/*
 * Copyright 2019 The Emscripten Authors.  All rights reserved.
 * Emscripten is available under two separate licenses, the MIT license and the
 * University of Illinois/NCSA Open Source License.  Both these licenses can be
 * found in the LICENSE file.
 */

#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

#ifdef __EMSCRIPTEN__
#include <emscripten.h>
#endif

#define FNAME_RO "data_ro.dat"
#define FNAME_RW "data_rw.dat"

/*
 * Each test will return 0 as success (no error) and error code in case of failure:
 * - > 0 it is errno value
 * - < 0 test specific failure (not related to any syscall)
 */

#define ASSERT(cond, msg) do {                          \
    if (!(cond)) {                                      \
        printf("%s:%03d FAILED '%s' - %s errno: %d\n",  \
                __func__, __LINE__, #cond, msg, errno); \
        return (errno != 0 ? errno : -1);               \
    }                                                   \
} while (0)

#define TEST_START() printf("%s - START\n", __func__)
#define TEST_PASS() do {               \
    printf("%s - PASSED\n", __func__); \
    return 0;                          \
} while (0)

const char file_data[] =
    "Copyright 2019 The Emscripten Authors.  All rights reserved.\n"
    "Emscripten is available under two separate licenses, the MIT license and the\n"
    "University of Illinois/NCSA Open Source License.  Both these licenses can be\n"
    "found in the LICENSE file.\n";

FILE *f_ro = NULL;
FILE *f_rw = NULL;

// Length of the file data excluding trailing '\0'. Equivalent to strlen(file_data) .
size_t file_len() {
    return sizeof(file_data) - 1;
}

int test_mmap_read() {
    TEST_START();
    errno = 0;

    char *m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, fileno(f_ro), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    for (size_t i = 0; i < file_len(); ++i) {
        ASSERT(m[i] == file_data[i], "Wrong file data mmaped");
    }
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");
    TEST_PASS();
}

int test_mmap_write() {
    TEST_START();
    errno = 0;

    char *m = (char *)mmap(NULL, file_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fileno(f_rw), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    // Reverse the data in the mapped file in memory, which should be written
    // out.
    for (size_t i = 0; i < file_len(); ++i) {
        size_t k = file_len() - i - 1;
        m[k] = file_data[i];
    }
    // Write to a byte past the end of the file. mmap will allocate a multiple
    // of the page size, which is bigger than our small file, and it will zero
    // that out. So it is ok for us to write there, but those changes should
    // not be saved anywhere.
    ASSERT(m[file_len()] == 0, "No zero past file contents");
    m[file_len()] = 42;
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");

    // mmap it again, where we should see the reversed data that was written.
    m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, fileno(f_rw), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    for (size_t i = 0; i < file_len(); ++i) {
        size_t k = file_len() - i - 1;
        ASSERT(m[k] == file_data[i], "Wrong file data written or mapped");
    }
    ASSERT(m[file_len()] == 0, "No zero past file contents");
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");

    TEST_PASS();
}

int test_mmap_write_private() {
    TEST_START();
    errno = 0;

    /*
     * POSIX spec (http://pubs.opengroup.org/onlinepubs/9699919799/) for mmap
     * says that it should be possible to set PROT_WRITE flag for file opened
     * in RO mode if we use MAP_PRIVATE flag.
     */
    char *m = (char *)mmap(NULL, file_len(), PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(f_ro), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    for (size_t i = 0; i < file_len(); ++i) {
        size_t k = file_len() - i;
        m[k] = file_data[i];
    }
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");

    /*
     * It is undefined however, if subsequent maps in the same process will or won't
     * see data written by such mmap.
     */
    m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, fileno(f_ro), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    for (size_t i = 0; i < file_len(); ++i) {
        size_t k = file_len() - i;
        ASSERT(m[k] == file_data[i] || m[i] == file_data[i],
               "Wrong file data written or mapped");
    }
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");

