From: Tobias Heider <tobias.heider@stusta.de>
Subject: Re: dd commas
To: tech@openbsd.org
Date: Mon, 18 Nov 2024 20:50:21 +0100

On Mon, Nov 18, 2024 at 01:36:55PM GMT, joshua stein wrote:
> Maybe someone else will find this useful, but when I ^T dd and see 
> output like 1257557196800, I have to highlight three digits at a 
> time in my terminal for my brain to understand if it's at hundreds 
> of gigabytes or in terabytes.

I have often wished it was human readable by default and print a more
reasonable unit than Bytes, but this is definitely a step in the right
direction.

> 
> Before:
> 
>     11994+0 records in
>     11993+0 records out
>     1257557196800 bytes transferred in 5017.398 secs (250659198 bytes/sec)
> 
> After:
> 
>     11994+0 records in
>     11993+0 records out
>     1,257,557,196,800 bytes transferred in 5017.398 secs (250,659,198 bytes/sec)
> 
> 
> diff --git bin/dd/extern.h bin/dd/extern.h
> index aff85daf021..2f2ce4629ad 100644
> --- bin/dd/extern.h
> +++ bin/dd/extern.h
> @@ -38,6 +38,7 @@
>  
>  void block(void);
>  void block_close(void);
> +void commafy(unsigned long long, char *, size_t);
>  void dd_out(int);
>  void def(void);
>  void def_close(void);
> diff --git bin/dd/misc.c bin/dd/misc.c
> index cd0ba9fa41d..0671c35ed42 100644
> --- bin/dd/misc.c
> +++ bin/dd/misc.c
> @@ -49,6 +49,7 @@
>  void
>  sig_summary(int notused)
>  {
> +	char bstr[26], pstr[26];
>  	int save_errno = errno;
>  	struct timespec elapsed, now;
>  	unsigned long long bps, msec;
> @@ -85,10 +86,12 @@ sig_summary(int notused)
>  		    st.trunc, (st.trunc == 1) ? "block" : "blocks");
>  	}
>  	if (!(ddflags & C_NOXFER)) {
> +		commafy(st.bytes, bstr, sizeof(bstr));
> +		commafy(bps, pstr, sizeof(pstr));
>  		dprintf(STDERR_FILENO,
> -		    "%lld bytes transferred in %lld.%03ld secs "
> -		    "(%llu bytes/sec)\n", (long long)st.bytes,
> -		    (long long)elapsed.tv_sec, elapsed.tv_nsec / 1000000, bps);
> +		    "%s bytes transferred in %lld.%03ld secs "
> +		    "(%s bytes/sec)\n", bstr, elapsed.tv_sec,
> +		    elapsed.tv_nsec / 1000000, pstr);
>  	}
>  	errno = save_errno;
>  }
> @@ -107,3 +110,24 @@ exit_summary(void)
>  {
>  	sig_summary(0);
>  }
> +
> +void
> +commafy(unsigned long long count, char *dst, size_t size)
> +{
> +	char llstr[26];
> +	int n, len, pos, cpos;
> +
> +	len = snprintf(llstr, sizeof(llstr), "%llu", count);
> +	cpos = len + ((len - 1) / 3);
> +
> +	if (cpos > size)
> +		return;
> +
> +	dst[cpos--] = '\0';
> +
> +	for (n = 0, pos = len - 1; n < len; n++) {
> +		if (n && n % 3 == 0)
> +			dst[cpos--] = ',';
> +		dst[cpos--] = llstr[pos--];
> +	}
> +}
>