livepatch/klp-build: support patches that add/remove files

The klp-build script prepares a clean patch by populating two temporary
directories ('a' and 'b') with source files and diffing the result.
However, this process fails when a patch introduces a new source file,
as the script attempts to copy files that do not yet exist in the
original source tree.  Likewise, it fails when a patch removes a source
file and the script attempts to copy a file that no longer exists.

Refactor the file-gathering logic to distinguish between original input
files and patched output files:

- Split get_patch_files() into get_patch_input_files() and
  get_patch_output_files() to identify which files exist before and
  after patch application.
- Filter out "/dev/null" from both to handle file creation/deletion.
- Update refresh_patch() to only copy existing input files to the 'a'
  directory and the resulting output files to the 'b' directory.

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Link: https://patch.msgid.link/20260310203751.1479229-4-joe.lawrence@redhat.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index 809e198a561d54236419ea66a6299a8c5add3006..94ed3b4a91d87873d190a39a3092bd0b047905a6 100755 (executable)
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -296,15 +296,33 @@ set_kernelversion() {
        sed -i "2i echo $localversion; exit 0" scripts/setlocalversion
 }
 
-get_patch_files() {
+get_patch_input_files() {
+       local patch="$1"
+
+       grep0 -E '^--- ' "$patch"                               \
+               | gawk '{print $2}'                             \
+               | grep0 -v '^/dev/null$'                        \
+               | sed 's|^[^/]*/||'                             \
+               | sort -u
+}
+
+get_patch_output_files() {
        local patch="$1"
 
-       grep0 -E '^(--- |\+\+\+ )' "$patch"                     \
+       grep0 -E '^\+\+\+ ' "$patch"                            \
                | gawk '{print $2}'                             \
+               | grep0 -v '^/dev/null$'                        \
                | sed 's|^[^/]*/||'                             \
                | sort -u
 }
 
+get_patch_files() {
+       local patch="$1"
+
+       { get_patch_input_files "$patch"; get_patch_output_files "$patch"; } \
+               | sort -u
+}
+
 # Make sure git re-stats the changed files
 git_refresh() {
        local patch="$1"
@@ -312,7 +330,7 @@ git_refresh() {
 
        [[ ! -e "$SRC/.git" ]] && return
 
-       get_patch_files "$patch" | mapfile -t files
+       get_patch_input_files "$patch" | mapfile -t files
 
        (
                cd "$SRC"
@@ -426,21 +444,23 @@ do_init() {
 refresh_patch() {
        local patch="$1"
        local tmpdir="$PATCH_TMP_DIR"
-       local files=()
+       local input_files=()
+       local output_files=()
 
        rm -rf "$tmpdir"
        mkdir -p "$tmpdir/a"
        mkdir -p "$tmpdir/b"
 
        # Get all source files affected by the patch
-       get_patch_files "$patch" | mapfile -t files
+       get_patch_input_files "$patch" | mapfile -t input_files
+       get_patch_output_files "$patch" | mapfile -t output_files
 
        # Copy orig source files to 'a'
-       ( cd "$SRC" && echo "${files[@]}" | xargs cp --parents --target-directory="$tmpdir/a" )
+       ( cd "$SRC" && echo "${input_files[@]}" | xargs cp --parents --target-directory="$tmpdir/a" )
 
        # Copy patched source files to 'b'
        apply_patch "$patch" --recount
-       ( cd "$SRC" && echo "${files[@]}" | xargs cp --parents --target-directory="$tmpdir/b" )
+       ( cd "$SRC" && echo "${output_files[@]}" | xargs cp --parents --target-directory="$tmpdir/b" )
        revert_patch "$patch" --recount
 
        # Diff 'a' and 'b' to make a clean patch