Add tests for imgdiff.

Factor out libimgdiff static library for testing purpose.

This CL adds the imgdiff tests on host and on target both (similar to
libimgpatch). In practice, we only need imgdiff binary on host, and
libimgpatch on target. But they should build and pass tests on both
platforms.

Test: recovery_host_test passes; recovery_component_test passes.
Change-Id: I0eafb7faf727cdf70066310e845af6ee245d4f60
diff --git a/applypatch/Android.mk b/applypatch/Android.mk
index fa0fe8a..61e1106 100644
--- a/applypatch/Android.mk
+++ b/applypatch/Android.mk
@@ -17,7 +17,6 @@
 # libapplypatch (static library)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
 LOCAL_SRC_FILES := \
     applypatch.cpp \
     bspatch.cpp \
@@ -26,11 +25,11 @@
     utils.cpp
 LOCAL_MODULE := libapplypatch
 LOCAL_MODULE_TAGS := eng
-LOCAL_C_INCLUDES += \
+LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/include \
     bootable/recovery
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES += \
+LOCAL_STATIC_LIBRARIES := \
     libotafault \
     libbase \
     libcrypto \
@@ -42,36 +41,45 @@
 # libimgpatch (static library)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := bspatch.cpp imgpatch.cpp utils.cpp
+LOCAL_SRC_FILES := \
+    bspatch.cpp \
+    imgpatch.cpp \
+    utils.cpp
 LOCAL_MODULE := libimgpatch
-LOCAL_C_INCLUDES += \
+LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/include \
     bootable/recovery
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES += libcrypto libbz libz
+LOCAL_STATIC_LIBRARIES := \
+    libcrypto \
+    libbz \
+    libz
 LOCAL_CFLAGS := -Werror
 include $(BUILD_STATIC_LIBRARY)
 
 # libimgpatch (host static library)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := bspatch.cpp imgpatch.cpp utils.cpp
+LOCAL_SRC_FILES := \
+    bspatch.cpp \
+    imgpatch.cpp \
+    utils.cpp
 LOCAL_MODULE := libimgpatch
 LOCAL_MODULE_HOST_OS := linux
-LOCAL_C_INCLUDES += \
+LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/include \
     bootable/recovery
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES += libcrypto libbz libz
+LOCAL_STATIC_LIBRARIES := \
+    libcrypto \
+    libbz \
+    libz
 LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 # libapplypatch_modes (static library)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
 LOCAL_SRC_FILES := \
     applypatch_modes.cpp
 LOCAL_MODULE := libapplypatch_modes
@@ -87,7 +95,6 @@
 # applypatch (target executable)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
 LOCAL_SRC_FILES := applypatch_main.cpp
 LOCAL_MODULE := applypatch
 LOCAL_C_INCLUDES := bootable/recovery
@@ -106,18 +113,59 @@
 LOCAL_CFLAGS := -Werror
 include $(BUILD_EXECUTABLE)
 
+libimgdiff_src_files := \
+    imgdiff.cpp \
+    utils.cpp
+
+# libbsdiff is compiled with -D_FILE_OFFSET_BITS=64.
+libimgdiff_cflags := \
+    -Werror \
+    -D_FILE_OFFSET_BITS=64
+
+libimgdiff_static_libraries := \
+    libbsdiff \
+    libz
+
+# libimgdiff (static library)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    $(libimgdiff_src_files)
+LOCAL_MODULE := libimgdiff
+LOCAL_CFLAGS := \
+    $(libimgdiff_cflags)
+LOCAL_STATIC_LIBRARIES := \
+    $(libimgdiff_static_libraries)
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+include $(BUILD_STATIC_LIBRARY)
+
+# libimgdiff (host static library)
+# ===============================
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := \
+    $(libimgdiff_src_files)
+LOCAL_MODULE := libimgdiff
+LOCAL_CFLAGS := \
+    $(libimgdiff_cflags)
+LOCAL_STATIC_LIBRARIES := \
+    $(libimgdiff_static_libraries)
+LOCAL_C_INCLUDES := \
+    $(LOCAL_PATH)/include
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
+include $(BUILD_HOST_STATIC_LIBRARY)
+
 # imgdiff (host static executable)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_CLANG := true
-LOCAL_SRC_FILES := imgdiff.cpp utils.cpp
+LOCAL_SRC_FILES := imgdiff_main.cpp
 LOCAL_MODULE := imgdiff
-LOCAL_STATIC_LIBRARIES += \
-    libbsdiff \
-    libbz \
-    libdivsufsort64 \
-    libdivsufsort \
-    libz
 LOCAL_CFLAGS := -Werror
-LOCAL_FORCE_STATIC_EXECUTABLE := true
+LOCAL_STATIC_LIBRARIES := \
+    libimgdiff \
+    $(libimgdiff_static_libraries) \
+    libbz \
+    libdivsufsort \
+    libdivsufsort64
 include $(BUILD_HOST_EXECUTABLE)
diff --git a/applypatch/imgdiff.cpp b/applypatch/imgdiff.cpp
index 528daf1..18a15a1 100644
--- a/applypatch/imgdiff.cpp
+++ b/applypatch/imgdiff.cpp
@@ -121,19 +121,19 @@
  * information that is stored on the system partition.
  */
 
+#include "applypatch/imgdiff.h"
+
 #include <errno.h>
-#include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
-#include <unistd.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #include <bsdiff.h>
+#include <zlib.h>
 
-#include "zlib.h"
-#include "imgdiff.h"
 #include "utils.h"
 
 typedef struct {
@@ -374,8 +374,7 @@
  * return value when done with all the chunks.  Returns NULL on
  * failure.
  */
-unsigned char* ReadImage(const char* filename,
-                         int* num_chunks, ImageChunk** chunks) {
+unsigned char* ReadImage(const char* filename, int* num_chunks, ImageChunk** chunks) {
   struct stat st;
   if (stat(filename, &st) != 0) {
     printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
@@ -403,7 +402,7 @@
   *chunks = NULL;
 
   while (pos < sz) {
-    unsigned char* p = img+pos;
+    unsigned char* p = img + pos;
 
     if (sz - pos >= 4 &&
         p[0] == 0x1f && p[1] == 0x8b &&
@@ -413,8 +412,7 @@
       size_t chunk_offset = pos;
 
