15 files changed, 798 insertions, 35 deletions

diff --git a/otautil/Android.bp b/otautil/Android.bp
index 0b2314374..a109d39b6 100644
--- a/otautil/Android.bp
+++ b/otautil/Android.bp
@@ -15,11 +15,15 @@
 cc_library_static {
     name: "libotautil",
 
+    host_supported: true,
+
     srcs: [
         "SysUtil.cpp",
         "DirUtil.cpp",
         "ZipUtil.cpp",
         "ThermalUtil.cpp",
+        "cache_location.cpp",
+        "rangeset.cpp",
     ],
 
     static_libs: [
@@ -28,7 +32,12 @@ cc_library_static {
     ],
 
     cflags: [
+        "-D_FILE_OFFSET_BITS=64",
         "-Werror",
         "-Wall",
     ],
+
+    export_include_dirs: [
+        "include",
+    ],
 }
diff --git a/otautil/Android.mk b/otautil/Android.mk
index 45e0f765d..feb468de5 100644
--- a/otautil/Android.mk
+++ b/otautil/Android.mk
@@ -36,4 +36,6 @@ LOCAL_CFLAGS := \
     -Werror \
     -Wall
 
+LOCAL_C_INCLUDES := include
+
 include $(BUILD_STATIC_LIBRARY)
diff --git a/otautil/DirUtil.cpp b/otautil/DirUtil.cpp
index e08e360c0..8d364b74f 100644
--- a/otautil/DirUtil.cpp
+++ b/otautil/DirUtil.cpp
@@ -14,24 +14,107 @@
  * limitations under the License.
  */
 
-#include "DirUtil.h"
+#include "otautil/DirUtil.h"
 
+#include <dirent.h>
+#include <errno.h>
 #include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/types.h>
 #include <unistd.h>
-#include <errno.h>
-#include <dirent.h>
-#include <limits.h>
+#include <utime.h>
 
 #include <string>
 
 #include <selinux/label.h>
 #include <selinux/selinux.h>
 
-typedef enum { DMISSING, DDIR, DILLEGAL } DirStatus;
+enum class DirStatus { DMISSING, DDIR, DILLEGAL };
+
+static DirStatus dir_status(const std::string& path) {
+  struct stat sb;
+  if (stat(path.c_str(), &sb) == 0) {
+    // Something's there; make sure it's a directory.
+    if (S_ISDIR(sb.st_mode)) {
+      return DirStatus::DDIR;
+    }
+    errno = ENOTDIR;
+    return DirStatus::DILLEGAL;
+  } else if (errno != ENOENT) {
+    // Something went wrong, or something in the path is bad. Can't do anything in this situation.
+    return DirStatus::DILLEGAL;
+  }
+  return DirStatus::DMISSING;
+}
+
+int mkdir_recursively(const std::string& input_path, mode_t mode, bool strip_filename,
+                      const selabel_handle* sehnd) {
+  // Check for an empty string before we bother making any syscalls.
+  if (input_path.empty()) {
+    errno = ENOENT;
+    return -1;
+  }
+
+  // Allocate a path that we can modify; stick a slash on the end to make things easier.
+  std::string path = input_path;
+  if (strip_filename) {
+    // Strip everything after the last slash.
+    size_t pos = path.rfind('/');
+    if (pos == std::string::npos) {
+      errno = ENOENT;
+      return -1;
+    }
+    path.resize(pos + 1);
+  } else {
+    // Make sure that the path ends in a slash.
+    path.push_back('/');
+  }
+
+  // See if it already exists.
+  DirStatus ds = dir_status(path);
+  if (ds == DirStatus::DDIR) {
+    return 0;
+  } else if (ds == DirStatus::DILLEGAL) {
+    return -1;
+  }
+
+  // Walk up the path from the root and make each level.
+  size_t prev_end = 0;
+  while (prev_end < path.size()) {
+    size_t next_end = path.find('/', prev_end + 1);
+    if (next_end == std::string::npos) {
+      break;
+    }
+    std::string dir_path = path.substr(0, next_end);
+    // Check this part of the path and make a new directory if necessary.
+    switch (dir_status(dir_path)) {
+      case DirStatus::DILLEGAL:
+        // Could happen if some other process/thread is messing with the filesystem.
+        return -1;
+      case DirStatus::DMISSING: {
+        char* secontext = nullptr;
+        if (sehnd) {
+          selabel_lookup(const_cast<selabel_handle*>(sehnd), &secontext, dir_path.c_str(), mode);
+          setfscreatecon(secontext);
+        }
+        int err = mkdir(dir_path.c_str(), mode);
+        if (secontext) {
+          freecon(secontext);
+          setfscreatecon(nullptr);
+        }
+        if (err != 0) {
+          return -1;
+        }
+        break;
+      }
+      default:
+        // Already exists.
+        break;
+    }
+    prev_end = next_end;
+  }
+  return 0;
+}
 
