refspec: factor out parsing a single refspec

Factor out the logic which parses a single refspec into its own
function.  This makes it easier to reuse this logic in a future patch.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refspec.c

@@ -14,110 +14,123 @@ static struct refspec_item s_tag_refspec = {
 /* See TAG_REFSPEC for the string version */
 const struct refspec_item *tag_refspec = &s_tag_refspec;
-static struct refspec_item *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
+/*
+ * Parses the provided refspec 'refspec' and populates the refspec_item 'item'.
+ * Returns 1 if successful and 0 if the refspec is invalid.
+ */
+static int parse_refspec(struct refspec_item *item, const char *refspec, int fetch)
 {
-	int i;
-	struct refspec_item *rs = xcalloc(nr_refspec, sizeof(*rs));
-	for (i = 0; i < nr_refspec; i++) {
-		size_t llen;
-		int is_glob;
-		const char *lhs, *rhs;
-		int flags;
-		is_glob = 0;
-		lhs = refspec[i];
-		if (*lhs == '+') {
-			rs[i].force = 1;
-			lhs++;
-		}
-		rhs = strrchr(lhs, ':');
+	size_t llen;
+	int is_glob;
+	const char *lhs, *rhs;
+	int flags;
+	is_glob = 0;
+	lhs = refspec;
+	if (*lhs == '+') {
+		item->force = 1;
+		lhs++;
+	}
+	rhs = strrchr(lhs, ':');
+	/*
+	 * Before going on, special case ":" (or "+:") as a refspec
+	 * for pushing matching refs.
+	 */
+	if (!fetch && rhs == lhs && rhs[1] == '\0') {
+		item->matching = 1;
+		return 1;
+	}
+	if (rhs) {
+		size_t rlen = strlen(++rhs);
+		is_glob = (1 <= rlen && strchr(rhs, '*'));
+		item->dst = xstrndup(rhs, rlen);
+	}
+
+	llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
+	if (1 <= llen && memchr(lhs, '*', llen)) {
+		if ((rhs && !is_glob) || (!rhs && fetch))
+			return 0;
+		is_glob = 1;
+	} else if (rhs && is_glob) {
+		return 0;
+	}
+
+	item->pattern = is_glob;
+	item->src = xstrndup(lhs, llen);
+	flags = REFNAME_ALLOW_ONELEVEL | (is_glob ? REFNAME_REFSPEC_PATTERN : 0);
+
+	if (fetch) {
+		struct object_id unused;
+
+		/* LHS */
+		if (!*item->src)
+			; /* empty is ok; it means "HEAD" */
+		else if (llen == GIT_SHA1_HEXSZ && !get_oid_hex(item->src, &unused))
+			item->exact_sha1 = 1; /* ok */
+		else if (!check_refname_format(item->src, flags))
+			; /* valid looking ref is ok */
+		else
+			return 0;
+		/* RHS */
+		if (!item->dst)
+			; /* missing is ok; it is the same as empty */
+		else if (!*item->dst)
+			; /* empty is ok; it means "do not store" */
+		else if (!check_refname_format(item->dst, flags))
+			; /* valid looking ref is ok */
+		else
+			return 0;
+	} else {
 		/*
-		 * Before going on, special case ":" (or "+:") as a refspec
-		 * for pushing matching refs.
+		 * LHS
+		 * - empty is allowed; it means delete.
+		 * - when wildcarded, it must be a valid looking ref.
+		 * - otherwise, it must be an extended SHA-1, but
+		 *   there is no existing way to validate this.
 		 */
-		if (!fetch && rhs == lhs && rhs[1] == '\0') {
-			rs[i].matching = 1;
-			continue;
+		if (!*item->src)
+			; /* empty is ok */
+		else if (is_glob) {
+			if (check_refname_format(item->src, flags))
+				return 0;
 		}
-
-		if (rhs) {
-			size_t rlen = strlen(++rhs);
-			is_glob = (1 <= rlen && strchr(rhs, '*'));
-			rs[i].dst = xstrndup(rhs, rlen);
+		else
+			; /* anything goes, for now */
+		/*
+		 * RHS
+		 * - missing is allowed, but LHS then must be a
+		 *   valid looking ref.
+		 * - empty is not allowed.
+		 * - otherwise it must be a valid looking ref.
+		 */
+		if (!item->dst) {
+			if (check_refname_format(item->src, flags))
+				return 0;
+		} else if (!*item->dst) {
+			return 0;
+		} else {
+			if (check_refname_format(item->dst, flags))
+				return 0;
 		}
-		llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
-		if (1 <= llen && memchr(lhs, '*', llen)) {
-			if ((rhs && !is_glob) || (!rhs && fetch))
-				goto invalid;
-			is_glob = 1;
-		} else if (rhs && is_glob) {
-			goto invalid;
-		}
-		rs[i].pattern = is_glob;
-		rs[i].src = xstrndup(lhs, llen);
-		flags = REFNAME_ALLOW_ONELEVEL | (is_glob ? REFNAME_REFSPEC_PATTERN : 0);
-
-		if (fetch) {
-			struct object_id unused;
-
-			/* LHS */
-			if (!*rs[i].src)
-				; /* empty is ok; it means "HEAD" */
-			else if (llen == GIT_SHA1_HEXSZ && !get_oid_hex(rs[i].src, &unused))
-				rs[i].exact_sha1 = 1; /* ok */
-			else if (!check_refname_format(rs[i].src, flags))
-				; /* valid looking ref is ok */
-			else
-				goto invalid;
-			/* RHS */
-			if (!rs[i].dst)
-				; /* missing is ok; it is the same as empty */
-			else if (!*rs[i].dst)
-				; /* empty is ok; it means "do not store" */
-			else if (!check_refname_format(rs[i].dst, flags))
-				; /* valid looking ref is ok */
-			else
-				goto invalid;
-		} else {
-			/*
-			 * LHS
-			 * - empty is allowed; it means delete.
-			 * - when wildcarded, it must be a valid looking ref.
-			 * - otherwise, it must be an extended SHA-1, but
-			 *   there is no existing way to validate this.
-			 */
-			if (!*rs[i].src)
-				; /* empty is ok */
-			else if (is_glob) {
-				if (check_refname_format(rs[i].src, flags))
-					goto invalid;
-			}
-			else
-				; /* anything goes, for now */
-			/*
-			 * RHS
-			 * - missing is allowed, but LHS then must be a
-			 *   valid looking ref.
-			 * - empty is not allowed.
-			 * - otherwise it must be a valid looking ref.
-			 */
-			if (!rs[i].dst) {
-				if (check_refname_format(rs[i].src, flags))
-					goto invalid;
-			} else if (!*rs[i].dst) {
-				goto invalid;
-			} else {
-				if (check_refname_format(rs[i].dst, flags))
-					goto invalid;
-			}
-		}
+	}
+	return 1;
+}
+static struct refspec_item *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
+{
+	int i;
+	struct refspec_item *rs = xcalloc(nr_refspec, sizeof(*rs));
+
+	for (i = 0; i < nr_refspec; i++) {
+		if (!parse_refspec(&rs[i], refspec[i], fetch))
+			goto invalid;
 	}
+
 	return rs;
  invalid: