From 92d1ceffe8da58eaa0910ed9bcc17faab7416a43 Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Fri, 24 Sep 2021 14:36:18 -0700
Subject: [PATCH] macOS: add a timer_create() and timer_settimer() to fix the
 build.

Note that these aren't equivalent to the CLOCK_MONOTONIC timer we
have on Linux, but short of spinning up another thread ourselves I
can't see how to implement that on macOS at present.
---
 lib/portability.c | 24 ++++++++++++++++++++++++
 lib/portability.h | 10 ++++++++++
 2 files changed, 34 insertions(+)

diff --git a/lib/portability.c b/lib/portability.c
index 14de4222..ef9cc008 100644
--- a/lib/portability.c
+++ b/lib/portability.c
@@ -655,3 +655,27 @@ long long sendfile_len(int in, int out, long long bytes, long long *consumed)
   return total;
 }
 
+#if __APPLE__
+// The absolute minimum POSIX timer implementation to build timeout(1).
+// Note that although timeout(1) uses POSIX timers to get the monotonic clock,
+// that doesn't seem to be an option on macOS (without using other libraries),
+// so we just mangle that back into a regular setitimer(ITIMER_REAL) call.
+int timer_create(clock_t c, struct sigevent *se, timer_t *t)
+{
+  if (se->sigev_notify != SIGEV_SIGNAL || se->sigev_signo != SIGALRM)
+    error_exit("unimplemented");
+  *t = 1;
+  return 0;
+}
+
+int timer_settime(timer_t t, int flags, struct itimerspec *new, void *old)
+{
+  struct itimerval mangled;
+
+  if (flags != 0 || old != 0) error_exit("unimplemented");
+  memset(&mangled, 0, sizeof(mangled));
+  mangled.it_value.tv_sec = new->it_value.tv_sec;
+  mangled.it_value.tv_usec = new->it_value.tv_nsec / 1000;
+  return setitimer(ITIMER_REAL, &mangled, NULL);
+}
+#endif
diff --git a/lib/portability.h b/lib/portability.h
index bb792f10..9fc0c9b8 100644
--- a/lib/portability.h
+++ b/lib/portability.h
@@ -371,3 +371,13 @@ int dev_makedev(int major, int minor);
 char *fs_type_name(struct statfs *statfs);
 
 int get_block_device_size(int fd, unsigned long long *size);
+
+#if __APPLE__
+// Apple doesn't have POSIX timers; this is "just enough" for timeout(1).
+typedef int timer_t;
+struct itimerspec {
+  struct timespec it_value;
+};
+int timer_create(clock_t c, struct sigevent *se, timer_t *t);
+int timer_settime(timer_t t, int flags, struct itimerspec *new, void *old);
+#endif
-- 
2.39.2