From 06650545dd1082821b86b2b49c60e7b841f8762f Mon Sep 17 00:00:00 2001
From: John Ralls <jralls@ceridwen.us>
Date: Mon, 7 Nov 2022 13:01:47 +0000
Subject: [PATCH] [Darwin] Use the non-cancelable variant of close().

---
 glib/gstdio.c        |  3 +++
 glib/gstdioprivate.h | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/glib/gstdio.c b/glib/gstdio.c
index cd3c8b405..b35a0ec1c 100644
--- a/glib/gstdio.c
+++ b/glib/gstdio.c
@@ -1795,6 +1795,9 @@ g_close (gint       fd,
            * https://bugzilla.gnome.org/show_bug.cgi?id=682819
            * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR
            * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
+           *
+           * `close$NOCANCEL()` in gstdioprivate.h, on macOS, ensures that the fd is
+           * closed even if it did return EINTR.
            */
           return TRUE;
         }
diff --git a/glib/gstdioprivate.h b/glib/gstdioprivate.h
index ecc354ada..c9e7826eb 100644
--- a/glib/gstdioprivate.h
+++ b/glib/gstdioprivate.h
@@ -68,7 +68,36 @@ int g_win32_fstat         (int                fd,
                            GWin32PrivateStat *buf);
 
 #endif
-
+/* The POSIX standard specifies that if close() fails with EINTR the
+ * file descriptor may or may not be in fact closed. Since another
+ * thread might have already reused the FD if it was in fact closed
+ * either a test of FD to ensure that it's closed nor a second
+ * call to close() may indicate the wrong FD, so the error must be
+ * ignored.
+ *
+ * However, since Mac OS X 10.5 (Leopard) Apple provdes a hidden
+ * implementation of close that doesn't allow another thread
+ * to cancel the close so it never fails with EINTR.
+ *
+ * The official way to enable this is to set __DARWIN_NON_CANCELABLE
+ * in the build, but that applies to all system calls, not just
+ * close(). Following Chromium's example (see
+ * https://chromium.googlesource.com/chromium/src/base/+/refs/heads/main/mac/close_nocancel.cc )
+ * we choose to expose and use the hidden close variant only.
+ */
+#ifdef __APPLE__
+#include <sys/cdefs.h>
+#include <unistd.h>
+# if !__DARWIN_NON_CANCELABLE
+#  if !__DARWIN_ONLY_UNIX_CONFORMANCE
+#   define close close$NOCANCEL$UNIX2003
+int close$NOCANCEL$UNIX2003 (int fd);
+#  else
+#   define close close$NOCANCEL
+int close$NOCANCEL (int fd);
+#  endif
+# endif
+#endif
 G_END_DECLS
 
 #endif /* __G_STDIOPRIVATE_H__ */