diff --git a/tools/applypatch/Android.mk b/tools/applypatch/Android.mk
index 3956ea6..c25e0d6 100644
--- a/tools/applypatch/Android.mk
+++ b/tools/applypatch/Android.mk
@@ -21,8 +21,8 @@
 LOCAL_MODULE := applypatch
 LOCAL_FORCE_STATIC_EXECUTABLE := true
 LOCAL_MODULE_TAGS := eng
-LOCAL_C_INCLUDES += external/bzip2 external/zlib
-LOCAL_STATIC_LIBRARIES += libmincrypt libbz libz libc
+LOCAL_C_INCLUDES += external/bzip2 external/zlib bootable/recovery
+LOCAL_STATIC_LIBRARIES += libmtdutils libmincrypt libbz libz libc
 
 include $(BUILD_EXECUTABLE)
 
diff --git a/tools/applypatch/applypatch.c b/tools/applypatch/applypatch.c
index b9f28a2..6559533 100644
--- a/tools/applypatch/applypatch.c
+++ b/tools/applypatch/applypatch.c
@@ -25,12 +25,22 @@
 
 #include "mincrypt/sha.h"
 #include "applypatch.h"
+#include "mtdutils/mtdutils.h"
+
+int LoadMTDContents(const char* filename, FileContents* file);
+int ParseSha1(const char* str, uint8_t* digest);
 
 // Read a file into memory; store it and its associated metadata in
 // *file.  Return 0 on success.
 int LoadFileContents(const char* filename, FileContents* file) {
   file->data = NULL;
 
+  // A special 'filename' beginning with "MTD:" means to load the
+  // contents of an MTD partition.
+  if (strncmp(filename, "MTD:", 4) == 0) {
+    return LoadMTDContents(filename, file);
+  }
+
   if (stat(filename, &file->st) != 0) {
     fprintf(stderr, "failed to stat \"%s\": %s\n", filename, strerror(errno));
     return -1;
@@ -61,6 +71,178 @@
   return 0;
 }
 
