Fix struct sockaddr/sockaddr_in/sockaddr_un strict aliasing violations

Building gdbserver in C++ mode shows:

  gdb/gdbserver/tracepoint.c: In function ‘void* gdb_agent_helper_thread(void*)’:
  gdb/gdbserver/tracepoint.c:7190:47: error: cannot convert ‘sockaddr_un*’ to ‘sockaddr*’ for argument ‘2’ to ‘int accept(int, sockaddr*, socklen_t*)’
	  fd = accept (listen_fd, &sockaddr, &tmp);

A few places in the tree already have an explicit cast to struct
sockaddr *, but that's a strict aliasing violation.  Instead of
propagating invalid code, fix this by using a union instead.

gdb/ChangeLog:
2015-03-07  Pedro Alves  <palves@redhat.com>

	* common/gdb_socket.h: New file.
	* ser-tcp.c: Include gdb_socket.h.  Don't include netinet/in.h nor
	sys/socket.h.
	(net_open): Use union gdb_sockaddr_u.

gdb/gdbserver/ChangeLog:
2015-03-07  Pedro Alves  <palves@redhat.com>

	* gdbreplay.c: No longer include <netinet/in.h>, <sys/socket.h>,
	or <winsock2.h> here.  Instead include "gdb_socket.h".
	(remote_open): Use union gdb_sockaddr_u.
	* remote-utils.c: No longer include <netinet/in.h>, <sys/socket.h>
	or <winsock2.h> here.  Instead include "gdb_socket.h".
	(handle_accept_event, remote_prepare): Use union gdb_sockaddr_u.
	* tracepoint.c: Include "gdb_socket.h" instead of <sys/socket.h>
	or <sys/un.h>.
	(init_named_socket, gdb_agent_helper_thread): Use union
	gdb_sockaddr_u.

1 files changed, 9 insertions, 10 deletions

diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c
index 27fcf03..6c34ad4 100644
--- a/gdb/gdbserver/tracepoint.c
+++ b/gdb/gdbserver/tracepoint.c
@@ -6817,8 +6817,7 @@ run_inferior_command (char *cmd, int len)
 
 #else /* !IN_PROCESS_AGENT */
 
-#include <sys/socket.h>
-#include <sys/un.h>
+#include "gdb_socket.h"
 
 #ifndef UNIX_PATH_MAX
 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
@@ -6837,7 +6836,7 @@ static int
 init_named_socket (const char *name)
 {
   int result, fd;
-  struct sockaddr_un addr;
+  union gdb_sockaddr_u addr;
 
   result = fd = socket (PF_UNIX, SOCK_STREAM, 0);
   if (result == -1)
@@ -6846,10 +6845,10 @@ init_named_socket (const char *name)
       return -1;
     }
 
-  addr.sun_family = AF_UNIX;
+  addr.sa_un.sun_family = AF_UNIX;
 
-  strncpy (addr.sun_path, name, UNIX_PATH_MAX);
-  addr.sun_path[UNIX_PATH_MAX - 1] = '\0';
+  strncpy (addr.sa_un.sun_path, name, UNIX_PATH_MAX);
+  addr.sa_un.sun_path[UNIX_PATH_MAX - 1] = '\0';
 
   result = access (name, F_OK);
   if (result == 0)
@@ -6865,7 +6864,7 @@ init_named_socket (const char *name)
       warning ("socket %s already exists; overwriting", name);
     }
 
-  result = bind (fd, (struct sockaddr *) &addr, sizeof (addr));
+  result = bind (fd, &addr.sa, sizeof (addr.sa_un));
   if (result == -1)
     {
       warning ("bind failed: %s", strerror (errno));
@@ -7164,17 +7163,17 @@ gdb_agent_helper_thread (void *arg)
       while (1)
 	{
 	  socklen_t tmp;
-	  struct sockaddr_un sockaddr;
+	  union gdb_sockaddr_u sockaddr;
 	  int fd;
 	  char buf[1];
 	  int ret;
 	  int stop_loop = 0;
 
-	  tmp = sizeof (sockaddr);
+	  tmp = sizeof (sockaddr.sa_un);
 
 	  do
 	    {
-	      fd = accept (listen_fd, &sockaddr, &tmp);
+	      fd = accept (listen_fd, &sockaddr.sa, &tmp);
 	    }
 	  /* It seems an ERESTARTSYS can escape out of accept.  */
 	  while (fd == -512 || (fd == -1 && errno == EINTR));