 static DirStatus
 getPathDirStatus(const char *path)
@@ -44,17 +127,17 @@ getPathDirStatus(const char *path)
         /* Something's there; make sure it's a directory.
          */
         if (S_ISDIR(st.st_mode)) {
-            return DDIR;
+            return DirStatus::DDIR;
         }
         errno = ENOTDIR;
-        return DILLEGAL;
+        return DirStatus::DILLEGAL;
     } else if (errno != ENOENT) {
         /* Something went wrong, or something in the path
          * is bad.  Can't do anything in this situation.
          */
-        return DILLEGAL;
+        return DirStatus::DILLEGAL;
     }
-    return DMISSING;
+    return DirStatus::DMISSING;
 }
 
 int
@@ -90,9 +173,9 @@ dirCreateHierarchy(const char *path, int mode,
     /* See if it already exists.
      */
     ds = getPathDirStatus(cpath.c_str());
-    if (ds == DDIR) {
+    if (ds == DirStatus::DDIR) {
         return 0;
-    } else if (ds == DILLEGAL) {
+    } else if (ds == DirStatus::DILLEGAL) {
         return -1;
     }
 
@@ -124,12 +207,12 @@ dirCreateHierarchy(const char *path, int mode,
          * if necessary.
          */
         ds = getPathDirStatus(path_start);
-        if (ds == DILLEGAL) {
+        if (ds == DirStatus::DILLEGAL) {
             /* Could happen if some other process/thread is
              * messing with the filesystem.
              */
             return -1;
-        } else if (ds == DMISSING) {
+        } else if (ds == DirStatus::DMISSING) {
             int err;
 
             char *secontext = NULL;
diff --git a/otautil/SysUtil.cpp b/otautil/SysUtil.cpp
index dfa215073..48336ad07 100644
--- a/otautil/SysUtil.cpp
+++ b/otautil/SysUtil.cpp
@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-#include "SysUtil.h"
+#include "otautil/SysUtil.h"
 
+#include <errno.h>  // TEMP_FAILURE_RETRY
 #include <fcntl.h>
 #include <stdint.h>  // SIZE_MAX
 #include <sys/mman.h>
@@ -100,7 +101,7 @@ bool MemMapping::MapBlockFile(const std::string& filename) {
   }
 
   // Reserve enough contiguous address space for the whole file.
-  void* reserve = mmap64(nullptr, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+  void* reserve = mmap(nullptr, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
   if (reserve == MAP_FAILED) {
     PLOG(ERROR) << "failed to reserve address space";
     return false;
@@ -135,8 +136,8 @@ bool MemMapping::MapBlockFile(const std::string& filename) {
       break;
     }
 
-    void* range_start = mmap64(next, range_size, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd,
-                               static_cast<off64_t>(start) * blksize);
+    void* range_start = mmap(next, range_size, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd,
+                             static_cast<off_t>(start) * blksize);
     if (range_start == MAP_FAILED) {
       PLOG(ERROR) << "failed to map range " << i << ": " << line;
       success = false;
diff --git a/otautil/ThermalUtil.cpp b/otautil/ThermalUtil.cpp
index 13d36432a..5d9bd45c0 100644
--- a/otautil/ThermalUtil.cpp
+++ b/otautil/ThermalUtil.cpp
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "ThermalUtil.h"
+#include "otautil/ThermalUtil.h"
 
