configure: Check that checksum programs produce correct checksums. + bitter rant

So, it might be called sha1sum, or on some other OS, it might be called
sha1. It might be hidden away off of PATH on that OS. That's just expected
insanity; UNIX has been this way since 1980's. And these days, nobody even
gives the flying flip about standards that we briefly did in the 90's
after the first round of unix wars.

But it's the 2010's now, and we've certainly learned something.
So, let's make it so sometimes sha1 is a crazy program that wants to run as
root so it can lock memory while prompting for a passphrase, and outputting
binary garbage. Yes, that'd be wise. Let's package that in major Linux
distros, too, so users can stumble over it.

4 files changed, 37 insertions, 15 deletions

diff --git a/Build/Configure.hs b/Build/Configure.hs
index 7fb195ad4..96582f923 100644
--- a/Build/Configure.hs
+++ b/Build/Configure.hs
@@ -19,7 +19,7 @@ tests =
 	, testCp "cp_a" "-a"
 	, testCp "cp_p" "-p"
 	, testCp "cp_reflink_auto" "--reflink=auto"
-	, TestCase "uuid generator" $ selectCmd "uuid" ["uuid -m", "uuid", "uuidgen"] ""
+	, TestCase "uuid generator" $ selectCmd "uuid" [("uuid -m", ""), ("uuid", ""), ("uuidgen", "")]
 	, TestCase "xargs -0" $ requireCmd "xargs_0" "xargs -0 </dev/null"
 	, TestCase "rsync" $ requireCmd "rsync" "rsync --version >/dev/null"
 	, TestCase "curl" $ testCmd "curl" "curl --version >/dev/null"
@@ -28,19 +28,33 @@ tests =
 	, TestCase "gpg" $ testCmd "gpg" "gpg --version >/dev/null"
 	, TestCase "lsof" $ testCmd "lsof" "lsof -v >/dev/null 2>&1"
 	, TestCase "ssh connection caching" getSshConnectionCaching
-	] ++ shaTestCases [1, 256, 512, 224, 384]
+	] ++ shaTestCases
+	[ (1, "da39a3ee5e6b4b0d3255bfef95601890afd80709")
+	, (256, "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")
+	, (512, "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e")
+	, (224, "d14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f")
+	, (384, "38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b")
+	]
 
-shaTestCases :: [Int] -> [TestCase]
+{- shaNsum are the program names used by coreutils.
+ - On some systems, shaN is used instead, but on other
+ - systems, it might be "hashalot", which does not produce
+ - usable checksums. Only accept programs that produce
+ - known-good hashes. -}
+shaTestCases :: [(Int, String)] -> [TestCase]
 shaTestCases l = map make l
 	where
-		make n = TestCase key $ maybeSelectCmd key (shacmds n) "</dev/null"
+		make (n, knowngood) = 
+			TestCase key $ maybeSelectCmd key $ 
+				zip (shacmds n) (repeat check)
 			where
 				key = "sha" ++ show n
+				check = "</dev/null | grep -q '" ++ knowngood ++ "'"
 		shacmds n = concatMap (\x -> [x, osxpath </> x]) $
-			map (\x -> "sha" ++ show n ++ x) ["", "sum"]
-		-- Max OSX puts GNU tools outside PATH, so look in
-		-- the location it uses, and remember where to run them
-		-- from.
+			map (\x -> "sha" ++ show n ++ x) ["sum", ""]
+		{- Max OSX puts GNU tools outside PATH, so look in
+		 - the location it uses, and remember where to run them
+		 - from. -}
 		osxpath = "/opt/local/libexec/gnubin"
 
 tmpDir :: String
diff --git a/Build/TestConfig.hs b/Build/TestConfig.hs
index 0cc2019cf..eb920c13f 100644
--- a/Build/TestConfig.hs
+++ b/Build/TestConfig.hs
@@ -75,7 +75,7 @@ testCmd k cmdline = do
 
 {- Ensures that one of a set of commands is available by running each in
  - turn. The Config is set to the first one found. -}
-selectCmd :: ConfigKey -> [String] -> String -> Test
+selectCmd :: ConfigKey -> [(String, String)] -> Test
 selectCmd k = searchCmd
 		(return . Config k . StringConfig)
 		(\cmds -> do
@@ -83,17 +83,17 @@ selectCmd k = searchCmd
 			error $ "* need one of these commands, but none are available: " ++ show cmds
 		)
 
-maybeSelectCmd :: ConfigKey -> [String] -> String -> Test
+maybeSelectCmd :: ConfigKey -> [(String, String)] -> Test
 maybeSelectCmd k = searchCmd
 		(return . Config k . MaybeStringConfig . Just)
 		(\_ -> return $ Config k $ MaybeStringConfig Nothing)
 
-searchCmd :: (String -> Test) -> ([String] -> Test) -> [String] -> String -> Test
-searchCmd success failure cmds param = search cmds
+searchCmd :: (String -> Test) -> ([String] -> Test) -> [(String, String)] -> Test
+searchCmd success failure cmdsparams = search cmdsparams
 	where
-		search [] = failure cmds
-		search (c:cs) = do
-			ret <- system $ quiet c ++ " " ++ param
+		search [] = failure $ fst $ unzip cmdsparams
+		search ((c, params):cs) = do
+			ret <- system $ quiet $ c ++ " " ++ params
 			if ret == ExitSuccess
 				then success c
 				else search cs
diff --git a/debian/changelog b/debian/changelog
index 128adefef..246c0badc 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -21,6 +21,7 @@ git-annex (3.20121018) UNRELEASED; urgency=low
     does not accept that.
   * bugfix: Don't fail transferring content from read-only repos.
     Closes: #691341
+  * configure: Check that checksum programs produce correct checksums.
 
  -- Joey Hess <joeyh@debian.org>  Wed, 17 Oct 2012 14:24:10 -0400
 
diff --git a/doc/bugs/configure_mistakes_hashalot_bins_for_sha__63____63____63__sum_and_builds_a_broken_git-annex_executable.mdwn b/doc/bugs/configure_mistakes_hashalot_bins_for_sha__63____63____63__sum_and_builds_a_broken_git-annex_executable.mdwn
index c7ed04c65..46dfa4f70 100644
--- a/doc/bugs/configure_mistakes_hashalot_bins_for_sha__63____63____63__sum_and_builds_a_broken_git-annex_executable.mdwn
+++ b/doc/bugs/configure_mistakes_hashalot_bins_for_sha__63____63____63__sum_and_builds_a_broken_git-annex_executable.mdwn
@@ -48,3 +48,10 @@ This is not a runtime bug, only compile time.  Uninstalling Hashalot or simply r
 I found this bug on Gentoo when I installed git-annex on a system which already had hashalot installed.  In the case of Gentoo, git-annex is compiled with hashalot's executables in the path, but normal users don't have /usr/sbin/ in their path so git-annex just fails to find the executable.  If you put hashalot in the path, then git annex still fails to work as hashalot is not a replacement for sha1sum and friends.
 
 It may be enough to just prefer sha???sum over sha??? if they both exist.
+
+> Grr. There is no consistency across unixes as to the names of these
+> programs and now something is installing shaN commands that don't
+> generate a checksum?!
+> 
+> Ok, fine, configure now checks that the program it finds outputs a known
+> good checksum. [[done]] --[[Joey]]