[bug#27704] [PATCH] daemon: Show actual rather than collateral error when export fails.

[Jan Nieuwenhuizen <janneke@gnu.org>]

Having the wrong permissions on /etc/guix/signing-key.sec gives

    guix-daemon: nix/libutil/serialise.cc:15: virtual nix::BufferedSink::~BufferedSink(): Assertion `!bufPos' failed.

this patch changes that to

    guix-daemon: error: file `/etc/guix/signing-key.sec' should be secret (inaccessible to everybody else)!

* nix/nix-daemon/nix-daemon.cc (performOp): Catch any exportPath exception,
report and exit on that.  Fixes failing later with uninformative collateral error.
---
 nix/nix-daemon/nix-daemon.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/nix/nix-daemon/nix-daemon.cc b/nix/nix-daemon/nix-daemon.cc
index 7d26b6135..aeeadf144 100644
--- a/nix/nix-daemon/nix-daemon.cc
+++ b/nix/nix-daemon/nix-daemon.cc
@@ -436,7 +436,13 @@ static void performOp(bool trusted, unsigned int clientVersion,
         bool sign = readInt(from) == 1;
         startWork();
         TunnelSink sink(to);
-        store->exportPath(path, sign, sink);
+        try {
+            store->exportPath(path, sign, sink);
+        }
+        catch (std::exception &e) {
+            fprintf (stderr, "guix-daemon: error: %s\n", e.what ());
+            exit (EXIT_FAILURE);
+        }
         sink.flush();
         stopWork();
         writeInt(1, to);
-- 
Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond http://lilypond.org
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