 #include <dirent.h>
 #include <stdio.h>
@@ -77,4 +77,4 @@ int GetMaxValueFromThermalZone() {
   }
   LOG(INFO) << "current maximum temperature: " << max_temperature;
   return max_temperature;
-}
\ No newline at end of file
+}
diff --git a/otautil/ZipUtil.cpp b/otautil/ZipUtil.cpp
index 714c956ed..a2d0cbac5 100644
--- a/otautil/ZipUtil.cpp
+++ b/otautil/ZipUtil.cpp
@@ -28,7 +28,7 @@
 #include <selinux/selinux.h>
 #include <ziparchive/zip_archive.h>
 
-#include "DirUtil.h"
+#include "otautil/DirUtil.h"
 
 static constexpr mode_t UNZIP_DIRMODE = 0755;
 static constexpr mode_t UNZIP_FILEMODE = 0644;
diff --git a/otautil/cache_location.cpp b/otautil/cache_location.cpp
new file mode 100644
index 000000000..8ddefec5e
--- /dev/null
+++ b/otautil/cache_location.cpp
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2018 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 "otautil/cache_location.h"
+
+constexpr const char kDefaultCacheTempSource[] = "/cache/saved.file";
+constexpr const char kDefaultLastCommandFile[] = "/cache/recovery/last_command";
+constexpr const char kDefaultStashDirectoryBase[] = "/cache/recovery";
+
+CacheLocation& CacheLocation::location() {
+  static CacheLocation cache_location;
+  return cache_location;
+}
+
+CacheLocation::CacheLocation()
+    : cache_temp_source_(kDefaultCacheTempSource),
+      last_command_file_(kDefaultLastCommandFile),
+      stash_directory_base_(kDefaultStashDirectoryBase) {}
diff --git a/otautil/DirUtil.h b/otautil/include/otautil/DirUtil.h
index 85b83c387..e3d021971 100644
--- a/otautil/DirUtil.h
+++ b/otautil/include/otautil/DirUtil.h
@@ -14,18 +14,28 @@
  * limitations under the License.
  */
 
-#ifndef MINZIP_DIRUTIL_H_
-#define MINZIP_DIRUTIL_H_
+#ifndef OTAUTIL_DIRUTIL_H_
+#define OTAUTIL_DIRUTIL_H_
 
-#include <stdbool.h>
-#include <utime.h>
+#include <sys/stat.h>  // mode_t
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+#include <string>
 
 struct selabel_handle;
 
+// Like "mkdir -p", try to guarantee that all directories specified in path are present, creating as
+// many directories as necessary. The specified mode is passed to all mkdir calls; no modifications
+// are made to umask.
+//
+// If strip_filename is set, everything after the final '/' is stripped before creating the
+// directory
+// hierarchy.
+//
+// Returns 0 on success; returns -1 (and sets errno) on failure (usually if some element of path is
+// not a directory).
+int mkdir_recursively(const std::string& path, mode_t mode, bool strip_filename,
+                      const struct selabel_handle* sehnd);
+
 /* Like "mkdir -p", try to guarantee that all directories
  * specified in path are present, creating as many directories
  * as necessary.  The specified mode is passed to all mkdir
@@ -47,8 +57,4 @@ int dirCreateHierarchy(const char *path, int mode,
  */
 int dirUnlinkHierarchy(const char *path);
 