+static size_t* size_array;
+// comparison function for qsort()ing an int array of indexes into
+// size_array[].
+static int compare_size_indices(const void* a, const void* b) {
+  int aa = *(int*)a;
+  int bb = *(int*)b;
+  if (size_array[aa] < size_array[bb]) {
+    return -1;
+  } else if (size_array[aa] > size_array[bb]) {
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+// Load the contents of an MTD partition into the provided
+// FileContents.  filename should be a string of the form
+// "MTD:<partition_name>:<size_1>:<sha1_1>:<size_2>:<sha1_2>:...".
+// The smallest size_n bytes for which that prefix of the mtd contents
+// has the corresponding sha1 hash will be loaded.  It is acceptable
+// for a size value to be repeated with different sha1s.  Will return
+// 0 on success.
+//
+// This complexity is needed because if an OTA installation is
+// interrupted, the partition might contain either the source or the
+// target data, which might be of different lengths.  We need to know
+// the length in order to read from MTD (there is no "end-of-file"
+// marker), so the caller must specify the possible lengths and the
+// hash of the data, and we'll do the load expecting to find one of
+// those hashes.
+int LoadMTDContents(const char* filename, FileContents* file) {
+  char* copy = strdup(filename);
+  const char* magic = strtok(copy, ":");
+  if (strcmp(magic, "MTD") != 0) {
+    fprintf(stderr, "LoadMTDContents called with bad filename (%s)\n",
+            filename);
+    return -1;
+  }
+  const char* partition = strtok(NULL, ":");
+
+  int i;
+  int colons = 0;
+  for (i = 0; filename[i] != '\0'; ++i) {
+    if (filename[i] == ':') {
+      ++colons;
+    }
+  }
+  if (colons < 3 || colons%2 == 0) {
+    fprintf(stderr, "LoadMTDContents called with bad filename (%s)\n",
+            filename);
+  }
+
+  int pairs = (colons-1)/2;     // # of (size,sha1) pairs in filename
+  int* index = malloc(pairs * sizeof(int));
+  size_t* size = malloc(pairs * sizeof(size_t));
+  char** sha1sum = malloc(pairs * sizeof(char*));
+
+  for (i = 0; i < pairs; ++i) {
+    const char* size_str = strtok(NULL, ":");
+    size[i] = strtol(size_str, NULL, 10);
+    if (size[i] == 0) {
+      fprintf(stderr, "LoadMTDContents called with bad size (%s)\n", filename);
+      return -1;
+    }
+    sha1sum[i] = strtok(NULL, ":");
+    index[i] = i;
+  }
+
+  // sort the index[] array so it indexs the pairs in order of
+  // increasing size.
+  size_array = size;
+  qsort(index, pairs, sizeof(int), compare_size_indices);
+
+  static int partitions_scanned = 0;
+  if (!partitions_scanned) {
+    mtd_scan_partitions();
+    partitions_scanned = 1;
+  }
+
+  const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+  if (mtd == NULL) {
+    fprintf(stderr, "mtd partition \"%s\" not found (loading %s)\n",
+            partition, filename);
+    return -1;
+  }
+
+  MtdReadContext* ctx = mtd_read_partition(mtd);
+  if (ctx == NULL) {
+    fprintf(stderr, "failed to initialize read of mtd partition \"%s\"\n",
+            partition);
+    return -1;
+  }
+
+  SHA_CTX sha_ctx;
+  SHA_init(&sha_ctx);
+  uint8_t parsed_sha[SHA_DIGEST_SIZE];
+
+  // allocate enough memory to hold the largest size.
+  file->data = malloc(size[index[pairs-1]]);
+  char* p = (char*)file->data;
+  file->size = 0;                // # bytes read so far
+
+  for (i = 0; i < pairs; ++i) {
+    // Read enough additional bytes to get us up to the next size
+    // (again, we're trying the possibilities in order of increasing
+    // size).
+    size_t next = size[index[i]] - file->size;
+    size_t read = 0;
+    if (next > 0) {
+      read = mtd_read_data(ctx, p, next);
+      if (next != read) {
+        fprintf(stderr, "short read (%d bytes of %d) for partition \"%s\"\n",
+                read, next, partition);
+        free(file->data);
+        file->data = NULL;
+        return -1;
+      }
+      SHA_update(&sha_ctx, p, read);
+      file->size += read;
+    }
+
+    // Duplicate the SHA context and finalize the duplicate so we can
+    // check it against this pair's expected hash.
+    SHA_CTX temp_ctx;
+    memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
+    const uint8_t* sha_so_far = SHA_final(&temp_ctx);
+
+    if (ParseSha1(sha1sum[index[i]], parsed_sha) != 0) {
+      fprintf(stderr, "failed to parse sha1 %s in %s\n",
+              sha1sum[index[i]], filename);
+      free(file->data);
+      file->data = NULL;
+      return -1;
+    }
+
+    if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_SIZE) == 0) {
+      // we have a match.  stop reading the partition; we'll return
+      // the data we've read so far.
+      printf("mtd read matched size %d sha %s\n",
+             size[index[i]], sha1sum[index[i]]);
+      break;
+    }
+
+    p += read;
+  }
+
+  mtd_read_close(ctx);
+
+  if (i == pairs) {
+    // Ran off the end of the list of (size,sha1) pairs without
+    // finding a match.
+    fprintf(stderr, "contents of MTD partition \"%s\" didn't match %s\n",
+            partition, filename);
+    free(file->data);
+    file->data = NULL;
+    return -1;
+  }
+
+  const uint8_t* sha_final = SHA_final(&sha_ctx);
+  for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+    file->sha1[i] = sha_final[i];
+  }
+
+  free(copy);
+  free(index);
+  free(size);
+  free(sha1sum);
+
+  return 0;
+}
+
+
 // Save the contents of the given FileContents object under the given
 // filename.  Return 0 on success.
 int SaveFileContents(const char* filename, FileContents file) {
@@ -178,8 +360,13 @@
   FileContents file;
   file.data = NULL;
 
+  // It's okay to specify no sha1s; the check will pass if the
+  // LoadFileContents is successful.  (Useful for reading MTD
+  // partitions, where the filename encodes the sha1s; no need to
+  // check them twice.)
   if (LoadFileContents(argv[2], &file) != 0 ||
-      FindMatchingPatch(file.sha1, patches, num_patches) == NULL) {
+      (num_patches > 0 &&
+       FindMatchingPatch(file.sha1, patches, num_patches) == NULL)) {
     fprintf(stderr, "file \"%s\" doesn't have any of expected "
             "sha1 sums; checking cache\n", argv[2]);
 
