Add support for generating coverage reports

This change adds autoconf/automake support for building all of mosh
with gcov, and generates an lcov html report. This allows seeing which
parts ofthe source tree have good test coverage, and which can be
shored up. Eventually, it would be good to hook this up to Github
Actions to be generated automatically.

8 files changed, 564 insertions, 0 deletions

diff --git a/m4/ax_ac_append_to_file.m4 b/m4/ax_ac_append_to_file.m4
new file mode 100644
index 0000000..242b3d5
--- /dev/null
+++ b/m4/ax_ac_append_to_file.m4
@@ -0,0 +1,32 @@
+# ===========================================================================
+#   https://www.gnu.org/software/autoconf-archive/ax_ac_append_to_file.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_AC_APPEND_TO_FILE([FILE],[DATA])
+#
+# DESCRIPTION
+#
+#   Appends the specified data to the specified Autoconf is run. If you want
+#   to append to a file when configure is run use AX_APPEND_TO_FILE instead.
+#
+# LICENSE
+#
+#   Copyright (c) 2009 Allan Caffee <allan.caffee@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 10
+
+AC_DEFUN([AX_AC_APPEND_TO_FILE],[
+AC_REQUIRE([AX_FILE_ESCAPES])
+m4_esyscmd(
+AX_FILE_ESCAPES
+[
+printf "%s" "$2" >> "$1"
+])
+])
diff --git a/m4/ax_ac_print_to_file.m4 b/m4/ax_ac_print_to_file.m4
new file mode 100644
index 0000000..642dfc1
--- /dev/null
+++ b/m4/ax_ac_print_to_file.m4
@@ -0,0 +1,32 @@
+# ===========================================================================
+#   https://www.gnu.org/software/autoconf-archive/ax_ac_print_to_file.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_AC_PRINT_TO_FILE([FILE],[DATA])
+#
+# DESCRIPTION
+#
+#   Writes the specified data to the specified file when Autoconf is run. If
+#   you want to print to a file when configure is run use AX_PRINT_TO_FILE
+#   instead.
+#
+# LICENSE
+#
+#   Copyright (c) 2009 Allan Caffee <allan.caffee@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 10
+
+AC_DEFUN([AX_AC_PRINT_TO_FILE],[
+m4_esyscmd(
+AC_REQUIRE([AX_FILE_ESCAPES])
+[
+printf "%s" "$2" > "$1"
+])
+])
diff --git a/m4/ax_add_am_macro_static.m4 b/m4/ax_add_am_macro_static.m4
new file mode 100644
index 0000000..6442d24
--- /dev/null
+++ b/m4/ax_add_am_macro_static.m4
@@ -0,0 +1,28 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_add_am_macro_static.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_ADD_AM_MACRO_STATIC([RULE])
+#
+# DESCRIPTION
+#
+#   Adds the specified rule to $AMINCLUDE.
+#
+# LICENSE
+#
+#   Copyright (c) 2009 Tom Howard <tomhoward@users.sf.net>
+#   Copyright (c) 2009 Allan Caffee <allan.caffee@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 8
+
+AC_DEFUN([AX_ADD_AM_MACRO_STATIC],[
+  AC_REQUIRE([AX_AM_MACROS_STATIC])
+  AX_AC_APPEND_TO_FILE(AMINCLUDE_STATIC,[$1])
+])
diff --git a/m4/ax_am_macros_static.m4 b/m4/ax_am_macros_static.m4
new file mode 100644
index 0000000..f4cee8c
--- /dev/null
+++ b/m4/ax_am_macros_static.m4
@@ -0,0 +1,38 @@
+# ===========================================================================
+#   https://www.gnu.org/software/autoconf-archive/ax_am_macros_static.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_AM_MACROS_STATIC
+#
+# DESCRIPTION
+#
+#   Adds support for macros that create Automake rules. You must manually
+#   add the following line
+#
+#     include $(top_srcdir)/aminclude_static.am
+#
+#   to your Makefile.am files.
