thodg/got

diff --git a/got/got.1 b/got/got.1
index ec8f587..8100849 100644
--- a/got/got.1
+++ b/got/got.1
@@ -190,6 +190,35 @@ The options for
 .Cm got clone
 are as follows:
 .Bl -tag -width Ds
+.It Fl m
+Create the cloned repository as a mirror of the original repository.
+This is useful if the cloned repository will not be used to store
+local changes as created by
+.Cm got commit .
+.Pp
+The repository's
+.Pa config
+file will be set up with the
+.Dq mirror
+option enabled, such that
+.Cm got fetch
+or
+.Xr git-fetch 1
+will write incoming changes directly to branches in the
+.Dq refs/heads/
+reference namespace, rather than to branches in the
+.Dq refs/remotes/
+namespace.
+This avoids the usual requirement of having to run
+.Cm got rebase
+after
+.Cm got fetch
+in order to make incoming changes appear on branches in the
+.Dq refs/heads/
+namespace.
+But maintaining custom branches with local changes in the cloned
+repository becomes difficult since local changes are at risk of
+being discarded whenever incoming changes are fetched.
 .It Fl q
 Suppress progress reporting output.
 The same option will be passed to
@@ -220,16 +249,26 @@ file of the repository, as created by
 .Pp
 Branch references in the
 .Dq refs/remotes/
-reference namespace will be updated to point at the newly fetched commits.
-The
+reference namespace will be updated to point at the newly fetched commits,
+and the
 .Cm got rebase
 command can then be used to make new changes visible on branches in the
 .Dq refs/heads/
+reference namespace, merging incoming changes with local changes as necessary.
+.Pp
+However, if the repository is configured as a mirror then all references will
+be updated as needed to match the corresponding references in the remote
+repository, including branches in the
+.Dq refs/heads/
 reference namespace.
+If those branches contained local commits, these will no longer be reachable
+via a reference and will therefore be at risk of being discarded by Git's
+garbage collector.
 .Pp
-Existing references in the
+In any case, existing references in the
 .Dq refs/tags/
-namespace will be changed to match tags contained in the remote repository.
+namespace will always be changed to match tags contained in the remote
+repository.
 .Pp
 The options for
 .Cm got fetch
@@ -1715,12 +1754,31 @@ to be amended and perhaps committed again:
 .Dl $ # now back out the previous backout :-)
 .Dl $ got backout unified-buffer-cache
 .Pp
-Fetch new upstream commits into the local repository's master branch.
-This step currently requires
-.Xr git 1 :
+Fetch new upstream commits into the local repository's
+.Dq origin/master
+branch:
+.Pp
+.Dl $ cd /usr/src
+.Dl $ got fetch
+.Pp
+In a repository created with a HTTP URL and
+.Cm git clone --bare
+the
+.Xr git-fetch 1
+command must be used instead:
 .Pp
 .Dl $ cd /var/git/src.git
-.Dl $ git fetch origin master:master
+.Dl $ git fetch origin master:refs/remotes/origin/master
+.Pp
+Rebase the local
+.Dq master
+branch to merge the new changes that are now visible on the
+.Dq origin/master
+branch:
+.Pp
+.Dl $ cd /usr/src
+.Dl $ got update -b origin/master
+.Dl $ got rebase master
 .Pp
 Rebase the
 .Dq unified-buffer-cache
@@ -1746,11 +1804,12 @@ branch:
 .Dl $ got update -c master
 .Dl $ got histedit
 .Pp
-Additional steps are necessary if local changes need to be pushed back
+.Pp
+Additional steps may be necessary if local changes need to be pushed back
 to the remote repository, which currently requires
 .Cm git push .
 Before working against existing branches in a repository cloned with
-.Dq git clone --bare
+.Cm git clone --bare
 instead of
 .Cm got clone ,
 a Git
@@ -1769,9 +1828,15 @@ command:
 .Pp
 .Dl $ cd /var/git/repo
 .Dl $ git config remote.origin.fetch '+refs/heads/*:refs/remotes/origin/*'
+Additionally, the
+.Dq mirror
+option must be disabled:
+.Pp
+.Dl $ cd /var/git/repo
+.Dl $ git config remote.origin.mirror false
 .Pp
 Alternatively, the following
-.Pa fetch
+.Xr git-fetch 1
 configuration item can be added manually to the Git repository's
 .Pa config
 file:
@@ -1779,6 +1844,7 @@ file:
 .Dl [remote "origin"]
 .Dl url = ...
 .Dl fetch = +refs/heads/*:refs/remotes/origin/*
+.Dl mirror = false
 .Pp
 This configuration leaves the local repository's
 .Dq refs/heads
@@ -1789,12 +1855,15 @@ and, if needed, created with
 .Pp
 Branches in the
 .Dq remotes/origin
-namespace can be updated with incoming changes from the remote
+namespace can now be updated with incoming changes from the remote
 repository with
-.Cm got fetch :
+.Cm got fetch
+or
+.Xr git-fetch 1
+without extra command line arguments:
 .Pp
 .Dl $ cd /var/git/repo
-.Dl $ got fetch
+.Dl $ git fetch
 .Pp
 To make changes fetched from the remote repository appear on the
 .Dq master
diff --git a/got/got.c b/got/got.c
index 5ab89fa..740999c 100644
--- a/got/got.c
+++ b/got/got.c
@@ -811,7 +811,7 @@ done:
 __dead static void
 usage_clone(void)
 {
-	fprintf(stderr, "usage: %s clone [-q] [-v] repository-url "
+	fprintf(stderr, "usage: %s clone [-m] [-q] [-v] repository-url "
 	    "[target-directory]\n", getprogname());
 	exit(1);
 }
@@ -903,13 +903,16 @@ cmd_clone(int argc, char *argv[])
 	char *gitconfig = NULL;
 	FILE *gitconfig_file = NULL;
 	ssize_t n;
-	int verbosity = 0;
+	int verbosity = 0, mirror_references = 0;
 