-#ifdef __cplusplus
-}
-#endif
-
-#endif  // MINZIP_DIRUTIL_H_
+#endif  // OTAUTIL_DIRUTIL_H_
diff --git a/otautil/SysUtil.h b/otautil/include/otautil/SysUtil.h
index 52f6d20a7..52f6d20a7 100644
--- a/otautil/SysUtil.h
+++ b/otautil/include/otautil/SysUtil.h
diff --git a/otautil/ThermalUtil.h b/otautil/include/otautil/ThermalUtil.h
index 43ab55940..43ab55940 100644
--- a/otautil/ThermalUtil.h
+++ b/otautil/include/otautil/ThermalUtil.h
diff --git a/otautil/include/otautil/cache_location.h b/otautil/include/otautil/cache_location.h
new file mode 100644
index 000000000..f2f663816
--- /dev/null
+++ b/otautil/include/otautil/cache_location.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+#ifndef _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
+#define _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
+
+#include <string>
+
+#include "android-base/macros.h"
+
+// A singleton class to maintain the update related locations. The locations should be only set
+// once at the start of the program.
+class CacheLocation {
+ public:
+  static CacheLocation& location();
+
+  // getter and setter functions.
+  std::string cache_temp_source() const {
+    return cache_temp_source_;
+  }
+  void set_cache_temp_source(const std::string& temp_source) {
+    cache_temp_source_ = temp_source;
+  }
+
+  std::string last_command_file() const {
+    return last_command_file_;
+  }
+  void set_last_command_file(const std::string& last_command) {
+    last_command_file_ = last_command;
+  }
+
+  std::string stash_directory_base() const {
+    return stash_directory_base_;
+  }
+  void set_stash_directory_base(const std::string& base) {
+    stash_directory_base_ = base;
+  }
+
+ private:
+  CacheLocation();
+  DISALLOW_COPY_AND_ASSIGN(CacheLocation);
+
+  // When there isn't enough room on the target filesystem to hold the patched version of the file,
+  // we copy the original here and delete it to free up space.  If the expected source file doesn't
+  // exist, or is corrupted, we look to see if the cached file contains the bits we want and use it
+  // as the source instead.  The default location for the cached source is "/cache/saved.file".
+  std::string cache_temp_source_;
+
+  // Location to save the last command that stashes blocks.
+  std::string last_command_file_;
+
+  // The base directory to write stashes during update.
+  std::string stash_directory_base_;
+};
+
+#endif  // _OTAUTIL_OTAUTIL_CACHE_LOCATION_H_
diff --git a/otautil/include/otautil/error_code.h b/otautil/include/otautil/error_code.h
new file mode 100644
index 000000000..b0ff42d8d
--- /dev/null
+++ b/otautil/include/otautil/error_code.h
@@ -0,0 +1,78 @@
+/*
+ * 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.
+ */
+
+#ifndef _ERROR_CODE_H_
+#define _ERROR_CODE_H_
+
+enum ErrorCode : int {
+  kNoError = -1,
+  kLowBattery = 20,
+  kZipVerificationFailure,
+  kZipOpenFailure,
+  kBootreasonInBlacklist,
+  kPackageCompatibilityFailure,
+  kScriptExecutionFailure,
+  kMapFileFailure,
+  kForkUpdateBinaryFailure,
+  kUpdateBinaryCommandFailure,
+};
+
+enum CauseCode : int {
+  kNoCause = -1,
+  kArgsParsingFailure = 100,
+  kStashCreationFailure,
+  kFileOpenFailure,
+  kLseekFailure,
+  kFreadFailure,
+  kFwriteFailure,
+  kFsyncFailure,
+  kLibfecFailure,
+  kFileGetPropFailure,
+  kFileRenameFailure,
+  kSymlinkFailure,
+  kSetMetadataFailure,
+  kTune2FsFailure,
+  kRebootFailure,
+  kPackageExtractFileFailure,
+  kPatchApplicationFailure,
+  kVendorFailure = 200
+};
+
+enum UncryptErrorCode : int {
+  kUncryptNoError = -1,
+  kUncryptErrorPlaceholder = 50,
+  kUncryptTimeoutError = 100,
+  kUncryptFileRemoveError,
+  kUncryptFileOpenError,
+  kUncryptSocketOpenError,
+  kUncryptSocketWriteError,
+  kUncryptSocketListenError,
+  kUncryptSocketAcceptError,
