Merge branch 'ks/ref-filter-signature' into jch

The "git for-each-ref" family of commands learned placeholders
related to GPG signature verification.

* ks/ref-filter-signature:
  ref-filter: add new "signature" atom
  t/lib-gpg: introduce new prereq GPG2

Documentation/git-for-each-ref.txt

@@ -221,6 +221,33 @@ symref::
 	`:lstrip` and `:rstrip` options in the same way as `refname`
 	above.
 
+signature::
+	The GPG signature of a commit.
+
+signature:grade::
+	Show "G" for a good (valid) signature, "B" for a bad
+	signature, "U" for a good signature with unknown validity, "X"
+	for a good signature that has expired, "Y" for a good
+	signature made by an expired key, "R" for a good signature
+	made by a revoked key, "E" if the signature cannot be
+	checked (e.g. missing key) and "N" for no signature.
+
+signature:signer::
+	The signer of the GPG signature of a commit.
+
+signature:key::
+	The key of the GPG signature of a commit.
+
+signature:fingerprint::
+	The fingerprint of the GPG signature of a commit.
+
+signature:primarykeyfingerprint::
+	The primary key fingerprint of the GPG signature of a commit.
+
+signature:trustlevel::
+	The trust level of the GPG signature of a commit. Possible
+	outputs are `ultimate`, `fully`, `marginal`, `never` and `undefined`.
+
 worktreepath::
 	The absolute path to the worktree in which the ref is checked
 	out, if it is checked out in any linked worktree. Empty string

ref-filter.c

@@ -150,6 +150,7 @@ enum atom_type {
 	ATOM_BODY,
 	ATOM_TRAILERS,
 	ATOM_CONTENTS,
+	ATOM_SIGNATURE,
 	ATOM_RAW,
 	ATOM_UPSTREAM,
 	ATOM_PUSH,
@@ -215,6 +216,10 @@ static struct used_atom {
 		struct email_option {
 			enum { EO_RAW, EO_TRIM, EO_LOCALPART } option;
 		} email_option;
+		struct {
+			enum { S_BARE, S_GRADE, S_SIGNER, S_KEY,
+			       S_FINGERPRINT, S_PRI_KEY_FP, S_TRUST_LEVEL } option;
+		} signature;
 		struct refname_atom refname;
 		char *head;
 	} u;
@@ -407,8 +412,37 @@ static int subject_atom_parser(struct ref_format *format UNUSED,
 	return 0;
 }
 
-static int trailers_atom_parser(struct ref_format *format UNUSED,
-				struct used_atom *atom,
+static int parse_signature_option(const char *arg)
+{
+	if (!arg)
+		return S_BARE;
+	else if (!strcmp(arg, "signer"))
+		return S_SIGNER;
+	else if (!strcmp(arg, "grade"))
+		return S_GRADE;
+	else if (!strcmp(arg, "key"))
+		return S_KEY;
+	else if (!strcmp(arg, "fingerprint"))
+		return S_FINGERPRINT;
+	else if (!strcmp(arg, "primarykeyfingerprint"))
+		return S_PRI_KEY_FP;
+	else if (!strcmp(arg, "trustlevel"))
+		return S_TRUST_LEVEL;
+	return -1;
+}
+
+static int signature_atom_parser(struct ref_format *format UNUSED,
+				 struct used_atom *atom,
+				 const char *arg, struct strbuf *err)
+{
+	int opt = parse_signature_option(arg);
+	if (opt < 0)
+		return err_bad_arg(err, "signature", arg);
+	atom->u.signature.option = opt;
+	return 0;
+}
+
+static int trailers_atom_parser(struct ref_format *format, struct used_atom *atom,
 				const char *arg, struct strbuf *err)
 {
 	atom->u.contents.trailer_opts.no_divider = 1;
@@ -668,6 +702,7 @@ static struct {
 	[ATOM_BODY] = { "body", SOURCE_OBJ, FIELD_STR, body_atom_parser },
 	[ATOM_TRAILERS] = { "trailers", SOURCE_OBJ, FIELD_STR, trailers_atom_parser },
 	[ATOM_CONTENTS] = { "contents", SOURCE_OBJ, FIELD_STR, contents_atom_parser },
+	[ATOM_SIGNATURE] = { "signature", SOURCE_OBJ, FIELD_STR, signature_atom_parser },
 	[ATOM_RAW] = { "raw", SOURCE_OBJ, FIELD_STR, raw_atom_parser },
 	[ATOM_UPSTREAM] = { "upstream", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
 	[ATOM_PUSH] = { "push", SOURCE_NONE, FIELD_STR, remote_ref_atom_parser },
@@ -1405,6 +1440,92 @@ static void grab_person(const char *who, struct atom_value *val, int deref, void
 	}
 }
 
