readfile.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

#define BUFFER_SIZE 1
#define MAX_TOKEN_LEN 128

size_t do_read(char *filename) {

    char buffer[BUFFER_SIZE];
    size_t total_read = 0, chars_read;
    int fh = open(filename, O_RDONLY);
    if (fh >= 0) {
        while ((chars_read = read(fh, buffer, BUFFER_SIZE)) > 0)
            total_read += chars_read;
        close(fh);
    } else {
        total_read = -1;
    }
    return total_read;
    
}

size_t do_fread(char *filename) {
    
    char buffer[BUFFER_SIZE];
    size_t total_read = 0, chars_read;
    FILE *fp = fopen(filename, "rb");
    if (fp != NULL) {
        while ((chars_read = fread(buffer, 1, BUFFER_SIZE, fp)) > 0)
            total_read += chars_read;
        fclose(fp);
    } else {
        total_read = -1;
    }
    return total_read;
    
}

int main() {
    
    char command[MAX_TOKEN_LEN];
    char parameter[MAX_TOKEN_LEN];
    size_t ret;
    
    while (1) {
        
        printf(">");
        scanf("%s %s", command, parameter);
        if (!strncmp(command, "read", MAX_TOKEN_LEN)) {
            ret = do_read(parameter);
            printf("==>READ %zu\n", ret);
        } else if (!strncmp(command, "fread", MAX_TOKEN_LEN)) {
            ret = do_fread(parameter);
            printf("==>FREAD %zu\n", ret);
        } else if (!strncmp(command, "quit", MAX_TOKEN_LEN)) {
            printf("Bye!\n");
            return 0;
        } else {
            printf("Unknown command. Possible commands are:\n"
                    "read <file>\n"
                    "fread <file>\n"
                    "quit me\n");
        }
        
    }
    
}