+  kUncryptFstabReadError,
+  kUncryptFileStatError,
+  kUncryptBlockOpenError,
+  kUncryptIoctlError,
+  kUncryptReadError,
+  kUncryptWriteError,
+  kUncryptFileSyncError,
+  kUncryptFileCloseError,
+  kUncryptFileRenameError,
+  kUncryptPackageMissingError,
+  kUncryptRealpathFindError,
+  kUncryptBlockDeviceFindError,
+};
+
+#endif  // _ERROR_CODE_H_
diff --git a/otautil/include/otautil/print_sha1.h b/otautil/include/otautil/print_sha1.h
new file mode 100644
index 000000000..03a8d292a
--- /dev/null
+++ b/otautil/include/otautil/print_sha1.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef RECOVERY_PRINT_SHA1_H
+#define RECOVERY_PRINT_SHA1_H
+
+#include <stdint.h>
+#include <string>
+
+#include <openssl/sha.h>
+
+static std::string print_sha1(const uint8_t* sha1, size_t len) {
+  const char* hex = "0123456789abcdef";
+  std::string result = "";
+  for (size_t i = 0; i < len; ++i) {
+    result.push_back(hex[(sha1[i] >> 4) & 0xf]);
+    result.push_back(hex[sha1[i] & 0xf]);
+  }
+  return result;
+}
+
+[[maybe_unused]] static std::string print_sha1(const uint8_t sha1[SHA_DIGEST_LENGTH]) {
+  return print_sha1(sha1, SHA_DIGEST_LENGTH);
+}
+
+[[maybe_unused]] static std::string short_sha1(const uint8_t sha1[SHA_DIGEST_LENGTH]) {
+  return print_sha1(sha1, 4);
+}
+
+[[maybe_unused]] static std::string print_hex(const uint8_t* bytes, size_t len) {
+  return print_sha1(bytes, len);
+}
+
+#endif  // RECOVERY_PRINT_SHA1_H
diff --git a/otautil/include/otautil/rangeset.h b/otautil/include/otautil/rangeset.h
new file mode 100644
index 000000000..e91d02ca6
--- /dev/null
+++ b/otautil/include/otautil/rangeset.h
@@ -0,0 +1,170 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#include <string>
+#include <utility>
+#include <vector>
+
+using Range = std::pair<size_t, size_t>;
+
+class RangeSet {
+ public:
+  RangeSet() : blocks_(0) {}
+
+  explicit RangeSet(std::vector<Range>&& pairs);
+
+  // Parses the given string into a RangeSet. Returns the parsed RangeSet, or an empty RangeSet on
+  // errors.
+  static RangeSet Parse(const std::string& range_text);
+
+  // Appends the given Range to the current RangeSet.
+  bool PushBack(Range range);
+
+  // Clears all the ranges from the RangeSet.
+  void Clear();
+
+  std::string ToString() const;
+
+  // Gets the block number for the i-th (starting from 0) block in the RangeSet.
+  size_t GetBlockNumber(size_t idx) const;
+
+  // Returns whether the current RangeSet overlaps with other. RangeSet has half-closed half-open
+  // bounds. For example, "3,5" contains blocks 3 and 4. So "3,5" and "5,7" are not overlapped.
+  bool Overlaps(const RangeSet& other) const;
+
+  // Returns a vector of RangeSets that contain the same set of blocks represented by the current
+  // RangeSet. The RangeSets in the vector contain similar number of blocks, with a maximum delta
+  // of 1-block between any two of them. For example, 14 blocks would be split into 4 + 4 + 3 + 3,
+  // as opposed to 4 + 4 + 4 + 2. If the total number of blocks (T) is less than groups, it
+  // returns a vector of T 1-block RangeSets. Otherwise the number of the returned RangeSets must
+  // equal to groups. The current RangeSet remains intact after the split.
+  std::vector<RangeSet> Split(size_t groups) const;
+
+  // Returns the number of Range's in this RangeSet.
+  size_t size() const {
+    return ranges_.size();
+  }
+
+  // Returns the total number of blocks in this RangeSet.
+  size_t blocks() const {
+    return blocks_;
+  }
+
+  std::vector<Range>::const_iterator cbegin() const {
+    return ranges_.cbegin();
+  }
+
+  std::vector<Range>::const_iterator cend() const {
+    return ranges_.cend();
+  }
+
+  std::vector<Range>::iterator begin() {
+    return ranges_.begin();
+  }
+
+  std::vector<Range>::iterator end() {
