diff --git a/tools/applypatch/applypatch.sh b/tools/applypatch/applypatch.sh
new file mode 100755
index 0000000..181cd5c
--- /dev/null
+++ b/tools/applypatch/applypatch.sh
@@ -0,0 +1,272 @@
+#!/bin/bash
+#
+# A test suite for applypatch.  Run in a client where you have done
+# envsetup, choosecombo, etc.
+#
+# DO NOT RUN THIS ON A DEVICE YOU CARE ABOUT.  It will mess up your
+# system partition.
+#
+#
+# TODO: find some way to get this run regularly along with the rest of
+# the tests.
+
+EMULATOR_PORT=5580
+DATA_DIR=$ANDROID_BUILD_TOP/build/tools/applypatch/testdata
+
+# This must be the filename that applypatch uses for its copies.
+CACHE_TEMP_SOURCE=/cache/saved.file
+
+# Put all binaries and files here.  We use /cache because it's a
+# temporary filesystem in the emulator; it's created fresh each time
+# the emulator starts.
+WORK_DIR=/system
+
+# partition that WORK_DIR is located on, without the leading slash
+WORK_FS=system
+
+# ------------------------
+
+tmpdir=$(mktemp -d)
+
+emulator -wipe-data -noaudio -no-window -port $EMULATOR_PORT &
+pid_emulator=$!
+
+ADB="adb -s emulator-$EMULATOR_PORT "
+
+echo "emulator is $pid_emulator; waiting for startup"
+$ADB wait-for-device
+echo "device is available"
+$ADB remount
+# free up enough space on the system partition for the test to run.
+$ADB shell rm -r /system/media
+
+# run a command on the device; exit with the exit status of the device
+# command.
+run_command() {
+  $ADB shell "$@" \; echo \$? | awk '{if (b) {print a}; a=$0; b=1} END {exit a}'
+}
+
+testname() {
+  echo
+  echo "$1"...
+  testname="$1"
+}
+
+fail() {
+  echo
+  echo FAIL: $testname
+  echo
+  kill $pid_emulator
+  exit 1
+}
+
+sha1() {
+  sha1sum $1 | awk '{print $1}'
+}
+
+free_space() {
+  run_command df | awk "/$1/ {print gensub(/K/, \"\", \"g\", \$6)}"
+}
+
+
+$ADB push $ANDROID_PRODUCT_OUT/system/bin/applypatch $WORK_DIR/applypatch
+
+BAD1_SHA1=$(printf "%040x" $RANDOM)
+BAD2_SHA1=$(printf "%040x" $RANDOM)
+OLD_SHA1=$(sha1 $DATA_DIR/old.file)
+NEW_SHA1=$(sha1 $DATA_DIR/new.file)
+NEW_SIZE=$(stat -c %s $DATA_DIR/new.file)
+
+# --------------- basic execution ----------------------
+
+testname "usage message"
+run_command $WORK_DIR/applypatch && fail
+
+testname "display license"
+run_command $WORK_DIR/applypatch -l | grep -q -i copyright || fail
+
+
+# --------------- check mode ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+
+testname "check mode single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# put some junk in the old file
+run_command dd if=/dev/urandom of=$WORK_DIR/old.file count=100 bs=1024 || fail
+
+testname "check mode cache (corrupted) single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode cache (corrupted) multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode cache (corrupted) failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+# remove the old file entirely
+run_command rm $WORK_DIR/old.file
+
+testname "check mode cache (missing) single"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $OLD_SHA1 || fail
+
+testname "check mode cache (missing) multiple"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD1_SHA1 $OLD_SHA1 $BAD2_SHA1|| fail
+
+testname "check mode cache (missing) failure"
+run_command $WORK_DIR/applypatch -c $WORK_DIR/old.file $BAD2_SHA1 $BAD1_SHA1 && fail
+
+
+# --------------- apply patch ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+# Check that the partition has enough space to apply the patch without
+# copying.  If it doesn't, we'll be testing the low-space condition
+# when we intend to test the not-low-space condition.
+testname "apply patches (with enough space)"
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS."
+if (( free_kb * 1024 < NEW_SIZE * 3 / 2 )); then
+  echo "Not enough space on /$WORK_FS to patch test file."