+#
+# LICENSE
+#
+#   Copyright (c) 2009 Tom Howard <tomhoward@users.sf.net>
+#   Copyright (c) 2009 Allan Caffee <allan.caffee@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 11
+
+AC_DEFUN([AMINCLUDE_STATIC],[aminclude_static.am])
+
+AC_DEFUN([AX_AM_MACROS_STATIC],
+[
+AX_AC_PRINT_TO_FILE(AMINCLUDE_STATIC,[
+# ]AMINCLUDE_STATIC[ generated automatically by Autoconf
+# from AX_AM_MACROS_STATIC on ]m4_esyscmd([LC_ALL=C date])[
+])
+])
diff --git a/m4/ax_check_gnu_make.m4 b/m4/ax_check_gnu_make.m4
new file mode 100644
index 0000000..785dc96
--- /dev/null
+++ b/m4/ax_check_gnu_make.m4
@@ -0,0 +1,95 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_check_gnu_make.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_GNU_MAKE([run-if-true],[run-if-false])
+#
+# DESCRIPTION
+#
+#   This macro searches for a GNU version of make. If a match is found:
+#
+#     * The makefile variable `ifGNUmake' is set to the empty string, otherwise
+#       it is set to "#". This is useful for including a special features in a
+#       Makefile, which cannot be handled by other versions of make.
+#     * The makefile variable `ifnGNUmake' is set to #, otherwise
+#       it is set to the empty string. This is useful for including a special
+#       features in a Makefile, which can be handled
+#       by other versions of make or to specify else like clause.
+#     * The variable `_cv_gnu_make_command` is set to the command to invoke
+#       GNU make if it exists, the empty string otherwise.
+#     * The variable `ax_cv_gnu_make_command` is set to the command to invoke
+#       GNU make by copying `_cv_gnu_make_command`, otherwise it is unset.
+#     * If GNU Make is found, its version is extracted from the output of
+#       `make --version` as the last field of a record of space-separated
+#       columns and saved into the variable `ax_check_gnu_make_version`.
+#     * Additionally if GNU Make is found, run shell code run-if-true
+#       else run shell code run-if-false.
+#
+#   Here is an example of its use:
+#
+#   Makefile.in might contain:
+#
+#     # A failsafe way of putting a dependency rule into a makefile
+#     $(DEPEND):
+#             $(CC) -MM $(srcdir)/*.c > $(DEPEND)
+#
+#     @ifGNUmake@ ifeq ($(DEPEND),$(wildcard $(DEPEND)))
+#     @ifGNUmake@ include $(DEPEND)
+#     @ifGNUmake@ else
+#     fallback code
+#     @ifGNUmake@ endif
+#
+#   Then configure.in would normally contain:
+#
+#     AX_CHECK_GNU_MAKE()
+#     AC_OUTPUT(Makefile)
+#
+#   Then perhaps to cause gnu make to override any other make, we could do
+#   something like this (note that GNU make always looks for GNUmakefile
+#   first):
+#
+#     if  ! test x$_cv_gnu_make_command = x ; then
+#             mv Makefile GNUmakefile
+#             echo .DEFAULT: > Makefile ;
+#             echo \  $_cv_gnu_make_command \$@ >> Makefile;
+#     fi
+#
+#   Then, if any (well almost any) other make is called, and GNU make also
+#   exists, then the other make wraps the GNU make.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 John Darrington <j.darrington@elvis.murdoch.edu.au>
+#   Copyright (c) 2015 Enrico M. Crisostomo <enrico.m.crisostomo@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 12
+
+AC_DEFUN([AX_CHECK_GNU_MAKE],dnl
+  [AC_PROG_AWK
+  AC_CACHE_CHECK([for GNU make],[_cv_gnu_make_command],[dnl
+    _cv_gnu_make_command="" ;
+dnl Search all the common names for GNU make
+    for a in "$MAKE" make gmake gnumake ; do
+      if test -z "$a" ; then continue ; fi ;