+    return ranges_.end();
+  }
+
+  std::vector<Range>::const_iterator begin() const {
+    return ranges_.begin();
+  }
+
+  std::vector<Range>::const_iterator end() const {
+    return ranges_.end();
+  }
+
+  // Reverse const iterators for MoveRange().
+  std::vector<Range>::const_reverse_iterator crbegin() const {
+    return ranges_.crbegin();
+  }
+
+  std::vector<Range>::const_reverse_iterator crend() const {
+    return ranges_.crend();
+  }
+
+  // Returns whether the RangeSet is valid (i.e. non-empty).
+  explicit operator bool() const {
+    return !ranges_.empty();
+  }
+
+  const Range& operator[](size_t i) const {
+    return ranges_[i];
+  }
+
+  bool operator==(const RangeSet& other) const {
+    // The orders of Range's matter. "4,1,5,8,10" != "4,8,10,1,5".
+    return (ranges_ == other.ranges_);
+  }
+
+  bool operator!=(const RangeSet& other) const {
+    return ranges_ != other.ranges_;
+  }
+
+ protected:
+  // Actual limit for each value and the total number are both INT_MAX.
+  std::vector<Range> ranges_;
+  size_t blocks_;
+};
+
+// The class is a sorted version of a RangeSet; and it's useful in imgdiff to split the input
+// files when we're handling large zip files. Specifically, we can treat the input file as a
+// continuous RangeSet (i.e. RangeSet("0-99") for a 100 blocks file); and break it down into
+// several smaller chunks based on the zip entries.
+
+// For example, [source: 0-99] can be split into
+// [split_src1: 10-29]; [split_src2: 40-49, 60-69]; [split_src3: 70-89]
+// Here "10-29" simply means block 10th to block 29th with respect to the original input file.
+// Also, note that the split sources should be mutual exclusive, but they don't need to cover
+// every block in the original source.
+class SortedRangeSet : public RangeSet {
+ public:
+  // The block size when working with offset and file length.
+  static constexpr size_t kBlockSize = 4096;
+
+  SortedRangeSet() {}
+
+  // Ranges in the the set should be mutually exclusive; and they're sorted by the start block.
+  explicit SortedRangeSet(std::vector<Range>&& pairs);
+
+  void Insert(const Range& to_insert);
+
+  // Insert the input SortedRangeSet; keep the ranges sorted and merge the overlap ranges.
+  void Insert(const SortedRangeSet& rs);
+
+  // Compute the block range the file occupies, and insert that range.
+  void Insert(size_t start, size_t len);
+
+  using RangeSet::Overlaps;
+
+  bool Overlaps(size_t start, size_t len) const;
+
+  // Given an offset of the file, checks if the corresponding block (by considering the file as
+  // 0-based continuous block ranges) is covered by the SortedRangeSet. If so, returns the offset
+  // within this SortedRangeSet.
+  //
+  // For example, the 4106-th byte of a file is from block 1, assuming a block size of 4096-byte.
+  // The mapped offset within a SortedRangeSet("1-9 15-19") is 10.
+  //
+  // An offset of 65546 falls into the 16-th block in a file. Block 16 is contained as the 10-th
+  // item in SortedRangeSet("1-9 15-19"). So its data can be found at offset 40970 (i.e. 4096 * 10
+  // + 10) in a range represented by this SortedRangeSet.
+  size_t GetOffsetInRangeSet(size_t old_offset) const;
+};
diff --git a/otautil/rangeset.cpp b/otautil/rangeset.cpp
new file mode 100644
index 000000000..96955b9d0
--- /dev/null
+++ b/otautil/rangeset.cpp
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2017 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 "otautil/rangeset.h"
+
+#include <limits.h>
+#include <stddef.h>
+
+#include <algorithm>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/stringprintf.h>
+#include <android-base/strings.h>
+
+RangeSet::RangeSet(std::vector<Range>&& pairs) {
+  blocks_ = 0;
+  if (pairs.empty()) {
+    LOG(ERROR) << "Invalid number of tokens";
