Generate version including git commit

Use git describe to get the current commit and other information to set
VERSION in config.h, when we are not using a tarball release. The file
".tarball-version" stores the version inside the tarball, so it is fixed
for releases. The .version file is not used, so no need to generate it.

If the git program is not present when running autogen.sh, the version
will be set to UNKNOWN. This situation will be very rare as you will
need git to fetch the sources, but continues to allow building Dillo
without the git program.

Fixes: #288

Makefile.am

@@ -16,3 +16,6 @@ appicon128dir = $(datadir)/icons/hicolor/128x128/apps/
 appicon128_DATA = icons/128x128/dillo.png
 
 EXTRA_DIST += $(desktop_DATA) $(appicon48_DATA) $(appicon128_DATA)
+
+dist-hook:
+	echo '$(VERSION)' > $(distdir)/.tarball-version

aux/git-version-gen

@@ -0,0 +1,226 @@
+#!/bin/sh
+# Print a version string.
+scriptversion=2022-07-09.08; # UTC
+
+# Copyright (C) 2007-2024 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# This script is derived from GIT-VERSION-GEN from GIT: https://git-scm.com/.
+# It may be run two ways:
+# - from a git repository in which the "git describe" command below
+#   produces useful output (thus requiring at least one signed tag)
+# - from a non-git-repo directory containing a .tarball-version file, which
+#   presumes this script is invoked like "./git-version-gen .tarball-version".
+
+# In order to use intra-version strings in your project, you will need two
+# separate generated version string files:
+#
+# .tarball-version - present only in a distribution tarball, and not in
+#   a checked-out repository.  Created with contents that were learned at
+#   the last time autoconf was run, and used by git-version-gen.  Must not
+#   be present in either $(srcdir) or $(builddir) for git-version-gen to
+#   give accurate answers during normal development with a checked out tree,
+#   but must be present in a tarball when there is no version control system.
+#   Therefore, it cannot be used in any dependencies.  GNUmakefile has
+#   hooks to force a reconfigure at distribution time to get the value
+#   correct, without penalizing normal development with extra reconfigures.
+#
+# .version - present in a checked-out repository and in a distribution
+#   tarball.  Usable in dependencies, particularly for files that don't
+#   want to depend on config.h but do want to track version changes.
+#   Delete this file prior to any autoconf run where you want to rebuild
+#   files to pick up a version string change; and leave it stale to
+#   minimize rebuild time after unrelated changes to configure sources.
+#
+# As with any generated file in a VC'd directory, you should add
+# /.version to .gitignore, so that you don't accidentally commit it.
+# .tarball-version is never generated in a VC'd directory, so needn't
+# be listed there.
+#
+# Use the following line in your configure.ac, so that $(VERSION) will
+# automatically be up-to-date each time configure is run (and note that
+# since configure.ac no longer includes a version string, Makefile rules
+# should not depend on configure.ac for version updates).
+#
+# AC_INIT([GNU project],
+#         m4_esyscmd([build-aux/git-version-gen .tarball-version]),
+#         [bug-project@example])
+#
+# Then use the following lines in your Makefile.am, so that .version
+# will be present for dependencies, and so that .version and
+# .tarball-version will exist in distribution tarballs.
+#
+# EXTRA_DIST = $(top_srcdir)/.version
+# BUILT_SOURCES = $(top_srcdir)/.version
+# $(top_srcdir)/.version:
+#	echo '$(VERSION)' > $@-t
+#	mv $@-t $@
+# dist-hook:
+#	echo '$(VERSION)' > $(distdir)/.tarball-version
+
+
+me=$0
+
+year=`expr "$scriptversion" : '\([^-]*\)'`
+version="git-version-gen $scriptversion
+
+Copyright (C) ${year} Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law."
+
+usage="\
+Usage: $me [OPTION]... \$srcdir/.tarball-version [TAG-NORMALIZATION-SED-SCRIPT]
+Print a version string.
+
+Options:
+
+   --prefix PREFIX    prefix of git tags (default 'v')
+   --fallback VERSION
+                      fallback version to use if \"git --version\" fails
+
+   --help             display this help and exit
+   --version          output version information and exit
