diff --git a/tools/applypatch/applypatch.c b/tools/applypatch/applypatch.c
index 9954869..23b41d7 100644
--- a/tools/applypatch/applypatch.c
+++ b/tools/applypatch/applypatch.c
@@ -43,6 +43,7 @@
   if (f == NULL) {
     fprintf(stderr, "failed to open \"%s\": %s\n", filename, strerror(errno));
     free(file->data);
+    file->data = NULL;
     return -1;
   }
 
@@ -51,6 +52,7 @@
     fprintf(stderr, "short read of \"%s\" (%d bytes of %d)\n",
             filename, bytes_read, file->size);
     free(file->data);
+    file->data = NULL;
     return -1;
   }
   fclose(f);
@@ -226,14 +228,16 @@
 // replacement for it) and idempotent (it's okay to run this program
 // multiple times).
 //
-// - if the sha1 hash of <file> is <tgt-sha1>, does nothing and exits
+// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
 //   successfully.
 //
-// - otherwise, if the sha1 hash of <file> is <src-sha1>, applies the
-//   bsdiff <patch> to <file> to produce a new file (the type of patch
+// - otherwise, if the sha1 hash of <src-file> is <src-sha1>, applies the
+//   bsdiff <patch> to <src-file> to produce a new file (the type of patch
 //   is automatically detected from the file header).  If that new
-//   file has sha1 hash <tgt-sha1>, moves it to replace <file>, and
-//   exits successfully.
+//   file has sha1 hash <tgt-sha1>, moves it to replace <tgt-file>, and
+//   exits successfully.  Note that if <src-file> and <tgt-file> are
+//   not the same, <src-file> is NOT deleted on success.  <tgt-file>
+//   may be the string "-" to mean "the same as src-file".
 //
 // - otherwise, or if any error is encountered, exits with non-zero
 //   status.
@@ -241,7 +245,7 @@
 int main(int argc, char** argv) {
   if (argc < 2) {
  usage:
-    fprintf(stderr, "usage: %s <file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]\n"
+    fprintf(stderr, "usage: %s <src-file> <tgt-file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]\n"
                     "   or  %s -c <file> [<sha1> ...]\n"
                     "   or  %s -s <bytes>\n"
                     "   or  %s -l\n",
@@ -273,26 +277,31 @@
   uint8_t target_sha1[SHA_DIGEST_SIZE];
 
   const char* source_filename = argv[1];
+  const char* target_filename = argv[2];
+  if (target_filename[0] == '-' &&
+      target_filename[1] == '\0') {
+    target_filename = source_filename;
+  }
 
-  // assume that source_filename (eg "/system/app/Foo.apk") is located
+  // assume that target_filename (eg "/system/app/Foo.apk") is located
   // on the same filesystem as its top-level directory ("/system").
   // We need something that exists for calling statfs().
-  char* source_fs = strdup(argv[1]);
-  char* slash = strchr(source_fs+1, '/');
+  char* target_fs = strdup(target_filename);
+  char* slash = strchr(target_fs+1, '/');
   if (slash != NULL) {
     *slash = '\0';
   }
 
-  if (ParseSha1(argv[2], target_sha1) != 0) {
-    fprintf(stderr, "failed to parse tgt-sha1 \"%s\"\n", argv[2]);
+  if (ParseSha1(argv[3], target_sha1) != 0) {
+    fprintf(stderr, "failed to parse tgt-sha1 \"%s\"\n", argv[3]);
     return 1;
   }
 
-  unsigned long target_size = strtoul(argv[3], NULL, 0);
+  unsigned long target_size = strtoul(argv[4], NULL, 0);
 
   int num_patches;
   Patch* patches;
-  if (ParseShaArgs(argc-4, argv+4, &patches, &num_patches) < 0) { return 1; }
+  if (ParseShaArgs(argc-5, argv+5, &patches, &num_patches) < 0) { return 1; }
 
