networkupstools · jimklimov · Oct 2, 2025 · Oct 2, 2025 · Oct 2, 2025 · Oct 2, 2025
diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -53,6 +53,12 @@ jobs:
         #type: string
         #default: "/opt/homebrew" # since July 2024 CircleCI only serves Apple Silicon instances
         #default: "/usr/local" # was when CircleCI builders had x86
+      DO_CLEAN_AUTOCONF_CACHE:
+        type: string
+        default: "no"
+      DO_USE_AUTOCONF_CACHE:
+        type: string
+        default: "yes"
 
     environment:
       CC: << parameters.CC >>
@@ -64,6 +70,8 @@ jobs:
       CI_BUILDDIR: << parameters.CI_BUILDDIR >>
       BREW_MORE: << parameters.BREW_MORE >>
       #HOMEBREW_PREFIX: << parameters.HOMEBREW_PREFIX >>
+      DO_CLEAN_AUTOCONF_CACHE: << parameters.DO_CLEAN_AUTOCONF_CACHE >>
+      DO_USE_AUTOCONF_CACHE: << parameters.DO_USE_AUTOCONF_CACHE >>
 
     # Specify the execution environment. You can specify an image from Dockerhub or use one of our Convenience Images from CircleCI's Developer Hub.
     # See: https://circleci.com/docs/2.0/configuration-reference/#docker-machine-macos-windows-executor
@@ -126,6 +134,7 @@ jobs:
           keys:
             - ccache-{{ .Branch }}-{{ arch }}-{{ .Environment.CIRCLE_JOB }}
             - ccache-master-{{ arch }}-{{ .Environment.CIRCLE_JOB }}
+            - config-cache-{{ .Branch }}-{{ arch }}-{{ .Environment.CIRCLE_JOB }}
 
       # Help SEMVER look right (optionally)
       - run:
@@ -194,10 +203,17 @@ jobs:
       # be beneficial to instead share the cache between jobs; more so
       # while we are on free CircleCI tier and run them sequentially.
       - save_cache:
+          name: Save .ccache for later runs
           paths:
             - ~/.ccache
           key: ccache-{{ .Branch }}-{{ arch }}-{{ .Environment.CIRCLE_JOB }}
 
+      - save_cache:
+          name: Save config.cache for later runs
+          paths:
+            - config.cache
+          key: config-cache-{{ .Branch }}-{{ arch }}-{{ .Environment.CIRCLE_JOB }}
+
       - store_artifacts:
           path: config.log
 

diff --git a/NEWS.adoc b/NEWS.adoc
@@ -150,6 +150,9 @@ https://github.com/networkupstools/nut/milestone/12
    syntax is not supported everywhere (or the `!` operator generally).
    [#3099, #1660]
 
+ - Introduced `ci_build.sh` settings and respective CI workflow settings
+   to optionally re-use a `config.cache` file from older runs. [#3108]
+
 
 Release notes for NUT 2.8.4 - what's new since 2.8.3
 ----------------------------------------------------

diff --git a/appveyor.yml b/appveyor.yml
@@ -27,6 +27,8 @@ environment:
   APPVEYOR_SAVE_CACHE_ON_ERROR: true
   APPVEYOR_CACHE_ENTRY_ZIP_ARGS: -t7z -m0=lzma -mx=6
   CCACHE_DIR: /home/appveyor/.ccache
+  DO_CLEAN_AUTOCONF_CACHE: no
+  DO_USE_AUTOCONF_CACHE: yes
 
