linux-user: add tee, splice and vmsplice

Add support for tee, splice and vmsplice.

Originally from: vibi sreenivasan <vibi_sreenivasan@cms.com>

Riku: squashed patches together, added a test to configure
and removed compliler warning by picking up correct type for
splice param
Signed-off-by: Nvibisreenivasan <vibi_sreenivasan@cms.com>
Signed-off-by: NRiku Voipio <riku.voipio@iki.fi>

configure

@@ -1322,6 +1322,26 @@ if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
   pipe2=yes
 fi
 
+# check if tee/splice is there. vmsplice was added same time.
+splice=no
+cat > $TMPC << EOF
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+#include <limits.h>
+
+int main(void)
+{
+    int len, fd;
+    len = tee(STDIN_FILENO, STDOUT_FILENO, INT_MAX, SPLICE_F_NONBLOCK);
+    splice(STDIN_FILENO, NULL, fd, NULL, len, SPLICE_F_MOVE);
+    return 0;
+}
+EOF
+if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+  splice=yes
+fi
+
 # Check if tools are available to build documentation.
 if test "$build_docs" = "yes" -a \( ! -x "`which texi2html 2>/dev/null`" -o ! -x "`which pod2man 2>/dev/null`" \) ; then
   build_docs="no"
@@ -1725,6 +1745,9 @@ fi
 if test "$pipe2" = "yes" ; then
   echo "#define CONFIG_PIPE2 1" >> $config_h
 fi
+if test "$splice" = "yes" ; then
+  echo "#define CONFIG_SPLICE 1" >> $config_h
+fi
 if test "$inotify" = "yes" ; then
   echo "#define CONFIG_INOTIFY 1" >> $config_h
 fi

linux-user/syscall.c

@@ -6865,6 +6865,46 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         break;
 #endif
 
+#ifdef CONFIG_SPLICE
+#ifdef TARGET_NR_tee
+    case TARGET_NR_tee:
+        {
+            ret = get_errno(tee(arg1,arg2,arg3,arg4));
+        }
+        break;
+#endif
+#ifdef TARGET_NR_splice
+    case TARGET_NR_splice:
+        {
+            loff_t loff_in, loff_out;
+            loff_t *ploff_in = NULL, *ploff_out = NULL;
+            if(arg2) {
+                get_user_u64(loff_in, arg2);
+                ploff_in = &loff_in;
+            }
+            if(arg4) {
+                get_user_u64(loff_out, arg2);
+                ploff_out = &loff_out;
+            }
+            ret = get_errno(splice(arg1, ploff_in, arg3, ploff_out, arg5, arg6));
+        }
+        break;
+#endif
+#ifdef TARGET_NR_vmsplice
+	case TARGET_NR_vmsplice:
+        {
+            int count = arg3;
+            struct iovec *vec;
+
+            vec = alloca(count * sizeof(struct iovec));
+            if (lock_iovec(VERIFY_READ, vec, arg2, count, 1) < 0)
+                goto efault;
+            ret = get_errno(vmsplice(arg1, vec, count, arg4));
+            unlock_iovec(vec, arg2, count, 0);
+        }
+        break;
+#endif
+#endif /* CONFIG_SPLICE */
     default:
     unimplemented:
         gemu_log("qemu: Unsupported syscall: %d\n", num);