diff --git a/common/utils.h b/common/utils.h
index 50b6cb1..4ff4050 100644
--- a/common/utils.h
+++ b/common/utils.h
@@ -38,6 +38,7 @@
 #include <brillo/secure_blob.h>
 
 #include "android-base/mapped_file.h"
+#include "google/protobuf/repeated_field.h"
 #include "update_engine/common/action.h"
 #include "update_engine/common/action_processor.h"
 #include "update_engine/common/constants.h"
@@ -137,6 +138,8 @@
 off_t FileSize(const std::string& path);
 off_t FileSize(int fd);
 
+bool SendFile(int out_fd, int in_fd, size_t count);
+
 std::string ErrnoNumberAsString(int err);
 
 // Returns true if the file exists for sure. Returns false if it doesn't exist,
@@ -308,6 +311,27 @@
                  ssize_t out_data_size,
                  size_t block_size);
 
+bool WriteExtents(const std::string& path,
+                  const google::protobuf::RepeatedPtrField<Extent>& extents,
+                  const brillo::Blob& data,
+                  size_t block_size);
+
+constexpr bool ReadExtents(const std::string& path,
+                           const std::vector<Extent>& extents,
+                           brillo::Blob* out_data,
+                           size_t block_size) {
+  return ReadExtents(path,
+                     extents,
+                     out_data,
+                     utils::BlocksInExtents(extents) * block_size,
+                     block_size);
+}
+
+bool ReadExtents(const std::string& path,
+                 const google::protobuf::RepeatedPtrField<Extent>& extents,
+                 brillo::Blob* out_data,
+                 size_t block_size);
+
 // Read the current boot identifier and store it in |boot_id|. This identifier
 // is constants during the same boot of the kernel and is regenerated after
 // reboot. Returns whether it succeeded getting the boot_id.
@@ -485,6 +509,11 @@
 std::string HexEncode(const brillo::Blob& blob) noexcept;
 std::string HexEncode(const std::string_view blob) noexcept;
 
+template <size_t kSize>
+std::string HexEncode(const std::array<uint8_t, kSize> blob) noexcept {
+  return base::HexEncode(blob.data(), blob.size());
+}
+
 }  // namespace chromeos_update_engine
 
 #define TEST_AND_RETURN_FALSE_ERRNO(_x)                              \