add support for gitinfo2

git-latexdiff

@@ -234,6 +234,62 @@ verbose_say () {
     fi
 }
 
+gitinfo () {
+    local CURPWD=$(pwd)
+    cd "$git_dir"
+    
+    local OLDFIRSTTAG=$(git describe --tags $old 2>/dev/null)
+    local OLDRELTAG=$(git describe --tags --long --match '[0-9]*.*' $old 2>/dev/null)
+    
+    local NEWFIRSTTAG=$(git describe --tags $new 2>/dev/null)
+    local NEWRELTAG=$(git describe --tags --long --match '[0-9]*.*' $new 2>/dev/null)
+
+    local FIRSTTAGDELIM=$([ ! -z "$OLDFIRSTTAG" ] && echo ", new:")
+    local RELTAGDELIM=$([ ! -z "$OLDRELTAG" ] && echo ", new:")
+    
+    # Hoover up the metadata
+    git --no-pager log -1 --date=short \
+	--pretty=format:"\usepackage[%
+        shash={old: %h, 
+        lhash={old: %H, 
+        authname={old: %an, 
+        authemail={old: %ae, 
+        authsdate={old: %ad, 
+        authidate={old: %ai, 
+        authudate={old: %at, 
+        commname={old: %an, 
+        commemail={old: %ae, 
+        commsdate={old: %ad, 
+        commidate={old: %ai, 
+        commudate={old: %at, 
+        refnames={
+        firsttagdescribe={$OLDFIRSTTAG$FIRSTTAGDELIM
+        reltag={$OLDRELTAG$RELTAGDELIM
+" $old > "$CURPWD"/old.gin
+
+    git --no-pager log -1 --date=short \
+	--pretty=format:"
+new: %h},
+new: %H},
+new: %an},
+new: %ae},
+new: %ad},
+new: %ai},
+new: %at},
+new: %an},
+new: %ae},
+new: %ad},
+new: %ai},
+new: %at},
+},
+$NEWFIRSTTAG},
+$NEWRELTAG}
+    ]{gitexinfo}" $new > "$CURPWD"/new.gin
+ 
+    cd "$CURPWD"
+    paste -d '\0' old.gin new.gin > .git/gitHeadInfo.gin
+}
+
 old=
 new=
 main=
@@ -667,6 +723,12 @@ cd ..
 
 verbose_done
 
+# pull git commit information into a gitinfo2 style text file
+cd new
+mkdir .git
+gitinfo
+cd ..
+
 for dir in old new
 do
     verbose "Running preparation command $prepare_cmd in $dir/$git_prefix"