[libvirt] [PATCH] build: port qemu to cygwin

[Eric Blake]

A cygwin build of the qemu driver fails with:

qemu/qemu_process.c: In function 'qemuPrepareCpumap':
qemu/qemu_process.c:1803:31: error: 'CPU_SETSIZE' undeclared (first use in this function)

CPU_SETSIZE is a Linux extension in <sched.h>; a bit more portable
is using sysconf if _SC_NPROCESSORS_CONF is defined (several platforms
have it, including Cygwin).  Ultimately, I would have preferred to
use gnulib's 'nproc' module, but it is currently under an incompatible
license.

* src/qemu/qemu_conf.h (QEMUD_CPUMASK_LEN): Provide definition on
cygwin.

Signed-off-by: Eric Blake <eblake at redhat.com>
---

I'll wait for a review on this one, particularly since I'm still
trying to solve another qemu failure on cygwin:

qemu/qemu_monitor.c:418:9: error: passing argument 2 of 'sendmsg' from incmpatible pointer type
/usr/include/sys/socket.h:42:11: note: expected 'const struct msghdr *' but argument is of type 'struct msghdr *'

 src/qemu/qemu_conf.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index df0791e..42566b4 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -45,7 +45,13 @@
 # include "locking/lock_manager.h"
 # include "qemu_capabilities.h"

-# define QEMUD_CPUMASK_LEN CPU_SETSIZE
+# ifdef CPU_SETSIZE /* Linux */
+#  define QEMUD_CPUMASK_LEN CPU_SETSIZE
+# elif defined(_SC_NPROCESSORS_CONF) /* Cygwin */
+#  define QEMUD_CPUMASK_LEN (sysconf(_SC_NPROCESSORS_CONF))
+# else
+#  error "Port me"
+# endif

 typedef struct _virQEMUCloseCallbacks virQEMUCloseCallbacks;
 typedef virQEMUCloseCallbacks *virQEMUCloseCallbacksPtr;
-- 
1.8.1.4