Commit Diff


commit - 136ec6c982b97cce2847aeba304d9562130f111c
commit + e6bcace54ccc965bd93cf6769c7119f21cc1311e
blob - /dev/null
blob + cddff333b1f0292034312d89f789fef6b2dcf720 (mode 644)
--- /dev/null
+++ lib/got_lib_pack_create.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021 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.
+ */
+
+/*
+ * Write pack file data into the provided open packfile handle, for all
+ * objects reachable via the commits listed in 'ours'.
+ * Exclude any objects for commits listed in 'theirs' if 'theirs' is not NULL.
+ * Return the SHA1 digest of the resulting pack file in pack_sha1 which must
+ * be pre-allocated by the caller with at least SHA1_DIGEST_LENGTH bytes.
+ */
+const struct got_error *got_pack_create(uint8_t *pack_sha1, FILE *packfile,
+    struct got_object_id **theirs, int ntheirs,
+    struct got_object_id **ours, int nours,
+    struct got_repository *repo, got_cancel_cb cancel_cb, void *cancel_arg);
blob - /dev/null
blob + 5d3b9a7d345565cc8c91eb8cf92b750344d2998c (mode 644)
--- /dev/null
+++ lib/pack_create.c
@@ -0,0 +1,1112 @@
+/*
+ * Copyright (c) 2020 Ori Bernstein
+ * Copyright (c) 2021 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/queue.h>
+#include <sys/stat.h>
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sha1.h>
+#include <limits.h>
+#include <zlib.h>
+
+#include "got_error.h"
+#include "got_cancel.h"
+#include "got_object.h"
+
+#include "got_lib_deltify.h"
+#include "got_lib_delta.h"
+#include "got_lib_object.h"
+#include "got_lib_object_idset.h"
+#include "got_lib_deflate.h"
+#include "got_lib_pack.h"
+
+#ifndef MAX
+#define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
+#endif
+
+struct got_pack_meta {
+	struct got_object_id id;
+	char	*path;
+	int	obj_type;
+	time_t	mtime;
+
+	/* The best delta we picked */
+	struct got_pack_meta *head;
+	struct got_pack_meta *prev;
+	struct got_delta_instruction *deltas;
+	int	ndeltas;
+	int	nchain;
+
+	/* Only used for delta window */
+	struct got_delta_table *dtab;
+
+	/* Only used for writing offset deltas */
+	off_t	off;
+};
+
+struct got_pack_metavec {
+	struct got_pack_meta **meta;
+	int nmeta;
+	int metasz;
+};
+
+static const struct got_error *
+alloc_meta(struct got_pack_meta **new, struct got_object_id *id,
+    const char *path, int obj_type, time_t mtime)
+{
+	const struct got_error *err = NULL;
+	struct got_pack_meta *m;
+
+	*new = NULL;
+
+	m = calloc(1, sizeof(*m));
+	if (m == NULL)
+		return got_error_from_errno("malloc");
+
+	memcpy(&m->id, id, sizeof(m->id));
+
+	m->path = strdup(path);
+	if (m->path == NULL) {
+		err = got_error_from_errno("strdup");
+		free(m);
+		return err;
+	}
+
+	m->obj_type = obj_type;
+	m->mtime = mtime;
+	*new = m;
+	return NULL;
+}
+
+static void
+clear_meta(struct got_pack_meta *meta)
+{
+	if (meta == NULL)
+		return;
+	free(meta->deltas);
+	meta->deltas = NULL;
+	free(meta->path);
+	meta->path = NULL;
+}
+
+static void
+free_nmeta(struct got_pack_meta **meta, int nmeta)
+{
