Uros Bizjak <ubiz...@gmail.com> writes:
> It turned out that the EpollEvent definition in
> libgo/syscalls/epoll/socket_epoll.go is non-portable (if not outright
> dangerous...). The definition does have a FIXME comment, but does not
> take into account the effects of __attribute__((__packed__)) from
> system headers. Contrary to alpha header, x86 has
> __attribute__((__packed__)) added to struct epoll_event definition in
> sys/epoll.h header.
I couldn't work out a way to handle this correctly in mksysinfo.sh or
-fdump-go-spec, so I did it in configure instead. Bootstrapped and
tested on x86_64-unknown-linux-gnu. Committed to mainline. Let me know
if it seems to do the right sort of thing on Alpha GNU/Linux--see if the
generated file TARGET/libgo/epoll.h looks OK.
Ian
Index: libgo/configure.ac
===================================================================
--- libgo/configure.ac (revision 180345)
+++ libgo/configure.ac (working copy)
@@ -505,6 +505,28 @@ CFLAGS="$CFLAGS -D_LARGEFILE_SOURCE -D_L
AC_CHECK_TYPES(off64_t)
CFLAGS=$CFLAGS_hold
+dnl Work out the size of the epoll_events struct on GNU/Linux.
+AC_CACHE_CHECK([epoll_event size],
+[libgo_cv_c_epoll_event_size],
+[AC_COMPUTE_INT(libgo_cv_c_epoll_event_size,
+[sizeof (struct epoll_event)],
+[#include <sys/epoll.h>],
+[libgo_cv_c_epoll_event_size=0])])
+SIZEOF_STRUCT_EPOLL_EVENT=${libgo_cv_c_epoll_event_size}
+AC_SUBST(SIZEOF_STRUCT_EPOLL_EVENT)
+
+dnl Work out the offset of the fd field in the epoll_events struct on
+dnl GNU/Linux.
+AC_CACHE_CHECK([epoll_event data.fd offset],
+[libgo_cv_c_epoll_event_fd_offset],
+[AC_COMPUTE_INT(libgo_cv_c_epoll_event_fd_offset,
+[offsetof (struct epoll_event, data.fd)],
+[#include <stddef.h>
+#include <sys/epoll.h>],
+[libgo_cv_c_epoll_event_fd_offset=0])])
+STRUCT_EPOLL_EVENT_FD_OFFSET=${libgo_cv_c_epoll_event_fd_offset}
+AC_SUBST(STRUCT_EPOLL_EVENT_FD_OFFSET)
+
AC_CACHE_SAVE
if test ${multilib} = yes; then
Index: libgo/go/syscall/socket_linux.go
===================================================================
--- libgo/go/syscall/socket_linux.go (revision 180552)
+++ libgo/go/syscall/socket_linux.go (working copy)
@@ -164,15 +164,6 @@ func anyToSockaddrOS(rsa *RawSockaddrAny
return nil, EAFNOSUPPORT
}
-// We don't take this type directly from the header file because it
-// uses a union. FIXME.
-
-type EpollEvent struct {
- Events uint32
- Fd int32
- Pad int32
-}
-
//sysnb EpollCreate(size int) (fd int, errno int)
//epoll_create(size int) int
Index: libgo/Makefile.am
===================================================================
--- libgo/Makefile.am (revision 180552)
+++ libgo/Makefile.am (working copy)
@@ -1498,7 +1498,7 @@ endif # !LIBGO_IS_LINUX
# Define socket sizes and types.
if LIBGO_IS_LINUX
-syscall_socket_file = go/syscall/socket_linux.go
+syscall_socket_file = go/syscall/socket_linux.go epoll.go
else
if LIBGO_IS_SOLARIS
syscall_socket_file = go/syscall/socket_solaris.go
@@ -1582,6 +1582,34 @@ s-sysinfo: $(srcdir)/mksysinfo.sh config
$(SHELL) $(srcdir)/../move-if-change tmp-sysinfo.go sysinfo.go
$(STAMP) $@
+# The epoll struct has an embedded union and is packed on x86_64,
+# which is too complicated for mksysinfo.sh. We find the offset of
+# the only field we care about in configure.ac, and generate the
+# struct here.
+epoll.go: s-epoll; @true
+s-epoll: Makefile
+ rm -f epoll.go.tmp
+ echo 'package syscall' > epoll.go.tmp
+ echo 'type EpollEvent struct {' >> epoll.go.tmp
+ echo ' Events uint32' >> epoll.go.tmp
+ case "$(SIZEOF_STRUCT_EPOLL_EVENT),$(STRUCT_EPOLL_EVENT_FD_OFFSET)" in \
+ 0,0) echo 1>&2 "*** struct epoll_event data.fd offset unknown"; \
+ exit 1; ;; \
+ 8,4) echo ' Fd int32' >> epoll.go.tmp; ;; \
+ 12,4) echo ' Fd int32' >> epoll.go.tmp; \
+ echo ' Pad [4]byte' >> epoll.go.tmp; ;; \
+ 12,8) echo ' Pad [4]byte' >> epoll.go.tmp; \
+ echo ' Fd int32' >> epoll.go.tmp; ;; \
+ 16,8) echo ' Pad [4]byte' >> epoll.go.tmp; \
+ echo ' Fd int32' >> epoll.go.tmp; \
+ echo ' Pad2 [4]byte' >> epoll.go.tmp; ;; \
+ *) echo 1>&2 "*** struct epoll_event unsupported"; \
+ exit 1; ;; \
+ esac
+ echo '}' >> epoll.go.tmp
+ $(SHELL) $(srcdir)/../move-if-change epoll.go.tmp epoll.go
+ $(STAMP) $@
+
if LIBGO_IS_LINUX
# os_lib_inotify_lo = os/inotify.lo
os_lib_inotify_lo =
