Avoid leaving repo with a detached head when there is a failure checking out an updat...

I don't know of scenarios where that can happen (besides the bug
fixed by the parent commit), but there probably are some.

Sponsored-by: Boyd Stephen Smith Jr. on Patreon

diff --git a/Annex/AdjustedBranch.hs b/Annex/AdjustedBranch.hs
index 7ea5b234aa15f73ef656308a9c70ed7d0744837c..5cef6ec29cf00be3d4efca466a7aa2f594069ed9 100644 (file)
--- a/Annex/AdjustedBranch.hs
+++ b/Annex/AdjustedBranch.hs
@@ -248,26 +248,42 @@ checkoutAdjustedBranch (AdjBranch b) quietcheckout = do
 updateAdjustedBranch :: Adjustment -> AdjBranch -> OrigBranch -> Annex Bool
 updateAdjustedBranch adj (AdjBranch currbranch) origbranch
        | not (adjustmentIsStable adj) = do
-               b <- preventCommits $ \commitlck -> do
+               (b, origheadfile, newheadfile) <- preventCommits $ \commitlck -> do
                        -- Avoid losing any commits that the adjusted branch
                        -- has that have not yet been propigated back to the
                        -- origbranch.
                        _ <- propigateAdjustedCommits' origbranch adj commitlck
+                               
+                       origheadfile <- inRepo $ readFile . Git.Ref.headFile
 
                        -- Git normally won't do anything when asked to check
                        -- out the currently checked out branch, even when its
                        -- ref has changed. Work around this by writing a raw
                        -- sha to .git/HEAD.
-                       inRepo (Git.Ref.sha currbranch) >>= \case
-                               Just headsha -> inRepo $ \r ->
-                                       writeFile (Git.Ref.headFile r) (fromRef headsha)
-                               _ -> noop
+                       newheadfile <- inRepo (Git.Ref.sha currbranch) >>= \case
+                               Just headsha -> do
+                                       inRepo $ \r -> do
+                                               let newheadfile = fromRef headsha
+                                               writeFile (Git.Ref.headFile r) newheadfile
+                                               return (Just newheadfile)
+                               _ -> return Nothing
        
-                       adjustBranch adj origbranch
+                       b <- adjustBranch adj origbranch
+                       return (b, origheadfile, newheadfile)
        
                -- Make git checkout quiet to avoid warnings about
                -- disconnected branch tips being lost.
-               checkoutAdjustedBranch b True
+               ok <- checkoutAdjustedBranch b True
+
+               -- Avoid leaving repo with detached head.
+               unless ok $ case newheadfile of
+                       Nothing -> noop
+                       Just v -> preventCommits $ \_commitlck -> inRepo $ \r -> do
+                               v' <- readFile (Git.Ref.headFile r)
+                               when (v == v') $
+                                       writeFile (Git.Ref.headFile r) origheadfile
+
+               return ok
        | otherwise = preventCommits $ \commitlck -> do
                -- Done for consistency.
                _ <- propigateAdjustedCommits' origbranch adj commitlck

diff --git a/CHANGELOG b/CHANGELOG
index 33a27d6a022622499754d02b9f69bde639c89f33..1a2f35bad3b0991f8cd30c11ff1231aad24f34fa 100644 (file)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -3,6 +3,8 @@ git-annex (10.20230322) UNRELEASED; urgency=medium
   * sync: Fix parsing of gcrypt::rsync:// urls that use a relative path.
   * Avoid failure to update adjusted branch --unlock-present after git-annex
     drop when annex.adjustedbranchrefresh=1
+  * Avoid leaving repo with a detached head when there is a failure
+    checking out an updated adjusted branch.
 
  -- Joey Hess <id@joeyh.name>  Thu, 23 Mar 2023 15:04:41 -0400
 

diff --git a/doc/bugs/Failed_adjusted_branch_update_after_error_in_drop.mdwn b/doc/bugs/Failed_adjusted_branch_update_after_error_in_drop.mdwn
index 7e4f38e9cdf168fb501f8895dc1335038e849636..a190b262e764523e812a350bf03d4877d1dde5e2 100644 (file)
--- a/doc/bugs/Failed_adjusted_branch_update_after_error_in_drop.mdwn
+++ b/doc/bugs/Failed_adjusted_branch_update_after_error_in_drop.mdwn
@@ -53,4 +53,4 @@ local repository version: 8
 
 git-annex is too good. It so rarely causes problems that one does not develop the "git-annex troubleshooting muscle". :)
 
-
+> [[fixed|done]] --[[Joey]]