HTMLify

/* cat */

#define POSIX_C_SOURCE 200809L

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <unistd.h>

struct args {
    bool unbuffered;
} args = {
    false
};

void cat_file(FILE *file) {
    if (file == NULL)
        return;
    int byte;
    if (args.unbuffered)
        setvbuf(stdout, NULL, _IONBF, 0);
    while ((byte = getc(file)) != EOF)
        putchar(byte);
}

int main(int argc, char *argv[]) {
    int key;
    while ((key = getopt(argc, argv, "u")) != -1) {
        switch (key) {
            case 'u': {
                args.unbuffered = true;
                break;
            }
            default: {
                fprintf(stderr, "cat: invalid option -- '%c'", key);
                return 1;
            }
        }
    }
    argc -= optind;
    argv += optind;

    int return_code = 0;
    if (argc == 0) {
        cat_file(stdin);
        return 0;
    }
    for (int i=0; i<argc; i++) {
        if (!strcmp(argv[i], "-")) {
            cat_file(stdin);
            continue;
        }
        FILE *f = fopen(argv[i], "r");
        if (!f) {
            fprintf(stderr, "cat: %s: No such file or directory\n", argv[i]);
            return_code = 1;
            continue;
        }
        cat_file(f);
    }
    return return_code;
}