types.go

package mimemagic

import "bytes"

type section struct {
	Name     string
	matchers []matcher
}
type matcher struct {
	Level, Offset, Range int
	Value                []byte
	Mask                 []byte
}

func Match(guess string, dat []byte) string {
	if s := smap[guess]; s != nil && matchSection(s, dat) {
		return s.Name
	}
	for i := 0; i < len(sarr); i++ {
		if matchSection(&sarr[i], dat) {
			return sarr[i].Name
		}
	}
	return ""
}

func matchSection(s *section, b []byte) bool {
	lvl := 0
	state := false
	for i := 0; i < len(s.matchers); i++ {
		m := &s.matchers[i]

		if m.Level <= lvl && state {
			return true
		}
		if m.Level > lvl && !state {
			continue
		}

		state = false
		lvl = m.Level
		if len(b) < m.Offset+len(m.Value) {
			continue
		}
		max := m.Offset + len(m.Value) + m.Range
		if max > len(b) {
			max = len(b)
		}
		if bytes.Index(b[m.Offset:max], m.Value) >= 0 {
			state = true
		}
	}
	return state
}