#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

ssize_t Max(ssize_t a, ssize_t b) {
    return a > b ? a : b;
}

ssize_t CatFile(int fd) {
    char buf[4096];
    ssize_t r;

    do {
        r = read(fd, buf, 4096);
        if (r < 0) {
            dprintf(STDERR_FILENO, "there is something wrong with read\n");
            return 0;
        }

        ssize_t wr;
        for (size_t i = 0; i < r; i += Max(wr, 0)) {
            wr = write(STDOUT_FILENO, buf + i, r - i);
            if (wr >= 0 || errno == EINTR || errno == EAGAIN) {
                continue;
            }

            return 1;
        }
    } while (r != 0);

    return 0;
}

int main(int argc, char *argv[]) {
    if (argc == 1) {
        return (int) CatFile(STDIN_FILENO);
    }

    for (int i = 1; i < argc; ++i) {
        int fd = open(argv[i], O_RDONLY);
        if (fd < 0) {
            if (errno == ENOENT) {
                dprintf(STDERR_FILENO, "there is something wrong with the file\n");
                continue;
            }

            return 1;
        }

        ssize_t cat_res = CatFile(fd);
        close(fd);

        if (cat_res) {
            return 1;
        }
    }

    return 0;
}