 # https://github.com/networkupstools/nut/blob/Windows-v2.8.0-1/docs/config-prereqs.txt#L951
 # or look for the chapter in nearby lines in later (current) revisions.
@@ -163,6 +165,7 @@ artifacts:
 # Example optional cache (depends on file change):
 # - C:\msys64 -> appveyor.yml
 cache:
+  - C:\projects\nut\config.cache
   - C:\msys64\home\appveyor\nut-win-deps
   - C:\msys64\home\appveyor\.ccache
   - C:\msys64\home\appveyor\ccache # likely missing, no problem - but the name is reported in ccache status

diff --git a/ci_build.sh b/ci_build.sh
@@ -55,7 +55,7 @@ case "$BUILD_TYPE" in
             echo "SKIPPING BUILD_TYPE=fightwarn-clang: compiler not found" >&2
         fi
         if $TRIED_BUILD ; then true
-	else
+        else
             echo "FAILED to run: no default-named compilers were found" >&2
             exit 1
         fi
@@ -1151,6 +1151,16 @@ configure_nut() {
       echo "=== CONFIGURING NUT: $CONFIGURE_SCRIPT ${CONFIG_OPTS_STR}"
       echo "=== CC='$CC' CXX='$CXX' CPP='$CPP'"
       [ -z "${CI_SHELL_IS_FLAKY-}" ] || echo "=== CI_SHELL_IS_FLAKY='$CI_SHELL_IS_FLAKY'"
+      if [ x"${DO_USE_AUTOCONF_CACHE}" = xyes ] && [ -s config.cache ]; then
+        echo "$0: using existing config.cache" >&2
+      else
+        if [ x"${DO_USE_AUTOCONF_CACHE}" = xyes ]; then
+          echo "$0: NOT using config.cache because it did not exist" >&2
+        else if [ -s config.cache ]; then
+          echo "$0: NOT using existing config.cache because DO_USE_AUTOCONF_CACHE=$DO_USE_AUTOCONF_CACHE" >&2
+        fi; fi
+      fi
+
       $CI_TIME $CONFIGURE_SCRIPT "${CONFIG_OPTS[@]}" \
       && echo "$0: configure phase complete (0)" >&2 \
       && return 0 \
@@ -1283,6 +1293,9 @@ check_gitignore() {
     [ -n "${FILE_GLOB-}" ] || FILE_GLOB="'*'"
     # Always filter these names away:
     FILE_GLOB_EXCLUDE="':!.ci*.log*' ':!VERSION_DEFAULT' ':!VERSION_FORCED*'"
+    if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] ; then
+        FILE_GLOB_EXCLUDE="$FILE_GLOB_EXCLUDE ':!config.cache*'"
+    fi
     [ -n "${GIT_ARGS-}" ] || GIT_ARGS='' # e.g. GIT_ARGS="--ignored"
     # Display contents of the diff?
     # (Helps copy-paste from CI logs to source to amend quickly)
@@ -1349,12 +1362,20 @@ consider_cleanup_shortcut() {
         fi
     fi
 
+    if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xyes ]; then
+        rm -f config.cache*
+    fi
+
     # When iterating configure.ac or m4 sources, we can end up with an
     # existing but useless script file - nuke it and restart from scratch!
     if [ -s "${CI_BUILDDIR}"/configure ] ; then
         # FIXME: Consider CONFIG_SHELL, maybe from script shebang,
         #  here - like autogen.sh does
-        if sh -n "${CI_BUILDDIR}"/configure 2>/dev/null ; then
+        USE_CONFIG_SHELL=sh
+        if [ -n "${CONFIG_SHELL-}" ]; then
+            USE_CONFIG_SHELL="${CONFIG_SHELL}"
+        fi
+        if ${USE_CONFIG_SHELL} -n "${CI_BUILDDIR}"/configure 2>/dev/null ; then
             true
         else
             echo "=== Starting initial clean-up (from old build products): TAKING SHORTCUT because current configure script syntax is broken"
@@ -1399,15 +1420,30 @@ optional_maintainer_clean_check() {
     else
         [ -z "$CI_TIME" ] || echo "`date`: Starting maintainer-clean check of currently tested project..."
 
