Asynchronously pre-fault the native library pages.

third_party/android_crazy_linker/src/src/crazy_linker_api.cpp

Index: third_party/android_crazy_linker/src/src/crazy_linker_api.cpp
diff --git a/third_party/android_crazy_linker/src/src/crazy_linker_api.cpp b/third_party/android_crazy_linker/src/src/crazy_linker_api.cpp
index 8ea4a1258de953d22f170e58e5530dc4887c2d57..e752f4503f7ecf023423aefa9434bf1c648a17d8 100644
--- a/third_party/android_crazy_linker/src/src/crazy_linker_api.cpp
+++ b/third_party/android_crazy_linker/src/src/crazy_linker_api.cpp
@@ -6,7 +6,10 @@
 
 #include <crazy_linker.h>
 
+#include <unistd.h>
 #include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 #include "crazy_linker_error.h"
 #include "crazy_linker_ashmem.h"
@@ -17,7 +20,9 @@
 #include "crazy_linker_thread.h"
 #include "crazy_linker_util.h"
 #include "crazy_linker_library_view.h"
+#include "crazy_linker_memory_mapping.h"
 #include "crazy_linker_system.h"
+#include "crazy_linker_zip.h"
 
 using crazy::Globals;
 using crazy::Error;
@@ -396,6 +401,55 @@ crazy_status_t crazy_library_file_path_in_zip_file(const char* lib_name,
   return CRAZY_STATUS_SUCCESS;
 }
 
+crazy_status_t crazy_library_offset_size_in_zip_file(const char* zip_filename,
+                                                    const char* lib_name,
+                                                    int* offset, int* size) {
+  char path_in_zip[kMaxFilePathLengthInZip] = "lib/armeabi-v7/libchrome.so";
+  crazy_status_t status;
+  status = crazy_library_file_path_in_zip_file(lib_name, path_in_zip,
+                                               kMaxFilePathLengthInZip);
+  if (status == CRAZY_STATUS_FAILURE) return CRAZY_STATUS_FAILURE;
+  crazy::OffsetSize offset_size =
+    crazy::FindStartOffsetAndLengthOfFileInZipFile(zip_filename, path_in_zip);
+  *offset = offset_size.offset;
+  *size = offset_size.size;
+  if (offset_size.offset == -1) return CRAZY_STATUS_FAILURE;
+  return CRAZY_STATUS_SUCCESS;
+}
+
+crazy_status_t crazy_prefault_library(const char* filename, int offset,
+				      int size) {
+  struct stat stat_buf;
+  int fd;
+
+  if (stat(filename, &stat_buf) == -1) return CRAZY_STATUS_FAILURE;
+  if ((fd = open(filename, 0, O_RDONLY)) == -1) return CRAZY_STATUS_FAILURE;
+
+  if (size == -1)
+    size = (int) stat_buf.st_size;
+
+  crazy::MemoryMapping mapping;
+  bool ok =
+    mapping.AllocateWithOffset(NULL, size, crazy::MemoryMapping::CAN_READ, fd,
+			       offset);
+  if (!ok) {
+    mapping.Deallocate();
+    close(fd);
+    return CRAZY_STATUS_FAILURE;
+  }
+
+  unsigned char* mapped = (unsigned char*) mapping.Get();
+  unsigned char dummy = 0;
+  for (int i = 0; i < size - sizeof(long); i += 4096) {
+    // volatile is required to prevent the compiler from removing this loop.
+    dummy ^= *((volatile unsigned char*) mapped + i);
+  }
+
+  mapping.Deallocate();
+  close(fd);
+  return CRAZY_STATUS_SUCCESS;
+}
+
 crazy_status_t crazy_linker_check_library_is_mappable_in_zip_file(
     const char* zipfile_name,
     const char* lib_name) {