+      if "$a" --version 2> /dev/null | grep GNU 2>&1 > /dev/null ; then
+        _cv_gnu_make_command=$a ;
+        AX_CHECK_GNU_MAKE_HEADLINE=$("$a" --version 2> /dev/null | grep "GNU Make")
+        ax_check_gnu_make_version=$(echo ${AX_CHECK_GNU_MAKE_HEADLINE} | ${AWK} -F " " '{ print $(NF); }')
+        break ;
+      fi
+    done ;])
+dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' otherwise
+  AS_VAR_IF([_cv_gnu_make_command], [""], [AS_VAR_SET([ifGNUmake], ["#"])],   [AS_VAR_SET([ifGNUmake], [""])])
+  AS_VAR_IF([_cv_gnu_make_command], [""], [AS_VAR_SET([ifnGNUmake], [""])],   [AS_VAR_SET([ifnGNUmake], ["#"])])
+  AS_VAR_IF([_cv_gnu_make_command], [""], [AS_UNSET(ax_cv_gnu_make_command)], [AS_VAR_SET([ax_cv_gnu_make_command], [${_cv_gnu_make_command}])])
+  AS_VAR_IF([_cv_gnu_make_command], [""],[$2],[$1])
+  AC_SUBST([ifGNUmake])
+  AC_SUBST([ifnGNUmake])
+])
diff --git a/m4/ax_code_coverage.m4 b/m4/ax_code_coverage.m4
new file mode 100644
index 0000000..352165b
--- /dev/null
+++ b/m4/ax_code_coverage.m4
@@ -0,0 +1,272 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_code_coverage.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CODE_COVERAGE()
+#
+# DESCRIPTION
+#
+#   Defines CODE_COVERAGE_CPPFLAGS, CODE_COVERAGE_CFLAGS,
+#   CODE_COVERAGE_CXXFLAGS and CODE_COVERAGE_LIBS which should be included
+#   in the CPPFLAGS, CFLAGS CXXFLAGS and LIBS/LIBADD variables of every
+#   build target (program or library) which should be built with code
+#   coverage support. Also add rules using AX_ADD_AM_MACRO_STATIC; and
+#   $enable_code_coverage which can be used in subsequent configure output.
+#   CODE_COVERAGE_ENABLED is defined and substituted, and corresponds to the
+#   value of the --enable-code-coverage option, which defaults to being
+#   disabled.
+#
+#   Test also for gcov program and create GCOV variable that could be
+#   substituted.
+#
+#   Note that all optimization flags in CFLAGS must be disabled when code
+#   coverage is enabled.
+#
+#   Usage example:
+#
+#   configure.ac:
+#
+#     AX_CODE_COVERAGE
+#
+#   Makefile.am:
+#
+#     include $(top_srcdir)/aminclude_static.am
+#
+#     my_program_LIBS = ... $(CODE_COVERAGE_LIBS) ...
+#     my_program_CPPFLAGS = ... $(CODE_COVERAGE_CPPFLAGS) ...
+#     my_program_CFLAGS = ... $(CODE_COVERAGE_CFLAGS) ...
+#     my_program_CXXFLAGS = ... $(CODE_COVERAGE_CXXFLAGS) ...
+#
+#     clean-local: code-coverage-clean
+#     distclean-local: code-coverage-dist-clean
+#
+#   This results in a "check-code-coverage" rule being added to any
+#   Makefile.am which do "include $(top_srcdir)/aminclude_static.am"
+#   (assuming the module has been configured with --enable-code-coverage).
+#   Running `make check-code-coverage` in that directory will run the
+#   module's test suite (`make check`) and build a code coverage report
+#   detailing the code which was touched, then print the URI for the report.
+#
+#   This code was derived from Makefile.decl in GLib, originally licensed
+#   under LGPLv2.1+.
+#
+# LICENSE
+#
+#   Copyright (c) 2012, 2016 Philip Withnall
+#   Copyright (c) 2012 Xan Lopez
+#   Copyright (c) 2012 Christian Persch
+#   Copyright (c) 2012 Paolo Borelli
+#   Copyright (c) 2012 Dan Winship
+#   Copyright (c) 2015,2018 Bastien ROUCARIES
+#
+#   This library is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU Lesser General Public License as published by
+#   the Free Software Foundation; either version 2.1 of the License, or (at
+#   your option) any later version.