+static void grab_signature(struct atom_value *val, int deref, struct object *obj)
+{
+	int i;
+	struct commit *commit = (struct commit *) obj;
+	struct signature_check sigc = { 0 };
+	int signature_checked = 0;
+
+	for (i = 0; i < used_atom_cnt; i++) {
+		struct used_atom *atom = &used_atom[i];
+		const char *name = atom->name;
+		struct atom_value *v = &val[i];
+		int opt;
+
+		if (!!deref != (*name == '*'))
+			continue;
+		if (deref)
+			name++;
+
+		if (!skip_prefix(name, "signature", &name) ||
+		    (*name && *name != ':'))
+			continue;
+		if (!*name)
+			name = NULL;
+		else
+			name++;
+
+		opt = parse_signature_option(name);
+		if (opt < 0)
+			continue;
+
+		if (!signature_checked) {
+			check_commit_signature(commit, &sigc);
+			signature_checked = 1;
+		}
+
+		switch (opt) {
+		case S_BARE:
+			v->s = xstrdup(sigc.output ? sigc.output: "");
+			break;
+		case S_SIGNER:
+			v->s = xstrdup(sigc.signer ? sigc.signer : "");
+			break;
+		case S_GRADE:
+			switch (sigc.result) {
+			case 'G':
+				switch (sigc.trust_level) {
+				case TRUST_UNDEFINED:
+				case TRUST_NEVER:
+					v->s = xstrfmt("%c", (char)'U');
+					break;
+				default:
+					v->s = xstrfmt("%c", (char)'G');
+					break;
+				}
+				break;
+			case 'B':
+			case 'E':
+			case 'N':
+			case 'X':
+			case 'Y':
+			case 'R':
+				v->s = xstrfmt("%c", (char)sigc.result);
+				break;
+			}
+			break;
+		case S_KEY:
+			v->s = xstrdup(sigc.key ? sigc.key : "");
+			break;
+		case S_FINGERPRINT:
+			v->s = xstrdup(sigc.fingerprint ?
+				       sigc.fingerprint : "");
+			break;
+		case S_PRI_KEY_FP:
+			v->s = xstrdup(sigc.primary_key_fingerprint ?
+				       sigc.primary_key_fingerprint : "");
+			break;
+		case S_TRUST_LEVEL:
+			v->s = xstrdup(gpg_trust_level_to_str(sigc.trust_level));
+			break;
+		}
+	}
+
+	if (signature_checked)
+		signature_check_clear(&sigc);
+}
+
 static void find_subpos(const char *buf,
 			const char **sub, size_t *sublen,
 			const char **body, size_t *bodylen,
@@ -1598,6 +1719,7 @@ static void grab_values(struct atom_value *val, int deref, struct object *obj, s
 		grab_sub_body_contents(val, deref, data);
 		grab_person("author", val, deref, buf);
 		grab_person("committer", val, deref, buf);
+		grab_signature(val, deref, obj);
 		break;
 	case OBJ_TREE:
 		/* grab_tree_values(val, deref, obj, buf, sz); */

t/lib-gpg.sh

@@ -51,6 +51,27 @@ test_lazy_prereq GPG '
 	esac
 '
 
+test_lazy_prereq GPG2 '
+	gpg_version=$(gpg --version 2>&1)
+	test $? != 127 || exit 1
+
+	case "$gpg_version" in
+	"gpg (GnuPG) "[01].*)
+		say "This test requires a GPG version >= v2.0.0"
+		exit 1
+		;;
+	*)
+		(gpgconf --kill all || : ) &&
+		gpg --homedir "${GNUPGHOME}" --import \
+			"$TEST_DIRECTORY"/lib-gpg/keyring.gpg &&
+		gpg --homedir "${GNUPGHOME}" --import-ownertrust \
+			"$TEST_DIRECTORY"/lib-gpg/ownertrust &&
+		gpg --homedir "${GNUPGHOME}" </dev/null >/dev/null \
+			--sign -u committer@example.com
+		;;
+	esac
+'
+
 test_lazy_prereq GPGSM '
 	test_have_prereq GPG &&
 	# Available key info: