Daniel Trebbien

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

int main()
{
    int fildes[2];
    if (pipe(fildes) == -1) {
        const int e = errno;
        fprintf(stderr, "`pipe` failed: %s (%d)\n", strerror(e), e);
        return EXIT_FAILURE;
    }

    struct stat buf;
    if (fstat(fildes[0], &buf) == -1) {
        const int e = errno;
        fprintf(stderr, "`fstat` failed: %s (%d)\n", strerror(e), e);
        return EXIT_FAILURE;
    }

    printf("buf.st_mode=0x%08x\n", (int)buf.st_mode);
    if (!S_ISFIFO(buf.st_mode)) {
        printf("!");
    }
    printf("S_ISFIFO(buf.st_mode)\n");

    return EXIT_SUCCESS;
}