linux-user: Implement sendfile and sendfile64

Implement the sendfile and sendfile64 syscalls. This implementation
passes all the LTP test cases for these syscalls.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

configure

@@ -2760,6 +2760,20 @@ if compile_prog "" "" ; then
   epoll_pwait=yes
 fi
 
+# check for sendfile support
+sendfile=no
+cat > $TMPC << EOF
+#include <sys/sendfile.h>
+
+int main(void)
+{
+    return sendfile(0, 0, 0, 0);
+}
+EOF
+if compile_prog "" "" ; then
+  sendfile=yes
+fi
+
 # Check if tools are available to build documentation.
 if test "$docs" != "no" ; then
   if has makeinfo && has pod2man; then
@@ -3628,6 +3642,9 @@ fi
 if test "$epoll_pwait" = "yes" ; then
   echo "CONFIG_EPOLL_PWAIT=y" >> $config_host_mak
 fi
+if test "$sendfile" = "yes" ; then
+  echo "CONFIG_SENDFILE=y" >> $config_host_mak
+fi
 if test "$inotify" = "yes" ; then
   echo "CONFIG_INOTIFY=y" >> $config_host_mak
 fi

linux-user/syscall.c

@@ -78,6 +78,9 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
 #ifdef CONFIG_ATTR
 #include "qemu/xattr.h"
 #endif
+#ifdef CONFIG_SENDFILE
+#include <sys/sendfile.h>
+#endif
 
 #define termios host_termios
 #define winsize host_winsize
@@ -7531,8 +7534,58 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 #else
         goto unimplemented;
 #endif
+
+#ifdef CONFIG_SENDFILE
+    case TARGET_NR_sendfile:
+    {
+        off_t *offp = NULL;
+        off_t off;
+        if (arg3) {
+            ret = get_user_sal(off, arg3);
+            if (is_error(ret)) {
+                break;
+            }
+            offp = &off;
+        }
+        ret = get_errno(sendfile(arg1, arg2, offp, arg4));
+        if (!is_error(ret) && arg3) {
+            abi_long ret2 = put_user_sal(off, arg3);
+            if (is_error(ret2)) {
+                ret = ret2;
+            }
+        }
+        break;
+    }
+#ifdef TARGET_NR_sendfile64
+    case TARGET_NR_sendfile64:
+    {
+        off_t *offp = NULL;
+        off_t off;
+        if (arg3) {
+            ret = get_user_s64(off, arg3);
+            if (is_error(ret)) {
+                break;
+            }
+            offp = &off;
+        }
+        ret = get_errno(sendfile(arg1, arg2, offp, arg4));
+        if (!is_error(ret) && arg3) {
+            abi_long ret2 = put_user_s64(off, arg3);
+            if (is_error(ret2)) {
+                ret = ret2;
+            }
+        }
+        break;
+    }
+#endif
+#else
     case TARGET_NR_sendfile:
+#ifdef TARGET_NR_sendfile64:
+    case TARGET_NR_sendfile64:
+#endif
         goto unimplemented;
+#endif
+
 #ifdef TARGET_NR_getpmsg
     case TARGET_NR_getpmsg:
         goto unimplemented;