       *num_chunks += 3;
-      *chunks = static_cast<ImageChunk*>(realloc(*chunks,
-          *num_chunks * sizeof(ImageChunk)));
+      *chunks = static_cast<ImageChunk*>(realloc(*chunks, *num_chunks * sizeof(ImageChunk)));
       ImageChunk* curr = *chunks + (*num_chunks-3);
 
       // create a normal chunk for the header.
@@ -502,8 +500,7 @@
       // the decompression.
       size_t footer_size = Read4(p-4);
       if (footer_size != curr[-2].len) {
-        printf("Error: footer size %zu != decompressed size %zu\n",
-            footer_size, curr[-2].len);
+        printf("Error: footer size %zu != decompressed size %zu\n", footer_size, curr[-2].len);
         free(img);
         return NULL;
       }
@@ -637,7 +634,11 @@
     }
   }
 
+#if defined(__ANDROID__)
+  char ptemp[] = "/data/local/tmp/imgdiff-patch-XXXXXX";
+#else
   char ptemp[] = "/tmp/imgdiff-patch-XXXXXX";
+#endif
   int fd = mkstemp(ptemp);
 
   if (fd == -1) {
@@ -793,10 +794,8 @@
   *num_chunks = out;
 }
 
-ImageChunk* FindChunkByName(const char* name,
-                            ImageChunk* chunks, int num_chunks) {
-  int i;
-  for (i = 0; i < num_chunks; ++i) {
+ImageChunk* FindChunkByName(const char* name, ImageChunk* chunks, int num_chunks) {
+  for (int i = 0; i < num_chunks; ++i) {
     if (chunks[i].type == CHUNK_DEFLATE && chunks[i].filename &&
         strcmp(name, chunks[i].filename) == 0) {
       return chunks+i;
@@ -812,11 +811,11 @@
     }
 }
 
-int main(int argc, char** argv) {
-  int zip_mode = 0;
+int imgdiff(int argc, const char** argv) {
+  bool zip_mode = false;
 
   if (argc >= 2 && strcmp(argv[1], "-z") == 0) {
-    zip_mode = 1;
+    zip_mode = true;
     --argc;
     ++argv;
   }
@@ -880,12 +879,10 @@
     // Verify that the source and target images have the same chunk
     // structure (ie, the same sequence of deflate and normal chunks).
 
-    if (!zip_mode) {
-        // Merge the gzip header and footer in with any adjacent
-        // normal chunks.
-        MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
-        MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
-    }
+    // Merge the gzip header and footer in with any adjacent
+    // normal chunks.
+    MergeAdjacentNormalChunks(tgt_chunks, &num_tgt_chunks);
+    MergeAdjacentNormalChunks(src_chunks, &num_src_chunks);
 
     if (num_src_chunks != num_tgt_chunks) {
       printf("source and target don't have same number of chunks!\n");
@@ -897,8 +894,7 @@
     }
     for (i = 0; i < num_src_chunks; ++i) {
       if (src_chunks[i].type != tgt_chunks[i].type) {
-        printf("source and target don't have same chunk "
-                "structure! (chunk %d)\n", i);
+        printf("source and target don't have same chunk structure! (chunk %d)\n", i);
         printf("source chunks:\n");
         DumpChunks(src_chunks, num_src_chunks);
         printf("target chunks:\n");
@@ -983,8 +979,7 @@
     if (zip_mode) {
       ImageChunk* src;
       if (tgt_chunks[i].type == CHUNK_DEFLATE &&
-          (src = FindChunkByName(tgt_chunks[i].filename, src_chunks,
-                                 num_src_chunks))) {
+          (src = FindChunkByName(tgt_chunks[i].filename, src_chunks, num_src_chunks))) {
         patch_data[i] = MakePatch(src, tgt_chunks+i, patch_size+i);
       } else {
         patch_data[i] = MakePatch(src_chunks, tgt_chunks+i, patch_size+i);
@@ -1000,8 +995,7 @@
 
       patch_data[i] = MakePatch(src_chunks+i, tgt_chunks+i, patch_size+i);
     }
-    printf("patch %3d is %zu bytes (of %zu)\n",
-           i, patch_size[i], tgt_chunks[i].source_len);
+    printf("patch %3d is %zu bytes (of %zu)\n", i, patch_size[i], tgt_chunks[i].source_len);
   }
 
   // Figure out how big the imgdiff file header is going to be, so
diff --git a/applypatch/imgdiff_main.cpp b/applypatch/imgdiff_main.cpp
new file mode 100644
index 0000000..7d5bdf9
--- /dev/null
+++ b/applypatch/imgdiff_main.cpp
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2016 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/imgdiff.h"
+
+int main(int argc, char** argv) {
+  return imgdiff(argc, const_cast<const char**>(argv));
+}
diff --git a/applypatch/imgpatch.cpp b/applypatch/imgpatch.cpp
index 1c4409e..ae6071f 100644
--- a/applypatch/imgpatch.cpp
+++ b/applypatch/imgpatch.cpp
@@ -14,32 +14,34 @@
  * limitations under the License.
  */
 
-// See imgdiff.c in this directory for a description of the patch file
+// See imgdiff.cpp in this directory for a description of the patch file
 // format.
 
