curl: apply eventfd free patch (#373692)

pkgs/by-name/cu/curlMinimal/fix-eventfd-free.patch

@@ -0,0 +1,33 @@
+From ff5091aa9f73802e894b1cbdf24ab84e103200e2 Mon Sep 17 00:00:00 2001
+From: Andy Pan <i@andypan.me>
+Date: Thu, 12 Dec 2024 12:48:56 +0000
+Subject: [PATCH] async-thread: avoid closing eventfd twice
+
+When employing eventfd for socketpair, there is only one file
+descriptor. Closing that fd twice might result in fd corruption.
+Thus, we should avoid closing the eventfd twice, following the
+pattern in lib/multi.c.
+
+Fixes #15725
+Closes #15727
+Reported-by: Christian Heusel
+---
+ lib/asyn-thread.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/lib/asyn-thread.c b/lib/asyn-thread.c
+index a58e4b790494..32d496b107cb 100644
+--- a/lib/asyn-thread.c
++++ b/lib/asyn-thread.c
+@@ -195,9 +195,11 @@ void destroy_thread_sync_data(struct thread_sync_data *tsd)
+    * close one end of the socket pair (may be done in resolver thread);
+    * the other end (for reading) is always closed in the parent thread.
+    */
++#ifndef USE_EVENTFD
+   if(tsd->sock_pair[1] != CURL_SOCKET_BAD) {
+     wakeup_close(tsd->sock_pair[1]);
+   }
++#endif
+ #endif
+   memset(tsd, 0, sizeof(*tsd));
+ }

pkgs/by-name/cu/curlMinimal/package.nix

@@ -63,6 +63,12 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-x8p9tIsJCXQ+rvNCUNoCwZvGHU8dzt1mA/EJQJU2q1Y=";
   };
 
+  # FIXME: avoid rebuilding darwin stdenv for now
+  patches = lib.optionals (!stdenv.isDarwin) [
+    # https://github.com/curl/curl/issues/15725
+    ./fix-eventfd-free.patch
+  ];
+
   # this could be accomplished by updateAutotoolsGnuConfigScriptsHook, but that causes infinite recursion
   # necessary for FreeBSD code path in configure
   postPatch = ''