// sumbytes.c - sum bytes in a file, omitting {space, tab, CR, LF}
// Randy Dunlap 2010.08.17

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

#define CR	0x0d
#define LF	0x0a
#define TAB	0x09
#define SPC	0x20

unsigned long countallbytes = 0;
unsigned long countedbytes = 0;	// not counting the omitted bytes
unsigned long sumbytes = 0;

int fd;
char *filename;

void usage(void)
{
	fprintf(stderr, "usage: sumbytes file_name\n");
}

void read_sum_bytes(void)
{
	ssize_t bytes_read;
	int ix;
	unsigned char buf[16 * 1024];
	unsigned char ch;

	while (bytes_read = read(fd, buf, sizeof(buf)))
	{
		for (ix = 0 ; ix < bytes_read; ix++)
		{
			countallbytes++;
			ch = buf[ix];
			if (ch == CR || ch == LF ||
			    ch == SPC || ch == TAB)
				;
			else
			{
				countedbytes++;
				sumbytes += ch;
			}
		} // end for ix
	} // end while bytes_read

} // end read_sum_bytes;

int main(int argc, char *argv[])
{
	if (argc != 2)
	{
		usage();
		exit(0);
	}

	filename = argv[1];
	fd = open(filename, O_RDONLY);
	if (fd < 0)
	{
		fprintf(stderr, "error %d: %s\n",
			errno, strerror(errno));
		exit(1);
	}

	read_sum_bytes();

	printf("for file '%s':\n", filename);
	printf("total number of bytes / number of counted bytes in file: %lu / %lu\n",
		countallbytes, countedbytes);
	printf("sum of counted bytes in file: %lu (0x%lx)\n", sumbytes, sumbytes);

	fd = close(fd);
	if (fd < 0)
	{
		fprintf(stderr, "error %d: %s\n",
			errno, strerror(errno));
		exit(1);
	}

	exit(0);
} // end main;

// end sumbytes.c;