My resolution of the S.O. 2nd Practical Test

arguments.ggo

package "is_ascii"
version "0.0.1"
purpose "Find if a file contains valid ASCII data"
description "This utility checks if the contents of a file are valid acording to the ASCII table."

option "filename" f "File to read"
        string yes

option "verbose" v "Verbose output"
        no

is_ascii.c

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

#include "arguments.h"

#define CMDLINE_PARSER_ERROR    1
#define FILE_ERROR              2

#define logv(...) \
    if(args_info.verbose_given) printf(__VA_ARGS__);

extern int errno;

int main(int argc, char** argv)
{
    struct gengetopt_args_info args_info;

    if (cmdline_parser(argc, argv, &args_info) != 0)
    {
        fprintf(stderr, "Error parsing command line arguments.");
        return CMDLINE_PARSER_ERROR;
    }

    logv("[Verbose mode]\n");

    /*  filename is required
        verbose is optional */

    /* open file */
    int fd = open(args_info.filename_arg, O_RDONLY);

    if(fd == -1)
    {
        fprintf(stderr, "Can't open file '%s' (%s)\n", args_info.filename_arg, strerror(errno));

        cmdline_parser_free(&args_info);
        return FILE_ERROR;
    }

    /* all good - now let's start verifying the file */
    uint8_t byte;
    unsigned int count = 0;
    int ret;
    for(unsigned int i = 0;; ++i)
    {
        ret = read(fd, &byte, sizeof(byte));

        /* check for error reading the file */
        if(ret == -1)
        {
            perror(argv[0]);

            cmdline_parser_free(&args_info);
            return FILE_ERROR;
        }

        if(ret == sizeof(byte))
        {
            if(byte > 127)
            {
                ++count;

                logv("Byte %u:%u (>127)\n", i, byte);
            }
        } else
            /* no data read - we arrived at the end */
            break;
    }

    logv("Summary: %u bytes not ASCII\n", count);

    if(count == 0)
        printf("'%s' is ASCII\n", args_info.filename_arg);
    else
        printf("'%s' is NOT ASCII\n", args_info.filename_arg);

    if(close(fd) == -1)
    {
        perror(argv[0]);

        cmdline_parser_free(&args_info);
        return FILE_ERROR;
    }

    cmdline_parser_free(&args_info);
    return 0;
}

Makefile

CFLAGS	:=$(CFLAGS) -Wall -Wextra -std=c99 -pedantic -ggdb
LDFLAGS	:=$(LDFLAGS) #-lm -pthread

PROGRAM	=is_ASCII

SRCDIR	=source
INCDIR	=include
OUTDIR	=out

SRCS	:=$(wildcard $(SRCDIR)/*.c)
OBJS	:=$(SRCS:$(SRCDIR)/%.c=$(OUTDIR)/%.o)

CFLAGS	:=$(CFLAGS) -I$(INCDIR) -I$(OUTDIR)

all: link

link: $(OUTDIR) gengetopt $(OBJS)
	$(CC) $(LDFLAGS) $(OUTDIR)/arguments.o $(OBJS) -o $(OUTDIR)/$(PROGRAM)

$(OUTDIR)/%.o: $(SRCDIR)/%.c
	$(CC) $(CFLAGS) -c $(@:$(OUTDIR)/%.o=$(SRCDIR)/%.c) -o $@

gengetopt:
	gengetopt --file-name arguments --output-dir $(OUTDIR) --unamed-opts -i $(SRCDIR)/arguments.ggo
	$(CC) $(CFLAGS) -c $(OUTDIR)/arguments.c -o $(OUTDIR)/arguments.o

$(OUTDIR):
	mkdir -p $(OUTDIR)

clean:
	rm -rf $(OUTDIR)

.PHONY: all link clean