+#include <applypatch/imgpatch.h>
+
+#include <errno.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/cdefs.h>
 #include <sys/stat.h>
-#include <errno.h>
 #include <unistd.h>
-#include <string.h>
 
 #include <string>
 #include <vector>
 
-#include "zlib.h"
-#include "openssl/sha.h"
-#include "applypatch/applypatch.h"
-#include "imgdiff.h"
+#include <applypatch/applypatch.h>
+#include <applypatch/imgdiff.h>
+#include <openssl/sha.h>
+#include <zlib.h>
+
 #include "utils.h"
 
 int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
                     const unsigned char* patch_data, ssize_t patch_size,
                     SinkFn sink, void* token) {
-    Value patch(VAL_BLOB, std::string(
-            reinterpret_cast<const char*>(patch_data), patch_size));
+  Value patch(VAL_BLOB, std::string(reinterpret_cast<const char*>(patch_data), patch_size));
 
-    return ApplyImagePatch(old_data, old_size, &patch, sink, token, nullptr, nullptr);
+  return ApplyImagePatch(old_data, old_size, &patch, sink, token, nullptr, nullptr);
 }
 
 /*
@@ -48,208 +50,201 @@
  * file, and update the SHA context with the output data as well.
  * Return 0 on success.
  */
-int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
-                    const Value* patch,
-                    SinkFn sink, void* token, SHA_CTX* ctx,
-                    const Value* bonus_data) {
-    if (patch->data.size() < 12) {
-        printf("patch too short to contain header\n");
+int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size, const Value* patch,
+                    SinkFn sink, void* token, SHA_CTX* ctx, const Value* bonus_data) {
+  if (patch->data.size() < 12) {
+    printf("patch too short to contain header\n");
+    return -1;
+  }
+
+  // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
+  // (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
+  // CHUNK_GZIP.)
+  size_t pos = 12;
+  const char* header = &patch->data[0];
+  if (memcmp(header, "IMGDIFF2", 8) != 0) {
+    printf("corrupt patch file header (magic number)\n");
+    return -1;
+  }
+
+  int num_chunks = Read4(header + 8);
+
+  for (int i = 0; i < num_chunks; ++i) {
+    // each chunk's header record starts with 4 bytes.
+    if (pos + 4 > patch->data.size()) {
+      printf("failed to read chunk %d record\n", i);
+      return -1;
+    }
+    int type = Read4(&patch->data[pos]);
+    pos += 4;
+
+    if (type == CHUNK_NORMAL) {
+      const char* normal_header = &patch->data[pos];
+      pos += 24;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d normal header data\n", i);
         return -1;
-    }
+      }
 
-    // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
-    // (IMGDIFF1, which is no longer supported, used CHUNK_NORMAL and
-    // CHUNK_GZIP.)
-    size_t pos = 12;
-    const char* header = &patch->data[0];
-    if (memcmp(header, "IMGDIFF2", 8) != 0) {
-        printf("corrupt patch file header (magic number)\n");
+      size_t src_start = Read8(normal_header);
+      size_t src_len = Read8(normal_header + 8);
+      size_t patch_offset = Read8(normal_header + 16);
+
+      if (src_start + src_len > static_cast<size_t>(old_size)) {
+        printf("source data too short\n");
         return -1;
-    }
+      }
+      ApplyBSDiffPatch(old_data + src_start, src_len, patch, patch_offset, sink, token, ctx);
+    } else if (type == CHUNK_RAW) {
+      const char* raw_header = &patch->data[pos];
+      pos += 4;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d raw header data\n", i);
+        return -1;
+      }
 
-    int num_chunks = Read4(header+8);
+      ssize_t data_len = Read4(raw_header);
 
-    for (int i = 0; i < num_chunks; ++i) {
-        // each chunk's header record starts with 4 bytes.
-        if (pos + 4 > patch->data.size()) {
-            printf("failed to read chunk %d record\n", i);
-            return -1;
+      if (pos + data_len > patch->data.size()) {
+        printf("failed to read chunk %d raw data\n", i);
+        return -1;
+      }
+      if (ctx) SHA1_Update(ctx, &patch->data[pos], data_len);
+      if (sink(reinterpret_cast<const unsigned char*>(&patch->data[pos]), data_len, token) !=
+          data_len) {
+        printf("failed to write chunk %d raw data\n", i);
+        return -1;
+      }
+      pos += data_len;
+    } else if (type == CHUNK_DEFLATE) {
+      // deflate chunks have an additional 60 bytes in their chunk header.
+      const char* deflate_header = &patch->data[pos];
+      pos += 60;
+      if (pos > patch->data.size()) {
+        printf("failed to read chunk %d deflate header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = Read8(deflate_header);
+      size_t src_len = Read8(deflate_header + 8);
+      size_t patch_offset = Read8(deflate_header + 16);
+      size_t expanded_len = Read8(deflate_header + 24);
+      size_t target_len = Read8(deflate_header + 32);
+      int level = Read4(deflate_header + 40);
+      int method = Read4(deflate_header + 44);
+      int windowBits = Read4(deflate_header + 48);
+      int memLevel = Read4(deflate_header + 52);
+      int strategy = Read4(deflate_header + 56);
+
+      if (src_start + src_len > static_cast<size_t>(old_size)) {
+        printf("source data too short\n");
+        return -1;
+      }
+
+      // Decompress the source data; the chunk header tells us exactly
+      // how big we expect it to be when decompressed.
+
+      // Note: expanded_len will include the bonus data size if
+      // the patch was constructed with bonus data.  The
+      // deflation will come up 'bonus_size' bytes short; these
+      // must be appended from the bonus_data value.
+      size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->data.size() : 0;
+
+      std::vector<unsigned char> expanded_source(expanded_len);
+
+      // inflate() doesn't like strm.next_out being a nullptr even with
+      // avail_out being zero (Z_STREAM_ERROR).
+      if (expanded_len != 0) {
+        z_stream strm;
+        strm.zalloc = Z_NULL;
+        strm.zfree = Z_NULL;
+        strm.opaque = Z_NULL;
+        strm.avail_in = src_len;
+        strm.next_in = const_cast<unsigned char*>(old_data + src_start);
+        strm.avail_out = expanded_len;
+        strm.next_out = expanded_source.data();
+
+        int ret = inflateInit2(&strm, -15);
+        if (ret != Z_OK) {
+          printf("failed to init source inflation: %d\n", ret);
+          return -1;
         }
-        int type = Read4(&patch->data[pos]);
-        pos += 4;
 