+        rm -f config.cache.tmp || true
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache ]; then
+            echo "=== Keeping old config.cache as asked by BUILD_TYPE default or caller request"
+            cp -f config.cache config.cache.tmp
+        fi
+
         # Note: currently Makefile.am has just a dummy "distcleancheck" rule
+        MAKE_RES=0
         case "$MAKE_FLAGS $DISTCHECK_FLAGS $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN" in
         *V=0*)
-            $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN maintainer-clean > /dev/null || return
+            $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN maintainer-clean > /dev/null || MAKE_RES=$?
             ;;
         *)
-            $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN maintainer-clean || return
+            $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN maintainer-clean || MAKE_RES=$?
         esac
 
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache.tmp ]; then
+            mv -f config.cache.tmp config.cache || true
+        fi
+
+        if [ x"$MAKE_RES" != x0 ]; then
+            return $MAKE_RES
+        fi
+
         GIT_ARGS="--ignored" check_gitignore "maintainer-clean" || return
     fi
 
@@ -1434,8 +1470,23 @@ optional_dist_clean_check() {
     else
         [ -z "$CI_TIME" ] || echo "`date`: Starting dist-clean check of currently tested project..."
 
+        rm -f config.cache.tmp || true
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache ]; then
+            echo "=== Keeping old config.cache as asked by BUILD_TYPE default or caller request"
+            cp -f config.cache config.cache.tmp
+        fi
+
         # Note: currently Makefile.am has just a dummy "distcleancheck" rule
-        $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN distclean || return
+        MAKE_RES=0
+        $CI_TIME $MAKE DISTCHECK_FLAGS="$DISTCHECK_FLAGS" $PARMAKE_FLAGS $MAKE_FLAGS_CLEAN distclean || MAKE_RES=$?
+
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache.tmp ]; then
+            mv -f config.cache.tmp config.cache || true
+        fi
+
+        if [ x"$MAKE_RES" != x0 ]; then
+            return $MAKE_RES
+        fi
 
         check_gitignore "distclean" || return
     fi
@@ -1508,13 +1559,70 @@ if [ -z "$BUILD_TYPE" ] ; then
             fi
             ;;
 
-        *) echo "WARNING: Command-line argument '$1' wsa not recognized as a BUILD_TYPE alias" >&2 ;;
+        *) echo "WARNING: Command-line argument '$1' was not recognized as a BUILD_TYPE alias" >&2 ;;
     esac
 fi
 
