Re: [9front] [PATCH] diff: retain original file names

[Jacob Moody <moody@mail.posixcafe.org>]

On 5/22/22 10:41, Ori Bernstein wrote:
> 
> When diffing non-regular files, like /dev/null,
> pipes, and similar, diff will generate a temp
> file to diff against. This is the right thing
> to do, but the temp file leaks into the diff.
> 
> This patch retains the original file name all
> the way through to diff output.

This has been a pet peeve of mine, glad to see
I wasn't the only one. Looks good to me! One
small comment inline that I could take or leave.

> ---
> diff 4649189126e1ad98f9a07afd078096227668bfd1 23f8872bc10fbe9ffd2b0067db1f91d8eaaabb40
> --- a/sys/src/cmd/diff/diff.h	Sun May 22 12:34:33 2022
> +++ b/sys/src/cmd/diff/diff.h	Sun May 22 12:41:47 2022
> @@ -23,8 +23,8 @@
>  void *erealloc(void *, unsigned);
>  void diff(char *, char *, int);
>  void diffdir(char *, char *, int);
> -void diffreg(char *, char *);
> -Biobuf *prepare(int, char *);
> +void diffreg(char *, char *, char *, char *);
> +Biobuf *prepare(int, char *, char *);
>  void panic(int, char *, ...);
>  void check(Biobuf *, Biobuf *);
>  void change(int, int, int, int);
> --- a/sys/src/cmd/diff/diffio.c	Sun May 22 12:34:33 2022
> +++ b/sys/src/cmd/diff/diffio.c	Sun May 22 12:41:47 2022
> @@ -104,7 +104,7 @@
>  }
>  
>  Biobuf *
> -prepare(int i, char *arg)
> +prepare(int i, char *arg, char *orig)
>  {
>  	Line *p;
>  	int j, h;
> @@ -143,11 +143,10 @@
>  	file[i] = p;
>  	input[i] = bp;			/*fix*/
>  	if (i == 0) {			/*fix*/

Is there any context for why these /*fix*/ comments are here? Could
we just delete them?

> -		file1 = arg;
> +		file1 = orig;
>  		firstchange = 0;
> -	}
> -	else
> -		file2 = arg;
> +	} else
> +		file2 = orig;
>  	return bp;
>  }
>  
> --- a/sys/src/cmd/diff/diffreg.c	Sun May 22 12:34:33 2022
> +++ b/sys/src/cmd/diff/diffreg.c	Sun May 22 12:41:47 2022
> @@ -363,16 +363,16 @@
>  }
>  
>  void
> -diffreg(char *f, char *t)
> +diffreg(char *f, char *fo, char *t, char *to)
>  {
>  	Biobuf *b0, *b1;
>  	int k;
>  
>  	binary = 0;
> -	b0 = prepare(0, f);
> +	b0 = prepare(0, f, fo);
>  	if (!b0)
>  		return;
> -	b1 = prepare(1, t);
> +	b1 = prepare(1, t, to);
>  	if (!b1) {
>  		Bterm(b0);
>  		return;
> --- a/sys/src/cmd/diff/main.c	Sun May 22 12:34:33 2022
> +++ b/sys/src/cmd/diff/main.c	Sun May 22 12:41:47 2022
> @@ -149,7 +149,7 @@
>  			Bprint(&stdout, "Common subdirectories: %s and %s\n", fp, tp);
>  	}
>  	else if (REGULAR_FILE(fsb) && REGULAR_FILE(tsb))
> -		diffreg(fp, tp);
> +		diffreg(fp, f, tp, t);
>  	else {
>  		if (REGULAR_FILE(fsb)) {
>  			if ((p = utfrrune(f, '/')) == 0)
> @@ -157,14 +157,14 @@
>  			else
>  				p++;
>  			if (mkpathname(tb, tp, p) == 0)
> -				diffreg(fp, tb);
> +				diffreg(fp, f, tb, t);
>  		} else {
>  			if ((p = utfrrune(t, '/')) == 0)
>  				p = t;
>  			else
>  				p++;
>  			if (mkpathname(fb, fp, p) == 0)
> -				diffreg(fb, tp);
> +				diffreg(fb, f, tp, t);
>  		}
>  	}
>  	free(fsb);