@@ -241,14 +428,24 @@
 //
 // - otherwise, or if any error is encountered, exits with non-zero
 //   status.
+//
+// <src-file> (or <file> in check mode) may refer to an MTD partition
+// to read the source data.  See the comments for the
+// LoadMTDContents() function above for the format of such a filename.
 
 int main(int argc, char** argv) {
   if (argc < 2) {
  usage:
-    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",
+    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"
+            "\n"
+            "<src-file> or <file> may be of the form\n"
+            "  MTD:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
+            "to specify reading from an MTD partition.\n\n",
             argv[0], argv[0], argv[0], argv[0]);
     return 1;
   }
@@ -370,6 +567,15 @@
     // Using the original source, but not enough free space.  First
     // copy the source file to cache, then delete it from the original
     // location.
+
+    if (strncmp(source_filename, "MTD:", 4) == 0) {
+      // It's impossible to free space on the target filesystem by
+      // deleting the source if the source is an MTD partition.  If
+      // we're ever in a state where we need to do this, fail.
+      fprintf(stderr, "not enough free space for target but source is MTD\n");
+      return 1;
+    }
+
     if (MakeFreeSpaceOnCache(source_file.size) < 0) {
       fprintf(stderr, "not enough free space on /cache\n");
       return 1;
diff --git a/tools/applypatch/imgpatch.c b/tools/applypatch/imgpatch.c
index f4abc60..2efe874 100644
--- a/tools/applypatch/imgpatch.c
+++ b/tools/applypatch/imgpatch.c
@@ -124,7 +124,8 @@
 
       unsigned char* expanded_source = malloc(expanded_len);
       if (expanded_source == NULL) {
-        fprintf(stderr, "failed to allocate %d bytes for expanded_source\n", expanded_len);
+        fprintf(stderr, "failed to allocate %d bytes for expanded_source\n",
+                expanded_len);
         return -1;
       }
 
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 364f751..cd063a1 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -322,9 +322,12 @@
                              for b in bootloaders]))
 
 
-def IncludeBinary(name, input_zip, output_zip):
+def IncludeBinary(name, input_zip, output_zip, input_path=None):
   try:
-    data = input_zip.read(os.path.join("OTA/bin", name))
+    if input_path is not None:
+      data = open(input_path).read()
+    else:
+      data = input_zip.read(os.path.join("OTA/bin", name))
     output_zip.writestr(name, data)
   except IOError:
     raise ExternalError('unable to include device binary "%s"' % (name,))
@@ -402,8 +405,11 @@
   return out
 
 
-def Difference(tf, sf):
-  """Return the patch (as a string of data) needed to turn sf into tf."""
+def Difference(tf, sf, diff_program):
+  """Return the patch (as a string of data) needed to turn sf into tf.
+  diff_program is the name of an external program (or list, if
+  additional arguments are desired) to run to generate the diff.
+  """
 
   ttemp = tf.WriteToTemp()
   stemp = sf.WriteToTemp()
@@ -412,10 +418,17 @@
 
   try:
     ptemp = tempfile.NamedTemporaryFile()
-    p = common.Run(["bsdiff", stemp.name, ttemp.name, ptemp.name])
+    if isinstance(diff_program, list):
+      cmd = copy.copy(diff_program)
+    else:
+      cmd = [diff_program]
+    cmd.append(stemp.name)
+    cmd.append(ttemp.name)
+    cmd.append(ptemp.name)
+    p = common.Run(cmd)
     _, err = p.communicate()
     if err:
-      raise ExternalError("failure running bsdiff:\n%s\n" % (err,))
+      raise ExternalError("failure running %s:\n%s\n" % (diff_program, err))
     diff = ptemp.read()
     ptemp.close()
   finally:
@@ -461,7 +474,10 @@
       verbatim_targets.append((fn, tf.size))
     elif tf.sha1 != sf.sha1:
       # File is different; consider sending as a patch
-      d = Difference(tf, sf)
+      diff_method = "bsdiff"
+      if tf.name.endswith(".gz"):
+        diff_method = "imgdiff"
+      d = Difference(tf, sf, diff_method)
       print fn, tf.size, len(d), (float(len(d)) / tf.size)
       if len(d) > tf.size * OPTIONS.patch_threshold:
         # patch is almost as big as the file; don't bother patching
@@ -493,11 +509,13 @@
       os.path.join(OPTIONS.target_tmp, "BOOT"))
   updating_boot = (source_boot != target_boot)
 
