pm/pkg/install.go

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package pkg
import (
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"archive/tar"
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"io"
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"log"
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"net/http"
"os"
"path/filepath"
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"github.com/pkg/errors"
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"mcquay.me/fs"
"mcquay.me/pm"
"mcquay.me/pm/db"
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"mcquay.me/pm/keyring"
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)
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const cache = "var/cache/pm"
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// Install fetches and installs pkgs from appropriate remotes.
func Install(root string, pkgs []string) error {
av, err := db.LoadAvailable(root)
if err != nil {
return errors.Wrap(err, "loading available db")
}
ms, err := av.Installable(pkgs)
if err != nil {
return errors.Wrap(err, "checking ability to install")
}
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cacheDir := filepath.Join(root, cache)
if !fs.Exists(cacheDir) {
if err := os.MkdirAll(cacheDir, 0755); err != nil {
return errors.Wrap(err, "creating non-existent cache dir")
}
}
if !fs.IsDir(cacheDir) {
return errors.Errorf("%q is not a directory!", cacheDir)
}
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if err := download(cacheDir, ms); err != nil {
return errors.Wrap(err, "downloading")
}
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for _, m := range ms {
if err := verifyManifestIntegrity(root, m); err != nil {
return errors.Wrap(err, "verifying pkg integrity")
}
}
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return errors.New("NYI")
}
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func download(cache string, ms pm.Metas) error {
// TODO (sm): concurrently fetch
for _, m := range ms {
resp, err := http.Get(m.URL())
if err != nil {
return errors.Wrap(err, "http get")
}
fn := filepath.Join(cache, m.Pkg())
f, err := os.Create(fn)
if err != nil {
return errors.Wrap(err, "creating")
}
if n, err := io.Copy(f, resp.Body); err != nil {
return errors.Wrapf(err, "copy %q to disk after %d bytes", m.URL(), n)
}
if err := resp.Body.Close(); err != nil {
return errors.Wrap(err, "closing resp body")
}
}
return nil
}
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func verifyManifestIntegrity(root string, m pm.Meta) error {
pn := filepath.Join(root, cache, m.Pkg())
man, err := getReadCloser(pn, "manifest.sha256")
if err != nil {
return errors.Wrap(err, "getting manifest reader")
}
sig, err := getReadCloser(pn, "manifest.sha256.asc")
if err != nil {
return errors.Wrap(err, "getting manifest reader")
}
if err := keyring.Verify(root, man, sig); err != nil {
return errors.Wrap(err, "verifying manifest")
}
if err := man.Close(); err != nil {
return errors.Wrap(err, "closing manifest reader")
}
if err := sig.Close(); err != nil {
return errors.Wrap(err, "closing manifest signature reader")
}
return nil
}
type tarSlurper struct {
f *os.File
tr *tar.Reader
}
func (ts *tarSlurper) Close() error {
return ts.f.Close()
}
func (ts *tarSlurper) Read(p []byte) (int, error) {
return ts.tr.Read(p)
}
func getReadCloser(tn, fn string) (io.ReadCloser, error) {
pf, err := os.Open(tn)
if err != nil {
return nil, errors.Wrap(err, "opening pkg file")
}
tr := tar.NewReader(pf)
for {
hdr, err := tr.Next()
if err == io.EOF {
break
}
if err != nil {
return nil, errors.Wrap(err, "tar traversal")
}
if hdr.Name == fn {
return &tarSlurper{pf, tr}, nil
}
}
return nil, errors.Errorf("%q not found", fn)
}