7 @@ Usage:
 
 Options:
   -c|--config         Specifies the config file to use (required)
+  -C|--preclean       Clean up loose artifacts from previous runs
   -v|--verbose        Send output of commands to console as well as log
   -k|--keep-tmpdir    Don't remove temp dir when build finishes
   -t|--test           Stop after mangling specs and copying files
@@ -119,6 +121,9 @@ do
     -t|--test)
       testing=1
       ;;
+    -C|--preclean)
+      preclean=1
+      ;;
     -*)
       usage "ERROR: You have specified an invalid option: ${a}"
       exit 1
@@ -149,6 +154,12 @@ BUILD_SRCDIR_BASE=$(catalyst_var storedir)
 TMPDIR=$(mktemp -d --tmpdir="${TMP_PATH:-/tmp}" catalyst-auto.XXXXXX)
 DATESTAMP=$(date +%Y%m%d)
 
+# Nuke any previous tmpdirs to keep them from accumulating.
+if [[ ${preclean} -eq 1 ]]; then
+  rm -rf "${TMPDIR%.??????}".*
+  mkdir "${TMPDIR}"
+fi
+
 if [ ${verbose} = 1 ]; then
   echo "TMPDIR = ${TMPDIR}"
   echo "DATESTAMP = ${DATESTAMP}"
@@ -225,6 +236,18 @@ if [ "${testing}" -eq 1 ]; then
   exit
 fi
 
+if [[ ${preclean} -eq 1 ]]; then
+  snapshot_cache=$(catalyst_var snapshot_cache)
+  if [[ -z ${snapshot_cache} ]]; then
+    echo "error: snapshot_cache not set in config file"
+    exit 1
+  fi
+  pushd "${BUILD_SRCDIR_BASE}" >/dev/null || exit 1
+  rm -rf --one-file-system \
+    kerncache packages snapshots tmp "${snapshot_cache}"/*
+  popd >/dev/null
+fi
+
 # Create snapshot
 if ! run_cmd "catalyst -c ${CATALYST_CONFIG} -s ${DATESTAMP}" "${TMPDIR}/log/snapshot.log"; then
   send_email "Catalyst build error - snapshot" "" "${TMPDIR}/log/snapshot.log"