From 9ee590e11301cda2b5d6341fb77f13369c3107e6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 4 Mar 2024 21:54:35 +0100
Subject: [PATCH 1/2] PosixSourceAccessor::cachedLstat(): Use absolute path

Using the relative path can cause collisions between cache entries for
PosixSourceAccessors with different roots.
---
 src/libutil/posix-source-accessor.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/libutil/posix-source-accessor.cc b/src/libutil/posix-source-accessor.cc
index f8ec7fc6b..e91943c4c 100644
--- a/src/libutil/posix-source-accessor.cc
+++ b/src/libutil/posix-source-accessor.cc
@@ -85,16 +85,18 @@ bool PosixSourceAccessor::pathExists(const CanonPath & path)
 
 std::optional<struct stat> PosixSourceAccessor::cachedLstat(const CanonPath & path)
 {
-    static Sync<std::unordered_map<CanonPath, std::optional<struct stat>>> _cache;
+    static Sync<std::unordered_map<std::filesystem::path, std::optional<struct stat>>> _cache;
+
+    auto absPath = makeAbsPath(path);
 
     {
         auto cache(_cache.lock());
-        auto i = cache->find(path);
+        auto i = cache->find(absPath);
         if (i != cache->end()) return i->second;
     }
 
     std::optional<struct stat> st{std::in_place};
-    if (::lstat(makeAbsPath(path).c_str(), &*st)) {
+    if (::lstat(absPath.c_str(), &*st)) {
         if (errno == ENOENT || errno == ENOTDIR)
             st.reset();
         else
@@ -103,7 +105,7 @@ std::optional<struct stat> PosixSourceAccessor::cachedLstat(const CanonPath & pa
 
     auto cache(_cache.lock());
     if (cache->size() >= 16384) cache->clear();
-    cache->emplace(path, st);
+    cache->emplace(absPath, st);
 
     return st;
 }

From 4967c5ff6ba96b27ad1d855b3b32712c0fc3dfcf Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 4 Mar 2024 22:24:12 +0100
Subject: [PATCH 2/2] Fix macOS build

---
 src/libutil/posix-source-accessor.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/libutil/posix-source-accessor.cc b/src/libutil/posix-source-accessor.cc
index e91943c4c..41c2db59a 100644
--- a/src/libutil/posix-source-accessor.cc
+++ b/src/libutil/posix-source-accessor.cc
@@ -85,9 +85,11 @@ bool PosixSourceAccessor::pathExists(const CanonPath & path)
 
 std::optional<struct stat> PosixSourceAccessor::cachedLstat(const CanonPath & path)
 {
-    static Sync<std::unordered_map<std::filesystem::path, std::optional<struct stat>>> _cache;
+    static Sync<std::unordered_map<Path, std::optional<struct stat>>> _cache;
 
-    auto absPath = makeAbsPath(path);
+    // Note: we convert std::filesystem::path to Path because the
+    // former is not hashable on libc++.
+    Path absPath = makeAbsPath(path);
 
     {
         auto cache(_cache.lock());