+#
+#   This library is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+#   General Public License for more details.
+#
+#   You should have received a copy of the GNU Lesser General Public License
+#   along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+#serial 34
+
+m4_define(_AX_CODE_COVERAGE_RULES,[
+AX_ADD_AM_MACRO_STATIC([
+# Code coverage
+#
+# Optional:
+#  - CODE_COVERAGE_DIRECTORY: Top-level directory for code coverage reporting.
+#    Multiple directories may be specified, separated by whitespace.
+#    (Default: \$(top_builddir))
+#  - CODE_COVERAGE_OUTPUT_FILE: Filename and path for the .info file generated
+#    by lcov for code coverage. (Default:
+#    \$(PACKAGE_NAME)-\$(PACKAGE_VERSION)-coverage.info)
+#  - CODE_COVERAGE_OUTPUT_DIRECTORY: Directory for generated code coverage
+#    reports to be created. (Default:
+#    \$(PACKAGE_NAME)-\$(PACKAGE_VERSION)-coverage)
+#  - CODE_COVERAGE_BRANCH_COVERAGE: Set to 1 to enforce branch coverage,
+#    set to 0 to disable it and leave empty to stay with the default.
+#    (Default: empty)
+#  - CODE_COVERAGE_LCOV_SHOPTS_DEFAULT: Extra options shared between both lcov
+#    instances. (Default: based on $CODE_COVERAGE_BRANCH_COVERAGE)
+#  - CODE_COVERAGE_LCOV_SHOPTS: Extra options to shared between both lcov
+#    instances. (Default: $CODE_COVERAGE_LCOV_SHOPTS_DEFAULT)
+#  - CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH: --gcov-tool pathtogcov
+#  - CODE_COVERAGE_LCOV_OPTIONS_DEFAULT: Extra options to pass to the
+#    collecting lcov instance. (Default: $CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH)
+#  - CODE_COVERAGE_LCOV_OPTIONS: Extra options to pass to the collecting lcov
+#    instance. (Default: $CODE_COVERAGE_LCOV_OPTIONS_DEFAULT)
+#  - CODE_COVERAGE_LCOV_RMOPTS_DEFAULT: Extra options to pass to the filtering
+#    lcov instance. (Default: empty)
+#  - CODE_COVERAGE_LCOV_RMOPTS: Extra options to pass to the filtering lcov
+#    instance. (Default: $CODE_COVERAGE_LCOV_RMOPTS_DEFAULT)
+#  - CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT: Extra options to pass to the
+#    genhtml instance. (Default: based on $CODE_COVERAGE_BRANCH_COVERAGE)
+#  - CODE_COVERAGE_GENHTML_OPTIONS: Extra options to pass to the genhtml
+#    instance. (Default: $CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT)
+#  - CODE_COVERAGE_IGNORE_PATTERN: Extra glob pattern of files to ignore
+#
+# The generated report will be titled using the \$(PACKAGE_NAME) and
+# \$(PACKAGE_VERSION). In order to add the current git hash to the title,
+# use the git-version-gen script, available online.