+
+Send patches and bug reports to <[email protected]>."
+
+prefix=v
+fallback=
+
+while test $# -gt 0; do
+  case $1 in
+    --help) echo "$usage"; exit 0;;
+    --version) echo "$version"; exit 0;;
+    --prefix) shift; prefix=${1?};;
+    --fallback) shift; fallback=${1?};;
+    -*)
+      echo "$0: Unknown option '$1'." >&2
+      echo "$0: Try '--help' for more information." >&2
+      exit 1;;
+    *)
+      if test "x$tarball_version_file" = x; then
+        tarball_version_file="$1"
+      elif test "x$tag_sed_script" = x; then
+        tag_sed_script="$1"
+      else
+        echo "$0: extra non-option argument '$1'." >&2
+        exit 1
+      fi;;
+  esac
+  shift
+done
+
+if test "x$tarball_version_file" = x; then
+    echo "$usage"
+    exit 1
+fi
+
+tag_sed_script="${tag_sed_script:-s/x/x/}"
+
+nl='
+'
+
+# Avoid meddling by environment variable of the same name.
+v=
+v_from_git=
+
+# First see if there is a tarball-only version file.
+# then try "git describe", then default.
+if test -f $tarball_version_file
+then
+    v=`cat $tarball_version_file` || v=
+    case $v in
+        *$nl*) v= ;; # reject multi-line output
+    esac
+    test "x$v" = x \
+        && echo "$0: WARNING: $tarball_version_file is damaged" 1>&2
+fi
+
+if test "x$v" != x
+then
+    : # use $v
+# Otherwise, if there is at least one git commit involving the working
+# directory, and "git describe" output looks sensible, use that to
+# derive a version string.
+elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
+    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
+          || git describe --abbrev=4 HEAD 2>/dev/null` \
+    && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
+    && case $v in
+         $prefix[0-9]*) ;;
+         *) (exit 1) ;;
+       esac
+then
+    # Is this a new git that lists number of commits since the last
+    # tag or the previous older version that did not?
+    #   Newer: v6.10-77-g0f8faeb
+    #   Older: v6.10-g0f8faeb
+    vprefix=`expr "X$v" : 'X\(.*\)-g[^-]*$'` || vprefix=$v
+    case $vprefix in
+        *-*) : git describe is probably okay three part flavor ;;
+        *)
+            : git describe is older two part flavor
+            # Recreate the number of commits and rewrite such that the
+            # result is the same as if we were using the newer version
+            # of git describe.
+            vtag=`echo "$v" | sed 's/-.*//'`
+            commit_list=`git rev-list "$vtag"..HEAD 2>/dev/null` \
+                || { commit_list=failed;
+                     echo "$0: WARNING: git rev-list failed" 1>&2; }
+            numcommits=`echo "$commit_list" | wc -l`
+            v=`echo "$v" | sed "s/\(.*\)-\(.*\)/\1-$numcommits-\2/"`;
+            test "$commit_list" = failed && v=UNKNOWN
+            ;;
+    esac
+
+    # Leave both the - and the g
+    # v=`echo "$v" | sed 's/-\([^-]*\)-g\([^-]*\)$/.\1-\2/'`;
+    v_from_git=1
+elif test "x$fallback" = x || git --version >/dev/null 2>&1; then
+    v=UNKNOWN
+else
+    v=$fallback
+fi
+
+v=`echo "$v" |sed "s/^$prefix//"`
+
+# Test whether to append the "-dirty" suffix only if the version
+# string we're using came from git.  I.e., skip the test if it's "UNKNOWN"
+# or if it came from .tarball-version.
+if test "x$v_from_git" != x; then
+  # Don't declare a version "dirty" merely because a timestamp has changed.
+  git update-index --refresh > /dev/null 2>&1
+
+  dirty=`exec 2>/dev/null;git diff-index --name-only HEAD` || dirty=
+  case "$dirty" in
+      '') ;;
+      *) # Append the suffix only if there isn't one already.
+          case $v in
+            *-dirty) ;;
+            *) v="$v-dirty" ;;
+          esac ;;
+  esac
+fi
+
+# Omit the trailing newline, so that m4_esyscmd can use the result directly.
+printf %s "$v"
+
+# Local variables:
+# eval: (add-hook 'before-save-hook 'time-stamp)
+# time-stamp-start: "scriptversion="
+# time-stamp-format: "%:y-%02m-%02d.%02H"
+# time-stamp-time-zone: "UTC0"
+# time-stamp-end: "; # UTC"
+# End:

configure.ac

@@ -1,6 +1,6 @@
 dnl Process this file with aclocal, autoconf and automake.
 
-AC_INIT([dillo], [3.1.1])
+AC_INIT([dillo], m4_esyscmd([aux/git-version-gen .tarball-version]))
 
 dnl Detect the canonical target build environment
 AC_CANONICAL_TARGET