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, 195 insertions, 0 deletions

diff --git a/third_party/git/builtin/credential-store.c b/third_party/git/builtin/credential-store.c
new file mode 100644
index 0000000000..5331ab151a
--- /dev/null
+++ b/third_party/git/builtin/credential-store.c
@@ -0,0 +1,195 @@
+#include "builtin.h"
+#include "lockfile.h"
+#include "credential.h"
+#include "string-list.h"
+#include "parse-options.h"
+
+static struct lock_file credential_lock;
+
+static int parse_credential_file(const char *fn,
+				  struct credential *c,
+				  void (*match_cb)(struct credential *),
+				  void (*other_cb)(struct strbuf *))
+{
+	FILE *fh;
+	struct strbuf line = STRBUF_INIT;
+	struct credential entry = CREDENTIAL_INIT;
+	int found_credential = 0;
+
+	fh = fopen(fn, "r");
+	if (!fh) {
+		if (errno != ENOENT && errno != EACCES)
+			die_errno("unable to open %s", fn);
+		return found_credential;
+	}
+
+	while (strbuf_getline_lf(&line, fh) != EOF) {
+		if (!credential_from_url_gently(&entry, line.buf, 1) &&
+		    entry.username && entry.password &&
+		    credential_match(c, &entry)) {
+			found_credential = 1;
+			if (match_cb) {
+				match_cb(&entry);
+				break;
+			}
+		}
+		else if (other_cb)
+			other_cb(&line);
+	}
+
+	credential_clear(&entry);
+	strbuf_release(&line);
+	fclose(fh);
+	return found_credential;
+}
+
+static void print_entry(struct credential *c)
+{
+	printf("username=%s\n", c->username);
+	printf("password=%s\n", c->password);
+}
+
+static void print_line(struct strbuf *buf)
+{
+	strbuf_addch(buf, '\n');
+	write_or_die(get_lock_file_fd(&credential_lock), buf->buf, buf->len);
+}
+
+static void rewrite_credential_file(const char *fn, struct credential *c,
+				    struct strbuf *extra)
+{
+	if (hold_lock_file_for_update(&credential_lock, fn, 0) < 0)
+		die_errno("unable to get credential storage lock");
+	if (extra)
+		print_line(extra);
+	parse_credential_file(fn, c, NULL, print_line);
+	if (commit_lock_file(&credential_lock) < 0)
+		die_errno("unable to write credential store");
+}
+
+static void store_credential_file(const char *fn, struct credential *c)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_addf(&buf, "%s://", c->protocol);
+	strbuf_addstr_urlencode(&buf, c->username, is_rfc3986_unreserved);
+	strbuf_addch(&buf, ':');
+	strbuf_addstr_urlencode(&buf, c->password, is_rfc3986_unreserved);
+	strbuf_addch(&buf, '@');
+	if (c->host)
+		strbuf_addstr_urlencode(&buf, c->host, is_rfc3986_unreserved);
+	if (c->path) {
+		strbuf_addch(&buf, '/');
+		strbuf_addstr_urlencode(&buf, c->path,
+					is_rfc3986_reserved_or_unreserved);
+	}
+
+	rewrite_credential_file(fn, c, &buf);
+	strbuf_release(&buf);
+}
+
+static void store_credential(const struct string_list *fns, struct credential *c)
+{
+	struct string_list_item *fn;
+
+	/*
+	 * Sanity check that what we are storing is actually sensible.
+	 * In particular, we can't make a URL without a protocol field.
+	 * Without either a host or pathname (depending on the scheme),
+	 * we have no primary key. And without a username and password,
+	 * we are not actually storing a credential.
+	 */
+	if (!c->protocol || !(c->host || c->path) || !c->username || !c->password)
+		return;
+
+	for_each_string_list_item(fn, fns)
+		if (!access(fn->string, F_OK)) {
+			store_credential_file(fn->string, c);
+			return;
+		}
+	/*
+	 * Write credential to the filename specified by fns->items[0], thus
+	 * creating it
+	 */
+	if (fns->nr)
+		store_credential_file(fns->items[0].string, c);
+}
+
+static void remove_credential(const struct string_list *fns, struct credential *c)
+{
+	struct string_list_item *fn;
+
+	/*
+	 * Sanity check that we actually have something to match
+	 * against. The input we get is a restrictive pattern,
+	 * so technically a blank credential means "erase everything".
+	 * But it is too easy to accidentally send this, since it is equivalent
+	 * to empty input. So explicitly disallow it, and require that the
+	 * pattern have some actual content to match.
+	 */
+	if (!c->protocol && !c->host && !c->path && !c->username)
+		return;
+	for_each_string_list_item(fn, fns)
+		if (!access(fn->string, F_OK))
+			rewrite_credential_file(fn->string, c, NULL);
+}
+
+static void lookup_credential(const struct string_list *fns, struct credential *c)
+{
+	struct string_list_item *fn;
+
+	for_each_string_list_item(fn, fns)
+		if (parse_credential_file(fn->string, c, print_entry, NULL))
+			return; /* Found credential */
+}
+
+int cmd_credential_store(int argc, const char **argv, const char *prefix)
+{
+	const char * const usage[] = {
+		"git credential-store [<options>] <action>",
+		NULL
+	};
+	const char *op;
+	struct credential c = CREDENTIAL_INIT;
+	struct string_list fns = STRING_LIST_INIT_DUP;
+	char *file = NULL;
+	struct option options[] = {
+		OPT_STRING(0, "file", &file, "path",
+			   "fetch and store credentials in <path>"),
+		OPT_END()
+	};
+
+	umask(077);
+
+	argc = parse_options(argc, (const char **)argv, prefix, options, usage, 0);
+	if (argc != 1)
+		usage_with_options(usage, options);
+	op = argv[0];
+
+	if (file) {
+		string_list_append(&fns, file);
+	} else {
+		if ((file = expand_user_path("~/.git-credentials", 0)))
+			string_list_append_nodup(&fns, file);
+		file = xdg_config_home("credentials");
+		if (file)
+			string_list_append_nodup(&fns, file);
+	}
+	if (!fns.nr)
+		die("unable to set up default path; use --file");
+
+	if (credential_read(&c, stdin) < 0)
+		die("unable to read credential");
+
+	if (!strcmp(op, "get"))
+		lookup_credential(&fns, &c);
+	else if (!strcmp(op, "erase"))
+		remove_credential(&fns, &c);
+	else if (!strcmp(op, "store"))
+		store_credential(&fns, &c);
+	else
+		; /* Ignore unknown operation. */
+
+	string_list_clear(&fns, 0);
+	return 0;
+}