[Xen-devel] [PATCH v6 14/19] tools/libxl: Check if fdt_{first, next}_subnode are present in libfdt

[Julien Grall <julien.grall@xxxxxxxxxx>]

From: Julien Grall <julien.grall@xxxxxxxxxx>

The functions fdt_{fisrt,next}_subnode may not be available because:
    * It has been introduced in 2013 => Doesn't work on Wheezy
    * The prototype exists but the functions are not exposed. Don't ask
    why...

The later has been fixed recently in the dtc repo [1]

When the functions are not available, implement our own in order to use
them in a following patch.

[1] git://git.kernel.org/pub/scm/utils/dtc/dtc.git
    commit a4b093f7366fdb429ca1781144d3985fa50d0fbb

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>

---
    tools/configure needs to be regenerate as this patch is modifying
    tools/configure.ac

    Changes in v6:
        - Add Ian's Ack

    Changes in v5:
        - Add Ian's Signed-off-by for the license part and update the
        license
        - Rename libxl_fdt to libxl_libfdt_compat.c

    Changes in v4:
        - Patch added
---
 tools/config.h.in                 |  6 +++
 tools/configure.ac                |  5 +++
 tools/libxl/Makefile              |  2 +-
 tools/libxl/libxl_libfdt_compat.c | 92 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 tools/libxl/libxl_libfdt_compat.c

diff --git a/tools/config.h.in b/tools/config.h.in
index 2a0ae48..06f8b6c 100644
--- a/tools/config.h.in
+++ b/tools/config.h.in
@@ -3,6 +3,12 @@
 /* Blktap2 enabled */
 #undef HAVE_BLKTAP2
 
+/* Define to 1 if you have the `fdt_first_subnode' function. */
+#undef HAVE_FDT_FIRST_SUBNODE
+
+/* Define to 1 if you have the `fdt_next_subnode' function. */
+#undef HAVE_FDT_NEXT_SUBNODE
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
diff --git a/tools/configure.ac b/tools/configure.ac
index d31c2f3..cc13336 100644
--- a/tools/configure.ac
+++ b/tools/configure.ac
@@ -355,6 +355,11 @@ AC_SUBST(libiconv)
 case "$host_cpu" in
 arm*|aarch64)
 AC_CHECK_LIB([fdt], [fdt_create], [], [AC_MSG_ERROR([Could not find libfdt])])
+
+# The functions fdt_{first,next}_subnode may not be available because:
+#   * It has been introduced in 2013 => Doesn't work on Wheezy
+#   * The prototype exists but the functions are not exposed. Don't ask why...
+AC_CHECK_FUNCS([fdt_first_subnode fdt_next_subnode])
 esac
 
 # Checks for header files.
diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
index 1b16598..2afb146 100644
--- a/tools/libxl/Makefile
+++ b/tools/libxl/Makefile
@@ -59,7 +59,7 @@ endif
 LIBXL_OBJS-y += libxl_remus_device.o libxl_remus_disk_drbd.o
 
 LIBXL_OBJS-$(CONFIG_X86) += libxl_cpuid.o libxl_x86.o libxl_psr.o
-LIBXL_OBJS-$(CONFIG_ARM) += libxl_nocpuid.o libxl_arm.o
+LIBXL_OBJS-$(CONFIG_ARM) += libxl_nocpuid.o libxl_arm.o libxl_libfdt_compat.o
 
 ifeq ($(CONFIG_NetBSD),y)
 LIBXL_OBJS-y += libxl_netbsd.o
diff --git a/tools/libxl/libxl_libfdt_compat.c 
b/tools/libxl/libxl_libfdt_compat.c
new file mode 100644
index 0000000..d0519f9
--- /dev/null
+++ b/tools/libxl/libxl_libfdt_compat.c
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2006 David Gibson, IBM Corporation.
+ *
+ * This file is part of libxl, and was originally taken from libfdt.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * Additionally, this particular file is dual licensed.  That is,
+ * alternatively, at your option:
+ *
+ *      Redistribution and use in source and binary forms, with or
+ *      without modification, are permitted provided that the following
+ *      conditions are met:
+ *
+ *      1. Redistributions of source code must retain the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer.
+ *      2. Redistributions in binary form must reproduce the above
+ *         copyright notice, this list of conditions and the following
+ *         disclaimer in the documentation and/or other materials
+ *         provided with the distribution.
+ *
+ *      THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *      CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *      INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *      MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *      DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ *      CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *      SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *      NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ *      LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ *      HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *      CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ *      OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ *      EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Note that this applies only to this file, and other files with a
+ * similar notice.  Also, note that when the same code is distributed
+ * along with the rest of libxl, you must comply with the terms of the
+ * LGPLv2.1 for the whole of libxl including this file.
+ *
+ * The intent is to permit, in particular, upstream libfdt to
+ * incorporate improvements to this file within upstream libfdt.  At
+ * the time of writing, upstream libfdt is dual licensed: 2-clause BSD
+ * (as above) and GPLv2-or-later.  The 2-clause BSD licence is
+ * compatible with both GPLv2-or-later and LGPLv2.1-only; this permits
+ * copying in both directions, and the optional licence upgrade to a
+ * copyleft licence by libdft upstream or the Xen Project,
+ * respectively.
+ */
+
+#include <libfdt.h>
+
+#ifndef HAVE_FDT_FIRST_SUBNODE
+int fdt_first_subnode(const void *fdt, int offset)
+{
+       int depth = 0;
+
+       offset = fdt_next_node(fdt, offset, &depth);
+       if (offset < 0 || depth != 1)
+               return -FDT_ERR_NOTFOUND;
+
+       return offset;
+}
+#endif
+
+#ifndef HAVE_FDT_NEXT_SUBNODE
+int fdt_next_subnode(const void *fdt, int offset)
+{
+       int depth = 1;
+
+       /*
+        * With respect to the parent, the depth of the next subnode will be
+        * the same as the last.
+        */
+       do {
+               offset = fdt_next_node(fdt, offset, &depth);
+               if (offset < 0 || depth < 1)
+                       return -FDT_ERR_NOTFOUND;
+       } while (depth > 1);
+
+       return offset;
+}
+#endif
-- 
2.1.4


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