Subject: Re: [PATCH 1/2] pathspec: allow querying for attributes

From: Brandon Williams <[email-masked]>
Date: Fri, 10 Mar 2017 10:26:44 -0800

On 03/09, Jonathan Tan wrote:
> On 03/09/2017 01:07 PM, Brandon Williams wrote:
> >diff --git a/Documentation/glossary-content.txt b/Documentation/glossary-content.txt
> >index fc9320e59..5c32d1905 100644
> >--- a/Documentation/glossary-content.txt
> >+++ b/Documentation/glossary-content.txt
> >@@ -384,6 +384,26 @@ full pathname may have special meaning:
> > +
> > Glob magic is incompatible with literal magic.
> >
> >+attr;;
> >+After `attr:` comes a space separated list of "attribute
> >+requirements", all of which must be met in order for the
> >+path to be considered a match; this is in addition to the
> >+usual non-magic pathspec pattern matching.
> >++
> >+Each of the attribute requirements for the path takes one of
> >+these forms:
> >+
> >+- "`ATTR`" requires that the attribute `ATTR` must be set.
> 
> As a relative newcomer to attributes, I was confused by the fact
> that "set" and "set to a value" is different (and likewise "unset"
> and "unspecified"). Maybe it's worthwhile including a link to
> "gitattributes" to explain the different (exclusive) states that an
> attribute can be in.

Good idea! I'll add in a link to gitattributes.
> 
> >+
> >+- "`-ATTR`" requires that the attribute `ATTR` must be unset.
> >+
> >+- "`ATTR=VALUE`" requires that the attribute `ATTR` must be
> >+  set to the string `VALUE`.
> >+
> >+- "`!ATTR`" requires that the attribute `ATTR` must be
> >+  unspecified.
> 
> It would read better to me if you omitted "must" in all 4 bullet
> points (and it is redundant anyway with "requires"), but I don't
> feel too strongly about this.

I agree, the first paragraph already says "must" so it reads better
without repeating must over and over again.

> 
> >diff --git a/pathspec.c b/pathspec.c
> >index b961f00c8..583ed5208 100644
> >--- a/pathspec.c
> >+++ b/pathspec.c
> >@@ -87,6 +89,72 @@ static void prefix_magic(struct strbuf *sb, int prefixlen, unsigned magic)
> > 	strbuf_addf(sb, ",prefix:%d)", prefixlen);
> > }
> >
> >+static void parse_pathspec_attr_match(struct pathspec_item *item, const char *value)
> >+{
> >+	struct string_list_item *si;
> >+	struct string_list list = STRING_LIST_INIT_DUP;
> >+
> >+	if (item->attr_check)
> >+		die(_("Only one 'attr:' specification is allowed."));
> >+
> >+	if (!value || !strlen(value))
> 
> You can write `!*value` instead of `!strlen(value)`.
> 

Done.

> >+	string_list_remove_empty_items(&list, 0);
> >+
> >+	item->attr_check = attr_check_alloc();
> >+	ALLOC_GROW(item->attr_match,
> >+		   item->attr_match_nr + list.nr,
> >+		   item->attr_match_alloc);
> 
> Is there a time when this function is called while
> item->attr_match_nr is not zero?

Nope, it pretty much has to be zero.  I'll change this to just use
list.nr.  item->attr_match_nr will be incremented up to list.nr over the
course of the for loop and I'll move the equality check to the end of
this function.

> >+	string_list_clear(&list, 0);
> >+	return;
> 
> Redundant return?

I'll remove it.

> 
> >@@ -544,6 +628,10 @@ void parse_pathspec(struct pathspec *pathspec,
> > 		if (item[i].nowildcard_len < item[i].len)
> > 			pathspec->has_wildcard = 1;
> > 		pathspec->magic |= item[i].magic;
> >+
> >+		if (item[i].attr_check &&
> >+		    item[i].attr_check->nr != item[i].attr_match_nr)
> >+			die("BUG: should have same number of entries");
> 
> I'm not sure if this check is giving us any benefit - I would expect
> this type of code before some other code that assumed that the
> numbers matched, and that will potentially segfault if not.

I'll push the check to right after the object creation (see comment
above).

-- 
Brandon Williams