+	int i;
+
+	for (i = 0; i < nmeta; i++)
+		clear_meta(meta[i]);
+	free(meta);
+}
+
+static int
+delta_order_cmp(const void *pa, const void *pb)
+{
+	struct got_pack_meta *a, *b;
+	int cmp;
+
+	a = *(struct got_pack_meta **)pa;
+	b = *(struct got_pack_meta **)pb;
+
+	if (a->obj_type != b->obj_type)
+		return a->obj_type - b->obj_type;
+	cmp = strcmp(a->path, b->path);
+	if (cmp != 0)
+		return cmp;
+	if (a->mtime != b->mtime)
+		return a->mtime - b->mtime;
+	return got_object_id_cmp(&a->id, &b->id);
+}
+
+static int
+showprogress(int x, int pct)
+{
+	if(x > pct){
+		pct = x;
+		fprintf(stderr, "\b\b\b\b%3d%%", pct);
+	}
+	return pct;
+}
+
+static int
+delta_size(struct got_delta_instruction *deltas, int ndeltas)
+{
+	int i, size = 32;
+	for (i = 0; i < ndeltas; i++) {
+		if (deltas[i].copy)
+			size += GOT_DELTA_SIZE_SHIFT;
+		else
+			size += deltas[i].len + 1;
+	}
+	return size;
+}
+
+
+static const struct got_error *
+pick_deltas(struct got_pack_meta **meta, int nmeta, struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	struct got_pack_meta *m = NULL, *base = NULL;
+	struct got_raw_object *raw = NULL, *base_raw = NULL;
+	struct got_delta_instruction *deltas;
+	int i, j, size, ndeltas, pct, best;
+	const int max_base_candidates = 10;
+
+	pct = 0;
+	fprintf(stderr, "picking deltas\n");
+	fprintf(stderr, "deltifying %d objects:   0%%", nmeta);
+	qsort(meta, nmeta, sizeof(struct got_pack_meta *), delta_order_cmp);
+	for (i = 0; i < nmeta; i++) {
+		if (cancel_cb) {
+			err = (*cancel_cb)(cancel_arg);
+			if (err)
+				break;
+		}
+
+		m = meta[i];
+		pct = showprogress((i*100) / nmeta, pct);
+		m->deltas = NULL;
+		m->ndeltas = 0;
+
+		if (m->obj_type == GOT_OBJ_TYPE_COMMIT ||
+		    m->obj_type == GOT_OBJ_TYPE_TAG)
+			continue;
+
+		err = got_object_raw_open(&raw, repo, &m->id, 8192);
+		if (err)
+			goto done;
+
+		err = got_deltify_init(&m->dtab, raw->f, raw->hdrlen,
+		    raw->size + raw->hdrlen);
+		if (err)
+			goto done;
+
+		if (i > max_base_candidates) {
+			struct got_pack_meta *n = NULL;
+			n = meta[i - (max_base_candidates + 1)];
+			got_deltify_free(n->dtab);
+			n->dtab = NULL;
+		}
+
+		best = raw->size;
+		for (j = MAX(0, i - max_base_candidates); j < i; j++) {
+			if (cancel_cb) {
+				err = (*cancel_cb)(cancel_arg);
+				if (err)
+					goto done;
+			}
+			base = meta[j];
+			/* long chains make unpacking slow, avoid such bases */
+			if (base->nchain >= 128 ||
+			    base->obj_type != m->obj_type)
+				continue;
+
+			err = got_object_raw_open(&base_raw, repo, &base->id,
+			    8192);
+			if (err)
+				goto done;
+			err = got_deltify(&deltas, &ndeltas,
+			    raw->f, raw->hdrlen, raw->size + raw->hdrlen,
+			    base->dtab, base_raw->f, base_raw->hdrlen,
+			    base_raw->size + base_raw->hdrlen);
+			got_object_raw_close(base_raw);
+			base_raw = NULL;
+			if (err)
+				goto done;
+
+			size = delta_size(deltas, ndeltas);
+			if (size + 32 < best){
+				/*
+				 * if we already picked a best delta,
+				 * replace it.
