busybox: backport hexdump fix for Big Endian systems

hexdump isn't working properly on some Big Endian systems, producing
incorrect output such as:
  hexdump -vn 5 -e '"fd" 1/1 "%02x:" 2/2 "%x:"' /dev/urandom
  fdff:542c0054:17920017:
Which should be:
  fdff:542c:1792:

This breaks the default ULA prefix generation on some systems. See:
https://github.com/openwrt/openwrt/issues/19844

The issue has already been fixed upstream, so we can backport the fix:
https://git.busybox.net/busybox/commit/libbb/dump.c?id=f5c7cae55fc3e19d074198bc12152486067ea8c7

Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/package/utils/busybox/patches/003-hexdump-fix-regression-for-uint16-on-big-endian-systems.patch b/package/utils/busybox/patches/003-hexdump-fix-regression-for-uint16-on-big-endian-systems.patch
new file mode 100644 (file)
index 0000000..5440c34
--- /dev/null
+++ b/package/utils/busybox/patches/003-hexdump-fix-regression-for-uint16-on-big-endian-systems.patch
@@ -0,0 +1,41 @@
+From f5c7cae55fc3e19d074198bc12152486067ea8c7 Mon Sep 17 00:00:00 2001
+From: Radoslav Kolev <[email protected]>
+Date: Thu, 24 Apr 2025 00:45:25 +0300
+Subject: [PATCH] hexdump: fix regression for uint16 on big endian systems
+
+Commit 34751d8bf introduced a bug in the handling of uint16
+values on big endian systems not considered safe for unaligned
+access when falling back to memcpy.
+
+Signed-off-by: Radoslav Kolev <[email protected]>
+Signed-off-by: Denys Vlasenko <[email protected]>
+---
+ libbb/dump.c | 10 ++++++++--
+ 1 file changed, 8 insertions(+), 2 deletions(-)
+
+--- a/libbb/dump.c
++++ b/libbb/dump.c
+@@ -667,15 +667,21 @@ static NOINLINE void display(priv_dumper
+                                                       conv_u(pr, bp);
+                                                       break;
+                                               case F_UINT: {
++                                                      union {
++                                                              uint16_t uval16;
++                                                              uint32_t uval32;
++                                                      } u;
+                                                       unsigned value = (unsigned char)*bp;
+                                                       switch (pr->bcnt) {
+                                                       case 1:
+                                                               break;
+                                                       case 2:
+-                                                              move_from_unaligned16(value, bp);
++                                                              move_from_unaligned16(u.uval16, bp);
++                                                              value = u.uval16;
+                                                               break;
+                                                       case 4:
+-                                                              move_from_unaligned32(value, bp);
++                                                              move_from_unaligned32(u.uval32, bp);
++                                                              value = u.uval32;
+                                                               break;
+                                                       /* case 8: no users yet */
+                                                       }