Merge "Move some utility functions to linker_utils"

am: fb3219fbd1

* commit 'fb3219fbd1dbb0a369d52cbd0200330fd8852bc1':
  Move some utility functions to linker_utils

linker/linker_mapped_file_fragment.cpp

@@ -16,32 +16,13 @@
 
 #include "linker_mapped_file_fragment.h"
 #include "linker_debug.h"
+#include "linker_utils.h"
 
 #include <inttypes.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <unistd.h>
 
-constexpr off64_t kPageMask = ~static_cast<off64_t>(PAGE_SIZE-1);
-
-static off64_t page_start(off64_t offset) {
-  return offset & kPageMask;
-}
-
-static bool safe_add(off64_t* out, off64_t a, size_t b) {
-  CHECK(a >= 0);
-  if (static_cast<uint64_t>(INT64_MAX - a) < b) {
-    return false;
-  }
-
-  *out = a + b;
-  return true;
-}
-
-static size_t page_offset(off64_t offset) {
-  return static_cast<size_t>(offset & (PAGE_SIZE-1));
-}
-
 MappedFileFragment::MappedFileFragment() : map_start_(nullptr), map_size_(0),
                                            data_(nullptr), size_ (0)
 { }

linker/linker_utils.cpp

@@ -105,3 +105,23 @@ bool parse_zip_path(const char* input_path, std::string* zip_path, std::string*
   return true;
 }
 
+constexpr off64_t kPageMask = ~static_cast<off64_t>(PAGE_SIZE-1);
+
+off64_t page_start(off64_t offset) {
+  return offset & kPageMask;
+}
+
+bool safe_add(off64_t* out, off64_t a, size_t b) {
+  CHECK(a >= 0);
+  if (static_cast<uint64_t>(INT64_MAX - a) < b) {
+    return false;
+  }
+
+  *out = a + b;
+  return true;
+}
+
+size_t page_offset(off64_t offset) {
+  return static_cast<size_t>(offset & (PAGE_SIZE-1));
+}
+

linker/linker_utils.h

@@ -24,4 +24,8 @@ bool normalize_path(const char* path, std::string* normalized_path);
 bool file_is_in_dir(const std::string& file, const std::string& dir);
 bool parse_zip_path(const char* input_path, std::string* zip_path, std::string* entry_path);
 
+off64_t page_start(off64_t offset);
+size_t page_offset(off64_t offset);
+bool safe_add(off64_t* out, off64_t a, size_t b);
+
 #endif

linker/tests/linker_utils_test.cpp

@@ -69,3 +69,24 @@ TEST(linker_utils, parse_zip_path_smoke) {
   ASSERT_EQ("", entry_path);
 }
 
+TEST(linker_utils, page_start) {
+  ASSERT_EQ(0x0001000, page_start(0x0001000));
+  ASSERT_EQ(0x3002000, page_start(0x300222f));
+  ASSERT_EQ(0x6001000, page_start(0x6001fff));
+}
+
+TEST(linker_utils, page_offset) {
+  ASSERT_EQ(0x0U, page_offset(0x0001000));
+  ASSERT_EQ(0x22fU, page_offset(0x300222f));
+  ASSERT_EQ(0xfffU, page_offset(0x6001fff));
+}
+
+TEST(linker_utils, safe_add) {
+  int64_t val = 42;
+  ASSERT_FALSE(safe_add(&val, INT64_MAX-20, 21U));
+  ASSERT_EQ(42, val);
+  ASSERT_TRUE(safe_add(&val, INT64_MAX-42, 42U));
+  ASSERT_EQ(INT64_MAX, val);
+  ASSERT_TRUE(safe_add(&val, 2000, 42U));
+  ASSERT_EQ(2042, val);
+}