+    return;
+  }
+
+  for (const auto& range : pairs) {
+    if (!PushBack(range)) {
+      Clear();
+      return;
+    }
+  }
+}
+
+RangeSet RangeSet::Parse(const std::string& range_text) {
+  std::vector<std::string> pieces = android::base::Split(range_text, ",");
+  if (pieces.size() < 3) {
+    LOG(ERROR) << "Invalid range text: " << range_text;
+    return {};
+  }
+
+  size_t num;
+  if (!android::base::ParseUint(pieces[0], &num, static_cast<size_t>(INT_MAX))) {
+    LOG(ERROR) << "Failed to parse the number of tokens: " << range_text;
+    return {};
+  }
+  if (num == 0) {
+    LOG(ERROR) << "Invalid number of tokens: " << range_text;
+    return {};
+  }
+  if (num % 2 != 0) {
+    LOG(ERROR) << "Number of tokens must be even: " << range_text;
+    return {};
+  }
+  if (num != pieces.size() - 1) {
+    LOG(ERROR) << "Mismatching number of tokens: " << range_text;
+    return {};
+  }
+
+  std::vector<Range> pairs;
+  for (size_t i = 0; i < num; i += 2) {
+    size_t first;
+    size_t second;
+    if (!android::base::ParseUint(pieces[i + 1], &first, static_cast<size_t>(INT_MAX)) ||
+        !android::base::ParseUint(pieces[i + 2], &second, static_cast<size_t>(INT_MAX))) {
+      return {};
+    }
+    pairs.emplace_back(first, second);
+  }
+  return RangeSet(std::move(pairs));
+}
+
+bool RangeSet::PushBack(Range range) {
+  if (range.first >= range.second) {
+    LOG(ERROR) << "Empty or negative range: " << range.first << ", " << range.second;
+    return false;
+  }
+  size_t sz = range.second - range.first;
+  if (blocks_ >= SIZE_MAX - sz) {
+    LOG(ERROR) << "RangeSet size overflow";
+    return false;
+  }
+
+  ranges_.push_back(std::move(range));
+  blocks_ += sz;
+  return true;
+}
+
+void RangeSet::Clear() {
+  ranges_.clear();
+  blocks_ = 0;
+}
+
+std::vector<RangeSet> RangeSet::Split(size_t groups) const {
+  if (ranges_.empty() || groups == 0) return {};
+
+  if (blocks_ < groups) {
+    groups = blocks_;
+  }
+
+  // Evenly distribute blocks, with the first few groups possibly containing one more.
+  size_t mean = blocks_ / groups;
+  std::vector<size_t> blocks_per_group(groups, mean);
+  std::fill_n(blocks_per_group.begin(), blocks_ % groups, mean + 1);
+
+  std::vector<RangeSet> result;
+
+  // Forward iterate Ranges and fill up each group with the desired number of blocks.
+  auto it = ranges_.cbegin();
+  Range range = *it;
+  for (const auto& blocks : blocks_per_group) {
+    RangeSet buffer;
+    size_t needed = blocks;
+    while (needed > 0) {
+      size_t range_blocks = range.second - range.first;
+      if (range_blocks > needed) {
+        // Split the current range and don't advance the iterator.
+        buffer.PushBack({ range.first, range.first + needed });
+        range.first = range.first + needed;
+        break;
+      }
+      buffer.PushBack(range);
+      it++;
+      if (it != ranges_.cend()) {
+        range = *it;
+      }
+      needed -= range_blocks;
+    }
+    result.push_back(std::move(buffer));
+  }
+  return result;
+}
+
+std::string RangeSet::ToString() const {
+  if (ranges_.empty()) {
+    return "";
+  }
+  std::string result = std::to_string(ranges_.size() * 2);
+  for (const auto& r : ranges_) {
+    result += android::base::StringPrintf(",%zu,%zu", r.first, r.second);
+  }
+
+  return result;
+}
+
+// Get the block number for the i-th (starting from 0) block in the RangeSet.
+size_t RangeSet::GetBlockNumber(size_t idx) const {
+  CHECK_LT(idx, blocks_) << "Out of bound index " << idx << " (total blocks: " << blocks_ << ")";
+
+  for (const auto& range : ranges_) {
+    if (idx < range.second - range.first) {
+      return range.first + idx;
+    }
+    idx -= (range.second - range.first);
+  }
+
+  CHECK(false) << "Failed to find block number for index " << idx;