 # Default follows autotools:
 [ -n "${DISTCHECK_TGT-}" ] || DISTCHECK_TGT="distcheck"
 
+# https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Cache-Files.html
+# By default, we clean up the config.cache between jobs (before start,
+# after finish), but do want to use (and retain) it between loop runs
+# of BUILD_TYPE="default-all-errors*".
+# FIXME: Currently disabled for the loops; we want to only cache the
+#  common system findings but forget the details we vary (implementations
+#  of libusb, ssl...) because this knowledge about "lack" of some methods
+#  breaks those very re-runs. The approach can still be used for runs of
+#  same configurations from one iteration to another on CI systems though.
+# Note that autotools automatically removes such file name during the
+# "make distclean" and stronger goals, so on our side we can only
+# stash and restore the file around such operations.
+[ -n "$DO_CLEAN_AUTOCONF_CACHE" ] || DO_CLEAN_AUTOCONF_CACHE="auto"
+[ -n "$DO_USE_AUTOCONF_CACHE" ] || DO_USE_AUTOCONF_CACHE="auto"
+# What about after tests (e.g. loops?)
+[ -n "$DO_CLEAN_AUTOCONF_CACHE_BEFORE" ] || DO_CLEAN_AUTOCONF_CACHE_BEFORE="$DO_CLEAN_AUTOCONF_CACHE"
+[ -n "$DO_CLEAN_AUTOCONF_CACHE_FINAL" ] || DO_CLEAN_AUTOCONF_CACHE_FINAL="$DO_CLEAN_AUTOCONF_CACHE"
+
+if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xauto ]; then
+    case "$BUILD_TYPE" in
+        #default-all-errors*) DO_CLEAN_AUTOCONF_CACHE="no" ;;
+        *) DO_CLEAN_AUTOCONF_CACHE="yes" ;;
+    esac
+fi
+export DO_CLEAN_AUTOCONF_CACHE
+
+if [ x"${DO_USE_AUTOCONF_CACHE}" = xauto ]; then
+    case "$BUILD_TYPE" in
+        #default-all-errors*) DO_USE_AUTOCONF_CACHE="yes" ;;
+        *) DO_USE_AUTOCONF_CACHE="no" ;;
+    esac
+fi
+export DO_USE_AUTOCONF_CACHE
+
+if [ x"${DO_CLEAN_AUTOCONF_CACHE_BEFORE}" = xauto ]; then
+    DO_CLEAN_AUTOCONF_CACHE_BEFORE="yes"
+fi
+if [ x"${DO_CLEAN_AUTOCONF_CACHE_FINAL}" = xauto ]; then
+    DO_CLEAN_AUTOCONF_CACHE_FINAL="yes"
+fi
+export DO_CLEAN_AUTOCONF_CACHE_BEFORE
+export DO_CLEAN_AUTOCONF_CACHE_FINAL
+
+if [ x"${DO_CLEAN_AUTOCONF_CACHE_BEFORE}" = xyes ]; then
+    rm -f config.cache*
+fi
+
+cleanup_exit() {
+    FINAL_RES=$?
+    if [ x"${DO_CLEAN_AUTOCONF_CACHE_FINAL}" = xyes ]; then
+        rm -f config.cache*
+    fi
+    return $FINAL_RES
+}
+
+trap 'cleanup_exit' 2 3 15
+
 echo "Processing BUILD_TYPE='${BUILD_TYPE}' ..."
 
 ensure_CI_CCACHE_SYMLINKDIR_envvar
@@ -1560,6 +1668,10 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-al
 
     detect_platform_CANBUILD_LIBGD_CGI
 
+    if [ x"${DO_USE_AUTOCONF_CACHE}" = xyes ] ; then
+        CONFIG_OPTS+=("-C")
+    fi
+
     # Prepend or use this build's preferred artifacts, if any
     DEFAULT_PKG_CONFIG_PATH="${BUILD_PREFIX}/lib/pkgconfig"
     detect_platform_PKG_CONFIG_PATH_and_FLAGS
@@ -1901,6 +2013,12 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-al
         trap 'echo "!!! If clean-up looped remaking the configure script for maintainer-clean, try to:"; echo "    rm -f Makefile configure include/config.h* ; $0 $SCRIPT_ARGS"' 2
 
         echo "=== Starting initial clean-up (from old build products)"
+        rm -f config.cache.tmp || true
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache ]; then
+            echo "=== Keeping old config.cache as asked by BUILD_TYPE default or caller request"
+            cp -f config.cache config.cache.tmp
+        fi
+
         case "$MAKE_FLAGS $MAKE_FLAGS_CLEAN" in
         *V=0*)
             ${MAKE} maintainer-clean $MAKE_FLAGS_CLEAN -k > /dev/null \
@@ -1913,7 +2031,12 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-al
         || true
         echo "=== Finished initial clean-up"
 
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache.tmp ]; then
+            mv -f config.cache.tmp config.cache || true
+        fi
+
         trap - 2
+        trap 'cleanup_exit' 2 3 15
     fi
 
