Binder file module

Test: mma
Bug: 302723053
Change-Id: Ie27f8a36ab56069c928079da8a0cf3d8bfb49813
diff --git a/libs/binder/tests/FileUtils.cpp b/libs/binder/tests/FileUtils.cpp
new file mode 100644
index 0000000..61509fe
--- /dev/null
+++ b/libs/binder/tests/FileUtils.cpp
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2023 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 "FileUtils.h"
+
+#ifdef BINDER_NO_LIBBASE
+
+#include <sys/stat.h>
+#include <filesystem>
+
+#if defined(__APPLE__)
+#include <mach-o/dyld.h>
+#endif
+#if defined(_WIN32)
+#include <direct.h>
+#include <windows.h>
+#endif
+
+namespace android::binder {
+
+bool ReadFdToString(borrowed_fd fd, std::string* content) {
+    content->clear();
+
+    // Although original we had small files in mind, this code gets used for
+    // very large files too, where the std::string growth heuristics might not
+    // be suitable. https://code.google.com/p/android/issues/detail?id=258500.
+    struct stat sb;
+    if (fstat(fd.get(), &sb) != -1 && sb.st_size > 0) {
+        content->reserve(sb.st_size);
+    }
+
+    char buf[4096] __attribute__((__uninitialized__));
+    ssize_t n;
+    while ((n = TEMP_FAILURE_RETRY(read(fd.get(), &buf[0], sizeof(buf)))) > 0) {
+        content->append(buf, n);
+    }
+    return (n == 0) ? true : false;
+}
+
+bool WriteStringToFd(std::string_view content, borrowed_fd fd) {
+    const char* p = content.data();
+    size_t left = content.size();
+    while (left > 0) {
+        ssize_t n = TEMP_FAILURE_RETRY(write(fd.get(), p, left));
+        if (n == -1) {
+            return false;
+        }
+        p += n;
+        left -= n;
+    }
+    return true;
+}
+
+static std::filesystem::path GetExecutablePath2() {
+#if defined(__linux__)
+    return std::filesystem::read_symlink("/proc/self/exe");
+#elif defined(__APPLE__)
+    char path[PATH_MAX + 1];
+    uint32_t path_len = sizeof(path);
+    int rc = _NSGetExecutablePath(path, &path_len);
+    if (rc < 0) {
+        std::unique_ptr<char> path_buf(new char[path_len]);
+        _NSGetExecutablePath(path_buf.get(), &path_len);
+        return path_buf.get();
+    }
+    return path;
+#elif defined(_WIN32)
+    char path[PATH_MAX + 1];
+    DWORD result = GetModuleFileName(NULL, path, sizeof(path) - 1);
+    if (result == 0 || result == sizeof(path) - 1) return "";
+    path[PATH_MAX - 1] = 0;
+    return path;
+#elif defined(__EMSCRIPTEN__)
+    abort();
+#else
+#error unknown OS
+#endif
+}
+
+std::string GetExecutableDirectory() {
+    return GetExecutablePath2().parent_path();
+}
+
+} // namespace android::binder
+
+#endif // BINDER_NO_LIBBASE