+				 */
+				free(m->deltas);
+				best = size;
+				m->deltas = deltas;
+				m->ndeltas = ndeltas;
+				m->nchain = base->nchain + 1;
+				m->prev = base;
+				m->head = base->head;
+				if (m->head == NULL)
+					m->head = base;
+			} else {
+				free(deltas);
+				deltas = NULL;
+				ndeltas = 0;
+			}
+		}
+
+		got_object_raw_close(raw);
+		raw = NULL;
+	}
+
+	fprintf(stderr, "\b\b\b\b100%%\n");
+done:
+	for (i = MAX(0, nmeta - max_base_candidates); i < nmeta; i++) {
+		got_deltify_free(meta[i]->dtab);
+		meta[i]->dtab = NULL;
+	}
+	if (raw)
+		got_object_raw_close(raw);
+	if (base_raw)
+		got_object_raw_close(base_raw);
+	return err;
+}
+
+static const struct got_error *
+add_meta(struct got_pack_metavec *v, struct got_object_idset *idset,
+    struct got_object_id *id, const char *path, int obj_type,
+    time_t mtime)
+{
+	const struct got_error *err;
+	struct got_pack_meta *m;
+
+	err = got_object_idset_add(idset, id, NULL);
+	if (err)
+		return err;
+
+	if (v == NULL)
+		return NULL;
+
+	err = alloc_meta(&m, id, path, obj_type, mtime);
+	if (err)
+		goto done;
+
+	if (v->nmeta == v->metasz){
+		size_t newsize = 2 * v->metasz;
+		struct got_pack_meta **new;
+		new = reallocarray(v->meta, newsize, sizeof(*new));
+		if (new == NULL) {
+			err = got_error_from_errno("reallocarray");
+			goto done;
+		}
+		v->meta = new;
+		v->metasz = newsize; 
+	}
+done:
+	if (err) {
+		clear_meta(m);
+		free(m);
+	} else
+		v->meta[v->nmeta++] = m;
+
+	return err;
+}
+
+static const struct got_error *
+load_tree_entries(struct got_object_id_queue *ids, struct got_pack_metavec *v,
+    struct got_object_idset *idset, struct got_object_id *tree_id,
+    const char *dpath, time_t mtime, struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err;
+	struct got_tree_object *tree;
+	char *p = NULL;
+	int i;
+
+	err = got_object_open_as_tree(&tree, repo, tree_id);
+	if (err)
+		return err;
+
+	for (i = 0; i < got_object_tree_get_nentries(tree); i++) {
+		struct got_tree_entry *e = got_object_tree_get_entry(tree, i);
+		struct got_object_id *id = got_tree_entry_get_id(e);
+		mode_t mode = got_tree_entry_get_mode(e);
+
+		if (cancel_cb) {
+			err = (*cancel_cb)(cancel_arg);
+			if (err)
+				break;
+		}
+
+		if (got_object_tree_entry_is_symlink(e) ||
+		    got_object_tree_entry_is_submodule(e) ||
+		    got_object_idset_contains(idset, id))
+			continue;
+		
+		if (asprintf(&p, "%s%s%s", dpath, dpath[0] != '\0' ? "/" : "",
+		    got_tree_entry_get_name(e)) == -1) {
+			err = got_error_from_errno("asprintf");
+			break;
+		}
+
+		if (S_ISDIR(mode)) {
+			struct got_object_qid *qid;
+			err = got_object_qid_alloc(&qid, id);
+			if (err)
+				break;
+			SIMPLEQ_INSERT_TAIL(ids, qid, entry);
+		} else if (S_ISREG(mode)) {
+			err = add_meta(v, idset, id, p, GOT_OBJ_TYPE_BLOB,
+			    mtime);
+			if (err)
+				break;
+		}
+		free(p);
+		p = NULL;
+	}
+
+	got_object_tree_close(tree);
+	free(p);
+	return err;
+}
+
+static const struct got_error *
+load_tree(struct got_pack_metavec *v, struct got_object_idset *idset,
+    struct got_object_id *tree_id, const char *dpath, time_t mtime,
+    struct got_repository *repo, got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	struct got_object_id_queue tree_ids;
+	struct got_object_qid *qid;
+
+	if (got_object_idset_contains(idset, tree_id))
+		return NULL;
+
+	err = got_object_qid_alloc(&qid, tree_id);
+	if (err)
