kpatch-build: fix Fedora 42+ kernel source directory nesting

Starting with Fedora 42, the kernel SRPM unpacks with an extra level
of nesting:

  BUILD/kernel-6.14.0-build/kernel-6.14/linux-6.14.0-63.fc42.x86_64/

The existing glob BUILD/kernel-*/linux-* only matches the traditional
flat layout and fails on this structure.

Extract the source-finding logic into find_rpm_linux_srcdir() in a new
kpatch-funcs.sh, using nullglob with a bash array to safely count
flat-glob matches:
- Exactly one match: move it (traditional RHEL/CentOS/Fedora < 42).
- Multiple matches: die with a clear diagnostic.
- Zero matches: search deeper with find -maxdepth 3, excluding
  configs/ directories, again requiring exactly one result.

Signed-off-by: Or Shoval <oshoval@redhat.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: oshoval

kpatch-build/kpatch-build

@@ -39,6 +39,7 @@ set -o pipefail
 
 BASE="$PWD"
 SCRIPTDIR="$(readlink -f "$(dirname "$(type -p "$0")")")"
+source "$SCRIPTDIR/kpatch-funcs.sh"
 ARCH="$(uname -m)"
 TARGET_ARCH="${TARGET_ARCH:-$ARCH}"
 CPUS="$(getconf _NPROCESSORS_ONLN)"
@@ -1082,7 +1083,7 @@ else
 		elif [[ "$DISTRO" = photon ]]; then
 			mv "$RPMTOPDIR"/BUILD/linux-"$KVER" "$KERNEL_SRCDIR" 2>&1 | logger || die
 		else
-			mv "$RPMTOPDIR"/BUILD/kernel-*/linux-* "$KERNEL_SRCDIR" 2>&1 | logger || die
+			find_rpm_linux_srcdir
 		fi
 
 		rm -rf "$RPMTOPDIR"

kpatch-build/kpatch-funcs.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Shared helper functions for kpatch-build (and tests).
+
+# Find and move the linux source directory from an RPM BUILD tree.
+# Handles both traditional flat layout (Fedora < 42, RHEL, CentOS):
+#   BUILD/kernel-6.12.0/linux-6.12.0-100.fc41.x86_64/
+# and nested layout (Fedora 42+):
+#   BUILD/kernel-6.14.0-build/kernel-6.14/linux-6.14.0-63.fc42.x86_64/
+#
+# Uses: RPMTOPDIR, KERNEL_SRCDIR (must be set by caller)
+find_rpm_linux_srcdir() {
+	shopt -s nullglob
+	local dirs=( "$RPMTOPDIR"/BUILD/kernel-*/linux-* )
+	shopt -u nullglob
+
+	if [[ ${#dirs[@]} -eq 1 ]]; then
+		mv "${dirs[0]}" "$KERNEL_SRCDIR" 2>&1 | logger || die
+	elif [[ ${#dirs[@]} -gt 1 ]]; then
+		die "Multiple linux-* directories found in BUILD: ${dirs[*]}"
+	else
+		local found count
+		found=$(find "$RPMTOPDIR/BUILD" -maxdepth 3 -type d -name "linux-*" \
+			! -path "*/configs/*")
+		count=$(echo "$found" | grep -c . || true)
+		if [[ "$count" -eq 1 ]]; then
+			mv "$found" "$KERNEL_SRCDIR" 2>&1 | logger || die
+		elif [[ "$count" -gt 1 ]]; then
+			die "Multiple linux source directories under $RPMTOPDIR/BUILD: $found"
+		else
+			die "Could not find linux source directory under $RPMTOPDIR/BUILD"
+		fi
+	fi
+}