     # Just prepare `configure` script; we run it at different points
@@ -2498,8 +2621,19 @@ default|default-alldrv|default-alldrv:no-distcheck|default-all-errors|default-al
                     echo "=== Completed sandbox cleanup-check after TESTCOMBO=${TESTCOMBO}, $BUILDSTODO build variants remaining"
                 else
                     if [ "$BUILDSTODO" -gt 0 ] && [ "${DO_CLEAN_CHECK-}" != no ]; then
+                        rm -f config.cache.tmp || true
+                        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache ]; then
+                            echo "=== Keeping old config.cache as asked by BUILD_TYPE default or caller request"
+                            cp -f config.cache config.cache.tmp
+                        fi
+
                         $MAKE distclean $MAKE_FLAGS_CLEAN -k \
                         || echo "WARNING: 'make distclean' FAILED: $? ... proceeding" >&2
+
+                        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache.tmp ]; then
+                            mv -f config.cache.tmp config.cache || true
+                        fi
+
                         echo "=== Completed sandbox cleanup after TESTCOMBO=${TESTCOMBO}, $BUILDSTODO build variants remaining"
                     else
                         echo "=== SKIPPED sandbox cleanup because DO_CLEAN_CHECK=$DO_CLEAN_CHECK and $BUILDSTODO build variants remaining"
@@ -2640,7 +2774,19 @@ bindings)
         # Help developers debug:
         # Let initial clean-up be at default verbosity
         echo "=== Starting initial clean-up (from old build products)"
+
+        rm -f config.cache.tmp || true
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache ]; then
+            echo "=== Keeping old config.cache as asked by BUILD_TYPE default or caller request"
+            cp -f config.cache config.cache.tmp
+        fi
+
         ${MAKE} realclean -k || true
+
+        if [ x"${DO_CLEAN_AUTOCONF_CACHE}" = xno ] && [ -s config.cache.tmp ]; then
+            mv -f config.cache.tmp config.cache || true
+        fi
+
         echo "=== Finished initial clean-up"
     fi
 
@@ -2661,6 +2807,10 @@ bindings)
         --disable-force-nut-version-header \
         --enable-check-NIT --enable-maintainer-mode)
 
+    if [ x"${DO_USE_AUTOCONF_CACHE}" = xyes ] ; then
+        CONFIG_OPTS+=("-C")
+    fi
+
     case x"${BUILD_TYPE}" in
         xdoc*) CONFIG_OPTS+=("--with-${BUILD_TYPE}") ;;
         *) CONFIG_OPTS+=("--with-doc=skip") ;;
@@ -2754,16 +2904,16 @@ bindings)
     esac
 
     if [ "${_EXPORT_FLAGS}" = true ] ; then
-            [ -z "${CFLAGS}" ]   || export CFLAGS
-            [ -z "${CXXFLAGS}" ] || export CXXFLAGS
-            [ -z "${CPPFLAGS}" ] || export CPPFLAGS
-            [ -z "${LDFLAGS}" ]  || export LDFLAGS
+        [ -z "${CFLAGS}" ]   || export CFLAGS
+        [ -z "${CXXFLAGS}" ] || export CXXFLAGS
+        [ -z "${CPPFLAGS}" ] || export CPPFLAGS
+        [ -z "${LDFLAGS}" ]  || export LDFLAGS
     else
-            # NOTE: Passing via CONFIG_OPTS also fails
-            [ -z "${CFLAGS}" ]   || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CFLAGS='${CFLAGS}'" >&2
-            [ -z "${CXXFLAGS}" ] || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CXXFLAGS='${CXXFLAGS}'" >&2
-            [ -z "${CPPFLAGS}" ] || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CPPFLAGS='${CPPFLAGS}'" >&2
-            [ -z "${LDFLAGS}" ]  || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export LDFLAGS='${LDFLAGS}'" >&2
+        # NOTE: Passing via CONFIG_OPTS also fails
+        [ -z "${CFLAGS}" ]   || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CFLAGS='${CFLAGS}'" >&2
+        [ -z "${CXXFLAGS}" ] || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CXXFLAGS='${CXXFLAGS}'" >&2
+        [ -z "${CPPFLAGS}" ] || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export CPPFLAGS='${CPPFLAGS}'" >&2
+        [ -z "${LDFLAGS}" ]  || echo "WARNING: SKIP: On '${CI_OS_NAME}' with ccache used, can not export LDFLAGS='${LDFLAGS}'" >&2
     fi
 
     PATH="`echo "${PATH}" | normalize_path`"