serenity/Tests/Kernel/TestPrivateInodeVMObject.cpp
brody-qq ebaa9f9d35 Tests/Kernel: Add more tests for shared and private mmaps
Adds the following tests:
* if there are multiple shared mmaps for the same file, writes to
  one mmap region should be visible in the other mmap regions.
* if you write to a file with write(), those changes should be
  visible in shared mmaps for that file.
* if you write to a shared mmap, those changes should be visible
  when you read() from the file.
* if you write to a private mmap, any changes you make should not
  be visible when you read() the file.
2024-07-07 18:25:32 +02:00

65 lines
1.8 KiB
C++

/*
* Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibTest/TestCase.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
static u8* private_ptr = nullptr;
size_t const buf_len = 0x1000;
static void private_non_empty_inode_vmobject_sync_signal_handler(int)
{
auto rc = msync(private_ptr, buf_len, MS_ASYNC);
EXPECT(rc == 0);
rc = munmap(private_ptr, buf_len);
EXPECT(rc == 0);
exit(0);
}
TEST_CASE(private_non_empty_inode_vmobject_sync)
{
{
struct sigaction new_action {
{ private_non_empty_inode_vmobject_sync_signal_handler }, 0, 0
};
int rc = sigaction(SIGBUS, &new_action, nullptr);
VERIFY(rc == 0);
}
int mmap_len = buf_len * 2;
u8 buf[buf_len];
memset(buf, 0, sizeof(buf));
int fd = open("/tmp/private_non_empty_msync_test", O_RDWR | O_CREAT, 0644);
VERIFY(fd >= 0);
auto rc = write(fd, buf, sizeof(buf));
VERIFY(rc == sizeof(buf));
private_ptr = (u8*)mmap(nullptr, mmap_len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
EXPECT(private_ptr != MAP_FAILED);
// test that writes to the private mmap are not visible to read()
u8 old_val = private_ptr[0];
private_ptr[0] = old_val + 1;
rc = msync(private_ptr, mmap_len, MS_SYNC);
VERIFY(rc == 0);
rc = lseek(fd, 0, SEEK_SET);
VERIFY(rc == 0);
u8 read_byte = 0;
rc = read(fd, &read_byte, 1);
VERIFY(rc == 1);
EXPECT(read_byte == old_val);
// test that writes between the file length (buf_len) and mmap_len cause a SIGBUS
rc = msync(private_ptr, mmap_len, MS_ASYNC);
EXPECT(rc == 0);
private_ptr[buf_len + 1] = 0x1;
VERIFY_NOT_REACHED();
}