+  echo
+  echo "This doesn't mean that applypatch is necessarily broken;"
+  echo "just that /$WORK_FS doesn't have enough free space to"
+  echo "properly run this test."
+  exit 1
+fi
+
+testname "apply bsdiff patch"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+
+# --------------- apply patch with low space on /system ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS; we'll soon fix that."
+echo run_command dd if=/dev/zero of=$WORK_DIR/bloat.dat count=$((free_kb-512)) bs=1024 || fail
+run_command dd if=/dev/zero of=$WORK_DIR/bloat.dat count=$((free_kb-512)) bs=1024 || fail
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS now."
+
+testname "apply bsdiff patch with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+# --------------- apply patch with low space on /system and /cache ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+free_kb=$(free_space $WORK_FS)
+echo "${free_kb}kb free on /$WORK_FS"
+
+run_command mkdir /cache/subdir
+run_command 'echo > /cache/subdir/a.file'
+run_command 'echo > /cache/a.file'
+run_command mkdir /cache/recovery /cache/recovery/otatest
+run_command 'echo > /cache/recovery/otatest/b.file'
+run_command "echo > $CACHE_TEMP_SOURCE"
+free_kb=$(free_space cache)
+echo "${free_kb}kb free on /cache; we'll soon fix that."
+run_command dd if=/dev/zero of=/cache/bloat_small.dat count=128 bs=1024 || fail
+run_command dd if=/dev/zero of=/cache/bloat_large.dat count=$((free_kb-640)) bs=1024 || fail
+free_kb=$(free_space cache)
+echo "${free_kb}kb free on /cache now."
+
+testname "apply bsdiff patch with low space, full cache, can't delete enough"
+$ADB shell 'cat >> /cache/bloat_large.dat' & open_pid=$!
+echo "open_pid is $open_pid"
+
+# size check should fail even though it deletes some stuff
+run_command $WORK_DIR/applypatch -s $NEW_SIZE && fail
+run_command ls /cache/bloat_small.dat && fail          # was deleted
+run_command ls /cache/a.file && fail                   # was deleted
+run_command ls /cache/recovery/otatest/b.file && fail  # was deleted
+run_command ls /cache/bloat_large.dat || fail          # wasn't deleted because it was open
+run_command ls /cache/subdir/a.file || fail            # wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail              # wasn't deleted because it's the source file copy
+
+# should fail; not enough files can be deleted
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff && fail
+run_command ls /cache/bloat_large.dat || fail   # wasn't deleted because it was open
+run_command ls /cache/subdir/a.file || fail     # wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail       # wasn't deleted because it's the source file copy
+
+kill $open_pid   # /cache/bloat_large.dat is no longer open
+
+testname "apply bsdiff patch with low space, full cache, can delete enough"
+
+# should succeed after deleting /cache/bloat_large.dat
+run_command $WORK_DIR/applypatch -s $NEW_SIZE || fail
+run_command ls /cache/bloat_large.dat && fail   # was deleted
+run_command ls /cache/subdir/a.file || fail     # still wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE || fail       # wasn't deleted because it's the source file copy
+
+# should succeed
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+run_command ls /cache/subdir/a.file || fail     # still wasn't deleted because it's in a subdir
+run_command ls $CACHE_TEMP_SOURCE && fail       # was deleted because patching overwrote it, then deleted it
+
+# --------------- apply patch from cache ----------------------
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# put some junk in the old file
+run_command dd if=/dev/urandom of=$WORK_DIR/old.file count=100 bs=1024 || fail
+
+testname "apply bsdiff patch from cache (corrupted source) with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+$ADB push $DATA_DIR/old.file $CACHE_TEMP_SOURCE
+# remove the old file entirely
+run_command rm $WORK_DIR/old.file
+
+testname "apply bsdiff patch from cache (missing source) with low space"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/old.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+
+# --------------- cleanup ----------------------
+
+# not necessary if we're about to kill the emulator, but nice for
+# running on real devices or already-running emulators.
+run_command rm /cache/bloat*.dat $WORK_DIR/bloat.dat $CACHE_TEMP_SOURCE $WORK_DIR/old.file $WORK_DIR/patch.xdelta3 $WORK_DIR/patch.bsdiff $WORK_DIR/applypatch
+
+kill $pid_emulator
+
+rm -rf $tmpdir
+
+echo
+echo PASS
+echo
+