Subject: Re: [PATCH v2 2/2] rev-parse: add option for absolute or relative path formatting

From: "brian m. carlson" <[email-masked]>
Date: Mon, 16 Nov 2020 02:15:00 +0000

On 2020-11-09 at 14:46:13, Johannes Schindelin wrote:
> On Fri, 9 Oct 2020, brian m. carlson wrote:
> > diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
> > index ed200c8af1..ec62b4cd16 100644
> > --- a/builtin/rev-parse.c
> > +++ b/builtin/rev-parse.c
> > @@ -583,6 +583,76 @@ static void handle_ref_opt(const char *pattern, const char *prefix)
> >  	clear_ref_exclusion(&ref_excludes);
> >  }
> >
> > +enum format_type {
> > +	/* We would like a relative path. */
> > +	FORMAT_RELATIVE,
> > +	/* We would like a canonical absolute path. */
> > +	FORMAT_CANONICAL,
> > +	/* We would like the default behavior. */
> > +	FORMAT_DEFAULT,
> > +};
> > +
> > +enum default_type {
> > +	/* Our default is a relative path. */
> > +	DEFAULT_RELATIVE,
> > +	/* Our default is a relative path if there's a shared root. */
> > +	DEFAULT_RELATIVE_IF_SHARED,
> > +	/* Our default is a canonical absolute path. */
> > +	DEFAULT_CANONICAL,
> > +	/* Our default is not to modify the item. */
> > +	DEFAULT_UNMODIFIED,
> > +};
> 
> I wonder whether it would make sense to consolidate these two enums into a
> single one.

Technically, we can, but because there are cases in each one which don't
make sense in the other, we end up with a situation that is hard to
reason about in print_path, which is, by this point, already a little
complex.  So I think I'd prefer not to consolidate them.

> >  int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  {
> >  	int i, as_is = 0, verify = 0, quiet = 0, revs_count = 0, type = 0;
> > @@ -595,6 +665,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  	struct object_context unused;
> >  	struct strbuf buf = STRBUF_INIT;
> >  	const int hexsz = the_hash_algo->hexsz;
> > +	enum format_type format = FORMAT_DEFAULT;
> >
> >  	if (argc > 1 && !strcmp("--parseopt", argv[1]))
> >  		return cmd_parseopt(argc - 1, argv + 1, prefix);
> > @@ -650,8 +721,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  			if (!argv[i + 1])
> >  				die("--git-path requires an argument");
> >  			strbuf_reset(&buf);
> > -			puts(relative_path(git_path("%s", argv[i + 1]),
> > -					   prefix, &buf));
> > +			print_path(git_path("%s", argv[i + 1]), prefix, format, DEFAULT_RELATIVE_IF_SHARED);
> 
> One thing that the original code did was to reuse the same `strbuf`. Not
> sure whether this matters in practice.

I don't think it does.  I'll make sure to free it, though, since
strbuf_reset doesn't do that.

> >  			i++;
> >  			continue;
> >  		}
> > @@ -683,6 +753,16 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  					show_file(arg, 0);
> >  				continue;
> >  			}
> > +			if (opt_with_value(arg, "--path-format", &arg)) {
> > +				if (!strcmp(arg, "absolute")) {
> > +					format = FORMAT_CANONICAL;
> > +				} else if (!strcmp(arg, "relative")) {
> > +					format = FORMAT_RELATIVE;
> > +				} else {
> > +					die("unknown argument to --path-format: %s", arg);
> > +				}
> > +				continue;
> > +			}
> >  			if (!strcmp(arg, "--default")) {
> >  				def = argv[++i];
> >  				if (!def)
> > @@ -803,7 +883,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  			if (!strcmp(arg, "--show-toplevel")) {
> >  				const char *work_tree = get_git_work_tree();
> >  				if (work_tree)
> > -					puts(work_tree);
> > +					print_path(work_tree, prefix, format, DEFAULT_CANONICAL);
> 
> The way `print_path()`'s code is structured, it is not immediately obvious
> to me whether the patch changes behavior here. I _suspect_ that we're now
> calling `strbuf_realpath_missing()` and react to its return value, which
> is different from before.
> 
> Wouldn't make `DEFAULT_UNMODIFIED` make more sense here?

It's documented to show the absolute path of the top of the repository,
so it should be safe to do either one.  Will switch.

> >  				else
> >  					die("this operation must be run in a work tree");
> >  				continue;
> > @@ -811,7 +891,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  			if (!strcmp(arg, "--show-superproject-working-tree")) {
> >  				struct strbuf superproject = STRBUF_INIT;
> >  				if (get_superproject_working_tree(&superproject))
> > -					puts(superproject.buf);
> > +					print_path(superproject.buf, prefix, format, DEFAULT_CANONICAL);
> 
> Shouldn't this be `DEFAULT_UNMODIFIED`?

Same thing as above.  Will change.

> > @@ -868,14 +950,14 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
> >  				}
> >  				cwd = xgetcwd();
> >  				len = strlen(cwd);
> > -				printf("%s%s.git\n", cwd, len && cwd[len-1] != '/' ? "/" : "");
> > +				strbuf_reset(&buf);
> > +				strbuf_addf(&buf, "%s%s.git", cwd, len && cwd[len-1] != '/' ? "/" : "");
> 
> So `DEFAULT_CANONICAL` ensures a trailing `/`? I do not see that in
> `print_path()`'s implementation, and also, I would love to see a different
> name for that ("canonical", from my Java past, suggests something like
> "real path" to me).

I don't think that's what's happening here.  I believe the intent is to
insert a slash between the current working directory and the ".git"
component if and only if the former lacks one.  My code doesn't change
that.
-- 
brian m. carlson (he/him or they/them)
Houston, Texas, US