tests/chmod/tests_for_mode_changed.c

#include "../../unity/unity.h"

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>

// The function under test is static in this translation unit and thus directly callable:
// static bool mode_changed (int dir_fd, char const *file, char const *file_full_name,
//                           mode_t old_mode, mode_t new_mode);

// Access the existing file-scope static 'force_silent' defined in the program source.
extern bool force_silent; // The variable is defined above in the same translation unit.

// Helpers
static mode_t get_mode(const char *path) {
    struct stat st;
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, stat(path, &st), "stat on temp file failed");
    return st.st_mode;
}

static void make_temp_path(char *buf, size_t buflen) {
    // Create a unique template in /tmp
    snprintf(buf, buflen, "/tmp/chmod_mode_changed_%ld_XXXXXX", (long)getpid());
}

static void create_temp_file(char *path_buf, size_t buflen) {
    make_temp_path(path_buf, buflen);
    int fd = mkstemp(path_buf);
    TEST_ASSERT_MESSAGE(fd >= 0, "mkstemp failed");
    // Close immediately; we only need the file to exist for stat/chmod
    close(fd);
}

static void remove_temp_file(const char *path) {
    // Best-effort cleanup
    unlink(path);
}

void setUp(void) {
    /* Setup code here, or leave empty */
}

void tearDown(void) {
    /* Cleanup code here, or leave empty */
}

// 1) No special bits, no change => expect false
void test_mode_changed_no_special_no_change(void) {
    char path[256];
    create_temp_file(path, sizeof(path));

    mode_t old_mode = get_mode(path);
    mode_t new_mode = old_mode; // No change, and no special bits added

    bool changed = mode_changed(AT_FDCWD, path, path, old_mode, new_mode);
    TEST_ASSERT_FALSE(changed);

    remove_temp_file(path);
}

// 2) No special bits, with a permission bit change => expect true
void test_mode_changed_no_special_with_change(void) {
    char path[256];
    create_temp_file(path, sizeof(path));

    mode_t old_mode = get_mode(path);
    // Flip owner execute bit (does not include suid/sgid/sticky)
    mode_t new_mode = old_mode ^ S_IXUSR;

    bool changed = mode_changed(AT_FDCWD, path, path, old_mode, new_mode);
    TEST_ASSERT_TRUE(changed);

    remove_temp_file(path);
}

// 3) Special bits present; fstatat fails (nonexistent file) => expect false
void test_mode_changed_special_fstatat_failure(void) {
    // Suppress error diagnostics from the function for this test
    bool prev_silent = force_silent;
    force_silent = true;

    const char *missing = "/this/path/does/not/exist/___definitely___";
    mode_t old_mode = 0;
    // Set a special bit to trigger the fstatat path
    mode_t new_mode = old_mode | S_ISUID;

    bool changed = mode_changed(AT_FDCWD, missing, missing, old_mode, new_mode);
    TEST_ASSERT_FALSE(changed);

    force_silent = prev_silent;
}

// 4) Special bits present; fstatat succeeds; no actual change to file => expect false
void test_mode_changed_special_no_actual_change(void) {
    char path[256];
    create_temp_file(path, sizeof(path));

    mode_t old_mode = get_mode(path);
    // Trigger special-bit path; function will use fstatat to get actual (unchanged) mode
    mode_t new_mode = old_mode | S_ISUID;

    bool changed = mode_changed(AT_FDCWD, path, path, old_mode, new_mode);
    TEST_ASSERT_FALSE(changed);

    remove_temp_file(path);
}

// 5) Special bits present; fstatat succeeds; actual mode changed via chmod => expect true
void test_mode_changed_special_actual_change(void) {
    char path[256];
    create_temp_file(path, sizeof(path));

    mode_t old_mode = get_mode(path);
    // Change a permission bit on the actual file (mask to permissions only for chmod)
    mode_t changed_perm = (old_mode ^ S_IXUSR) & 07777;
    int rc = chmod(path, changed_perm);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "chmod to alter file mode failed");

    // Trigger special-bit path; function will pick up the actual new mode from stat
    mode_t new_mode_param = old_mode | S_ISUID;

    bool changed = mode_changed(AT_FDCWD, path, path, old_mode, new_mode_param);
    TEST_ASSERT_TRUE(changed);

    // Restore original perms (best effort)
    chmod(path, old_mode & 07777);
    remove_temp_file(path);
}

// 6) No special bits, difference only in file type bits should be ignored => expect false
void test_mode_changed_ignores_file_type_bits(void) {
    // Craft synthetic modes: permission bits equal, file type bits different.
    mode_t old_mode = S_IFREG | 0644;
    mode_t new_mode = S_IFDIR | 0644; // Different type, same perms; no special bits

    bool changed = mode_changed(AT_FDCWD, "unused", "unused", old_mode, new_mode);
    TEST_ASSERT_FALSE(changed);
}

int main(void) {
    UNITY_BEGIN();

    RUN_TEST(test_mode_changed_no_special_no_change);
    RUN_TEST(test_mode_changed_no_special_with_change);
    RUN_TEST(test_mode_changed_special_fstatat_failure);
    RUN_TEST(test_mode_changed_special_no_actual_change);
    RUN_TEST(test_mode_changed_special_actual_change);
    RUN_TEST(test_mode_changed_ignores_file_type_bits);

    return UNITY_END();
}