wc.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <ctype.h>
#include <signal.h>

int is_end_of_sentence(char c) {
    return c == '.' || c == '?' || c == '!';
}

void wc(char *filename) {
    int fd = open(filename, O_RDONLY);

    if(fd < 0) {
        perror("open");
        return;
    }

    int sentences_count = 0, word_count = 0, char_count = 0;

    char data[100];

    ssize_t read_value = read(fd, data, 100);
    if(read_value < 0) {
        perror("read");
        return;
    }

    while(read_value != 0) {
        for(int i = 0; i < read_value; i++) {
            if(isspace(data[i])) {
                word_count++;
            } else if(is_end_of_sentence(data[i])) {
                sentences_count++;
            }

            char_count++;
        }

        read_value = read(fd, data, 100);
        if(read_value < 0) {
            perror("read");
            return;
        }
    }

    printf("%d %d %d %s\n", sentences_count, word_count, char_count, filename);

    if(close(fd) < 0) {
        perror("close");
        return;
    }
}

int main(int argc, char **argv) {
    pid_t pid;
    for(int i = 1; i < argc; i++) {
        pid = fork();
        if(pid < 0) {
            perror("fork");
            return -1;
        }

        if(pid == 0) {
            wc(argv[i]);
        } else {
            int *status = NULL;
            waitpid(pid, status, 0);
            return 0;
        }
    }

    return 0;
}