Check input for non-print bytes

asciicheck.c

//
//  Created by Leptos on 12/25/19.
//  Copyright © 2019 Leptos. All rights reserved.
//

#import <stdio.h>
#import <fcntl.h>
#import <unistd.h>
#import <ctype.h>

static int checkFileDescriptor(const int fileDescriptor, const char *const path) {
    char buff[0x200]; // this buffer size is fairly arbitrary
    unsigned lineNumber = 1;
    unsigned columnNumber = 1;
    
    ssize_t readResult = 0;
    do {
        readResult = read(fileDescriptor, buff, sizeof(buff));
        if (readResult < 0) {
            return -1;
        }
        
        for (ssize_t i = 0; i < readResult; i++) {
            const char chr = buff[i];
            if (chr == '\n') {
                lineNumber++;
                columnNumber = 0;
            } else if (!(isprint(chr) || chr == '\t')) {
                printf("%s:%u:%u non-print: 0x%02hhx\n", path, lineNumber, columnNumber, chr);
            }
            columnNumber++;
        }
    } while (readResult > 0);
    return 0;
}

int main(int argc, const char *argv[]) {
    if (!isatty(STDIN_FILENO)) {
        const char *const path = "<stdin>";
        if (checkFileDescriptor(STDIN_FILENO, path) != 0) {
            perror(path);
        }
    }
    
    for (int argi = 1; argi < argc; argi++) {
        const char *const path = argv[argi];
        const int fileDescriptor = open(path, O_RDONLY);
        if (fileDescriptor < 0) {
            perror(path);
            continue;
        }
        const int checkStatus = checkFileDescriptor(fileDescriptor, path);
        if (checkStatus != 0) {
            perror(path);
            // no `continue` here because we still want to `close` the file
        }
        const int closeStatus = close(fileDescriptor);
        if (closeStatus != 0) {
            perror(path);
        }
    }
}