+# Optional variables
+# run only on top dir
+if CODE_COVERAGE_ENABLED
+ ifeq (\$(abs_builddir), \$(abs_top_builddir))
+CODE_COVERAGE_DIRECTORY ?= \$(top_builddir)
+CODE_COVERAGE_OUTPUT_FILE ?= \$(PACKAGE_NAME)-\$(PACKAGE_VERSION)-coverage.info
+CODE_COVERAGE_OUTPUT_DIRECTORY ?= \$(PACKAGE_NAME)-\$(PACKAGE_VERSION)-coverage
+
+CODE_COVERAGE_BRANCH_COVERAGE ?=
+CODE_COVERAGE_LCOV_SHOPTS_DEFAULT ?= \$(if \$(CODE_COVERAGE_BRANCH_COVERAGE),\
+--rc lcov_branch_coverage=\$(CODE_COVERAGE_BRANCH_COVERAGE))
+CODE_COVERAGE_LCOV_SHOPTS ?= \$(CODE_COVERAGE_LCOV_SHOPTS_DEFAULT)
+CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH ?= --gcov-tool \"\$(GCOV)\"
+CODE_COVERAGE_LCOV_OPTIONS_DEFAULT ?= \$(CODE_COVERAGE_LCOV_OPTIONS_GCOVPATH)
+CODE_COVERAGE_LCOV_OPTIONS ?= \$(CODE_COVERAGE_LCOV_OPTIONS_DEFAULT)
+CODE_COVERAGE_LCOV_RMOPTS_DEFAULT ?=
+CODE_COVERAGE_LCOV_RMOPTS ?= \$(CODE_COVERAGE_LCOV_RMOPTS_DEFAULT)
+CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT ?=\
+\$(if \$(CODE_COVERAGE_BRANCH_COVERAGE),\
+--rc genhtml_branch_coverage=\$(CODE_COVERAGE_BRANCH_COVERAGE))
+CODE_COVERAGE_GENHTML_OPTIONS ?= \$(CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT)
+CODE_COVERAGE_IGNORE_PATTERN ?=
+
+GITIGNOREFILES := \$(GITIGNOREFILES) \$(CODE_COVERAGE_OUTPUT_FILE) \$(CODE_COVERAGE_OUTPUT_DIRECTORY)
+code_coverage_v_lcov_cap = \$(code_coverage_v_lcov_cap_\$(V))
+code_coverage_v_lcov_cap_ = \$(code_coverage_v_lcov_cap_\$(AM_DEFAULT_VERBOSITY))
+code_coverage_v_lcov_cap_0 = @echo \"  LCOV   --capture\" \$(CODE_COVERAGE_OUTPUT_FILE);
+code_coverage_v_lcov_ign = \$(code_coverage_v_lcov_ign_\$(V))
+code_coverage_v_lcov_ign_ = \$(code_coverage_v_lcov_ign_\$(AM_DEFAULT_VERBOSITY))
+code_coverage_v_lcov_ign_0 = @echo \"  LCOV   --remove /tmp/*\" \$(CODE_COVERAGE_IGNORE_PATTERN);
+code_coverage_v_genhtml = \$(code_coverage_v_genhtml_\$(V))
+code_coverage_v_genhtml_ = \$(code_coverage_v_genhtml_\$(AM_DEFAULT_VERBOSITY))
+code_coverage_v_genhtml_0 = @echo \"  GEN   \" \"\$(CODE_COVERAGE_OUTPUT_DIRECTORY)\";
+code_coverage_quiet = \$(code_coverage_quiet_\$(V))
+code_coverage_quiet_ = \$(code_coverage_quiet_\$(AM_DEFAULT_VERBOSITY))
+code_coverage_quiet_0 = --quiet
+
+# sanitizes the test-name: replaces with underscores: dashes and dots
+code_coverage_sanitize = \$(subst -,_,\$(subst .,_,\$(1)))
+
+# Use recursive makes in order to ignore errors during check
+check-code-coverage:
+	-\$(AM_V_at)\$(MAKE) \$(AM_MAKEFLAGS) -k check
+	\$(AM_V_at)\$(MAKE) \$(AM_MAKEFLAGS) code-coverage-capture
+
+# Capture code coverage data
+code-coverage-capture: code-coverage-capture-hook
+	\$(code_coverage_v_lcov_cap)\$(LCOV) \$(code_coverage_quiet) \$(addprefix --directory ,\$(CODE_COVERAGE_DIRECTORY)) --capture --output-file \"\$(CODE_COVERAGE_OUTPUT_FILE).tmp\" --test-name \"\$(call code_coverage_sanitize,\$(PACKAGE_NAME)-\$(PACKAGE_VERSION))\" --no-checksum --compat-libtool \$(CODE_COVERAGE_LCOV_SHOPTS) \$(CODE_COVERAGE_LCOV_OPTIONS)
