thodg/got

diff --git a/libexec/Makefile b/libexec/Makefile
index ca4265c..f56d567 100644
--- a/libexec/Makefile
+++ b/libexec/Makefile
@@ -1,4 +1,4 @@
 SUBDIR = got-read-blob got-read-commit got-read-object got-read-tree \
-	got-read-pack
+	got-read-tag got-read-pack
 
 .include <bsd.subdir.mk>
diff --git a/libexec/got-read-tag/Makefile b/libexec/got-read-tag/Makefile
new file mode 100644
index 0000000..64fb2ef
--- /dev/null
+++ b/libexec/got-read-tag/Makefile
@@ -0,0 +1,20 @@
+.PATH:${.CURDIR}/../../lib
+
+PROG=		got-read-tag
+SRCS=		got-read-tag.c delta.c error.c inflate.c object_parse.c \
+		privsep.c sha1.c
+
+CPPFLAGS = -I${.CURDIR}/../../include -I${.CURDIR}/../../lib
+LDADD = -lutil -lz
+DPADD = ${LIBZ} ${LIBUTIL}
+
+# For now, default to installing binary in ~/bin
+GROUP!=id -g -n
+install:
+	${INSTALL} ${INSTALL_COPY} -o ${USER} -g ${GROUP} \
+	-m ${BINMODE} ${PROG} ${GOT_LIBEXECDIR}/${PROG}
+
+# Don't install man pages yet
+NOMAN = Yes
+
+.include <bsd.prog.mk>
diff --git a/libexec/got-read-tag/got-read-tag.c b/libexec/got-read-tag/got-read-tag.c
new file mode 100644
index 0000000..b32627b
--- /dev/null
+++ b/libexec/got-read-tag/got-read-tag.c
@@ -0,0 +1,184 @@
+/*
+ * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/queue.h>
+#include <sys/uio.h>
+#include <sys/time.h>
+#include <sys/limits.h>
+#include <sys/syslimits.h>
+
+#include <stdint.h>
+#include <imsg.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sha1.h>
+#include <zlib.h>
+
+#include "got_error.h"
+#include "got_object.h"
+
+#include "got_lib_delta.h"
+#include "got_lib_inflate.h"
+#include "got_lib_object.h"
+#include "got_lib_object_parse.h"
+#include "got_lib_privsep.h"
+
+static volatile sig_atomic_t sigint_received;
+
+static void
+catch_sigint(int signo)
+{
+	sigint_received = 1;
+}
+
+static const struct got_error *
+read_tag_object(struct got_tag_object **tag, struct got_object *obj,
+    FILE *f)
+{
+	const struct got_error *err = NULL;
+	size_t len;
+	uint8_t *p;
+
+	if (obj->flags & GOT_OBJ_FLAG_PACKED)
+		err = got_read_file_to_mem(&p, &len, f);
+	else
+		err = got_inflate_to_mem(&p, &len, f);
+	if (err)
+		return err;
+
+	if (len < obj->hdrlen + obj->size) {
+		err = got_error(GOT_ERR_BAD_OBJ_DATA);
+		goto done;
+	}
+
+	/* Skip object header. */
+	len -= obj->hdrlen;
+	err = got_object_parse_tag(tag, p + obj->hdrlen, len);
+	free(p);
+done:
+	return err;
+}
+
+int
+main(int argc, char *argv[])
+{
+	const struct got_error *err = NULL;
+	struct got_tag_object *tag = NULL;
+	struct imsgbuf ibuf;
+	size_t datalen;
+
+	signal(SIGINT, catch_sigint);
+
+	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
+
+#ifndef PROFILE
+	/* revoke access to most system calls */
+	if (pledge("stdio recvfd", NULL) == -1) {
+		err = got_error_from_errno();
+		got_privsep_send_error(&ibuf, err);
+		return 1;
+	}
+#endif
+
+	while (1) {
+		struct imsg imsg;
+		struct got_imsg_object iobj;
+		FILE *f = NULL;
+		struct got_object *obj = NULL;
+
+		if (sigint_received) {
+			err = got_error(GOT_ERR_CANCELLED);
+			break;
+		}
+
+		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
+		if (err) {
+			if (err->code == GOT_ERR_PRIVSEP_PIPE)
+				err = NULL;
+			break;
+		}
+
+		if (imsg.hdr.type == GOT_IMSG_STOP)
+			break;
+
+		if (imsg.hdr.type != GOT_IMSG_TAG_REQUEST) {
+			err = got_error(GOT_ERR_PRIVSEP_MSG);
+			goto done;
+		}
+
+		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
+		if (datalen != sizeof(iobj)) {
+			err = got_error(GOT_ERR_PRIVSEP_LEN);
+			goto done;
+		}
+
+		memcpy(&iobj, imsg.data, sizeof(iobj));
+		if (iobj.type != GOT_OBJ_TYPE_TAG) {
+			err = got_error(GOT_ERR_OBJ_TYPE);
+			goto done;
+		}
+
+		if (imsg.fd == -1) {
+			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
+			goto done;
+		}
+
+		obj = calloc(1, sizeof(*obj));
+		if (obj == NULL) {
+			err = got_error_from_errno();
+			goto done;
+		}
+		obj->type = iobj.type;
+		obj->hdrlen = iobj.hdrlen;
+		obj->size = iobj.size;
+
+		/* Always assume file offset zero. */
+		f = fdopen(imsg.fd, "rb");
+		if (f == NULL) {
+			err = got_error_from_errno();
+			goto done;
+		}
+
+		err = read_tag_object(&tag, obj, f);
+		if (err)
+			goto done;
+
+		err = got_privsep_send_tag(&ibuf, tag);
+done:
+		if (f)
+			fclose(f);
+		else if (imsg.fd != -1)
+			close(imsg.fd);
+		imsg_free(&imsg);
+		if (obj)
+			got_object_close(obj);
+		if (err)
+			break;
+	}
+
+	imsg_clear(&ibuf);
+	if (err) {
+		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {
+			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
+			got_privsep_send_error(&ibuf, err);
+		}
+	}
+	close(GOT_IMSG_FD_CHILD);
+	return err ? 1 : 0;
+}