1 files changed, 102 insertions, 0 deletions
diff --git a/repack-promisor.c b/repack-promisor.c
new file mode 100644
index 0000000000..ee6e0669f6
--- /dev/null
+++ b/repack-promisor.c
@@ -0,0 +1,102 @@
+#include "git-compat-util.h"
+#include "repack.h"
+#include "hex.h"
+#include "pack.h"
+#include "packfile.h"
+#include "path.h"
+#include "repository.h"
+#include "run-command.h"
+
+struct write_oid_context {
+	struct child_process *cmd;
+	const struct git_hash_algo *algop;
+};
+
+/*
+ * Write oid to the given struct child_process's stdin, starting it first if
+ * necessary.
+ */
+static int write_oid(const struct object_id *oid,
+		     struct packed_git *pack UNUSED,
+		     uint32_t pos UNUSED, void *data)
+{
+	struct write_oid_context *ctx = data;
+	struct child_process *cmd = ctx->cmd;
+
+	if (cmd->in == -1) {
+		if (start_command(cmd))
+			die(_("could not start pack-objects to repack promisor objects"));
+	}
+
+	if (write_in_full(cmd->in, oid_to_hex(oid), ctx->algop->hexsz) < 0 ||
+	    write_in_full(cmd->in, "\n", 1) < 0)
+		die(_("failed to feed promisor objects to pack-objects"));
+	return 0;
+}
+
+void repack_promisor_objects(struct repository *repo,
+			     const struct pack_objects_args *args,
+			     struct string_list *names, const char *packtmp)
+{
+	struct write_oid_context ctx;
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	FILE *out;
+	struct strbuf line = STRBUF_INIT;
+
+	prepare_pack_objects(&cmd, args, packtmp);
+	cmd.in = -1;
+
+	/*
+	 * NEEDSWORK: Giving pack-objects only the OIDs without any ordering
+	 * hints may result in suboptimal deltas in the resulting pack. See if
+	 * the OIDs can be sent with fake paths such that pack-objects can use a
+	 * {type -> existing pack order} ordering when computing deltas instead
+	 * of a {type -> size} ordering, which may produce better deltas.
+	 */
+	ctx.cmd = &cmd;
+	ctx.algop = repo->hash_algo;
+	for_each_packed_object(repo, write_oid, &ctx,
+			       FOR_EACH_OBJECT_PROMISOR_ONLY);
+
+	if (cmd.in == -1) {
+		/* No packed objects; cmd was never started */
+		child_process_clear(&cmd);
+		return;
+	}
+
+	close(cmd.in);
+
+	out = xfdopen(cmd.out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+		char *promisor_name;
+
+		if (line.len != repo->hash_algo->hexsz)
+			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
+		item = string_list_append(names, line.buf);
+
+		/*
+		 * pack-objects creates the .pack and .idx files, but not the
+		 * .promisor file. Create the .promisor file, which is empty.
+		 *
+		 * NEEDSWORK: fetch-pack sometimes generates non-empty
+		 * .promisor files containing the ref names and associated
+		 * hashes at the point of generation of the corresponding
+		 * packfile, but this would not preserve their contents. Maybe
+		 * concatenate the contents of all .promisor files instead of
+		 * just creating a new empty file.
+		 */
+		promisor_name = mkpathdup("%s-%s.promisor", packtmp,
+					  line.buf);
+		write_promisor_file(promisor_name, NULL, 0);
+
+		item->util = generated_pack_populate(item->string, packtmp);
+
+		free(promisor_name);
+	}
+
+	fclose(out);
+	if (finish_command(&cmd))
+		die(_("could not finish pack-objects to repack promisor objects"));
+	strbuf_release(&line);
+}