conv_perm_test.c

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

#define S_IRUGO (S_IRUSR|S_IRGRP|S_IROTH)
#define S_IWUGO (S_IWUSR|S_IWGRP|S_IWOTH)
#define S_IXUGO (S_IXUSR|S_IXGRP|S_IXOTH)
#define ACCESS_TO_STAT(mask, user_mask) (((((mask)&R_OK)?S_IRUGO:0)|(((mask)&W_OK)?S_IWUGO:0)|(((mask)&X_OK)?S_IXUGO:0))&(user_mask))
#define STAT_TO_ACCESS(mode, user_mask) ((((mode)&(user_mask)&S_IRUGO)?R_OK:0)|(((mode)&(user_mask)&S_IWUGO)?W_OK:0)|(((mode)&(user_mask)&S_IXUGO)?X_OK:0))

void print_access(int mask)
{
    if (mask & R_OK)
    {
        printf("R_OK ");
    }

    if (mask & W_OK)
    {
        printf("W_OK ");
    }

    if (mask & X_OK)
    {
        printf("X_OK ");
    }

    printf("\n");
}

void print_stat(mode_t mode)
{
    printf("%04o\n", mode);
}

int main(int argc, char** argv)
{
    srandomdev();

    // 0700
    print_stat(ACCESS_TO_STAT(R_OK|W_OK|X_OK, S_IRWXU));

    // 0666
    print_stat(ACCESS_TO_STAT(R_OK|W_OK, ACCESSPERMS));

    // 0101
    print_stat(ACCESS_TO_STAT(X_OK, S_IRWXU|S_IRWXO));

    int mask;

    for (int i = 0; i < 10; i++)
    {
        mask = random() & 07;

        printf("access mask = ");
        print_access(mask);

        printf("user: ");
        print_stat(ACCESS_TO_STAT(mask, S_IRWXU));

        printf("group: ");
        print_stat(ACCESS_TO_STAT(mask, S_IRWXG));

        printf("other: ");
        print_stat(ACCESS_TO_STAT(mask, S_IRWXO));

        printf("all: ");
        print_stat(ACCESS_TO_STAT(mask, ACCESSPERMS));

        printf("\n");
    }

    mode_t mode = S_IRUSR | S_IRGRP | S_IWGRP;

    // R_OK W_OK X_OK
    print_access(STAT_TO_ACCESS(S_IRWXU, S_IRWXU));

    // R_OK
    print_access(STAT_TO_ACCESS(mode, S_IRWXU));

    // R_OK W_OK
    print_access(STAT_TO_ACCESS(mode, S_IRWXG));

    // nothing
    print_access(STAT_TO_ACCESS(mode, S_IRWXO));

    for (int i = 0; i < 10; i++)
    {
        mode = random() & 0777;

        printf("mode = ");
        print_stat(mode);

        printf("user: ");
        print_access(STAT_TO_ACCESS(mode, S_IRWXU));

        printf("group: ");
        print_access(STAT_TO_ACCESS(mode, S_IRWXG));

        printf("other: ");
        print_access(STAT_TO_ACCESS(mode, S_IRWXO));

        printf("\n");
    }

    return 0;
}