src/starnix/tests/syscalls/cpp/rlimit_test.cc

// Copyright 2024 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <fcntl.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include <atomic>
#include <thread>

#include <gtest/gtest.h>

#include "src/starnix/tests/syscalls/cpp/test_helper.h"

namespace {

std::atomic<size_t> g_signal_count = 0;

void handle_sigxfsz(int signum) { g_signal_count += 1; }

TEST(SetRLimitTest, ZeroFSizeOnRegularFiles) {
  test_helper::ForkHelper helper;

  helper.RunInForkedProcess([&] {
    signal(SIGXFSZ, handle_sigxfsz);

    struct rlimit limit = {
        .rlim_cur = 0,
        .rlim_max = 0,
    };

    char path_template[] = "/tmp/XXXXXX";
    char* tmp_path = mkdtemp(path_template);
    ASSERT_NE(tmp_path, nullptr) << "mkdtemp failed" << std::strerror(errno) << '\n';
    std::string file_path = std::string(tmp_path) + "/regular_file";

    ASSERT_EQ(setrlimit(RLIMIT_FSIZE, &limit), 0)
        << "setrlimit failed" << std::strerror(errno) << '\n';

    fbl::unique_fd fd(creat(file_path.c_str(), 0666));
    ASSERT_TRUE(fd.is_valid()) << "failed to create file" << std::strerror(errno) << '\n';

    uint8_t buf[0x20] = {0};
    EXPECT_EQ(write(fd.get(), buf, sizeof(buf)), -1);
    EXPECT_EQ(errno, EFBIG);
    EXPECT_EQ(g_signal_count, 1u);
    signal(SIGXFSZ, SIG_DFL);
    ASSERT_EQ(unlink(file_path.c_str()), 0) << "unlink failed" << std::strerror(errno) << '\n';
    ASSERT_EQ(rmdir(tmp_path), 0) << "rmdir failed" << std::strerror(errno) << '\n';
  });

  EXPECT_TRUE(helper.WaitForChildren());
}

TEST(SetRLimitTest, ZeroFSizeOnMemFd) {
  test_helper::ForkHelper helper;

  helper.RunInForkedProcess([&] {
    signal(SIGXFSZ, handle_sigxfsz);

    struct rlimit limit = {
        .rlim_cur = 0,
        .rlim_max = 0,
    };

    ASSERT_EQ(setrlimit(RLIMIT_FSIZE, &limit), 0)
        << "setrlimit failed" << std::strerror(errno) << '\n';

    fbl::unique_fd fd(test_helper::MemFdCreate("memfd", 0));
    ASSERT_TRUE(fd.is_valid()) << "failed to create file" << std::strerror(errno) << '\n';

    uint8_t buf[0x20] = {0};
    EXPECT_EQ(write(fd.get(), buf, sizeof(buf)), -1);
    EXPECT_EQ(errno, EFBIG);
    EXPECT_EQ(g_signal_count, 1u);
    signal(SIGXFSZ, SIG_DFL);
  });

  EXPECT_TRUE(helper.WaitForChildren());
}

// Test that we can write up to one byte to files.
TEST(SetRLimitTest, OneFSize) {
  test_helper::ForkHelper helper;

  helper.RunInForkedProcess([&] {
    signal(SIGXFSZ, handle_sigxfsz);

    struct rlimit limit = {
        .rlim_cur = 1,
        .rlim_max = 1,
    };

    ASSERT_EQ(setrlimit(RLIMIT_FSIZE, &limit), 0)
        << "setrlimit failed" << std::strerror(errno) << '\n';

    fbl::unique_fd fd(test_helper::MemFdCreate("memfd", 0));
    ASSERT_TRUE(fd.is_valid()) << "failed to create file" << std::strerror(errno) << '\n';

    uint8_t buf[0x1] = {0};
    EXPECT_EQ(write(fd.get(), buf, sizeof(buf)), 1);
    EXPECT_EQ(g_signal_count, 0u);

    // Next write should fail.
    EXPECT_EQ(write(fd.get(), buf, sizeof(buf)), -1);
    EXPECT_EQ(errno, EFBIG);
    EXPECT_EQ(g_signal_count, 1u);
    signal(SIGXFSZ, SIG_DFL);
  });

  EXPECT_TRUE(helper.WaitForChildren());
}

TEST(SetRLimitTest, ZeroFSizeOnPipe) {
  test_helper::ForkHelper helper;

  helper.RunInForkedProcess([&] {
    signal(SIGXFSZ, handle_sigxfsz);

    struct rlimit limit = {
        .rlim_cur = 0,
        .rlim_max = 0,
    };

    ASSERT_EQ(setrlimit(RLIMIT_FSIZE, &limit), 0)
        << "setrlimit failed" << std::strerror(errno) << '\n';

    int pipefd[2];
    EXPECT_EQ(0, pipe2(pipefd, 0)) << "failed to create pipe" << std::strerror(errno) << '\n';

    uint8_t buf[0x1] = {0};
    ASSERT_EQ(write(pipefd[1], buf, sizeof(buf)), 1);
    EXPECT_EQ(g_signal_count, 0u);

    EXPECT_EQ(read(pipefd[0], buf, sizeof(buf)), 1);
    signal(SIGXFSZ, SIG_DFL);

    close(pipefd[0]);
    close(pipefd[1]);
  });

  EXPECT_TRUE(helper.WaitForChildren());
}

TEST(SetRLimitTest, ZeroFSizeOnFIFO) {
  test_helper::ForkHelper helper;

  helper.RunInForkedProcess([&] {
    signal(SIGXFSZ, handle_sigxfsz);

    struct rlimit limit = {
        .rlim_cur = 0,
        .rlim_max = 0,
    };

    char path_template[] = "/tmp/XXXXXX";
    char* tmp_path = mkdtemp(path_template);
    ASSERT_NE(tmp_path, nullptr) << "mkdtemp failed" << std::strerror(errno) << '\n';
    std::string file_path = std::string(tmp_path) + "/regular_file";

    ASSERT_EQ(setrlimit(RLIMIT_FSIZE, &limit), 0)
        << "setrlimit failed" << std::strerror(errno) << '\n';

    ASSERT_EQ(0, mkfifo(file_path.c_str(), 0666))
        << "failed to create fifo" << std::strerror(errno) << '\n';

    std::thread reader([file_path]() {
      fbl::unique_fd fd(open(file_path.c_str(), O_RDONLY));
      ASSERT_TRUE(fd.is_valid()) << "failed to open file for reading" << std::strerror(errno)
                                 << '\n';

      uint8_t buf[0x1] = {0};
      EXPECT_EQ(read(fd.get(), buf, sizeof(buf)), 1)
          << "read failed" << std::strerror(errno) << '\n';
    });

    fbl::unique_fd fd(open(file_path.c_str(), O_WRONLY));
    ASSERT_TRUE(fd.is_valid()) << "failed to file for writing" << std::strerror(errno) << '\n';

    uint8_t buf[0x1] = {0};
    ASSERT_EQ(write(fd.get(), buf, sizeof(buf)), 1);

    reader.join();

    EXPECT_EQ(g_signal_count, 0u);
    signal(SIGXFSZ, SIG_DFL);

    ASSERT_EQ(unlink(file_path.c_str()), 0) << "unlink failed" << std::strerror(errno) << '\n';
    ASSERT_EQ(rmdir(tmp_path), 0) << "rmdir failed" << std::strerror(errno) << '\n';
  });

  EXPECT_TRUE(helper.WaitForChildren());
}

}  //  namespace