+		return err;
+
+	SIMPLEQ_INIT(&tree_ids);
+	SIMPLEQ_INSERT_TAIL(&tree_ids, qid, entry);
+
+	while (!SIMPLEQ_EMPTY(&tree_ids)) {
+		if (cancel_cb) {
+			err = (*cancel_cb)(cancel_arg);
+			if (err)
+				break;
+		}
+
+		qid = SIMPLEQ_FIRST(&tree_ids);
+		SIMPLEQ_REMOVE_HEAD(&tree_ids, entry);
+
+		if (got_object_idset_contains(idset, qid->id)) {
+			got_object_qid_free(qid);
+			continue;
+		}
+
+		err = add_meta(v, idset, qid->id, dpath, GOT_OBJ_TYPE_TREE,
+		    mtime);
+		if (err) {
+			got_object_qid_free(qid);
+			break;
+		}
+
+		err = load_tree_entries(&tree_ids, v, idset, qid->id, dpath,
+		    mtime, repo, cancel_cb, cancel_arg);
+		got_object_qid_free(qid);
+		if (err)
+			break;
+	}
+
+	got_object_id_queue_free(&tree_ids);
+	return err;
+}
+
+static const struct got_error *
+load_commit(struct got_pack_metavec *v, struct got_object_idset *idset,
+    struct got_object_id *id, struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err;
+	struct got_commit_object *commit;
+
+	if (got_object_idset_contains(idset, id))
+		return NULL;
+
+	err = got_object_open_as_commit(&commit, repo, id);
+	if (err)
+		return err;
+
+	err = add_meta(v, idset, id, "", GOT_OBJ_TYPE_COMMIT,
+	    got_object_commit_get_committer_time(commit));
+	if (err)
+		goto done;
+
+	err = load_tree(v, idset, got_object_commit_get_tree_id(commit),
+	    "", got_object_commit_get_committer_time(commit), repo,
+	    cancel_cb, cancel_arg);
+done:
+	got_object_commit_close(commit);
+	return err;
+}
+
+enum findtwixt_color {
+	COLOR_KEEP = 0,
+	COLOR_DROP,
+	COLOR_BLANK,
+};
+static const int findtwixt_colors[] = {
+	COLOR_KEEP,
+	COLOR_DROP,
+	COLOR_BLANK
+};
+
+static const struct got_error *
+queue_commit_id(struct got_object_id_queue *ids, struct got_object_id *id,
+    int color, struct got_repository *repo)
+{
+	const struct got_error *err;
+	struct got_object_qid *qid;
+	char *id_str;
+	int obj_type;
+
+	err = got_object_get_type(&obj_type, repo, id);
+	if (err)
+		return err;
+
+	if (obj_type != GOT_OBJ_TYPE_COMMIT) {
+		err = got_object_id_str(&id_str, id);
+		if (err)
+			return err;
+		err = got_error_fmt(GOT_ERR_OBJ_TYPE,
+		    "%s is not a commit", id_str);
+		free(id_str);
+		return err;
+	}
+	err = got_object_qid_alloc(&qid, id);
+	if (err)
+		return err;
+
+	SIMPLEQ_INSERT_TAIL(ids, qid, entry);
+	qid->data = (void *)&findtwixt_colors[color];
+	return NULL;
+}
+
+static const struct got_error *
+drop_commit(struct got_object_idset *keep, struct got_object_idset *drop,
+    struct got_object_id *id, struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	struct got_commit_object *commit;
+	const struct got_object_id_queue *parents;
+	struct got_object_id_queue ids;
+	struct got_object_qid *qid;
+
+	SIMPLEQ_INIT(&ids);
+
+	err = got_object_qid_alloc(&qid, id);
+	if (err)
+		return err;
+	SIMPLEQ_INSERT_HEAD(&ids, qid, entry);
+
+	while (!SIMPLEQ_EMPTY(&ids)) {
+		if (cancel_cb) {
+			err = (*cancel_cb)(cancel_arg);
+			if (err)
+				break;
+		}
+
+		qid = SIMPLEQ_FIRST(&ids);
+		SIMPLEQ_REMOVE_HEAD(&ids, entry);
+
+		if (got_object_idset_contains(drop, qid->id)) {
+			got_object_qid_free(qid);
+			continue;
+		}
+
+		err = got_object_idset_add(drop, qid->id, NULL);
+		if (err) {
+			got_object_qid_free(qid);
+			break;
+		}
+
+		if (!got_object_idset_contains(keep, qid->id)) {
+			got_object_qid_free(qid);
+			continue;
+		}
+
