branch: report errors in tracking branch setup

When setting up a new tracking branch fails due to issues with
the configuration file we do not report any errors to the user
and pretend setting the tracking branch succeeded.

Setting up the tracking branch is handled by the
`install_branch_config` function. We do not want to simply die
there as the function is not only invoked when explicitly setting
upstream information with `git branch --set-upstream-to=`, but
also by `git push --set-upstream` and `git clone`. While it is
reasonable to die in the explict first case, we would lose
information in the latter two cases, so we only print the error
message but continue the program as usual.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 36 insertions, 14 deletions

diff --git a/branch.c b/branch.c
index 7ff3f20..713ceda 100644
--- a/branch.c
+++ b/branch.c
@@ -49,7 +49,13 @@ static int should_setup_rebase(const char *origin)
 	return 0;
 }
 
-void install_branch_config(int flag, const char *local, const char *origin, const char *remote)
+static const char tracking_advice[] =
+N_("\n"
+"After fixing the error cause you may try to fix up\n"
+"the remote tracking information by invoking\n"
+"\"git branch --set-upstream-to=%s%s%s\".");
+
+int install_branch_config(int flag, const char *local, const char *origin, const char *remote)
 {
 	const char *shortname = NULL;
 	struct strbuf key = STRBUF_INIT;
@@ -60,20 +66,23 @@ void install_branch_config(int flag, const char *local, const char *origin, cons
 	    && !origin) {
 		warning(_("Not setting branch %s as its own upstream."),
 			local);
-		return;
+		return 0;
 	}
 
 	strbuf_addf(&key, "branch.%s.remote", local);
-	git_config_set(key.buf, origin ? origin : ".");
+	if (git_config_set(key.buf, origin ? origin : ".") < 0)
+		goto out_err;
 
 	strbuf_reset(&key);
 	strbuf_addf(&key, "branch.%s.merge", local);
-	git_config_set(key.buf, remote);
+	if (git_config_set(key.buf, remote) < 0)
+		goto out_err;
 
 	if (rebasing) {
 		strbuf_reset(&key);
 		strbuf_addf(&key, "branch.%s.rebase", local);
-		git_config_set(key.buf, "true");
+		if (git_config_set(key.buf, "true") < 0)
+			goto out_err;
 	}
 	strbuf_release(&key);
 
@@ -102,6 +111,19 @@ void install_branch_config(int flag, const char *local, const char *origin, cons
 					  local, remote);
 		}
 	}
+
+	return 0;
+
+out_err:
+	strbuf_release(&key);
+	error(_("Unable to write upstream branch configuration"));
+
+	advise(_(tracking_advice),
+	       origin ? origin : "",
+	       origin ? "/" : "",
+	       shortname ? shortname : remote);
+
+	return -1;
 }
 
 /*
@@ -109,8 +131,8 @@ void install_branch_config(int flag, const char *local, const char *origin, cons
  * to infer the settings for branch.<new_ref>.{remote,merge} from the
  * config.
  */
-static int setup_tracking(const char *new_ref, const char *orig_ref,
-			  enum branch_track track, int quiet)
+static void setup_tracking(const char *new_ref, const char *orig_ref,
+			   enum branch_track track, int quiet)
 {
 	struct tracking tracking;
 	int config_flags = quiet ? 0 : BRANCH_CONFIG_VERBOSE;
@@ -118,7 +140,7 @@ static int setup_tracking(const char *new_ref, const char *orig_ref,
 	memset(&tracking, 0, sizeof(tracking));
 	tracking.spec.dst = (char *)orig_ref;
 	if (for_each_remote(find_tracked_branch, &tracking))
-		return 1;
+		return;
 
 	if (!tracking.matches)
 		switch (track) {
@@ -127,18 +149,18 @@ static int setup_tracking(const char *new_ref, const char *orig_ref,
 		case BRANCH_TRACK_OVERRIDE:
 			break;
 		default:
-			return 1;
+			return;
 		}
 
 	if (tracking.matches > 1)
-		return error(_("Not tracking: ambiguous information for ref %s"),
-				orig_ref);
+		die(_("Not tracking: ambiguous information for ref %s"),
+		    orig_ref);
 
-	install_branch_config(config_flags, new_ref, tracking.remote,
-			      tracking.src ? tracking.src : orig_ref);
+	if (install_branch_config(config_flags, new_ref, tracking.remote,
+			      tracking.src ? tracking.src : orig_ref) < 0)
+		exit(-1);
 
 	free(tracking.src);
-	return 0;
 }
 
 int read_branch_desc(struct strbuf *buf, const char *branch_name)