 	TAILQ_INIT(&refs);
 	TAILQ_INIT(&symrefs);
 
-	while ((ch = getopt(argc, argv, "vq")) != -1) {
+	while ((ch = getopt(argc, argv, "mvq")) != -1) {
 		switch (ch) {
+		case 'm':
+			mirror_references = 1;
+			break;
 		case 'v':
 			if (verbosity < 0)
 				verbosity = 0;
@@ -1022,14 +1025,25 @@ cmd_clone(int argc, char *argv[])
 		error = got_error_from_errno2("fopen", gitconfig_path);
 		goto done;
 	}
-	if (asprintf(&gitconfig,
-	    "[remote \"%s\"]\n"
-	    "\turl = %s\n"
-	    "\tfetch = +refs/heads/*:refs/remotes/%s/*\n",
-	    GOT_FETCH_DEFAULT_REMOTE_NAME, git_url,
-	    GOT_FETCH_DEFAULT_REMOTE_NAME) == -1) {
-		error = got_error_from_errno("asprintf");
-		goto done;
+	if (mirror_references) {
+		if (asprintf(&gitconfig,
+		    "[remote \"%s\"]\n"
+		    "\turl = %s\n"
+		    "\tmirror = true\n",
+		    GOT_FETCH_DEFAULT_REMOTE_NAME, git_url) == -1) {
+			error = got_error_from_errno("asprintf");
+			goto done;
+		}
+	} else {
+		if (asprintf(&gitconfig,
+		    "[remote \"%s\"]\n"
+		    "\turl = %s\n"
+		    "\tfetch = +refs/heads/*:refs/remotes/%s/*\n",
+		    GOT_FETCH_DEFAULT_REMOTE_NAME, git_url,
+		    GOT_FETCH_DEFAULT_REMOTE_NAME) == -1) {
+			error = got_error_from_errno("asprintf");
+			goto done;
+		}
 	}
 	n = fwrite(gitconfig, 1, strlen(gitconfig), gitconfig_file);
 	if (n != strlen(gitconfig)) {
@@ -1042,8 +1056,8 @@ cmd_clone(int argc, char *argv[])
 	fpa.last_p_resolved = -1;
 	fpa.verbosity = verbosity;
 	error = got_fetch_pack(&pack_hash, &refs, &symrefs,
-	    GOT_FETCH_DEFAULT_REMOTE_NAME, fetchfd, repo,
-	    fetch_progress, &fpa);
+	    GOT_FETCH_DEFAULT_REMOTE_NAME, mirror_references,
+	    fetchfd, repo, fetch_progress, &fpa);
 	if (error)
 		goto done;
 