   FileContents copy_file;
   FileContents source_file;
@@ -300,15 +309,27 @@
   const char* copy_patch_filename = NULL;
   int made_copy = 0;
 
-  if (LoadFileContents(source_filename, &source_file) == 0) {
+  // We try to load the target file into the source_file object.
+  if (LoadFileContents(target_filename, &source_file) == 0) {
     if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
       // The early-exit case:  the patch was already applied, this file
       // has the desired hash, nothing for us to do.
       fprintf(stderr, "\"%s\" is already target; no patch needed\n",
-              source_filename);
+              target_filename);
       return 0;
     }
+  }
 
+  if (source_file.data == NULL ||
+      (target_filename != source_filename &&
+       strcmp(target_filename, source_filename) != 0)) {
+    // Need to load the source file:  either we failed to load the
+    // target file, or we did but it's different from the source file.
+    free(source_file.data);
+    LoadFileContents(source_filename, &source_file);
+  }
+
+  if (source_file.data != NULL) {
     const Patch* to_use =
         FindMatchingPatch(source_file.sha1, patches, num_patches);
     if (to_use != NULL) {
@@ -340,7 +361,7 @@
   }
 
   // Is there enough room in the target filesystem to hold the patched file?
-  size_t free_space = FreeSpaceForFile(source_fs);
+  size_t free_space = FreeSpaceForFile(target_fs);
   int enough_space = free_space > (target_size * 3 / 2);  // 50% margin of error
   printf("target %ld bytes; free space %ld bytes; enough %d\n",
          (long)target_size, (long)free_space, enough_space);
@@ -361,8 +382,8 @@
     made_copy = 1;
     unlink(source_filename);
 
-    size_t free_space = FreeSpaceForFile(source_fs);
-    printf("(now %ld bytes free for source)\n", (long)free_space);
+    size_t free_space = FreeSpaceForFile(target_fs);
+    printf("(now %ld bytes free for target)\n", (long)free_space);
   }
 
   FileContents* source_to_use;
@@ -375,14 +396,14 @@
     patch_filename = copy_patch_filename;
   }
 
-  // We write the decoded output to "<file>.patch".
-  char* outname = (char*)malloc(strlen(source_filename) + 10);
-  strcpy(outname, source_filename);
+  // We write the decoded output to "<tgt-file>.patch".
+  char* outname = (char*)malloc(strlen(target_filename) + 10);
+  strcpy(outname, target_filename);
   strcat(outname, ".patch");
   FILE* output = fopen(outname, "wb");
   if (output == NULL) {
     fprintf(stderr, "failed to patch file %s: %s\n",
-            source_filename, strerror(errno));
+            target_filename, strerror(errno));
     return 1;
   }
 
@@ -441,10 +462,10 @@
     return 1;
   }
 
-  // Finally, rename the .patch file to replace the original source file.
-  if (rename(outname, source_filename) != 0) {
+  // Finally, rename the .patch file to replace the target file.
+  if (rename(outname, target_filename) != 0) {
     fprintf(stderr, "rename of .patch to \"%s\" failed: %s\n",
-            source_filename, strerror(errno));
+            target_filename, strerror(errno));
     return 1;
   }
 
diff --git a/tools/applypatch/applypatch.sh b/tools/applypatch/applypatch.sh
index 181cd5c..88f3025 100755
--- a/tools/applypatch/applypatch.sh
+++ b/tools/applypatch/applypatch.sh
@@ -24,16 +24,22 @@
 # partition that WORK_DIR is located on, without the leading slash
 WORK_FS=system
 
+# set to 0 to use a device instead
+USE_EMULATOR=1
+
 # ------------------------
 
 tmpdir=$(mktemp -d)
 
-emulator -wipe-data -noaudio -no-window -port $EMULATOR_PORT &
-pid_emulator=$!
+if [ "$USE_EMULATOR" == 1 ]; then
+  emulator -wipe-data -noaudio -no-window -port $EMULATOR_PORT &
+  pid_emulator=$!
+  ADB="adb -s emulator-$EMULATOR_PORT "
+else
+  ADB="adb -d "
+fi
 
