From a243beab2c26f224066720ccd630a9eb9b2278f1 Mon Sep 17 00:00:00 2001
From: Erik de Castro Lopo <erikd@mega-nerd.com>
Date: Thu, 19 Mar 2020 08:45:34 +1100
Subject: [PATCH] Better error message for readPGPassFile failures

---
 cardano-db/src/Cardano/Db/PGConfig.hs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/cardano-db/src/Cardano/Db/PGConfig.hs b/cardano-db/src/Cardano/Db/PGConfig.hs
index 6a56bdd77..e87bf30ad 100644
--- a/cardano-db/src/Cardano/Db/PGConfig.hs
+++ b/cardano-db/src/Cardano/Db/PGConfig.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 
 module Cardano.Db.PGConfig
   ( PGConfig (..)
@@ -79,8 +80,12 @@ readPGPassFile (PGPassFile fpath) = do
     replaceUser pgc
       | pgcUser pgc /= "*" = pure pgc
       | otherwise = do
-          user <- getEffectiveUserName
-          pure $ pgc { pgcUser = BS.pack user }
+          euser <- Exception.try getEffectiveUserName
+          case euser of
+            Left (_ :: IOException) ->
+              error "readPGPassFile: User in pgpass file was specified as '*' but getEffectiveUserName failed."
+            Right user ->
+              pure $ pgc { pgcUser = BS.pack user }
 
 
 -- | Read 'PGPassFile' into 'PGConfig'.