Add android::base::Realpath.

Bug: http://b/31396973
Test: libbase_test on host and device
Change-Id: I1e5f15c76227ec1c2128baa38eb454d347987703

3 files changed, 47 insertions, 0 deletions

diff --git a/base/file.cpp b/base/file.cpp
index 81b04d74e..378a405bc 100644
--- a/base/file.cpp
+++ b/base/file.cpp
@@ -212,6 +212,20 @@ bool Readlink(const std::string& path, std::string* result) {
 }
 #endif
 
+#if !defined(_WIN32)
+bool Realpath(const std::string& path, std::string* result) {
+  result->clear();
+
+  char* realpath_buf = realpath(path.c_str(), nullptr);
+  if (realpath_buf == nullptr) {
+    return false;
+  }
+  result->assign(realpath_buf);
+  free(realpath_buf);
+  return true;
+}
+#endif
+
 std::string GetExecutablePath() {
 #if defined(__linux__)
   std::string path;
diff --git a/base/file_test.cpp b/base/file_test.cpp
index 102132626..266131ecf 100644
--- a/base/file_test.cpp
+++ b/base/file_test.cpp
@@ -159,6 +159,38 @@ TEST(file, Readlink) {
 #endif
 }
 
+TEST(file, Realpath) {
+#if !defined(_WIN32)
+  TemporaryDir td;
+  std::string basename = android::base::Basename(td.path);
+  std::string dir_name = android::base::Dirname(td.path);
+  std::string base_dir_name = android::base::Basename(dir_name);
+
+  {
+    std::string path = dir_name + "/../" + base_dir_name + "/" + basename;
+    std::string result;
+    ASSERT_TRUE(android::base::Realpath(path, &result));
+    ASSERT_EQ(td.path, result);
+  }
+
+  {
+    std::string path = std::string(td.path) + "/..";
+    std::string result;
+    ASSERT_TRUE(android::base::Realpath(path, &result));
+    ASSERT_EQ(dir_name, result);
+  }
+
+  {
+    errno = 0;
+    std::string path = std::string(td.path) + "/foo.noent";
+    std::string result = "wrong";
+    ASSERT_TRUE(!android::base::Realpath(path, &result));
+    ASSERT_TRUE(result.empty());
+    ASSERT_EQ(ENOENT, errno);
+  }
+#endif
+}
+
 TEST(file, GetExecutableDirectory) {
   std::string path = android::base::GetExecutableDirectory();
   ASSERT_NE("", path);
diff --git a/base/include/android-base/file.h b/base/include/android-base/file.h
index 33d1ab320..651f52962 100644
--- a/base/include/android-base/file.h
+++ b/base/include/android-base/file.h
@@ -47,6 +47,7 @@ bool WriteFully(int fd, const void* data, size_t byte_count);
 bool RemoveFileIfExists(const std::string& path, std::string* err = nullptr);
 
 #if !defined(_WIN32)
+bool Realpath(const std::string& path, std::string* result);
 bool Readlink(const std::string& path, std::string* result);
 #endif