-ADB="adb -s emulator-$EMULATOR_PORT "
-
-echo "emulator is $pid_emulator; waiting for startup"
+echo "waiting to connect to device"
 $ADB wait-for-device
 echo "device is available"
 $ADB remount
@@ -56,7 +62,8 @@
   echo
   echo FAIL: $testname
   echo
-  kill $pid_emulator
+  [ "$open_pid" == "" ] || kill $open_pid
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
   exit 1
 }
 
@@ -68,6 +75,23 @@
   run_command df | awk "/$1/ {print gensub(/K/, \"\", \"g\", \$6)}"
 }
 
+cleanup() {
+  # not necessary if we're about to kill the emulator, but nice for
+  # running on real devices or already-running emulators.
+  testname "removing test files"
+  run_command rm $WORK_DIR/bloat.dat
+  run_command rm $WORK_DIR/old.file
+  run_command rm $WORK_DIR/patch.bsdiff
+  run_command rm $WORK_DIR/applypatch
+  run_command rm $CACHE_TEMP_SOURCE
+  run_command rm /cache/bloat*.dat
+
+  [ "$pid_emulator" == "" ] || kill $pid_emulator
+
+  rm -rf $tmpdir
+}
+
+cleanup
 
 $ADB push $ANDROID_PRODUCT_OUT/system/bin/applypatch $WORK_DIR/applypatch
 
@@ -146,16 +170,71 @@
 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
+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
+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 in new location ----------------------
+
+$ADB push $DATA_DIR/old.file $WORK_DIR
+$ADB push $DATA_DIR/patch.bsdiff $WORK_DIR
+
+# Check that the partition has enough space to apply the patch without
+# copying.  If it doesn't, we'll be testing the low-space condition
+# when we intend to test the not-low-space condition.
+testname "apply patch to new location (with enough space)"
+free_kb=$(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
+
+run_command rm $WORK_DIR/new.file
+run_command rm $CACHE_TEMP_SOURCE
+
+testname "apply bsdiff patch to new location"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+testname "reapply bsdiff patch to new location"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $BAD1_SHA1:$WORK_DIR/foo $OLD_SHA1:$WORK_DIR/patch.bsdiff || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+$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 "apply bsdiff patch to new location with corrupted source"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo || fail
+$ADB pull $WORK_DIR/new.file $tmpdir/patched
+diff -q $DATA_DIR/new.file $tmpdir/patched || fail
+
+# put some junk in the cache copy, too
+run_command dd if=/dev/urandom of=$CACHE_TEMP_SOURCE count=100 bs=1024 || fail
+
+run_command rm $WORK_DIR/new.file
+testname "apply bsdiff patch to new location with corrupted source and copy (no new file)"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo && fail
+
+# put some junk in the new file
+run_command dd if=/dev/urandom of=$WORK_DIR/new.file count=100 bs=1024 || fail
+
+testname "apply bsdiff patch to new location with corrupted source and copy (bad new file)"
+run_command $WORK_DIR/applypatch $WORK_DIR/old.file $WORK_DIR/new.file $NEW_SHA1 $NEW_SIZE $OLD_SHA1:$WORK_DIR/patch.bsdiff $BAD1_SHA1:$WORK_DIR/foo && fail
+
 # --------------- apply patch with low space on /system ----------------------
 
 $ADB push $DATA_DIR/old.file $WORK_DIR
@@ -169,12 +248,12 @@
 echo "${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
+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
+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
 
@@ -213,7 +292,7 @@
 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 $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
@@ -229,7 +308,7 @@
 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
+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 $tmpdir/patched || fail
 run_command ls /cache/subdir/a.file || fail     # still wasn't deleted because it's in a subdir
@@ -242,7 +321,7 @@
 run_command dd if=/dev/urandom of=$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
+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
 
@@ -251,20 +330,14 @@
 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
+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
+cleanup
 
 echo
 echo PASS