-        if (type == CHUNK_NORMAL) {
-            const char* normal_header = &patch->data[pos];
-            pos += 24;
-            if (pos > patch->data.size()) {
-                printf("failed to read chunk %d normal header data\n", i);
-                return -1;
-            }
-
-            size_t src_start = Read8(normal_header);
-            size_t src_len = Read8(normal_header+8);
-            size_t patch_offset = Read8(normal_header+16);
-
-            if (src_start + src_len > static_cast<size_t>(old_size)) {
-                printf("source data too short\n");
-                return -1;
-            }
-            ApplyBSDiffPatch(old_data + src_start, src_len,
-                             patch, patch_offset, sink, token, ctx);
-        } else if (type == CHUNK_RAW) {
-            const char* raw_header = &patch->data[pos];
-            pos += 4;
-            if (pos > patch->data.size()) {
-                printf("failed to read chunk %d raw header data\n", i);
-                return -1;
-            }
-
-            ssize_t data_len = Read4(raw_header);
-
-            if (pos + data_len > patch->data.size()) {
-                printf("failed to read chunk %d raw data\n", i);
-                return -1;
-            }
-            if (ctx) SHA1_Update(ctx, &patch->data[pos], data_len);
-            if (sink(reinterpret_cast<const unsigned char*>(&patch->data[pos]),
-                     data_len, token) != data_len) {
-                printf("failed to write chunk %d raw data\n", i);
-                return -1;
-            }
-            pos += data_len;
-        } else if (type == CHUNK_DEFLATE) {
-            // deflate chunks have an additional 60 bytes in their chunk header.
-            const char* deflate_header = &patch->data[pos];
-            pos += 60;
-            if (pos > patch->data.size()) {
-                printf("failed to read chunk %d deflate header data\n", i);
-                return -1;
-            }
-
-            size_t src_start = Read8(deflate_header);
-            size_t src_len = Read8(deflate_header+8);
-            size_t patch_offset = Read8(deflate_header+16);
-            size_t expanded_len = Read8(deflate_header+24);
-            size_t target_len = Read8(deflate_header+32);
-            int level = Read4(deflate_header+40);
-            int method = Read4(deflate_header+44);
-            int windowBits = Read4(deflate_header+48);
-            int memLevel = Read4(deflate_header+52);
-            int strategy = Read4(deflate_header+56);
-
-            if (src_start + src_len > static_cast<size_t>(old_size)) {
-                printf("source data too short\n");
-                return -1;
-            }
-
-            // Decompress the source data; the chunk header tells us exactly
-            // how big we expect it to be when decompressed.
-
-            // Note: expanded_len will include the bonus data size if
-            // the patch was constructed with bonus data.  The
-            // deflation will come up 'bonus_size' bytes short; these
-            // must be appended from the bonus_data value.
-            size_t bonus_size = (i == 1 && bonus_data != NULL) ? bonus_data->data.size() : 0;
-
-            std::vector<unsigned char> expanded_source(expanded_len);
-
-            // inflate() doesn't like strm.next_out being a nullptr even with
-            // avail_out being zero (Z_STREAM_ERROR).
-            if (expanded_len != 0) {
-                z_stream strm;
-                strm.zalloc = Z_NULL;
-                strm.zfree = Z_NULL;
-                strm.opaque = Z_NULL;
-                strm.avail_in = src_len;
-                strm.next_in = (unsigned char*)(old_data + src_start);
-                strm.avail_out = expanded_len;
-                strm.next_out = expanded_source.data();
-
-                int ret;
-                ret = inflateInit2(&strm, -15);
-                if (ret != Z_OK) {
-                    printf("failed to init source inflation: %d\n", ret);
-                    return -1;
-                }
-
-                // Because we've provided enough room to accommodate the output
-                // data, we expect one call to inflate() to suffice.
-                ret = inflate(&strm, Z_SYNC_FLUSH);
-                if (ret != Z_STREAM_END) {
-                    printf("source inflation returned %d\n", ret);
-                    return -1;
-                }
-                // We should have filled the output buffer exactly, except
-                // for the bonus_size.
-                if (strm.avail_out != bonus_size) {
-                    printf("source inflation short by %zu bytes\n", strm.avail_out-bonus_size);
-                    return -1;
-                }
-                inflateEnd(&strm);
-
-                if (bonus_size) {
-                    memcpy(expanded_source.data() + (expanded_len - bonus_size),
-                           &bonus_data->data[0], bonus_size);
-                }
-            }
-
-            // Next, apply the bsdiff patch (in memory) to the uncompressed
-            // data.
-            std::vector<unsigned char> uncompressed_target_data;
-            if (ApplyBSDiffPatchMem(expanded_source.data(), expanded_len,
-                                    patch, patch_offset,
-                                    &uncompressed_target_data) != 0) {
-                return -1;
-            }
-            if (uncompressed_target_data.size() != target_len) {
-                printf("expected target len to be %zu, but it's %zu\n",
-                       target_len, uncompressed_target_data.size());
-                return -1;
-            }
-
-            // Now compress the target data and append it to the output.
-
-            // we're done with the expanded_source data buffer, so we'll
-            // reuse that memory to receive the output of deflate.
-            if (expanded_source.size() < 32768U) {
-                expanded_source.resize(32768U);
-            }
-
-            {
-                std::vector<unsigned char>& temp_data = expanded_source;
-
-                // now the deflate stream
-                z_stream strm;
-                strm.zalloc = Z_NULL;
-                strm.zfree = Z_NULL;
-                strm.opaque = Z_NULL;
-                strm.avail_in = uncompressed_target_data.size();
-                strm.next_in = uncompressed_target_data.data();
-                int ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
-                if (ret != Z_OK) {
-                    printf("failed to init uncompressed data deflation: %d\n", ret);
-                    return -1;
-                }
-                do {
-                    strm.avail_out = temp_data.size();
-                    strm.next_out = temp_data.data();
-                    ret = deflate(&strm, Z_FINISH);
-                    ssize_t have = temp_data.size() - strm.avail_out;
-
-                    if (sink(temp_data.data(), have, token) != have) {
-                        printf("failed to write %zd compressed bytes to output\n",
-                               have);
-                        return -1;
-                    }
-                    if (ctx) SHA1_Update(ctx, temp_data.data(), have);
-                } while (ret != Z_STREAM_END);
-                deflateEnd(&strm);
-            }
-        } else {
-            printf("patch chunk %d is unknown type %d\n", i, type);
-            return -1;
+        // Because we've provided enough room to accommodate the output
+        // data, we expect one call to inflate() to suffice.
+        ret = inflate(&strm, Z_SYNC_FLUSH);
+        if (ret != Z_STREAM_END) {
+          printf("source inflation returned %d\n", ret);
+          return -1;
         }
-    }
+        // We should have filled the output buffer exactly, except
+        // for the bonus_size.
+        if (strm.avail_out != bonus_size) {
+          printf("source inflation short by %zu bytes\n", strm.avail_out - bonus_size);
+          return -1;
+        }
+        inflateEnd(&strm);
 