-  source_recovery = common.BuildBootableImage(
-      os.path.join(OPTIONS.source_tmp, "RECOVERY"))
-  target_recovery = common.BuildBootableImage(
-      os.path.join(OPTIONS.target_tmp, "RECOVERY"))
-  updating_recovery = (source_recovery != target_recovery)
+  source_recovery = File("system/recovery.img",
+                         common.BuildBootableImage(
+      os.path.join(OPTIONS.source_tmp, "RECOVERY")))
+  target_recovery = File("system/recovery.img",
+                         common.BuildBootableImage(
+      os.path.join(OPTIONS.target_tmp, "RECOVERY")))
+  updating_recovery = (source_recovery.data != target_recovery.data)
 
   source_radio = source_zip.read("RADIO/image")
   target_radio = target_zip.read("RADIO/image")
@@ -515,13 +533,13 @@
 
   pb_verify = progress_bar_total * 0.3 * \
               (total_patched_size /
-               float(total_patched_size+total_verbatim_size))
+               float(total_patched_size+total_verbatim_size+1))
 
   for i, (fn, tf, sf, size) in enumerate(patch_list):
     if i % 5 == 0:
       next_sizes = sum([i[3] for i in patch_list[i:i+5]])
       script.append("show_progress %f 1" %
-                    (next_sizes * pb_verify / total_patched_size,))
+                    (next_sizes * pb_verify / (total_patched_size+1),))
     script.append("run_program PACKAGE:applypatch -c /%s %s %s" %
                   (fn, tf.sha1, sf.sha1))
 
@@ -531,6 +549,19 @@
     script.append("copy_dir PACKAGE:patch CACHE:../tmp/patchtmp")
     IncludeBinary("applypatch", target_zip, output_zip)
 
+  if updating_recovery:
+    d = Difference(target_recovery, source_recovery, "imgdiff")
+    print "recovery  target: %d  source: %d  diff: %d" % (
+        target_recovery.size, source_recovery.size, len(d))
+
+    output_zip.writestr("patch/recovery.img.p", d)
+
+    script.append(("run_program PACKAGE:applypatch -c "
+                   "MTD:recovery:%d:%s:%d:%s") %
+                  (source_recovery.size, source_recovery.sha1,
+                   target_recovery.size, target_recovery.sha1))
+
+
   script.append("\n# ---- start making changes here\n")
 
   if OPTIONS.wipe_user_data:
@@ -546,7 +577,15 @@
     print "boot image unchanged; skipping."
 
   if updating_recovery:
-    output_zip.writestr("system/recovery.img", target_recovery)
+    # Produce /system/recovery.img by applying a patch to the current
+    # contents of the recovery partition.
+    script.append(("run_program PACKAGE:applypatch MTD:recovery:%d:%s:%d:%s "
+                   "/system/recovery.img %s %d %s:/tmp/patchtmp/recovery.img.p")
+                  % (source_recovery.size, source_recovery.sha1,
+                     target_recovery.size, target_recovery.sha1,
+                     target_recovery.sha1,
+                     target_recovery.size,
+                     source_recovery.sha1))
     print "recovery image changed; including."
   else:
     print "recovery image unchanged; skipping."
@@ -561,12 +600,12 @@
 
   pb_apply = progress_bar_total * 0.7 * \
              (total_patched_size /
-              float(total_patched_size+total_verbatim_size))
+              float(total_patched_size+total_verbatim_size+1))
   for i, (fn, tf, sf, size) in enumerate(patch_list):
     if i % 5 == 0:
       next_sizes = sum([i[3] for i in patch_list[i:i+5]])
       script.append("show_progress %f 1" %
-                    (next_sizes * pb_apply / total_patched_size,))
+                    (next_sizes * pb_apply / (total_patched_size+1),))
     script.append(("run_program PACKAGE:applypatch "
                    "/%s - %s %d %s:/tmp/patchtmp/%s.p") %
                   (fn, tf.sha1, tf.size, sf.sha1, fn))
@@ -594,7 +633,7 @@
   if verbatim_targets:
     pb_verbatim = progress_bar_total * \
                   (total_verbatim_size /
-                   float(total_patched_size+total_verbatim_size))
+                   float(total_patched_size+total_verbatim_size+1))
     script.append("show_progress %f 5" % (pb_verbatim,))
     script.append("copy_dir PACKAGE:system SYSTEM:")