dumb simple access to the on-disk gentoo pkg database

main.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"strings"
)

func main() {
	var basepath = "/"
	if len(os.Args) > 1 && os.Args[1] != "" {
		basepath = os.Args[1]
	}
	db := DB{
		Prefix: basepath,
	}
	pkgs, err := db.ListPkgs()
	if err != nil {
		log.Fatal(err)
	}
	buf, err := json.MarshalIndent(pkgs, "", "  ")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(buf))
}

type DB struct {
	Prefix string
}

func (db *DB) pkgdir() string {
	return filepath.Join(db.Prefix, "/var/db/pkg/")
}

func (db *DB) ListPkgs() ([]Pkg, error) {
	var pkgs []Pkg
	err := filepath.Walk(db.pkgdir(), func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		if !info.IsDir() {
			return nil
		}

		fpath := strings.TrimPrefix(path, db.pkgdir()+"/")
		if !strings.Contains(fpath, "/") {
			return nil
		}

		pkg := Pkg{
			db:    db,
			Name:  strings.Split(fpath, "/")[1],
			Group: strings.Split(fpath, "/")[0],
		}
		pkgs = append(pkgs, pkg)
		return nil
	})
	if err != nil {
		return nil, err
	}
	return pkgs, nil
}

type Pkg struct {
	db    *DB
	Group string
	Name  string
}

func (pkg Pkg) MarshalJSON() ([]byte, error) {
	kv := map[string]string{}
	kv["name"] = pkg.Name
	kv["group"] = pkg.Group

	matches, err := filepath.Glob(filepath.Join(pkg.db.pkgdir(), pkg.Group, pkg.Name, "/*"))
	if err != nil {
		return nil, err
	}
mfor:
	for _, m := range matches {
		k := filepath.Base(m)
		if strings.HasSuffix(k, ".bz2") {
			continue mfor
		}
		val, err := ioutil.ReadFile(m)
		if err != nil {
			continue mfor
		}
		kv[k] = string(val)
	}

	return json.Marshal(kv)
}