+		err = got_object_open_as_commit(&commit, repo, qid->id);
+		got_object_qid_free(qid);
+		if (err)
+			break;
+
+		parents = got_object_commit_get_parent_ids(commit);
+		if (parents) {
+			err = got_object_id_queue_copy(parents, &ids);
+			if (err) {
+				got_object_commit_close(commit);
+				break;
+			}
+		}
+		got_object_commit_close(commit);
+	}
+
+	got_object_id_queue_free(&ids);
+	return err;
+}
+
+struct append_id_arg {
+	struct got_object_id **array;
+	int idx;
+};
+
+static const struct got_error *
+append_id(struct got_object_id *id, void *data, void *arg)
+{
+	struct append_id_arg *a = arg;
+
+	a->array[a->idx] = got_object_id_dup(id);
+	if (a->array[a->idx] == NULL)
+		return got_error_from_errno("got_object_id_dup");
+
+	a->idx++;
+	return NULL;
+}
+
+static const struct got_error *
+findtwixt(struct got_object_id ***res, int *nres,
+    struct got_object_id **head, int nhead,
+    struct got_object_id **tail, int ntail,
+    struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	struct got_object_id_queue ids;
+	struct got_object_idset *keep, *drop;
+	struct got_object_qid *qid;
+	int i, ncolor, nkeep;
+
+	SIMPLEQ_INIT(&ids);
+	*res = NULL;
+	*nres = 0;
+
+	keep = got_object_idset_alloc();
+	if (keep == NULL)
+		return got_error_from_errno("got_object_idset_alloc");
+
+	drop = got_object_idset_alloc();
+	if (drop == NULL) {
+		err = got_error_from_errno("got_object_idset_alloc");
+		goto done;
+	}
+
+	for (i = 0; i < nhead; i++){
+		if (head[i]) {
+			err = queue_commit_id(&ids, head[i], COLOR_KEEP, repo);
+			if (err)
+				goto done;
+		}
+	}		
+	for (i = 0; i < ntail; i++){
+		if (tail[i]) {
+			err = queue_commit_id(&ids, tail[i], COLOR_DROP, repo);
+			if (err)
+				goto done;
+		}
+	}
+
+	while (!SIMPLEQ_EMPTY(&ids)) {
+		int qcolor;
+		qid = SIMPLEQ_FIRST(&ids);
+		qcolor = *((int *)qid->data);
+
+		if (got_object_idset_contains(drop, qid->id))
+			ncolor = COLOR_DROP;
+		else if (got_object_idset_contains(keep, qid->id))
+			ncolor = COLOR_KEEP;
+		else
+			ncolor = COLOR_BLANK;
+
+		if (ncolor == COLOR_DROP || (ncolor == COLOR_KEEP &&
+		    qcolor == COLOR_KEEP)) {
+			SIMPLEQ_REMOVE_HEAD(&ids, entry);
+			got_object_qid_free(qid);
+			continue;
+		}
+
+		if (ncolor == COLOR_KEEP && qcolor == COLOR_DROP) {
+			err = drop_commit(keep, drop, qid->id, repo,
+			    cancel_cb, cancel_arg);
+			if (err)
+				goto done;
+		} else if (ncolor == COLOR_BLANK) {
+			struct got_commit_object *commit;
+			struct got_object_id *id;
+			const struct got_object_id_queue *parents;
+			struct got_object_qid *pid;
+
+			id = got_object_id_dup(qid->id);
+			if (id == NULL) {
+				err = got_error_from_errno("got_object_id_dup");
+				goto done;
+			}
+			if (qcolor == COLOR_KEEP)
+				err = got_object_idset_add(keep, id, NULL);
+			else
+				err = got_object_idset_add(drop, id, NULL);
+			if (err) {
+				free(id);
+				goto done;
+			}
+
+			err = got_object_open_as_commit(&commit, repo, id);
+			if (err) {
+				free(id);
+				goto done;
+			}
+			parents = got_object_commit_get_parent_ids(commit);
+			if (parents) {
+				SIMPLEQ_FOREACH(pid, parents, entry) {
+					err = queue_commit_id(&ids, pid->id,
+					    qcolor, repo);
+					if (err) {
+						free(id);
+						goto done;
+					}
+				}
+			}
+			got_object_commit_close(commit);
+			commit = NULL;
+		} else {
+			/* should not happen */
+			err = got_error_fmt(GOT_ERR_NOT_IMPL,
