merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 259 insertions, 0 deletions

diff --git a/third_party/git/promisor-remote.c b/third_party/git/promisor-remote.c
new file mode 100644
index 000000000000..3c572b1c811e
--- /dev/null
+++ b/third_party/git/promisor-remote.c
@@ -0,0 +1,259 @@
+#include "cache.h"
+#include "object-store.h"
+#include "promisor-remote.h"
+#include "config.h"
+#include "transport.h"
+#include "strvec.h"
+
+static char *repository_format_partial_clone;
+
+void set_repository_format_partial_clone(char *partial_clone)
+{
+	repository_format_partial_clone = xstrdup_or_null(partial_clone);
+}
+
+static int fetch_objects(const char *remote_name,
+			 const struct object_id *oids,
+			 int oid_nr)
+{
+	struct child_process child = CHILD_PROCESS_INIT;
+	int i;
+	FILE *child_in;
+
+	child.git_cmd = 1;
+	child.in = -1;
+	strvec_pushl(&child.args, "-c", "fetch.negotiationAlgorithm=noop",
+		     "fetch", remote_name, "--no-tags",
+		     "--no-write-fetch-head", "--recurse-submodules=no",
+		     "--filter=blob:none", "--stdin", NULL);
+	if (start_command(&child))
+		die(_("promisor-remote: unable to fork off fetch subprocess"));
+	child_in = xfdopen(child.in, "w");
+
+	for (i = 0; i < oid_nr; i++) {
+		if (fputs(oid_to_hex(&oids[i]), child_in) < 0)
+			die_errno(_("promisor-remote: could not write to fetch subprocess"));
+		if (fputc('\n', child_in) < 0)
+			die_errno(_("promisor-remote: could not write to fetch subprocess"));
+	}
+
+	if (fclose(child_in) < 0)
+		die_errno(_("promisor-remote: could not close stdin to fetch subprocess"));
+	return finish_command(&child) ? -1 : 0;
+}
+
+static struct promisor_remote *promisors;
+static struct promisor_remote **promisors_tail = &promisors;
+
+static struct promisor_remote *promisor_remote_new(const char *remote_name)
+{
+	struct promisor_remote *r;
+
+	if (*remote_name == '/') {
+		warning(_("promisor remote name cannot begin with '/': %s"),
+			remote_name);
+		return NULL;
+	}
+
+	FLEX_ALLOC_STR(r, name, remote_name);
+
+	*promisors_tail = r;
+	promisors_tail = &r->next;
+
+	return r;
+}
+
+static struct promisor_remote *promisor_remote_lookup(const char *remote_name,
+						      struct promisor_remote **previous)
+{
+	struct promisor_remote *r, *p;
+
+	for (p = NULL, r = promisors; r; p = r, r = r->next)
+		if (!strcmp(r->name, remote_name)) {
+			if (previous)
+				*previous = p;
+			return r;
+		}
+
+	return NULL;
+}
+
+static void promisor_remote_move_to_tail(struct promisor_remote *r,
+					 struct promisor_remote *previous)
+{
+	if (r->next == NULL)
+		return;
+
+	if (previous)
+		previous->next = r->next;
+	else
+		promisors = r->next ? r->next : r;
+	r->next = NULL;
+	*promisors_tail = r;
+	promisors_tail = &r->next;
+}
+
+static int promisor_remote_config(const char *var, const char *value, void *data)
+{
+	const char *name;
+	size_t namelen;
+	const char *subkey;
+
+	if (parse_config_key(var, "remote", &name, &namelen, &subkey) < 0)
+		return 0;
+
+	if (!strcmp(subkey, "promisor")) {
+		char *remote_name;
+
+		if (!git_config_bool(var, value))
+			return 0;
+
+		remote_name = xmemdupz(name, namelen);
+
+		if (!promisor_remote_lookup(remote_name, NULL))
+			promisor_remote_new(remote_name);
+
+		free(remote_name);
+		return 0;
+	}
+	if (!strcmp(subkey, "partialclonefilter")) {
+		struct promisor_remote *r;
+		char *remote_name = xmemdupz(name, namelen);
+
+		r = promisor_remote_lookup(remote_name, NULL);
+		if (!r)
+			r = promisor_remote_new(remote_name);
+
+		free(remote_name);
+
+		if (!r)
+			return 0;
+
+		return git_config_string(&r->partial_clone_filter, var, value);
+	}
+
+	return 0;
+}
+
+static int initialized;
+
+static void promisor_remote_init(void)
+{
+	if (initialized)
+		return;
+	initialized = 1;
+
+	git_config(promisor_remote_config, NULL);
+
+	if (repository_format_partial_clone) {
+		struct promisor_remote *o, *previous;
+
+		o = promisor_remote_lookup(repository_format_partial_clone,
+					   &previous);
+		if (o)
+			promisor_remote_move_to_tail(o, previous);
+		else
+			promisor_remote_new(repository_format_partial_clone);
+	}
+}
+
+static void promisor_remote_clear(void)
+{
+	while (promisors) {
+		struct promisor_remote *r = promisors;
+		promisors = promisors->next;
+		free(r);
+	}
+
+	promisors_tail = &promisors;
+}
+
+void promisor_remote_reinit(void)
+{
+	initialized = 0;
+	promisor_remote_clear();
+	promisor_remote_init();
+}
+
+struct promisor_remote *promisor_remote_find(const char *remote_name)
+{
+	promisor_remote_init();
+
+	if (!remote_name)
+		return promisors;
+
+	return promisor_remote_lookup(remote_name, NULL);
+}
+
+int has_promisor_remote(void)
+{
+	return !!promisor_remote_find(NULL);
+}
+
+static int remove_fetched_oids(struct repository *repo,
+			       struct object_id **oids,
+			       int oid_nr, int to_free)
+{
+	int i, remaining_nr = 0;
+	int *remaining = xcalloc(oid_nr, sizeof(*remaining));
+	struct object_id *old_oids = *oids;
+	struct object_id *new_oids;
+
+	for (i = 0; i < oid_nr; i++)
+		if (oid_object_info_extended(repo, &old_oids[i], NULL,
+					     OBJECT_INFO_SKIP_FETCH_OBJECT)) {
+			remaining[i] = 1;
+			remaining_nr++;
+		}
+
+	if (remaining_nr) {
+		int j = 0;
+		new_oids = xcalloc(remaining_nr, sizeof(*new_oids));
+		for (i = 0; i < oid_nr; i++)
+			if (remaining[i])
+				oidcpy(&new_oids[j++], &old_oids[i]);
+		*oids = new_oids;
+		if (to_free)
+			free(old_oids);
+	}
+
+	free(remaining);
+
+	return remaining_nr;
+}
+
+int promisor_remote_get_direct(struct repository *repo,
+			       const struct object_id *oids,
+			       int oid_nr)
+{
+	struct promisor_remote *r;
+	struct object_id *remaining_oids = (struct object_id *)oids;
+	int remaining_nr = oid_nr;
+	int to_free = 0;
+	int res = -1;
+
+	if (oid_nr == 0)
+		return 0;
+
+	promisor_remote_init();
+
+	for (r = promisors; r; r = r->next) {
+		if (fetch_objects(r->name, remaining_oids, remaining_nr) < 0) {
+			if (remaining_nr == 1)
+				continue;
+			remaining_nr = remove_fetched_oids(repo, &remaining_oids,
+							 remaining_nr, to_free);
+			if (remaining_nr) {
+				to_free = 1;
+				continue;
+			}
+		}
+		res = 0;
+		break;
+	}
+
+	if (to_free)
+		free(remaining_oids);
+
+	return res;
+}