-    return 0;
+        if (bonus_size) {
+          memcpy(expanded_source.data() + (expanded_len - bonus_size), &bonus_data->data[0],
+                 bonus_size);
+        }
+      }
+
+      // Next, apply the bsdiff patch (in memory) to the uncompressed data.
+      std::vector<unsigned char> uncompressed_target_data;
+      if (ApplyBSDiffPatchMem(expanded_source.data(), expanded_len, patch, patch_offset,
+                              &uncompressed_target_data) != 0) {
+        return -1;
+      }
+      if (uncompressed_target_data.size() != target_len) {
+        printf("expected target len to be %zu, but it's %zu\n", target_len,
+               uncompressed_target_data.size());
+        return -1;
+      }
+
+      // Now compress the target data and append it to the output.
+
+      // we're done with the expanded_source data buffer, so we'll
+      // reuse that memory to receive the output of deflate.
+      if (expanded_source.size() < 32768U) {
+        expanded_source.resize(32768U);
+      }
+
+      {
+        std::vector<unsigned char>& temp_data = expanded_source;
+
+        // now the deflate stream
+        z_stream strm;
+        strm.zalloc = Z_NULL;
+        strm.zfree = Z_NULL;
+        strm.opaque = Z_NULL;
+        strm.avail_in = uncompressed_target_data.size();
+        strm.next_in = uncompressed_target_data.data();
+        int ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
+        if (ret != Z_OK) {
+          printf("failed to init uncompressed data deflation: %d\n", ret);
+          return -1;
+        }
+        do {
+          strm.avail_out = temp_data.size();
+          strm.next_out = temp_data.data();
+          ret = deflate(&strm, Z_FINISH);
+          ssize_t have = temp_data.size() - strm.avail_out;
+
+          if (sink(temp_data.data(), have, token) != have) {
+            printf("failed to write %zd compressed bytes to output\n", have);
+            return -1;
+          }
+          if (ctx) SHA1_Update(ctx, temp_data.data(), have);
+        } while (ret != Z_STREAM_END);
+        deflateEnd(&strm);
+      }
+    } else {
+      printf("patch chunk %d is unknown type %d\n", i, type);
+      return -1;
+    }
+  }
+
+  return 0;
 }
diff --git a/applypatch/imgdiff.h b/applypatch/include/applypatch/imgdiff.h
similarity index 69%
rename from applypatch/imgdiff.h
rename to applypatch/include/applypatch/imgdiff.h
index f2069b4..22cbd4f 100644
--- a/applypatch/imgdiff.h
+++ b/applypatch/include/applypatch/imgdiff.h
@@ -14,17 +14,26 @@
  * limitations under the License.
  */
 
+#ifndef _APPLYPATCH_IMGDIFF_H
+#define _APPLYPATCH_IMGDIFF_H
+
+#include <stddef.h>
+
 // Image patch chunk types
-#define CHUNK_NORMAL   0
-#define CHUNK_GZIP     1   // version 1 only
-#define CHUNK_DEFLATE  2   // version 2 only
-#define CHUNK_RAW      3   // version 2 only
+#define CHUNK_NORMAL 0
+#define CHUNK_GZIP 1     // version 1 only
+#define CHUNK_DEFLATE 2  // version 2 only
+#define CHUNK_RAW 3      // version 2 only
 
 // The gzip header size is actually variable, but we currently don't
 // support gzipped data with any of the optional fields, so for now it
 // will always be ten bytes.  See RFC 1952 for the definition of the
 // gzip format.
-#define GZIP_HEADER_LEN   10
+static constexpr size_t GZIP_HEADER_LEN = 10;
 
 // The gzip footer size really is fixed.
-#define GZIP_FOOTER_LEN   8
+static constexpr size_t GZIP_FOOTER_LEN = 8;
+
+int imgdiff(int argc, const char** argv);
+
+#endif  // _APPLYPATCH_IMGDIFF_H
diff --git a/applypatch/include/applypatch/imgpatch.h b/applypatch/include/applypatch/imgpatch.h
index 64d9aa9..6549f79 100644
--- a/applypatch/include/applypatch/imgpatch.h
+++ b/applypatch/include/applypatch/imgpatch.h
@@ -14,13 +14,15 @@
  * limitations under the License.
  */
 
