Fix parsing of password-command option (#6268)

The password-command option does not parse its value correctly.
Quotes are ignored, making many kinds of commands impossible to
express (e.g.  `sh -c "foo | bar"`).  Also, `cabal user-config`
treats the argument list as a *list of option values*, rather than a
*value that is a list*.  As a consequence, `cabal user-config
update` corrupts the value in the config file.

Fix these issues by parsing the command as a space separated list of
tokens, and changing the getter to `unwords` the value and return a
*singleton* list.  Also update the argument placeholder from
`PASSWORD` to `COMMAND`.

Fixes: #6268

cabal-install/src/Distribution/Client/Setup.hs

@@ -116,6 +116,8 @@ import Distribution.Client.Targets
   ( UserConstraint
   , readUserConstraint
   )
+import Distribution.Deprecated.ParseUtils (parseSpaceList, parseTokenQ)
+import Distribution.Deprecated.ReadP (readP_to_E)
 import Distribution.Utils.NubList
   ( NubList
   , fromNubList
@@ -2706,7 +2708,14 @@ uploadCommand =
             "Command to get Hackage password."
             uploadPasswordCmd
             (\v flags -> flags{uploadPasswordCmd = v})
-            (reqArg' "PASSWORD" (Flag . words) (fromMaybe [] . flagToMaybe))
+            ( reqArg
+                "COMMAND"
+                ( readP_to_E
+                    ("Cannot parse command: " ++)
+                    (Flag <$> parseSpaceList parseTokenQ)
+                )
+                (flagElim [] (pure . unwords . fmap show))
+            )
         ]
     }
 

cabal-install/src/Distribution/Deprecated/ParseUtils.hs

@@ -38,6 +38,7 @@ module Distribution.Deprecated.ParseUtils
   , readFields
   , parseHaskellString
   , parseTokenQ
+  , parseSpaceList
   , parseOptCommaList
   , showFilePath
   , showToken

cabal-testsuite/PackageTests/UserConfig/cabal.out

@@ -12,3 +12,6 @@ Writing merged config to <ROOT>/cabal.dist/cabal-config.
 # cabal user-config
 Renaming <ROOT>/cabal.dist/cabal-config to <ROOT>/cabal.dist/cabal-config.backup.
 Writing merged config to <ROOT>/cabal.dist/cabal-config.
+# cabal user-config
+Renaming <ROOT>/cabal.dist/cabal-config to <ROOT>/cabal.dist/cabal-config.backup.
+Writing merged config to <ROOT>/cabal.dist/cabal-config.

cabal-testsuite/PackageTests/UserConfig/cabal.test.hs

@@ -15,3 +15,9 @@ main = cabalTest $ do
     assertFileDoesContain conf "foo,bar"
     cabalG ["--config-file", conf] "user-config" ["update", "-f", "-a", "extra-prog-path: foo, bar"]
     assertFileDoesContain conf "foo,bar"
+
+    -- regression test for #6268 (password-command parsing)
+    cabalG ["--config-file", conf]
+        "user-config" ["update", "-f", "-a", "password-command: sh -c \"echo secret\""]
+    -- non-quoted tokens do get quoted when writing, but this is expected
+    assertFileDoesContain conf "password-command: \"sh\" \"-c\" \"echo secret\""

doc/cabal-commands.rst

@@ -1086,7 +1086,19 @@ to Hackage.
 
 .. option:: -P, --password-command
 
-    Command to get your Hackage password.
+    Command to get your Hackage password.  Arguments with whitespace
+    must be quoted (double-quotes only).  For example:
+
+    ::
+
+        --password-command 'sh -c "grep hackage ~/secrets | cut -d : -f 2"'
+
+    Or in the config file:
+
+    ::
+
+        password-command: sh -c "grep hackage ~/secrets | cut -d : -f 2"
+
 
 cabal report
 ^^^^^^^^^^^^