add io_socketpair

CHANGES

@@ -1,3 +1,6 @@
+0.19:
+  add io_socketpair
+
 0.18:
   make libowfat compile on BSD again (sorry, and thanks to everyone who
     sent me a patch :-D)

io.h

@@ -12,6 +12,8 @@ int io_readfile(int64* d,const char* s);
 int io_createfile(int64* d,const char* s);
 /* like pipe(d) */
 int io_pipe(int64* d);
+/* like socketpair() */
+int io_socketpair(int64* d);
 
 /* non-blocking read(), -1 for EAGAIN and -3+errno for other errors */
 int64 io_tryread(int64 d,char* buf,int64 len);

io/io_socketpair.c

@@ -0,0 +1,24 @@
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include "io_internal.h"
+
+int io_socketpair(int64* d) {
+  int fds[2];
+  if (socketpair(AF_UNIX,SOCK_STREAM,0,fds)==-1)
+    if (socketpair(AF_INET6,SOCK_STREAM,IPPROTO_TCP,fds)==-1)
+      if (socketpair(AF_INET,SOCK_STREAM,IPPROTO_TCP,fds)==-1)
+	return 0;
+  if (io_fd(fds[1])) {
+    if (io_fd(fds[0])) {
+      d[0]=fds[0];
+      d[1]=fds[1];
+      return 1;
+    }
+    io_close(fds[1]);
+  }
+  close(fds[0]);
+  return 0;
+}