    TEST_PASS();
}

int test_mmap_write_to_ro_file() {
    TEST_START();
    errno = 0;

    char *m = (char *)mmap(NULL, file_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fileno(f_ro), 0);
    ASSERT(m == MAP_FAILED && errno == EACCES,
           "Expected EACCES when requesting writing to file opened in read-only mode");
    TEST_PASS();
}

int test_mmap_anon() {
    TEST_START();
    errno = 0;

    void *m = (char *)mmap(NULL, file_len(), PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap pages");
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmmap allocated pages");
    TEST_PASS();
}

int test_mmap_fixed() {
    TEST_START();
    errno = 0;
    size_t page_size = sysconf(_SC_PAGE_SIZE);

    char *m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, fileno(f_ro), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    char *invalid_addr = m;
    if (((uintptr_t)m) % page_size == 0) {
        invalid_addr++;
    }

    char *m2 = (char *)mmap(invalid_addr, file_len(), PROT_READ, MAP_FIXED, fileno(f_ro), 0);
    ASSERT(m2 == MAP_FAILED && errno == EINVAL, "Expected EINVAL for invalid addr");

    size_t invalid_offset = 1;
    char *m3 = (char *)mmap(m, file_len(), PROT_READ, MAP_FIXED, fileno(f_ro), invalid_offset);
    ASSERT(m3 == MAP_FAILED && errno == EINVAL, "Expected EINVAL for invalid offset");

    ASSERT(munmap(m, file_len()) == 0, "Failed to unmmap allocated pages");
    TEST_PASS();
}

int test_mmap_wrong_fd() {
    TEST_START();
    errno = 0;

    char *m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, -1, 0);
    ASSERT(m == MAP_FAILED && errno == EBADF, "Expected EBADF error");
    TEST_PASS();
}

int test_unmap_wrong_addr() {
    TEST_START();
    errno = 0;

    ASSERT(munmap((void*)0xdeadbeef, file_len()) == -1 && errno == EINVAL,
           "Expected EINVAL, as munmap should fail for wrong addr argument");
    TEST_PASS();
}

int test_unmap_zero_len() {
    TEST_START();
    errno = 0;

    char *m = (char *)mmap(NULL, file_len(), PROT_READ, MAP_PRIVATE, fileno(f_ro), 0);
    ASSERT(m != MAP_FAILED, "Failed to mmap file");
    ASSERT(munmap(m, 0) == -1 && errno == EINVAL,
           "Expected EINVAL, as munmap should fail when len argument is 0");
    ASSERT(munmap(m, file_len()) == 0, "Failed to unmap allocated pages");
    TEST_PASS();
}

typedef int (*test_fn)();

int set_up() {
    FILE *f = fopen(FNAME_RO, "w");
    ASSERT(f != NULL, "Failed to open file " FNAME_RO " for writing");
    fprintf(f, "%s", file_data);
    fclose(f);

    f = fopen(FNAME_RW, "w");
    ASSERT(f != NULL, "Failed to open file " FNAME_RW " for writing");
    fprintf(f, "%s", file_data);
    fclose(f);

    f_ro = fopen(FNAME_RO, "r");
    ASSERT(f_ro != NULL, "Failed to open file " FNAME_RO " for reading");
    f_rw = fopen(FNAME_RW, "r+");
    ASSERT(f_rw != NULL, "Failed to open file " FNAME_RW " for reading and writing");

    return 0;
}

void tear_down() {
    if (f_ro != NULL) {
        fclose(f_ro);
        f_ro = NULL;
    }

    if (f_rw != NULL) {
        fclose(f_rw);
        f_rw = NULL;
    }
}

int main() {
    int failures = 0;
    test_fn tests[] = {
        test_mmap_read,
        test_mmap_write,
        test_mmap_write_private,
        test_mmap_write_to_ro_file,
        test_mmap_anon,
        test_mmap_fixed,
        test_mmap_wrong_fd,
        test_unmap_wrong_addr,
        test_unmap_zero_len,
        NULL
    };

    int tests_run = 0;
    while (tests[tests_run] != NULL) {
        if (set_up() != 0) {
            printf("Failed to set_up environment for TC\n");
            ++failures;
        } else {
            failures += (tests[tests_run]() != 0 ? 1 : 0);
        }

        tear_down();
        ++tests_run;
    }

    printf("tests_run: %d failures: %d\n", tests_run, failures);
    return failures;
}