bionic-unit-tests: Create symlinks in runtime

Instead of creating symlinks in build time and then relying
on usage of adb sync (adb push follows symlinks) - create
them in test run time.

Test: mm && run bionic-unit-tests --gtest_filter=dl*:Dl*
Bug: http://b/22182538
Change-Id: I9d2a873e3ba303533c14ba5e3b779e4a67925462

1 files changed, 78 insertions, 0 deletions

diff --git a/tests/dlfcn_symlink_support.cpp b/tests/dlfcn_symlink_support.cpp
new file mode 100644
index 000000000..be1839ecf
--- /dev/null
+++ b/tests/dlfcn_symlink_support.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "dlfcn_symlink_support.h"
+
+#include <gtest/gtest.h>
+
+#include <dlfcn.h>
+#include <libgen.h>
+#include <link.h>
+#include <unistd.h>
+
+#include <android-base/strings.h>
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+static const constexpr char* source_file_name = "libdlext_test.so";
+static const constexpr char* symlink_name_prefix = "libdlext_test_";
+
+static int dl_callback(struct dl_phdr_info *info, size_t /* size */, void *data) {
+  // The case when path is not absolute and is equal to source_file_name
+  // is disregarded intentionally since in bionic dlpi_name should always
+  // be realpath to a shared object.
+  const std::string suffix = std::string("/") + source_file_name;
+
+  // TODO (dimitry): remove this check once fake libdl.so is gone
+  if (info->dlpi_name == nullptr) {
+    // This is linker imposing as libdl.so - skip it
+    return 0;
+  }
+
+  if (android::base::EndsWith(info->dlpi_name, suffix.c_str())) {
+    std::string* path = reinterpret_cast<std::string*>(data);
+    *path = info->dlpi_name;
+    return 1; // found
+  }
+
+  return 0;
+}
+
+void create_dlfcn_test_symlink(const char* suffix, std::string* result) {
+  void* handle = dlopen(source_file_name, RTLD_NOW);
+  std::string source_file_path;
+
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  ASSERT_TRUE(dl_iterate_phdr(dl_callback, &source_file_path) == 1)
+      << "dl_phdr_info for \"" << source_file_name << "\" was not found.";
+
+  dlclose(handle);
+  std::vector<char> buf;
+  std::copy(source_file_path.begin(), source_file_path.end(), std::back_inserter(buf));
+  buf.push_back('\0');
+
+  std::string path_dir = dirname(&buf[0]);
+  std::string link_path = path_dir + "/" + symlink_name_prefix + suffix + ".so";
+
+  ASSERT_TRUE(symlink(source_file_path.c_str(), link_path.c_str()) == 0) << strerror(errno);
+  *result = link_path;
+}
+
+void remove_dlfcn_test_symlink(const std::string& path) {
+  ASSERT_TRUE(unlink(path.c_str()) == 0) << strerror(errno);
+}