Various coverage improvements.

Mostly from extra test cases, but also:

* Move the fgets size < 0 assertion into fgets.

* Use ELF aliases for strtoq/strtouq rather than duplicating code.

* Don't check uname() succeeded, since it can't fail.

Test: treehugger
Change-Id: I2e6b3b88b0a3eb16bd68be68b9bc9f40d8043291
diff --git a/tests/sys_wait_test.cpp b/tests/sys_wait_test.cpp
new file mode 100644
index 0000000..c006972
--- /dev/null
+++ b/tests/sys_wait_test.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <gtest/gtest.h>
+
+#include <sys/wait.h>
+
+TEST(sys_wait, waitid) {
+  pid_t pid = fork();
+  ASSERT_NE(pid, -1);
+
+  if (pid == 0) _exit(66);
+
+  siginfo_t si = {};
+  ASSERT_EQ(0, waitid(P_PID, pid, &si, WEXITED));
+  ASSERT_EQ(pid, si.si_pid);
+  ASSERT_EQ(66, si.si_status);
+  ASSERT_EQ(CLD_EXITED, si.si_code);
+}