[PATCH 1/2] expose child fd in order to handle child exit in libvirt

[Bamvor Jian Zhang <bjzhang@suse.com>]

libvirt could handle fd and timeout event through
libxl_osevent_hooks. either of these will not inform the child
exit if libvirt set the libxl_sigchld_owner_libxl_always.

add a function for returning the sigchld_selfpipe in order to
handle the child exit in libvirt.
meanwhile, there is only one pipe in ctx, it seems that it is
not worth to add this to libxl_osevent_hooks.

Signed-off-by: Bamvor Jian Zhang <bjzhang@suse.com>
---
 tools/libxl/libxl.h      | 2 ++
 tools/libxl/libxl_fork.c | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 1c6675d..11e1bc3 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1071,6 +1071,8 @@ int libxl_flask_loadpolicy(libxl_ctx *ctx, void *policy, uint32_t size);
 int libxl_fd_set_cloexec(libxl_ctx *ctx, int fd, int cloexec);
 int libxl_fd_set_nonblock(libxl_ctx *ctx, int fd, int nonblock);
 
+int libxl_get_pipe_handle(libxl_ctx *ctx, int num);
+
 #include <libxl_event.h>
 
 #endif /* LIBXL_H */
diff --git a/tools/libxl/libxl_fork.c b/tools/libxl/libxl_fork.c
index 044ddad..1989258 100644
--- a/tools/libxl/libxl_fork.c
+++ b/tools/libxl/libxl_fork.c
@@ -418,6 +418,11 @@ int libxl__ev_child_xenstore_reopen(libxl__gc *gc, const char *what) {
     return rc;
 }
 
+int libxl_get_pipe_handle(libxl_ctx *ctx, int num)
+{
+    return ctx->sigchld_selfpipe[num];
+}
+
 /*
  * Local variables:
  * mode: C
-- 
1.8.1.4