scripts: add a new helper script to easily rediff a patchset

scripts/patch-rework.sh

@@ -0,0 +1,153 @@
+#!/bin/sh
+
+# Get our required options
+base="$1"
+src="$2"
+dst="$3"
+shift 3
+
+# The remainder is for diff
+diff="$@"
+
+# This function checks that the files listed in the file in "$1"
+# do exist, at the given depth-stripping level (aka diff -p#)
+do_check_files_at_depth() {
+  local flist="$1"
+  local depth="$2"
+  local ok=0  # 0: OK,  !0: KO
+
+  exec 6<&0
+  exec 7<"${flist}"
+
+  while read -u7 f; do
+    f="$( echo "${f}" |sed -r -e "s:^([^/]+/){${depth}}::;" )"
+    [ -f "${f}" ] || ok=1
+  done
+
+  exec 7<&-
+  exec <&6
+
+  return ${ok}
+}
+
+mkdir -p "${dst}"
+dst="$( cd "${dst}"; pwd )"
+
+# Iterate through patches
+for p in "${src}/"*.patch; do
+  pname="$( basename "${p}" )"
+
+  printf "Handling patch '${pname}'...\n"
+
+  printf "  creating reference..."
+  cp -a "${base}" "${base}.orig"
+  printf " done\n"
+
+  printf "  retrieving patch comment..."
+  comment="$( awk '
+BEGIN { mark=0; }
+$0~/^diff --/ { nextfile; }
+$1=="---" { mark=1; next; }
+$1=="+++" && mark==1 { nextfile; }
+{ mark=0; print; }
+' "${p}" )"
+  printf " done\n"
+
+  printf "  creating patched file list..."
+  diffstat -f 4 -r 2 -u -p 0 "${p}"                         \
+  |head -n -1                                               \
+  |awk '{ for(i=NF;i>=NF-5;i--) { $(i) = ""; } print; }'    \
+  |sort                                                     \
+  >"diffstat.orig"
+  printf " done\n"
+
+  pushd "${base}" >/dev/null 2>&1
+
+  # Check all files exist, up to depth 3
+  printf "  checking depth:"
+  for((d=0;d<4;d++)); do
+    printf " ${d}"
+    if do_check_files_at_depth "../diffstat.orig" ${d}; then
+      printf " ok, using depth '${d}'\n"
+      break
+    fi
+  done
+  if [ ${d} -ge 4 ]; then
+    printf "\n"
+    printf "  checking depth failed\n"
+    read -p "  --> enter patch depth (or Ctrl-C to abort): " d
+  fi
+
+  # Store the original list of fiels touched by the patch,
+  # removing the $d leading components
+  sed -r -e "s:^([^/]+/){${d}}::;" "../diffstat.orig" >"${dst}/${pname}.diffstat.orig"
+
+  # Apply the patch proper, and check it applied cleanly.
+  # We can't check with --dry-run because of patches that
+  # contain multiple accumulated patches onto a single file.
+  printf "  applying patch..."
+  if ! patch -g0 -F1 -f -p${d} <"${p}" >"../patch.out" 2>&1; then
+    printf " ERROR\n"
+    # Revert the patch
+    popd >/dev/null 2>&1
+    printf "  restoring '${base}'..."
+    rm -f "diffstat.tmp"
+    rm -rf "${base}"
+    mv "${base}.orig" "${base}"
+    printf " done\n\n"
+    printf "There was an error while applying:\n  -->  ${p}  <--\n"
+    printf "'${base}' was restored to the state it was prior to applying this faulty patch.\n"
+    printf "Here's the 'patch' command, and its output:\n"
+    printf "  ----8<----\n"
+    printf "  patch -g0 -F1 -f -p${d} <'${p}'\n"
+    cat "patch.out" |(IFS=$(printf "\n"); while read line; do printf "  ${line}\n"; done)
+    rm -f "patch.out"
+    printf "  ----8<----\n"
+    exit 1
+  fi
+  printf " done\n"
+
+  printf "  removing '.orig' files..."
+  find . -type f -name '*.orig' -exec rm -f {} +
+  printf " done\n"
+
+  popd >/dev/null 2>&1
+
+  printf "  re-diffing the patch..."
+  printf "%s\n\n" "${comment}" >"${dst}/${pname}"
+  diff -durN "${base}.orig" "${base}" >>"${dst}/${pname}"
+  printf " done\n"
+
+  if [ -n "${diff}" ]; then
+    printf "  applying diff filter..."
+    filterdiff -x "${diff}" "${dst}/${pname}" >"tmp-diff"
+    mv "tmp-diff" "${dst}/${pname}"
+    printf " done\n"
+  fi
+
+  printf "  creating new patched file list..."
+  diffstat -f 4 -r 2 -u -p 1 "${dst}/${pname}"              \
+  |head -n -1                                               \
+  |awk '{ for(i=NF;i>=NF-5;i--) { $(i) = ""; } print; }'    \
+  |sort                                                     \
+  >"${dst}/${pname}.diffstat.new"
+  printf " done\n"
+
+  printf "  removing temporary files/dirs..."
+  rm -f "patch.out"
+  rm -f "diffstat.tmp"
+  rm -rf "${base}.orig"
+  printf " done\n"
+done
+
+# Scan all new patches to see if they touch
+# more files than the original patches
+printf "\nChecking resulting patchset:\n"
+for p in "${dst}/"*.patch; do
+  pname="$( basename "${p}" )"
+
+  if ! cmp "${p}.diffstat.orig" "${p}.diffstat.new" >/dev/null; then
+    printf "  --> '${pname}' differ in touched files <--\n"
+  fi
+done
+printf "  done.\n"