@@ -1069,6 +1083,9 @@ cmd_clone(int argc, char *argv[])
 		if (error)
 			goto done;
 
+		if (mirror_references)
+			continue;
+
 		if (strncmp("refs/heads/", refname, 11) != 0)
 			continue;
 
@@ -1118,7 +1135,8 @@ cmd_clone(int argc, char *argv[])
 	}
 
 	if (verbosity >= 0)
-		printf("Created cloned repository '%s'\n", repo_path);
+		printf("Created %s repository '%s'\n",
+		    mirror_references ? "mirrored" : "cloned", repo_path);
 done:
 	if (fetchfd != -1 && close(fetchfd) == -1 && error == NULL)
 		error = got_error_from_errno("close");
@@ -1372,7 +1390,7 @@ cmd_fetch(int argc, char *argv[])
 	fpa.last_p_resolved = -1;
 	fpa.verbosity = verbosity;
 	error = got_fetch_pack(&pack_hash, &refs, &symrefs, remote->name,
-	    fetchfd, repo, fetch_progress, &fpa);
+	    remote->mirror_references, fetchfd, repo, fetch_progress, &fpa);
 	if (error)
 		goto done;
 
diff --git a/include/got_fetch.h b/include/got_fetch.h
index 43417f2..9df27fa 100644
--- a/include/got_fetch.h
+++ b/include/got_fetch.h
@@ -61,4 +61,4 @@ typedef const struct got_error *(*got_fetch_progress_cb)(void *,
  */
 const struct got_error *got_fetch_pack(struct got_object_id **,
 	struct got_pathlist_head *, struct got_pathlist_head *, const char *,
-	int, struct got_repository *, got_fetch_progress_cb, void *);
+	int, int, struct got_repository *, got_fetch_progress_cb, void *);
diff --git a/include/got_repository.h b/include/got_repository.h
index 106390c..1e0ca3b 100644
--- a/include/got_repository.h
+++ b/include/got_repository.h
@@ -51,6 +51,12 @@ const char *got_repo_get_gitconfig_owner(struct got_repository *);
 struct got_remote_repo {
 	char *name;
 	char *url;
+	
+	/*
+	 * If set, references are mirrored 1:1 into the local repository.
+	 * If not set, references are mapped into "refs/remotes/$name/".
+	 */
+	int mirror_references;
 };
 
 /* Obtain the list of remote repositories parsed from gitconfig. */ 
diff --git a/lib/fetch.c b/lib/fetch.c
index 132da7a..8edac2b 100644
--- a/lib/fetch.c
+++ b/lib/fetch.c
@@ -387,9 +387,9 @@ check_pack_hash(int fd, size_t sz, uint8_t *hcomp)
 
 const struct got_error*
 got_fetch_pack(struct got_object_id **pack_hash, struct got_pathlist_head *refs,
-    struct got_pathlist_head *symrefs, const char *remote_name, int fetchfd,
-    struct got_repository *repo, got_fetch_progress_cb progress_cb,
-    void *progress_arg)
+    struct got_pathlist_head *symrefs, const char *remote_name,
+    int mirror_references, int fetchfd, struct got_repository *repo,
+    got_fetch_progress_cb progress_cb, void *progress_arg)
 {
 	int imsg_fetchfds[2], imsg_idxfds[2];
 	int packfd = -1, npackfd = -1, idxfd = -1, nidxfd = -1, nfetchfd = -1;
@@ -418,9 +418,12 @@ got_fetch_pack(struct got_object_id **pack_hash, struct got_pathlist_head *refs,
 	TAILQ_INIT(&have_refs);
 	SIMPLEQ_INIT(&my_refs);
 
