diff --git a/aos/util/file.cc b/aos/util/file.cc
index 4473d4d..cec5a6e 100644
--- a/aos/util/file.cc
+++ b/aos/util/file.cc
@@ -2,6 +2,7 @@
 
 #include <fcntl.h>
 #include <fts.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -151,5 +152,24 @@
   }
 }
 
+std::shared_ptr<absl::Span<uint8_t>> MMapFile(const std::string &path) {
+  int fd = open(path.c_str(), O_RDONLY);
+  PCHECK(fd != -1) << "Unable to open file " << path;
+  struct stat sb;
+  PCHECK(fstat(fd, &sb) != -1) << ": Unable to get file size of " << path;
+  uint8_t *start = reinterpret_cast<uint8_t *>(
+      mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0));
+  CHECK(start != MAP_FAILED) << ": Unable to open mapping to file " << path;
+  std::shared_ptr<absl::Span<uint8_t>> span =
+      std::shared_ptr<absl::Span<uint8_t>>(
+          new absl::Span<uint8_t>(start, sb.st_size),
+          [](absl::Span<uint8_t> *span) {
+            PCHECK(munmap(span->data(), span->size()) != -1);
+            delete span;
+          });
+  close(fd);
+  return span;
+}
+
 }  // namespace util
 }  // namespace aos