-#ifndef _IMGPATCH_H
-#define _IMGPATCH_H
+#ifndef _APPLYPATCH_IMGPATCH_H
+#define _APPLYPATCH_IMGPATCH_H
 
-typedef ssize_t (*SinkFn)(const unsigned char*, ssize_t, void*);
+#include <sys/types.h>
+
+using SinkFn = ssize_t (*)(const unsigned char*, ssize_t, void*);
 
 int ApplyImagePatch(const unsigned char* old_data, ssize_t old_size,
                     const unsigned char* patch_data, ssize_t patch_size,
                     SinkFn sink, void* token);
 
-#endif  //_IMGPATCH_H
+#endif  // _APPLYPATCH_IMGPATCH_H
diff --git a/tests/Android.mk b/tests/Android.mk
index 8ae52d7..ec725d8 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -63,6 +63,7 @@
     component/applypatch_test.cpp \
     component/bootloader_message_test.cpp \
     component/edify_test.cpp \
+    component/imgdiff_test.cpp \
     component/uncrypt_test.cpp \
     component/updater_test.cpp \
     component/verifier_test.cpp
@@ -81,6 +82,9 @@
     libapplypatch_modes \
     libapplypatch \
     libedify \
+    libimgdiff \
+    libimgpatch \
+    libbsdiff \
     libotafault \
     libupdater \
     libbootloader_message \
@@ -88,6 +92,8 @@
     libminui \
     libotautil \
     libmounts \
+    libdivsufsort \
+    libdivsufsort64 \
     libfs_mgr \
     liblog \
     libselinux \
@@ -128,3 +134,26 @@
 LOCAL_PICKUP_FILES := $(testdata_continuous_zip_prefix)
 
