From b459a3e85600e1d3a326278a823ce0bdf71fcc21 Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Sat, 30 Oct 2021 12:25:59 +0200
Subject: [PATCH] git: extend cache dir lock over all mutating operations

---
 src/libfetchers/git.cc | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index 8468d2afc..a96642195 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -324,17 +324,13 @@ struct GitInputScheme : InputScheme
             Path cacheDir = getCacheDir() + "/nix/gitv3/" + hashString(htSHA256, actualUrl).to_string(Base32, false);
             repoDir = cacheDir;
 
-            Path cacheDirLock = cacheDir + ".lock";
             createDirs(dirOf(cacheDir));
-            AutoCloseFD lock = openLockFile(cacheDirLock, true);
-            lockFile(lock.get(), ltWrite, true);
+            PathLocks cacheDirLock({cacheDir + ".lock"});
 
             if (!pathExists(cacheDir)) {
                 runProgram("git", true, { "-c", "init.defaultBranch=" + gitInitialBranch, "init", "--bare", repoDir });
             }
 
-            deleteLockFile(cacheDirLock, lock.get());
-
             Path localRefFile =
                 input.getRef()->compare(0, 5, "refs/") == 0
                 ? cacheDir + "/" + *input.getRef()
@@ -399,6 +395,8 @@ struct GitInputScheme : InputScheme
 
             if (!input.getRev())
                 input.attrs.insert_or_assign("rev", Hash::parseAny(chomp(readFile(localRefFile)), htSHA1).gitRev());
+
+            // cache dir lock is removed at scope end; we will only use read-only operations on specific revisions in the remainder
         }
 
         bool isShallow = chomp(runProgram("git", true, { "-C", repoDir, "rev-parse", "--is-shallow-repository" })) == "true";