diff --git a/applypatch/applypatch_modes.cpp b/applypatch/applypatch_modes.cpp
new file mode 100644
index 0000000..7b191a8
--- /dev/null
+++ b/applypatch/applypatch_modes.cpp
@@ -0,0 +1,204 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "applypatch_modes.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <android-base/parseint.h>
+#include <android-base/strings.h>
+#include <openssl/sha.h>
+
+#include "applypatch/applypatch.h"
+#include "edify/expr.h"
+
+static int CheckMode(int argc, const char** argv) {
+    if (argc < 3) {
+        return 2;
+    }
+    std::vector<std::string> sha1;
+    for (int i = 3; i < argc; i++) {
+        sha1.push_back(argv[i]);
+    }
+
+    return applypatch_check(argv[2], sha1);
+}
+
+static int SpaceMode(int argc, const char** argv) {
+    if (argc != 3) {
+        return 2;
+    }
+
+    size_t bytes;
+    if (!android::base::ParseUint(argv[2], &bytes) || bytes == 0) {
+        printf("can't parse \"%s\" as byte count\n\n", argv[2]);
+        return 1;
+    }
+    return CacheSizeCheck(bytes);
+}
+
+// Parse arguments (which should be of the form "<sha1>:<filename>" into the
+// new parallel arrays *sha1s and *files. Returns true on success.
+static bool ParsePatchArgs(int argc, const char** argv, std::vector<std::string>* sha1s,
+                           std::vector<FileContents>* files) {
+    if (sha1s == nullptr) {
+        return false;
+    }
+    for (int i = 0; i < argc; ++i) {
+        std::vector<std::string> pieces = android::base::Split(argv[i], ":");
+        if (pieces.size() != 2) {
+            printf("failed to parse patch argument \"%s\"\n", argv[i]);
+            return false;
+        }
+
+        uint8_t digest[SHA_DIGEST_LENGTH];
+        if (ParseSha1(pieces[0].c_str(), digest) != 0) {
+            printf("failed to parse sha1 \"%s\"\n", argv[i]);
+            return false;
+        }
+
+        sha1s->push_back(pieces[0]);
+        FileContents fc;
+        if (LoadFileContents(pieces[1].c_str(), &fc) != 0) {
+            return false;
+        }
+        files->push_back(std::move(fc));
+    }
+    return true;
+}
+
+static int FlashMode(const char* src_filename, const char* tgt_filename,
+                     const char* tgt_sha1, size_t tgt_size) {
+    return applypatch_flash(src_filename, tgt_filename, tgt_sha1, tgt_size);
+}
+
+static int PatchMode(int argc, const char** argv) {
+    FileContents bonusFc;
+    Value bonus(VAL_INVALID, "");
+
+    if (argc >= 3 && strcmp(argv[1], "-b") == 0) {
+        if (LoadFileContents(argv[2], &bonusFc) != 0) {
+            printf("failed to load bonus file %s\n", argv[2]);
+            return 1;
+        }
+        bonus.type = VAL_BLOB;
+        bonus.data = std::string(bonusFc.data.cbegin(), bonusFc.data.cend());
+        argc -= 2;
+        argv += 2;
+    }
+
+    if (argc < 4) {
+        return 2;
+    }
+
+    size_t target_size;
+    if (!android::base::ParseUint(argv[4], &target_size) || target_size == 0) {
+        printf("can't parse \"%s\" as byte count\n\n", argv[4]);
+        return 1;
+    }
+
+    // If no <src-sha1>:<patch> is provided, it is in flash mode.
+    if (argc == 5) {
+        if (bonus.type != VAL_INVALID) {
+            printf("bonus file not supported in flash mode\n");
+            return 1;
+        }
+        return FlashMode(argv[1], argv[2], argv[3], target_size);
+    }
+
+    std::vector<std::string> sha1s;
+    std::vector<FileContents> files;
+    if (!ParsePatchArgs(argc-5, argv+5, &sha1s, &files)) {
+        printf("failed to parse patch args\n");
+        return 1;
+    }
+
+    std::vector<std::unique_ptr<Value>> patches;
+    for (size_t i = 0; i < files.size(); ++i) {
+        patches.push_back(std::make_unique<Value>(
+                VAL_BLOB, std::string(files[i].data.cbegin(), files[i].data.cend())));
+    }
+    return applypatch(argv[1], argv[2], argv[3], target_size, sha1s, patches, &bonus);
+}
+
+// This program (applypatch) applies binary patches to files in a way that
+// is safe (the original file is not touched until we have the desired
+// replacement for it) and idempotent (it's okay to run this program
+// multiple times).
+//
+// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
+//   successfully.
+//
+// - otherwise, if no <src-sha1>:<patch> is provided, flashes <tgt-file> with
+//   <src-file>. <tgt-file> must be a partition name, while <src-file> must
+//   be a regular image file. <src-file> will not be deleted on success.
+//
+// - 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 <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.
+//
+// <src-file> (or <file> in check mode) may refer to an EMMC partition
+// to read the source data.  See the comments for the
+// LoadPartitionContents() function for the format of such a filename.
+
+int applypatch_modes(int argc, const char** argv) {
+    if (argc < 2) {
+      usage:
+        printf(
+            "usage: %s [-b <bonus-file>] <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"
+            "Filenames may be of the form\n"
+            "  EMMC:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
+            "to specify reading from or writing to an EMMC partition.\n\n",
+            argv[0], argv[0], argv[0], argv[0]);
+        return 2;
+    }
+
+    int result;
+
+    if (strncmp(argv[1], "-l", 3) == 0) {
+        result = ShowLicenses();
+    } else if (strncmp(argv[1], "-c", 3) == 0) {
+        result = CheckMode(argc, argv);
+    } else if (strncmp(argv[1], "-s", 3) == 0) {
+        result = SpaceMode(argc, argv);
+    } else {
+        result = PatchMode(argc, argv);
+    }
+
+    if (result == 2) {
+        goto usage;
+    }
+    return result;
+}