p2phttp: Scan multilevel directories with --directory

This allows for eg dir/user/repo structure. But also other layouts. It
still does not look for repositories that are nested inside other
repositories.

The check for symlinks is mostly to avoid cycles that would prevent
findRepos from returning. Eg, foo/bar/baz being a symlink to foo/bar.

If the directory is writable by someone else they can still race it and
get it to follow a symlink to some other directory. I don't think p2phttp
needs to worry about that kind of situation though, and I doubt it avoids
such problems when operating on files in a git-annex repository either.

CHANGELOG

@@ -1,3 +1,9 @@
+git-annex (10.20250631) UNRELEASED; urgency=medium
+
+  * p2phttp: Scan multilevel directories with --directory.
+
+ -- Joey Hess <id@joeyh.name>  Mon, 07 Jul 2025 15:59:42 -0400
+
 git-annex (10.20250630) upstream; urgency=medium
 
   * Work around git 2.50 bug that caused it to crash when there is a merge

Command/P2PHttp.hs

@@ -1,6 +1,6 @@
 {- git-annex command
  -
- - Copyright 2024 Joey Hess <id@joeyh.name>
+ - Copyright 2024-2025 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -21,11 +21,13 @@ import qualified Git
 import qualified Git.Construct
 import qualified Annex
 import Types.Concurrency
+import qualified Utility.RawFilePath as R
 
 import Servant
 import qualified Network.Wai.Handler.Warp as Warp
 import qualified Network.Wai.Handler.WarpTLS as Warp
 import Network.Socket (PortNumber)
+import System.PosixCompat.Files (isSymbolicLink)
 import qualified Data.Map as M
 import Data.String
 import Control.Concurrent.STM
@@ -268,6 +270,20 @@ findRepos :: Options -> IO [Git.Repo]
 findRepos o = do
 	files <- concat
 		<$> mapM (dirContents . toOsPath) (directoryOption o)
-	map Git.Construct.newFrom . catMaybes 
-		<$> mapM Git.Construct.checkForRepo files
-
+	concat <$> mapM go files
+  where
+	go f = Git.Construct.checkForRepo f >>= \case
+		Just loc -> return [Git.Construct.newFrom loc]
+		Nothing -> 
+			-- Avoid following symlinks, both to avoid
+			-- cycles and in case there is an unexpected
+			-- symlink to some other directory we are not
+			-- supposed to serve.
+			ifM (isSymbolicLink <$> R.getSymbolicLinkStatus f)
+				( return []
+				-- Ignore any errors getting the contents of a
+				-- subdirectory.
+				, catchNonAsync
+					(concat <$> (mapM go =<< dirContents f))
+					(const (return []))
+				)

doc/git-annex-p2phttp.mdwn

@@ -41,8 +41,10 @@ convenient way to download the content of any key, by using the path
 
 * `--directory=path`
 
-  Serve each git-annex repository found in immediate 
-  subdirectories of a directory.
+  Serve each git-annex repository found in subdirectories of the directory.
+  For example, `--directory=/foo` will find git-annex repositories
+  in `/foo/bar`, `/foo/user/bar`, and so on. Note that a git-annex
+  repository located within another git-annex repository will not be found.
 
   This option can be provided more than once to serve several directories
   full of git-annex repositories.