+			    "%s ncolor=%d qcolor=%d", __func__, ncolor, qcolor);
+			goto done;
+		}
+
+		SIMPLEQ_REMOVE_HEAD(&ids, entry);
+		got_object_qid_free(qid);
+	}
+
+	nkeep = got_object_idset_num_elements(keep);
+	if (nkeep > 0) {
+		struct append_id_arg arg;
+		arg.array = calloc(nkeep, sizeof(struct got_object_id *));
+		if (arg.array == NULL) {
+			err = got_error_from_errno("calloc");
+			goto done;
+		}
+		arg.idx = 0;
+		err = got_object_idset_for_each(keep, append_id, &arg);
+		if (err) {
+			free(arg.array);
+			goto done;
+		}
+		*res = arg.array;
+		*nres = nkeep;
+	}
+done:
+	got_object_idset_free(keep);
+	got_object_idset_free(drop);
+	got_object_id_queue_free(&ids);
+	return err;
+}
+
+static const struct got_error *
+read_meta(struct got_pack_meta ***meta, int *nmeta,
+    struct got_object_id **theirs, int ntheirs,
+    struct got_object_id **ours, int nours, struct got_repository *repo,
+    got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err = NULL;
+	struct got_object_id **ids = NULL;
+	struct got_object_idset *idset;
+	int i, nobj = 0;
+	struct got_pack_metavec v;
+
+	*meta = NULL;
+	*nmeta = 0;
+
+	idset = got_object_idset_alloc();
+	if (idset == NULL)
+		return got_error_from_errno("got_object_idset_alloc");
+
+	v.nmeta = 0;
+	v.metasz = 64;
+	v.meta = calloc(v.metasz, sizeof(struct got_pack_meta *));
+	if (v.meta == NULL) {
+		err = got_error_from_errno("reallocarray");
+		goto done;
+	}
+
+	err = findtwixt(&ids, &nobj, ours, nours, theirs, ntheirs, repo,
+	    cancel_cb, cancel_arg);
+	if (err || nobj == 0)
+		goto done;
+
+	for (i = 0; i < ntheirs; i++) {
+		if (theirs[i] != NULL) {
+			err = load_commit(NULL, idset, theirs[i], repo,
+			    cancel_cb, cancel_arg);
+			if (err)
+				goto done;
+		}
+	}
+
+	for (i = 0; i < nobj; i++) {
+		err = load_commit(&v, idset, ids[i], repo,
+		    cancel_cb, cancel_arg);
+		if (err)
+			goto done;
+	}
+done:
+	for (i = 0; i < nobj; i++) {
+		free(ids[i]);
+	}
+	free(ids);
+	got_object_idset_free(idset);
+	if (err == NULL) {
+		*meta = v.meta;
+		*nmeta = v.nmeta;
+	} else
+		free(v.meta);
+
+	return err;
+}
+
+const struct got_error *
+hwrite(FILE *f, void *buf, int len, SHA1_CTX *ctx)
+{
+	size_t n;
+
+	SHA1Update(ctx, buf, len);
+	n = fwrite(buf, 1, len, f);
+	if (n != len)
+		return got_ferror(f, GOT_ERR_IO);
+	return NULL;
+}
+
+static void
+putbe32(char *b, uint32_t n)
+{
+	b[0] = n >> 24;
+	b[1] = n >> 16;
+	b[2] = n >> 8;
+	b[3] = n >> 0;
+}
+
+static int
+write_order_cmp(const void *pa, const void *pb)
+{
+	struct got_pack_meta *a, *b, *ahd, *bhd;
+
+	a = *(struct got_pack_meta **)pa;
+	b = *(struct got_pack_meta **)pb;
+	ahd = (a->head == NULL) ? a : a->head;
+	bhd = (b->head == NULL) ? b : b->head;
+	if (ahd->mtime != bhd->mtime)
+		return bhd->mtime - ahd->mtime;
+	if (ahd != bhd)
+		return (uintptr_t)bhd - (uintptr_t)ahd;
+	if (a->nchain != b->nchain)
+		return a->nchain - b->nchain;
+	return a->mtime - b->mtime;
+}
+
+static const struct got_error *
+packhdr(int *hdrlen, char *hdr, size_t bufsize, int obj_type, size_t len)
+{
+	size_t i;
+
+	*hdrlen = 0;
+
+	hdr[0] = obj_type << 4;
+	hdr[0] |= len & 0xf;
+	len >>= 4;
+	for (i = 1; len != 0; i++){
+		if (i >= bufsize)
+			return got_error(GOT_ERR_NO_SPACE);
+		hdr[i - 1] |= GOT_DELTA_SIZE_MORE;
+		hdr[i] = len & GOT_DELTA_SIZE_VAL_MASK;
+		len >>= GOT_DELTA_SIZE_SHIFT;
+	}
+
+	*hdrlen = i;
+	return NULL;
+}
+
+static const struct got_error *
