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




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.

+
+- "`-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.

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)`.

+		die(_("attr spec must not be empty"));
+
+	string_list_split(&list, value, ' ', -1);

You could avoid some allocations by using the in-place variant (since value is a newly allocated string not used elsewhere) but it is probably not that important in this argument parsing case.

+	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?

+
+	for_each_string_list_item(si, &list) {
+		size_t attr_len;
+		char *attr_name;
+		const struct git_attr *a;
+
+		int j = item->attr_match_nr++;
+		const char *attr = si->string;
+		struct attr_match *am = &item->attr_match[j];
+
+		switch (*attr) {
+		case '!':
+			am->match_mode = MATCH_UNSPECIFIED;
+			attr++;
+			attr_len = strlen(attr);
+			break;
+		case '-':
+			am->match_mode = MATCH_UNSET;
+			attr++;
+			attr_len = strlen(attr);
+			break;
+		default:
+			attr_len = strcspn(attr, "=");
+			if (attr[attr_len] != '=')
+				am->match_mode = MATCH_SET;
+			else {
+				am->match_mode = MATCH_VALUE;
+				am->value = xstrdup(&attr[attr_len + 1]);
+				if (strchr(am->value, '\\'))
+					die(_("attr spec values must not contain backslashes"));
+			}
+			break;
+		}
+
+		attr_name = xmemdupz(attr, attr_len);
+		a = git_attr(attr_name);
+		if (!a)
+			die(_("invalid attribute name %s"), attr_name);
+
+		attr_check_append(item->attr_check, a);
+
+		free(attr_name);
+	}
+
+	string_list_clear(&list, 0);
+	return;

Redundant return?

@@ -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.