-	if (asprintf(&ref_prefix, "refs/remotes/%s/", remote_name) == -1)
-		return got_error_from_errno("asprintf");
-	ref_prefixlen = strlen(ref_prefix);
+	if (!mirror_references) {
+		if (asprintf(&ref_prefix, "refs/remotes/%s/",
+		    remote_name) == -1)
+			return got_error_from_errno("asprintf");
+		ref_prefixlen = strlen(ref_prefix);
+	}
 
 	err = got_ref_list(&my_refs, repo, NULL, got_ref_cmp_by_name, NULL);
 	if (err)
@@ -434,6 +437,23 @@ got_fetch_pack(struct got_object_id **pack_hash, struct got_pathlist_head *refs,
 			continue;
 
 		refname = got_ref_get_name(re->ref);
+
+		if (mirror_references) {
+			char *name;
+			err = got_ref_resolve(&id, repo, re->ref);
+			if (err)
+				goto done;
+			name = strdup(refname);
+			if (name == NULL) {
+				err = got_error_from_errno("strdup");
+				goto done;
+			}
+			err = got_pathlist_append(&have_refs, name, id);
+			if (err)
+				goto done;
+			continue;
+		}
+
 		if (strncmp("refs/tags/", refname, 10) == 0) {
 			char *tagname;
 
diff --git a/lib/got_lib_privsep.h b/lib/got_lib_privsep.h
index 11db131..5d6fc07 100644
--- a/lib/got_lib_privsep.h
+++ b/lib/got_lib_privsep.h
@@ -341,6 +341,7 @@ struct got_imsg_traversed_commits {
 struct got_imsg_remote {
 	size_t name_len;
 	size_t url_len;
+	int mirror_references;
 
 	/* Followed by name_len + url_len data bytes. */
 };
diff --git a/lib/privsep.c b/lib/privsep.c
index d869c21..e0f4043 100644
--- a/lib/privsep.c
+++ b/lib/privsep.c
@@ -1935,6 +1935,13 @@ got_privsep_send_gitconfig_remotes(struct imsgbuf *ibuf,
 			ibuf_free(wbuf);
 			return err;
 		}
+		if (imsg_add(wbuf, &remotes[i].mirror_references,
+		    sizeof(iremote.mirror_references)) == -1) {
+			err = got_error_from_errno(
+			    "imsg_add GITCONFIG_REMOTE");
+			ibuf_free(wbuf);
+			return err;
+		}
 
 		wbuf->fd = -1;
 		imsg_close(ibuf, wbuf);
@@ -2023,6 +2030,7 @@ got_privsep_recv_gitconfig_remotes(struct got_remote_repo **remotes,
 				free(remote->name);
 				break;
 			}
+			remote->mirror_references = iremote.mirror_references;
 			(*nremotes)++;
 			break;
 		default:
diff --git a/libexec/got-read-gitconfig/got-read-gitconfig.c b/libexec/got-read-gitconfig/got-read-gitconfig.c
index 4d1f4a8..6f203d1 100644
--- a/libexec/got-read-gitconfig/got-read-gitconfig.c
+++ b/libexec/got-read-gitconfig/got-read-gitconfig.c
@@ -108,7 +108,7 @@ gitconfig_remotes_request(struct imsgbuf *ibuf, struct got_gitconfig *gitconfig)
 
 	i = 0;
 	TAILQ_FOREACH(node, &sections->fields, link) {
-		char *name, *end;
+		char *name, *end, *mirror;
 
 		if (strncasecmp("remote \"", node->field, 8) != 0)
 			continue;
@@ -130,6 +130,16 @@ gitconfig_remotes_request(struct imsgbuf *ibuf, struct got_gitconfig *gitconfig)
 			goto done;
 		}
 
+		remotes[i].mirror_references = 0;
+		mirror = got_gitconfig_get_str(gitconfig, node->field,
+		    "mirror");
+		if (mirror != NULL &&
+		    (strcasecmp(mirror, "true") == 0 ||
+		    strcasecmp(mirror, "on") == 0 ||
+		    strcasecmp(mirror, "yes") == 0 ||
+		    strcmp(mirror, "1") == 0))
+			remotes[i].mirror_references = 1;
+
 		i++;
 	}