 include $(BUILD_NATIVE_TEST)
+
+# Host tests
+include $(CLEAR_VARS)
+LOCAL_CFLAGS := -Werror
+LOCAL_MODULE := recovery_host_test
+LOCAL_MODULE_HOST_OS := linux
+LOCAL_C_INCLUDES := bootable/recovery
+LOCAL_SRC_FILES := \
+    component/imgdiff_test.cpp
+LOCAL_STATIC_LIBRARIES := \
+    libimgdiff \
+    libimgpatch \
+    libbsdiff \
+    libziparchive \
+    libbase \
+    libcrypto \
+    libbz \
+    libdivsufsort64 \
+    libdivsufsort \
+    libz
+LOCAL_SHARED_LIBRARIES := \
+    liblog
+include $(BUILD_HOST_NATIVE_TEST)
diff --git a/tests/component/imgdiff_test.cpp b/tests/component/imgdiff_test.cpp
new file mode 100644
index 0000000..3711859
--- /dev/null
+++ b/tests/component/imgdiff_test.cpp
@@ -0,0 +1,448 @@
+/*
+ * Copyright (C) 2016 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 <string>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/test_utils.h>
+#include <applypatch/imgdiff.h>
+#include <applypatch/imgpatch.h>
+#include <gtest/gtest.h>
+#include <ziparchive/zip_writer.h>
+
+#include "applypatch/utils.h"
+
+static ssize_t MemorySink(const unsigned char* data, ssize_t len, void* token) {
+  std::string* s = static_cast<std::string*>(token);
+  s->append(reinterpret_cast<const char*>(data), len);
+  return len;
+}
+
+// Sanity check for the given imgdiff patch header.
+static void verify_patch_header(const std::string& patch, size_t* num_normal, size_t* num_raw,
+                                size_t* num_deflate) {
+  const size_t size = patch.size();
+  const char* data = patch.data();
+
+  ASSERT_GE(size, 12U);
+  ASSERT_EQ("IMGDIFF2", std::string(data, 8));
+
+  const int num_chunks = Read4(data + 8);
+  ASSERT_GE(num_chunks, 0);
+
+  size_t normal = 0;
+  size_t raw = 0;
+  size_t deflate = 0;
+
+  size_t pos = 12;
+  for (int i = 0; i < num_chunks; ++i) {
+    ASSERT_LE(pos + 4, size);
+    int type = Read4(data + pos);
+    pos += 4;
+    if (type == CHUNK_NORMAL) {
+      pos += 24;
+      ASSERT_LE(pos, size);
+      normal++;
+    } else if (type == CHUNK_RAW) {
+      ASSERT_LE(pos + 4, size);
+      ssize_t data_len = Read4(data + pos);
+      ASSERT_GT(data_len, 0);
+      pos += 4 + data_len;
+      ASSERT_LE(pos, size);
+      raw++;
+    } else if (type == CHUNK_DEFLATE) {
+      pos += 60;
+      ASSERT_LE(pos, size);
+      deflate++;
+    } else {
+      FAIL() << "Invalid patch type: " << type;
+    }
+  }
+
+  if (num_normal != nullptr) *num_normal = normal;
+  if (num_raw != nullptr) *num_raw = raw;
+  if (num_deflate != nullptr) *num_deflate = deflate;
+}
+
+TEST(ImgdiffTest, invalid_args) {
+  // Insufficient inputs.
+  ASSERT_EQ(2, imgdiff(1, (const char* []){ "imgdiff" }));
+  ASSERT_EQ(2, imgdiff(2, (const char* []){ "imgdiff", "-z" }));
+  ASSERT_EQ(2, imgdiff(2, (const char* []){ "imgdiff", "-b" }));
+  ASSERT_EQ(2, imgdiff(3, (const char* []){ "imgdiff", "-z", "-b" }));
+
+  // Failed to read bonus file.
+  ASSERT_EQ(1, imgdiff(3, (const char* []){ "imgdiff", "-b", "doesntexist" }));
+
+  // Failed to read input files.
+  ASSERT_EQ(1, imgdiff(4, (const char* []){ "imgdiff", "doesntexist", "doesntexist", "output" }));
+  ASSERT_EQ(
+      1, imgdiff(5, (const char* []){ "imgdiff", "-z", "doesntexist", "doesntexist", "output" }));
+}
+
+TEST(ImgdiffTest, image_mode_smoke) {
+  // Random bytes.
+  const std::string src("abcdefg");
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  const std::string tgt("abcdefgxyz");
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect one CHUNK_RAW entry.
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(0U, num_deflate);
+  ASSERT_EQ(1U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, zip_mode_smoke_store) {
+  // Construct src and tgt zip files.
+  TemporaryFile src_file;
+  FILE* src_file_ptr = fdopen(src_file.fd, "wb");
+  ZipWriter src_writer(src_file_ptr);
+  ASSERT_EQ(0, src_writer.StartEntry("file1.txt", 0));  // Store mode.
+  const std::string src_content("abcdefg");
+  ASSERT_EQ(0, src_writer.WriteBytes(src_content.data(), src_content.size()));
+  ASSERT_EQ(0, src_writer.FinishEntry());
+  ASSERT_EQ(0, src_writer.Finish());
+  ASSERT_EQ(0, fclose(src_file_ptr));
+
+  TemporaryFile tgt_file;
+  FILE* tgt_file_ptr = fdopen(tgt_file.fd, "wb");
+  ZipWriter tgt_writer(tgt_file_ptr);
+  ASSERT_EQ(0, tgt_writer.StartEntry("file1.txt", 0));  // Store mode.
+  const std::string tgt_content("abcdefgxyz");
+  ASSERT_EQ(0, tgt_writer.WriteBytes(tgt_content.data(), tgt_content.size()));
+  ASSERT_EQ(0, tgt_writer.FinishEntry());
+  ASSERT_EQ(0, tgt_writer.Finish());
+  ASSERT_EQ(0, fclose(tgt_file_ptr));
+
+  // Compute patch.
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", "-z", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string tgt;
+  ASSERT_TRUE(android::base::ReadFileToString(tgt_file.path, &tgt));
+  std::string src;
+  ASSERT_TRUE(android::base::ReadFileToString(src_file.path, &src));
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect one CHUNK_RAW entry.
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(0U, num_deflate);
+  ASSERT_EQ(1U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, zip_mode_smoke_compressed) {
+  // Construct src and tgt zip files.
+  TemporaryFile src_file;
+  FILE* src_file_ptr = fdopen(src_file.fd, "wb");
+  ZipWriter src_writer(src_file_ptr);
+  ASSERT_EQ(0, src_writer.StartEntry("file1.txt", ZipWriter::kCompress));
+  const std::string src_content("abcdefg");
+  ASSERT_EQ(0, src_writer.WriteBytes(src_content.data(), src_content.size()));
+  ASSERT_EQ(0, src_writer.FinishEntry());
+  ASSERT_EQ(0, src_writer.Finish());
+  ASSERT_EQ(0, fclose(src_file_ptr));
+
+  TemporaryFile tgt_file;
+  FILE* tgt_file_ptr = fdopen(tgt_file.fd, "wb");
+  ZipWriter tgt_writer(tgt_file_ptr);
+  ASSERT_EQ(0, tgt_writer.StartEntry("file1.txt", ZipWriter::kCompress));
+  const std::string tgt_content("abcdefgxyz");
+  ASSERT_EQ(0, tgt_writer.WriteBytes(tgt_content.data(), tgt_content.size()));
+  ASSERT_EQ(0, tgt_writer.FinishEntry());
+  ASSERT_EQ(0, tgt_writer.Finish());
+  ASSERT_EQ(0, fclose(tgt_file_ptr));
+
+  // Compute patch.
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", "-z", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string tgt;
+  ASSERT_TRUE(android::base::ReadFileToString(tgt_file.path, &tgt));
+  std::string src;
+  ASSERT_TRUE(android::base::ReadFileToString(src_file.path, &src));
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect three entries: CHUNK_RAW (header) + CHUNK_DEFLATE (data) + CHUNK_RAW (footer).
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(1U, num_deflate);
+  ASSERT_EQ(2U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, image_mode_simple) {
+  // src: "abcdefgh" + gzipped "xyz" (echo -n "xyz" | gzip -f | hd).
+  const std::vector<char> src_data = { 'a',    'b',    'c',    'd',    'e',    'f',    'g',