+	\$(code_coverage_v_lcov_ign)\$(LCOV) \$(code_coverage_quiet) \$(addprefix --directory ,\$(CODE_COVERAGE_DIRECTORY)) --remove \"\$(CODE_COVERAGE_OUTPUT_FILE).tmp\" \"/tmp/*\" \$(CODE_COVERAGE_IGNORE_PATTERN) --output-file \"\$(CODE_COVERAGE_OUTPUT_FILE)\" \$(CODE_COVERAGE_LCOV_SHOPTS) \$(CODE_COVERAGE_LCOV_RMOPTS)
+	-@rm -f \"\$(CODE_COVERAGE_OUTPUT_FILE).tmp\"
+	\$(code_coverage_v_genhtml)LANG=C \$(GENHTML) \$(code_coverage_quiet) \$(addprefix --prefix ,\$(CODE_COVERAGE_DIRECTORY)) --output-directory \"\$(CODE_COVERAGE_OUTPUT_DIRECTORY)\" --title \"\$(PACKAGE_NAME)-\$(PACKAGE_VERSION) Code Coverage\" --legend --show-details \"\$(CODE_COVERAGE_OUTPUT_FILE)\" \$(CODE_COVERAGE_GENHTML_OPTIONS)
+	@echo \"file://\$(abs_builddir)/\$(CODE_COVERAGE_OUTPUT_DIRECTORY)/index.html\"
+
+code-coverage-clean:
+	-\$(LCOV) --directory \$(top_builddir) -z
+	-rm -rf \"\$(CODE_COVERAGE_OUTPUT_FILE)\" \"\$(CODE_COVERAGE_OUTPUT_FILE).tmp\" \"\$(CODE_COVERAGE_OUTPUT_DIRECTORY)\"
+	-find . \\( -name \"*.gcda\" -o -name \"*.gcno\" -o -name \"*.gcov\" \\) -delete
+
+code-coverage-dist-clean:
+
+A][M_DISTCHECK_CONFIGURE_FLAGS := \$(A][M_DISTCHECK_CONFIGURE_FLAGS) --disable-code-coverage
+ else # ifneq (\$(abs_builddir), \$(abs_top_builddir))
+check-code-coverage:
+
+code-coverage-capture: code-coverage-capture-hook
+
+code-coverage-clean:
+
+code-coverage-dist-clean:
+ endif # ifeq (\$(abs_builddir), \$(abs_top_builddir))
+else #! CODE_COVERAGE_ENABLED
+# Use recursive makes in order to ignore errors during check
+check-code-coverage:
+	@echo \"Need to reconfigure with --enable-code-coverage\"
+# Capture code coverage data
+code-coverage-capture: code-coverage-capture-hook
+	@echo \"Need to reconfigure with --enable-code-coverage\"
+
+code-coverage-clean:
+
+code-coverage-dist-clean:
+
+endif #CODE_COVERAGE_ENABLED
+# Hook rule executed before code-coverage-capture, overridable by the user
+code-coverage-capture-hook:
+
+.PHONY: check-code-coverage code-coverage-capture code-coverage-dist-clean code-coverage-clean code-coverage-capture-hook
+])
+])
+
+AC_DEFUN([_AX_CODE_COVERAGE_ENABLED],[
+	AX_CHECK_GNU_MAKE([],[AC_MSG_ERROR([not using GNU make that is needed for coverage])])
+	AC_REQUIRE([AX_ADD_AM_MACRO_STATIC])
+	# check for gcov
+	AC_CHECK_TOOL([GCOV],
+		  [$_AX_CODE_COVERAGE_GCOV_PROG_WITH],
+		  [:])
+	AS_IF([test "X$GCOV" = "X:"],
+	      [AC_MSG_ERROR([gcov is needed to do coverage])])
+	AC_SUBST([GCOV])
+
+	dnl Check if gcc is being used
+	AS_IF([ test "$GCC" = "no" ], [
+		AC_MSG_ERROR([not compiling with gcc, which is required for gcov code coverage])
+	      ])
+
+	AC_CHECK_PROG([LCOV], [lcov], [lcov])
+	AC_CHECK_PROG([GENHTML], [genhtml], [genhtml])
+
+	AS_IF([ test x"$LCOV" = x ], [
+		AC_MSG_ERROR([To enable code coverage reporting you must have lcov installed])
+	      ])
+
+	AS_IF([ test x"$GENHTML" = x ], [
+		AC_MSG_ERROR([Could not find genhtml from the lcov package])
+	])
+
+	dnl Build the code coverage flags