+append(char **p, int *len, int *sz, void *seg, int nseg)
+{
+	char *n;
+
+	if (*len + nseg >= *sz) {
+		while (*len + nseg >= *sz)
+			*sz += *sz / 2;
+		n = realloc(*p, *sz);
+		if (n == NULL)
+			return got_error_from_errno("realloc");
+		*p = n;
+	}
+	memcpy(*p + *len, seg, nseg);
+	*len += nseg;
+	return NULL;
+}
+
+
+static const struct got_error *
+encodedelta(int *nd, struct got_pack_meta *m, struct got_raw_object *o,
+    off_t base_size, char **pp)
+{
+	const struct got_error *err = NULL;
+	char *p;
+	unsigned char buf[16], *bp;
+	int len, sz, i, j;
+	off_t n;
+	struct got_delta_instruction *d;
+
+	*pp = NULL;
+	*nd = 0;
+
+	sz = 128;
+	len = 0;
+	p = malloc(sz);
+	if (p == NULL)
+		return got_error_from_errno("malloc");
+
+	/* base object size */
+	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
+	n = base_size >> GOT_DELTA_SIZE_SHIFT;
+	for (i = 1; n > 0; i++) {
+		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
+		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
+		n >>= GOT_DELTA_SIZE_SHIFT;
+	}
+	err = append(&p, &len, &sz, buf, i);
+	if (err)
+		return err;
+
+	/* target object size */
+	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
+	n = o->size >> GOT_DELTA_SIZE_SHIFT;
+	for (i = 1; n > 0; i++) {
+		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
+		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
+		n >>= GOT_DELTA_SIZE_SHIFT;
+	}
+	err = append(&p, &len, &sz, buf, i);
+	if (err)
+		return err;
+	for (j = 0; j < m->ndeltas; j++) {
+		d = &m->deltas[j];
+		if (d->copy) {
+			n = d->offset;
+			bp = &buf[1];
+			buf[0] = GOT_DELTA_BASE_COPY;
+			for (i = 0; i < 4; i++) {
+				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
+				buf[0] |= 1 << i;
+				*bp++ = n & 0xff;
+				n >>= 8;
+				if (n == 0)
+					break;
+			}
+
+			n = d->len;
+			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
+				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
+				for (i = 0; i < 3 && n > 0; i++) {
+					buf[0] |= 1 << (i + 4);
+					*bp++ = n & 0xff;
+					n >>= 8;
+				}
+			}
+			err = append(&p, &len, &sz, buf, bp - buf);
+			if (err)
+				return err;
+		} else {
+			char content[128];
+			size_t r;
+			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
+				return got_error_from_errno("fseeko");
+			n = 0;
+			while (n != d->len) {
+				buf[0] = (d->len - n < 127) ? d->len - n : 127;
+				err = append(&p, &len, &sz, buf, 1);
+				if (err)
+					return err;
+				r = fread(content, 1, buf[0], o->f);
+				if (r != buf[0])
+					return got_ferror(o->f, GOT_ERR_IO);
+				err = append(&p, &len, &sz, content, buf[0]);
+				if (err)
+					return err;
+				n += buf[0];
+			}
+		}
+	}
+	*pp = p;
+	*nd = len;
+	return NULL;
+}
+
+static int
+packoff(char *hdr, off_t off)
+{
+	int i, j;
+	char rbuf[8];
+
+	rbuf[0] = off & GOT_DELTA_SIZE_VAL_MASK;
+	for (i = 1; (off >>= GOT_DELTA_SIZE_SHIFT) != 0; i++) {
+		rbuf[i] = (--off & GOT_DELTA_SIZE_VAL_MASK) |
+		    GOT_DELTA_SIZE_MORE;
+	}
+
+	j = 0;
+	while (i > 0)
+		hdr[j++] = rbuf[--i];
+	return j;
+}
+
+static const struct got_error *
+genpack(uint8_t *pack_sha1, FILE *packfile,
+    struct got_pack_meta **meta, int nmeta, int use_offset_deltas,
+    struct got_repository *repo)
+{
+	const struct got_error *err = NULL;
+	int i, nh, nd, pct;
+	SHA1_CTX ctx;
+	struct got_pack_meta *m;
+	struct got_raw_object *raw;
+	char *p = NULL, buf[32];
