From 6521405c07485eb77c625c01b7afc6b8dd6c2e61 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Wed, 6 Sep 2017 15:01:17 -0400
Subject: [PATCH] misc: add function to get CPU affinity mask size

Implement it on Linux, FreeBSD, and Windows for now, and return
UV_ENOTSUP on other platforms.

Inspired-by: Kiran Pamnany <kiran.pamnany@intel.com>
Fixes: https://github.com/libuv/libuv/issues/1389
PR-URL: https://github.com/libuv/libuv/pull/1527
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
---
 docs/src/misc.rst |  7 +++++++
 include/uv.h      |  1 +
 src/unix/core.c   | 12 +++++++++++-
 src/win/core.c    |  4 ++++
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/docs/src/misc.rst b/docs/src/misc.rst
index 3587fdee..03878d60 100644
--- a/docs/src/misc.rst
+++ b/docs/src/misc.rst
@@ -246,6 +246,13 @@ API
 
     Frees the `cpu_infos` array previously allocated with :c:func:`uv_cpu_info`.
 
+.. c:function:: int uv_cpumask_size(void)
+
+    Returns the maximum size of the mask used for process/thread affinities,
+    or ``UV_ENOTSUP`` if affinities are not supported on the current platform.
+
+    .. versionadded:: 2.0.0
+
 .. c:function:: int uv_interface_addresses(uv_interface_address_t** addresses, int* count)
 
     Gets address information about the network interfaces on the system. An
diff --git a/include/uv.h b/include/uv.h
index e1bc4d99..b7e4798c 100644
--- a/include/uv.h
+++ b/include/uv.h
@@ -1142,6 +1142,7 @@ UV_EXTERN uv_pid_t uv_os_getppid(void);
 
 UV_EXTERN int uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count);
 UV_EXTERN void uv_free_cpu_info(uv_cpu_info_t* cpu_infos, int count);
+UV_EXTERN int uv_cpumask_size(void);
 
 UV_EXTERN int uv_interface_addresses(uv_interface_address_t** addresses,
                                      int* count);
diff --git a/src/unix/core.c b/src/unix/core.c
index 2680bd84..03be41c0 100644
--- a/src/unix/core.c
+++ b/src/unix/core.c
@@ -40,6 +40,7 @@
 #include <sys/uio.h> /* writev */
 #include <sys/resource.h> /* getrusage */
 #include <pwd.h>
+#include <sched.h>
 
 #ifdef __sun
 # include <netdb.h> /* MAXHOSTNAMELEN on Solaris */
@@ -63,6 +64,8 @@
 # include <sys/sysctl.h>
 # include <sys/filio.h>
 # include <sys/wait.h>
+# include <sys/param.h>
+# include <sys/cpuset.h>
 # define UV__O_CLOEXEC O_CLOEXEC
 # if defined(__FreeBSD__)
 #  define uv__accept4 accept4
@@ -1336,7 +1339,6 @@ int uv_os_gethostname(char* buffer, size_t* size) {
   return 0;
 }
 
-
 uv_pid_t uv_os_getpid(void) {
   return getpid();
 }
@@ -1345,3 +1347,11 @@ uv_pid_t uv_os_getpid(void) {
 uv_pid_t uv_os_getppid(void) {
   return getppid();
 }
+
+int uv_cpumask_size(void) {
+#if defined(__linux__) || defined(__FreeBSD__)
+  return CPU_SETSIZE;
+#else
+  return UV_ENOTSUP;
+#endif
+}
diff --git a/src/win/core.c b/src/win/core.c
index fbaa8b0e..89a4944a 100644
--- a/src/win/core.c
+++ b/src/win/core.c
@@ -427,3 +427,7 @@ int uv__socket_sockopt(uv_handle_t* handle, int optname, int* value) {
 
   return 0;
 }
+
+int uv_cpumask_size(void) {
+  return (int)(sizeof(DWORD_PTR) * 8);
+}