+	dnl Define CODE_COVERAGE_LDFLAGS for backwards compatibility
+	CODE_COVERAGE_CPPFLAGS="-DNDEBUG"
+	CODE_COVERAGE_CFLAGS="-O0 -g -fprofile-arcs -ftest-coverage"
+	CODE_COVERAGE_CXXFLAGS="-O0 -g -fprofile-arcs -ftest-coverage"
+	CODE_COVERAGE_LIBS="-lgcov"
+
+	AC_SUBST([CODE_COVERAGE_CPPFLAGS])
+	AC_SUBST([CODE_COVERAGE_CFLAGS])
+	AC_SUBST([CODE_COVERAGE_CXXFLAGS])
+	AC_SUBST([CODE_COVERAGE_LIBS])
+])
+
+AC_DEFUN([AX_CODE_COVERAGE],[
+	dnl Check for --enable-code-coverage
+
+	# allow to override gcov location
+	AC_ARG_WITH([gcov],
+	  [AS_HELP_STRING([--with-gcov[=GCOV]], [use given GCOV for coverage (GCOV=gcov).])],
+	  [_AX_CODE_COVERAGE_GCOV_PROG_WITH=$with_gcov],
+	  [_AX_CODE_COVERAGE_GCOV_PROG_WITH=gcov])
+
+	AC_MSG_CHECKING([whether to build with code coverage support])
+	AC_ARG_ENABLE([code-coverage],
+	  AS_HELP_STRING([--enable-code-coverage],
+	  [Whether to enable code coverage support]),,
+	  enable_code_coverage=no)
+
+	AM_CONDITIONAL([CODE_COVERAGE_ENABLED], [test "x$enable_code_coverage" = xyes])
+	AC_SUBST([CODE_COVERAGE_ENABLED], [$enable_code_coverage])
+	AC_MSG_RESULT($enable_code_coverage)
+
+	AS_IF([ test "x$enable_code_coverage" = xyes ], [
+		_AX_CODE_COVERAGE_ENABLED
+	      ])
+
+	_AX_CODE_COVERAGE_RULES
+])
diff --git a/m4/ax_file_escapes.m4 b/m4/ax_file_escapes.m4
new file mode 100644
index 0000000..a86fdc3
--- /dev/null
+++ b/m4/ax_file_escapes.m4
@@ -0,0 +1,30 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_file_escapes.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_FILE_ESCAPES
+#
+# DESCRIPTION
+#
+#   Writes the specified data to the specified file.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Tom Howard <tomhoward@users.sf.net>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 8
+
+AC_DEFUN([AX_FILE_ESCAPES],[
+AX_DOLLAR="\$"
+AX_SRB="\\135"
+AX_SLB="\\133"
+AX_BS="\\\\"
+AX_DQ="\""
+])
diff --git a/m4/ax_require_defined.m4 b/m4/ax_require_defined.m4
new file mode 100644
index 0000000..17c3eab
--- /dev/null
+++ b/m4/ax_require_defined.m4
@@ -0,0 +1,37 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_require_defined.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_REQUIRE_DEFINED(MACRO)
+#
+# DESCRIPTION
+#
+#   AX_REQUIRE_DEFINED is a simple helper for making sure other macros have
+#   been defined and thus are available for use.  This avoids random issues
+#   where a macro isn't expanded.  Instead the configure script emits a
+#   non-fatal:
+#
+#     ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found
+#
+#   It's like AC_REQUIRE except it doesn't expand the required macro.
+#
+#   Here's an example:
+#
+#     AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
+#
+# LICENSE
+#
+#   Copyright (c) 2014 Mike Frysinger <vapier@gentoo.org>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 2
+
+AC_DEFUN([AX_REQUIRE_DEFINED], [dnl
+  m4_ifndef([$1], [m4_fatal([macro ]$1[ is not defined; is a m4 file missing?])])
+])dnl AX_REQUIRE_DEFINED