android/utils/eintr_wrapper_unittest.cpp

// Copyright 2014 The Android Open Source Project
//
// This software is licensed under the terms of the GNU General Public
// License version 2, as published by the Free Software Foundation, and
// may be copied, distributed, and modified under those terms.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Forces debug mode
#define EINTR_WRAPPER_DEBUG 1

#include "android/utils/eintr_wrapper.h"

#include <stdarg.h>
#include <setjmp.h>

#include "android/utils/panic.h"

#include <gtest/gtest.h>

// Loop counter used by several functions below.
static int loop_count = 0;

// This function returns the first time it is called, or -1/EINVAL
// otherwise.
static int return_einval_after_first_call(void) {
    if (++loop_count == 1)
        return 0;

    errno = EINVAL;
    return -1;
}

TEST(eintr_wrapper,NoLoopOnSuccess) {
    loop_count = 0;
    EXPECT_EQ(0, HANDLE_EINTR(return_einval_after_first_call()));
    EXPECT_EQ(1, loop_count);
}

TEST(eintr_wrapper,NoLoopOnRegularError) {
    loop_count = 0;
    EXPECT_EQ(0, HANDLE_EINTR(return_einval_after_first_call()));
    EXPECT_EQ(-1, HANDLE_EINTR(return_einval_after_first_call()));
    EXPECT_EQ(EINVAL, errno);
    EXPECT_EQ(2, loop_count);
}

static int always_return_eintr(void) {
    loop_count++;
#ifdef _WIN32
    // Win32 cannot generate EINTR.
    return 0;
#else
    errno = EINTR;
    return -1;
#endif
}

TEST(eintr_wrapper,IgnoreEintr) {
    loop_count = 0;
    EXPECT_EQ(0, IGNORE_EINTR(always_return_eintr()));
    EXPECT_EQ(1, loop_count);
}

#ifndef _WIN32

// This function loops 10 times around |loop_count|, while returning
// -1/errno.
static int loop_eintr_10(void) {
    if (++loop_count < 10) {
        errno = EINTR;
        return -1;
    }
    return 0;
}

TEST(eintr_wrapper,LoopOnEintr) {
    loop_count = 0;
    EXPECT_EQ(0, HANDLE_EINTR(loop_eintr_10()));
    EXPECT_EQ(10, loop_count);
}

// Implementation of a custom panic function used to detect that
// HANDLE_EINTR() called panic after too many loop iterations.
// Uses setjmp()/longjmp() since the panic handler must be
// __attribute__((noreturn)).
static jmp_buf panic_jumper;
static bool panic_called = false;

static void __attribute__((noreturn))
        my_panic_handler(const char*, va_list);

static void my_panic_handler(const char* fmt, va_list args) {
    panic_called = true;
    longjmp(panic_jumper, 1);
}

static int loop_eintr_200(void) {
    if (++loop_count < 200) {
        errno = EINTR;
        return -1;
    }
    return 0;
}

TEST(eintr_wrapper,PanicOnTooManyLoops) {
    loop_count = 0;
    android_panic_registerHandler(my_panic_handler);
    if (setjmp(panic_jumper) == 0) {
        HANDLE_EINTR(loop_eintr_200());
        ASSERT_TRUE(0) << "HANDLE_EINTR() didn't panic!";
    } else {
        EXPECT_EQ(true, panic_called);
        EXPECT_EQ(MAX_EINTR_LOOP_COUNT, loop_count);
    }
}

#endif  // !_WIN32