+	size_t outlen, n;
+	struct got_deflate_checksum csum;
+
+	SHA1Init(&ctx);
+	csum.output_sha1 = &ctx;
+	csum.output_crc = NULL;
+
+	pct = 0;
+	fprintf(stderr, "generating pack\n");
+
+	err = hwrite(packfile, "PACK", 4, &ctx);
+	if (err)
+		return err;
+	putbe32(buf, GOT_PACKFILE_VERSION);
+	err = hwrite(packfile, buf, 4, &ctx);
+	if (err)
+		goto done;
+	putbe32(buf, nmeta);
+	err = hwrite(packfile, buf, 4, &ctx);
+	if (err)
+		goto done;
+	qsort(meta, nmeta, sizeof(struct got_pack_meta *), write_order_cmp);
+	fprintf(stderr, "writing %d objects:   0%%", nmeta);
+	for (i = 0; i < nmeta; i++) {
+		pct = showprogress((i*100)/nmeta, pct);
+		m = meta[i];
+		m->off = ftello(packfile);
+		err = got_object_raw_open(&raw, repo, &m->id, 8192);
+		if (err)
+			goto done;
+		if (m->deltas == NULL) {
+			err = packhdr(&nh, buf, sizeof(buf),
+			    m->obj_type, raw->size);
+			if (err)
+				goto done;
+			err = hwrite(packfile, buf, nh, &ctx);
+			if (err)
+				goto done;
+			if (fseeko(raw->f, raw->hdrlen, SEEK_SET) == -1) {
+				err = got_error_from_errno("fseeko");
+				goto done;
+			}
+			err = got_deflate_to_file(&outlen, raw->f, packfile,
+			    &csum);
+			if (err)
+				goto done;
+		} else {
+			FILE *delta_file;
+			struct got_raw_object *base_raw;
+			err = got_object_raw_open(&base_raw, repo,
+			    &m->prev->id, 8192);
+			if (err)
+				goto done;
+			err = encodedelta(&nd, m, raw, base_raw->size, &p);
+			if (err)
+				goto done;
+			got_object_raw_close(base_raw);
+			if (use_offset_deltas && m->prev->off != 0) {
+				err = packhdr(&nh, buf, sizeof(buf),
+				    GOT_OBJ_TYPE_OFFSET_DELTA, nd);
+				if (err)
+					goto done;
+				nh += packoff(buf + nh,
+				    m->off - m->prev->off);
+				err = hwrite(packfile, buf, nh, &ctx);
+				if (err)
+					goto done;
+			} else {
+				err = packhdr(&nh, buf, sizeof(buf),
+				    GOT_OBJ_TYPE_REF_DELTA, nd);
+				err = hwrite(packfile, buf, nh, &ctx);
+				if (err)
+					goto done;
+				err = hwrite(packfile, m->prev->id.sha1,
+				    sizeof(m->prev->id.sha1), &ctx);
+				if (err)
+					goto done;
+			}
+			/* XXX need got_deflate_from_mem() */
+			delta_file = fmemopen(p, nd, "r");
+			if (delta_file == NULL) {
+				err = got_error_from_errno("fmemopen");
+				goto done;
+			}
+			err = got_deflate_to_file(&outlen, delta_file,
+			    packfile, &csum);
+			fclose(delta_file);
+			if (err)
+				goto done;
+			free(p);
+			p = NULL;
+		}
+		got_object_raw_close(raw);
+		raw = NULL;
+	}
+	fprintf(stderr, "\b\b\b\b100%%\n");
+	SHA1Final(pack_sha1, &ctx);
+	n = fwrite(pack_sha1, 1, SHA1_DIGEST_LENGTH, packfile);
+	if (n != SHA1_DIGEST_LENGTH)
+		err = got_ferror(packfile, GOT_ERR_IO);
+done:
+	free(p);
+	return err;
+}
+
+const struct got_error *
+got_pack_create(uint8_t *packsha1, FILE *packfile,
+    struct got_object_id **theirs, int ntheirs,
+    struct got_object_id **ours, int nours,
+    struct got_repository *repo, got_cancel_cb cancel_cb, void *cancel_arg)
+{
+	const struct got_error *err;
+	struct got_pack_meta **meta;
+	int nmeta;
+
+	err = read_meta(&meta, &nmeta, theirs, ntheirs, ours, nours, repo,
+	    cancel_cb, cancel_arg);
+	if (err)
+		return err;
+
+	err = pick_deltas(meta, nmeta, repo, cancel_cb, cancel_arg);
+	if (err)
+		goto done;
+
+	err = genpack(packsha1, packfile, meta, nmeta, 1, repo);
+	if (err)
+		goto done;
+done:
+	free_nmeta(meta, nmeta);
+	return err;
+}