+                                       'h',    '\x1f', '\x8b', '\x08', '\x00', '\xc4', '\x1e',
+                                       '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8', '\xac',
+                                       '\x02', '\x00', '\x67', '\xba', '\x8e', '\xeb', '\x03',
+                                       '\x00', '\x00', '\x00' };
+  const std::string src(src_data.cbegin(), src_data.cend());
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  // tgt: "abcdefgxyz" + gzipped "xxyyzz".
+  const std::vector<char> tgt_data = {
+    'a',    'b',    'c',    'd',    'e',    'f',    'g',    'x',    'y',    'z',    '\x1f', '\x8b',
+    '\x08', '\x00', '\x62', '\x1f', '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8', '\xa8', '\xac',
+    '\xac', '\xaa', '\x02', '\x00', '\x96', '\x30', '\x06', '\xb7', '\x06', '\x00', '\x00', '\x00'
+  };
+  const std::string tgt(tgt_data.cbegin(), tgt_data.cend());
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect three entries: CHUNK_RAW (header) + CHUNK_DEFLATE (data) + CHUNK_RAW (footer).
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(1U, num_deflate);
+  ASSERT_EQ(2U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, image_mode_different_num_chunks) {
+  // src: "abcdefgh" + gzipped "xyz" (echo -n "xyz" | gzip -f | hd) + gzipped "test".
+  const std::vector<char> src_data = {
+    'a',    'b',    'c',    'd',    'e',    'f',    'g',    'h',    '\x1f', '\x8b', '\x08',
+    '\x00', '\xc4', '\x1e', '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8', '\xac', '\x02',
+    '\x00', '\x67', '\xba', '\x8e', '\xeb', '\x03', '\x00', '\x00', '\x00', '\x1f', '\x8b',
+    '\x08', '\x00', '\xb2', '\x3a', '\x53', '\x58', '\x00', '\x03', '\x2b', '\x49', '\x2d',
+    '\x2e', '\x01', '\x00', '\x0c', '\x7e', '\x7f', '\xd8', '\x04', '\x00', '\x00', '\x00'
+  };
+  const std::string src(src_data.cbegin(), src_data.cend());
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  // tgt: "abcdefgxyz" + gzipped "xxyyzz".
+  const std::vector<char> tgt_data = {
+    'a',    'b',    'c',    'd',    'e',    'f',    'g',    'x',    'y',    'z',    '\x1f', '\x8b',
+    '\x08', '\x00', '\x62', '\x1f', '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8', '\xa8', '\xac',
+    '\xac', '\xaa', '\x02', '\x00', '\x96', '\x30', '\x06', '\xb7', '\x06', '\x00', '\x00', '\x00'
+  };
+  const std::string tgt(tgt_data.cbegin(), tgt_data.cend());
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(1, imgdiff(args.size(), args.data()));
+}
+
+TEST(ImgdiffTest, image_mode_merge_chunks) {
+  // src: "abcdefgh" + gzipped "xyz" (echo -n "xyz" | gzip -f | hd).
+  const std::vector<char> src_data = { 'a',    'b',    'c',    'd',    'e',    'f',    'g',
+                                       'h',    '\x1f', '\x8b', '\x08', '\x00', '\xc4', '\x1e',
+                                       '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8', '\xac',
+                                       '\x02', '\x00', '\x67', '\xba', '\x8e', '\xeb', '\x03',
+                                       '\x00', '\x00', '\x00' };
+  const std::string src(src_data.cbegin(), src_data.cend());
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  // tgt: gzipped "xyz" + "abcdefgh".
+  const std::vector<char> tgt_data = {
+    '\x1f', '\x8b', '\x08', '\x00', '\x62', '\x1f', '\x53', '\x58', '\x00', '\x03', '\xab', '\xa8',
+    '\xa8', '\xac', '\xac', '\xaa', '\x02', '\x00', '\x96', '\x30', '\x06', '\xb7', '\x06', '\x00',
+    '\x00', '\x00', 'a',    'b',    'c',    'd',    'e',    'f',    'g',    'x',    'y',    'z'
+  };
+  const std::string tgt(tgt_data.cbegin(), tgt_data.cend());
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  // Since a gzipped entry will become CHUNK_RAW (header) + CHUNK_DEFLATE (data) +
+  // CHUNK_RAW (footer), they both should contain the same chunk types after merging.
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect three entries: CHUNK_RAW (header) + CHUNK_DEFLATE (data) + CHUNK_RAW (footer).
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(1U, num_deflate);
+  ASSERT_EQ(2U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, image_mode_spurious_magic) {
+  // src: "abcdefgh" + '0x1f8b0b00' + some bytes.
+  const std::vector<char> src_data = { 'a',    'b',    'c',    'd',    'e',    'f',    'g',
+                                       'h',    '\x1f', '\x8b', '\x08', '\x00', '\xc4', '\x1e',
+                                       '\x53', '\x58', 't',    'e',    's',    't' };
+  const std::string src(src_data.cbegin(), src_data.cend());
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  // tgt: "abcdefgxyz".
+  const std::vector<char> tgt_data = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'x', 'y', 'z' };
+  const std::string tgt(tgt_data.cbegin(), tgt_data.cend());
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect one CHUNK_RAW (header) entry.
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(0U, num_normal);
+  ASSERT_EQ(0U, num_deflate);
+  ASSERT_EQ(1U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}
+
+TEST(ImgdiffTest, image_mode_single_entry_long) {
+  // src: "abcdefgh" + '0x1f8b0b00' + some bytes.
+  const std::vector<char> src_data = { 'a',    'b',    'c',    'd',    'e',    'f',    'g',
+                                       'h',    '\x1f', '\x8b', '\x08', '\x00', '\xc4', '\x1e',
+                                       '\x53', '\x58', 't',    'e',    's',    't' };
+  const std::string src(src_data.cbegin(), src_data.cend());
+  TemporaryFile src_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(src, src_file.path));
+
+  // tgt: "abcdefgxyz" + 200 bytes.
+  std::vector<char> tgt_data = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'x', 'y', 'z' };
+  tgt_data.resize(tgt_data.size() + 200);
+
+  const std::string tgt(tgt_data.cbegin(), tgt_data.cend());
+  TemporaryFile tgt_file;
+  ASSERT_TRUE(android::base::WriteStringToFile(tgt, tgt_file.path));
+
+  TemporaryFile patch_file;
+  std::vector<const char*> args = {
+    "imgdiff", src_file.path, tgt_file.path, patch_file.path,
+  };
+  ASSERT_EQ(0, imgdiff(args.size(), args.data()));
+
+  // Verify.
+  std::string patch;
+  ASSERT_TRUE(android::base::ReadFileToString(patch_file.path, &patch));
+
+  // Expect one CHUNK_NORMAL entry, since it's exceeding the 160-byte limit for RAW.
+  size_t num_normal;
+  size_t num_raw;
+  size_t num_deflate;
+  verify_patch_header(patch, &num_normal, &num_raw, &num_deflate);
+  ASSERT_EQ(1U, num_normal);
+  ASSERT_EQ(0U, num_deflate);
+  ASSERT_EQ(0U, num_raw);
+
+  std::string patched;
+  ASSERT_EQ(0, ApplyImagePatch(reinterpret_cast<const unsigned char*>(src.data()), src.size(),
+                               reinterpret_cast<const unsigned char*>(patch.data()), patch.size(),
+                               MemorySink, &patched));
+  ASSERT_EQ(tgt, patched);
+}