+  return 0;  // Unreachable, but to make compiler happy.
+}
+
+// RangeSet has half-closed half-open bounds. For example, "3,5" contains blocks 3 and 4. So "3,5"
+// and "5,7" are not overlapped.
+bool RangeSet::Overlaps(const RangeSet& other) const {
+  for (const auto& range : ranges_) {
+    size_t start = range.first;
+    size_t end = range.second;
+    for (const auto& other_range : other.ranges_) {
+      size_t other_start = other_range.first;
+      size_t other_end = other_range.second;
+      // [start, end) vs [other_start, other_end)
+      if (!(other_start >= end || start >= other_end)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+// Ranges in the the set should be mutually exclusive; and they're sorted by the start block.
+SortedRangeSet::SortedRangeSet(std::vector<Range>&& pairs) : RangeSet(std::move(pairs)) {
+  std::sort(ranges_.begin(), ranges_.end());
+}
+
+void SortedRangeSet::Insert(const Range& to_insert) {
+  SortedRangeSet rs({ to_insert });
+  Insert(rs);
+}
+
+// Insert the input SortedRangeSet; keep the ranges sorted and merge the overlap ranges.
+void SortedRangeSet::Insert(const SortedRangeSet& rs) {
+  if (rs.size() == 0) {
+    return;
+  }
+  // Merge and sort the two RangeSets.
+  std::vector<Range> temp = std::move(ranges_);
+  std::copy(rs.begin(), rs.end(), std::back_inserter(temp));
+  std::sort(temp.begin(), temp.end());
+
+  Clear();
+  // Trim overlaps and insert the result back to ranges_.
+  Range to_insert = temp.front();
+  for (auto it = temp.cbegin() + 1; it != temp.cend(); it++) {
+    if (it->first <= to_insert.second) {
+      to_insert.second = std::max(to_insert.second, it->second);
+    } else {
+      ranges_.push_back(to_insert);
+      blocks_ += (to_insert.second - to_insert.first);
+      to_insert = *it;
+    }
+  }
+  ranges_.push_back(to_insert);
+  blocks_ += (to_insert.second - to_insert.first);
+}
+
+// Compute the block range the file occupies, and insert that range.
+void SortedRangeSet::Insert(size_t start, size_t len) {
+  Range to_insert{ start / kBlockSize, (start + len - 1) / kBlockSize + 1 };
+  Insert(to_insert);
+}
+
+bool SortedRangeSet::Overlaps(size_t start, size_t len) const {
+  RangeSet rs({ { start / kBlockSize, (start + len - 1) / kBlockSize + 1 } });
+  return Overlaps(rs);
+}
+
+// Given an offset of the file, checks if the corresponding block (by considering the file as
+// 0-based continuous block ranges) is covered by the SortedRangeSet. If so, returns the offset
+// within this SortedRangeSet.
+//
+// For example, the 4106-th byte of a file is from block 1, assuming a block size of 4096-byte.
+// The mapped offset within a SortedRangeSet("1-9 15-19") is 10.
+//
+// An offset of 65546 falls into the 16-th block in a file. Block 16 is contained as the 10-th
+// item in SortedRangeSet("1-9 15-19"). So its data can be found at offset 40970 (i.e. 4096 * 10
+// + 10) in a range represented by this SortedRangeSet.
+size_t SortedRangeSet::GetOffsetInRangeSet(size_t old_offset) const {
+  size_t old_block_start = old_offset / kBlockSize;
+  size_t new_block_start = 0;
+  for (const auto& range : ranges_) {
+    // Find the index of old_block_start.
+    if (old_block_start >= range.second) {
+      new_block_start += (range.second - range.first);
+    } else if (old_block_start >= range.first) {
+      new_block_start += (old_block_start - range.first);
+      return (new_block_start * kBlockSize + old_offset % kBlockSize);
+    } else {
+      CHECK(false) << "block_start " << old_block_start
+                   << " is missing between two ranges: " << this->ToString();
+      return 0;
+    }
+  }
+  CHECK(false) << "block_start " << old_block_start
+               << " exceeds the limit of current RangeSet: " << this->ToString();
+  return 0;
+}