Avoid pathological behavior in OpenBSD's fread.
Bug: https://code.google.com/p/android/issues/detail?id=81155
Bug: 18556607
Change-Id: Idc60976b79610e2202cc42dc393dcb4ca6c42e05
diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index 6be372c..854fc7b 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -813,3 +813,34 @@
fclose(fp);
}
+
+// https://code.google.com/p/android/issues/detail?id=81155
+// http://b/18556607
+TEST(stdio, fread_unbuffered_pathological_performance) {
+ FILE* fp = fopen("/dev/zero", "r");
+ ASSERT_TRUE(fp != NULL);
+
+ // Make this stream unbuffered.
+ setvbuf(fp, 0, _IONBF, 0);
+
+ char buf[65*1024];
+ memset(buf, 0xff, sizeof(buf));
+
+ time_t t0 = time(NULL);
+ for (size_t i = 0; i < 1024; ++i) {
+ fread(buf, 64*1024, 1, fp);
+ }
+ time_t t1 = time(NULL);
+
+ fclose(fp);
+
+ // 1024 64KiB reads should have been very quick.
+ ASSERT_LE(t1 - t0, 1);
+
+ for (size_t i = 0; i < 64*1024; ++i) {
+ ASSERT_EQ('\0', buf[i]);
+ }
+ for (size_t i = 64*1024; i < 65*1024; ++i) {
+ ASSERT_EQ('\xff', buf[i]);
+ }
+}