--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/zs_util.go	Sun Aug 30 12:20:35 2015 +0000
@@ -0,0 +1,108 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+)
+
+func varFunc(s string) func() string {
+	return func() string {
+		return s
+	}
+}
+
+func pluginFunc(cmd string, vars Vars) func(args ...string) string {
+	return func(args ...string) string {
+		out := bytes.NewBuffer(nil)
+		if err := run(cmd, args, vars, out); err != nil {
+			return cmd + ":" + err.Error()
+		} else {
+			return string(out.Bytes())
+		}
+	}
+}
+
+func builtins() Funcs {
+	exec := func(s ...string) string {
+		return ""
+	}
+	return Funcs{
+		"exec": exec,
+		"zs": func(args ...string) string {
+			cmd := []string{"zs"}
+			cmd = append(cmd, args...)
+			return exec(cmd...)
+		},
+	}
+}
+
+func renameExt(path, from, to string) string {
+	if from == "" {
+		from = filepath.Ext(path)
+	}
+	if strings.HasSuffix(path, from) {
+		return strings.TrimSuffix(path, from) + to
+	} else {
+		return path
+	}
+}
+
+func globals() Vars {
+	vars := Vars{}
+	for _, e := range os.Environ() {
+		pair := strings.Split(e, "=")
+		if strings.HasPrefix(pair[0], "ZS_") {
+			vars[strings.ToLower(pair[0][3:])] = pair[1]
+		}
+	}
+	return vars
+}
+
+// Converts zs markdown variables into environment variables
+func env(vars Vars) []string {
+	env := []string{"ZS=" + os.Args[0], "ZS_OUTDIR=" + PUBDIR}
+	env = append(env, os.Environ()...)
+	if vars != nil {
+		for k, v := range vars {
+			env = append(env, "ZS_"+strings.ToUpper(k)+"="+v)
+		}
+	}
+	return env
+}
+
+// Runs command with given arguments and variables, intercepts stderr and
+// redirects stdout into the given writer
+func run(cmd string, args []string, vars Vars, output io.Writer) error {
+	var errbuf bytes.Buffer
+	c := exec.Command(cmd, args...)
+	c.Env = env(vars)
+	c.Stdout = output
+	c.Stderr = &errbuf
+
+	err := c.Run()
+
+	if errbuf.Len() > 0 {
+		log.Println("ERROR:", errbuf.String())
+	}
+
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Splits a string in exactly two parts by delimiter
+// If no delimiter is found - the second string is be empty
+func split2(s, delim string) (string, string) {
+	parts := strings.SplitN(s, delim, 2)
+	if len(parts) == 2 {
+		return parts[0], parts[1]
+	} else {
+		return parts[0], ""
+	}
+}