base: Add sensitivity to TMPDIR environment for TemporaryDir and TemporaryFile

Test: compile
Bug: 119313545
Change-Id: I2917847f0e90df94d74f4bfc0b13fbc6a5f243c3
diff --git a/file.cpp b/file.cpp
index e4407d0..f362f94 100644
--- a/file.cpp
+++ b/file.cpp
@@ -72,7 +72,8 @@
 
 std::string GetSystemTempDir() {
 #if defined(__ANDROID__)
-  const char* tmpdir = "/data/local/tmp";
+  const auto* tmpdir = getenv("TMPDIR");
+  if (tmpdir == nullptr) tmpdir = "/data/local/tmp";
   if (access(tmpdir, R_OK | W_OK | X_OK) == 0) {
     return tmpdir;
   }
@@ -81,7 +82,7 @@
   return ".";
 #elif defined(_WIN32)
   char tmp_dir[MAX_PATH];
-  DWORD result = GetTempPathA(sizeof(tmp_dir), tmp_dir);
+  DWORD result = GetTempPathA(sizeof(tmp_dir), tmp_dir);  // checks TMP env
   CHECK_NE(result, 0ul) << "GetTempPathA failed, error: " << GetLastError();
   CHECK_LT(result, sizeof(tmp_dir)) << "path truncated to: " << result;
 
@@ -91,7 +92,9 @@
   tmp_dir[result - 1] = '\0';
   return tmp_dir;
 #else
-  return "/tmp";
+  const auto* tmpdir = getenv("TMPDIR");
+  if (tmpdir == nullptr) tmpdir = "/tmp";
+  return tmpdir;
 #endif
 }