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feat: add support for gopass as a credential store
This change adds support for `gopass` as a credential store, based on the `pass` implementation. Closes: docker#138 Closes: docker#166 Signed-off-by: sudoforge <[email protected]>
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.github/workflows/build.yml

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@@ -63,6 +63,12 @@ jobs:
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run: |
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sudo apt-get update
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sudo apt-get install -y dbus-x11 gnome-keyring libsecret-1-dev pass
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-
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name: Install gopass
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env:
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GOPASS_VERSION: v1.15.5
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run: go install github.com/gopasspw/gopass@${{ env.GOPASS_VERSION }}
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-
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name: GPG conf
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if: ${{ matrix.os == 'ubuntu-20.04' }}

Dockerfile

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@@ -5,6 +5,7 @@ ARG XX_VERSION=1.2.1
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ARG OSXCROSS_VERSION=11.3-r7-debian
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ARG GOLANGCI_LINT_VERSION=v1.51.1
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ARG DEBIAN_FRONTEND=noninteractive
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ARG GOPASS_VERSION=v1.15.5
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ARG PACKAGE=github.com/docker/docker-credential-helpers
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@@ -68,12 +69,19 @@ RUN xx-apt-get install -y binutils gcc libc6-dev libgcc-10-dev libsecret-1-dev p
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FROM base AS test
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ARG DEBIAN_FRONTEND
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ARG GOPASS_VERSION
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RUN xx-apt-get install -y dbus-x11 gnome-keyring gpg-agent gpgconf libsecret-1-dev pass
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RUN --mount=type=bind,target=. \
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--mount=type=cache,target=/root/.cache \
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--mount=type=cache,target=/go/pkg/mod \
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GOFLAGS='' go install github.com/gopasspw/gopass@${GOPASS_VERSION}
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RUN --mount=type=bind,target=. \
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--mount=type=cache,target=/root/.cache \
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--mount=type=cache,target=/go/pkg/mod <<EOT
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set -e
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cp -r .github/workflows/fixtures /root/.gnupg
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chmod 0400 /root/.gnupg
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gpg-connect-agent "RELOADAGENT" /bye
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gpg --import --batch --yes /root/.gnupg/7D851EB72D73BDA0.key
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gpg --update-trustdb
@@ -82,7 +90,20 @@ RUN --mount=type=bind,target=. \
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gpg-connect-agent "KEYINFO 3E2D1142AA59E08E16B7E2C64BA6DDC773B1A627" /bye
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gpg-connect-agent "PRESET_PASSPHRASE BA83FC8947213477F28ADC019F6564A956456163 -1 77697468207374757069642070617373706872617365" /bye
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gpg-connect-agent "KEYINFO BA83FC8947213477F28ADC019F6564A956456163" /bye
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# initialize password store for `pass`
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pass init 7D851EB72D73BDA0
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# initialize password store for `gopass`
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gopass config mounts.path /root/.gopass-password-store 1>/dev/null
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gopass config core.autopush false 1>/dev/null
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gopass config core.autosync false 1>/dev/null
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gopass config core.exportkeys false 1>/dev/null
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gopass config core.notifications false 1>/dev/null
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gopass config core.color false 1>/dev/null
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gopass config core.nopager true 1>/dev/null
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gopass init --crypto gpgcli --storage fs 7D851EB72D73BDA0
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gpg -k
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mkdir /out
@@ -106,7 +127,8 @@ RUN --mount=type=bind,target=. \
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--mount=type=bind,source=/tmp/.revision,target=/tmp/.revision,from=version <<EOT
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set -ex
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xx-go --wrap
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make build-pass build-secretservice PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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make build-gopass build-pass build-secretservice PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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xx-verify /out/docker-credential-gopass
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xx-verify /out/docker-credential-pass
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xx-verify /out/docker-credential-secretservice
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EOT
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set -ex
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xx-go --wrap
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go install std
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make build-osxkeychain build-pass PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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make build-gopass build-osxkeychain build-pass PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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xx-verify /out/docker-credential-gopass
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xx-verify /out/docker-credential-osxkeychain
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xx-verify /out/docker-credential-pass
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EOT
@@ -136,7 +159,9 @@ RUN --mount=type=bind,target=. \
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--mount=type=bind,source=/tmp/.revision,target=/tmp/.revision,from=version <<EOT
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set -ex
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xx-go --wrap
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make build-wincred PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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make build-gopass build-wincred PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out
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mv /out/docker-credential-gopass /out/docker-credential-gopass.exe
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xx-verify /out/docker-credential-gopass.exe
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mv /out/docker-credential-wincred /out/docker-credential-wincred.exe
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xx-verify /out/docker-credential-wincred.exe
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EOT

Makefile

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@@ -16,11 +16,12 @@ clean:
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rm -rf bin
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.PHONY: build-%
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build-%: # build, can be one of build-osxkeychain build-pass build-secretservice build-wincred
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build-%: # build, can be one of build-gopass build-osxkeychain build-pass build-secretservice build-wincred
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go build -trimpath -ldflags="$(GO_LDFLAGS) -X ${GO_PKG}/credentials.Name=docker-credential-$*" -o "$(DESTDIR)/docker-credential-$*" ./$*/cmd/
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# aliases for build-* targets
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.PHONY: osxkeychain secretservice pass wincred
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.PHONY: gopass osxkeychain secretservice pass wincred
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gopass: build-gopass
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osxkeychain: build-osxkeychain
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secretservice: build-secretservice
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pass: build-pass

README.md

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@@ -77,15 +77,26 @@ You can see examples of each function in the [client](https://godoc.org/github.c
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### Available programs
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1. osxkeychain: Provides a helper to use the OS X keychain as credentials store.
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2. secretservice: Provides a helper to use the D-Bus secret service as credentials store.
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3. wincred: Provides a helper to use Windows credentials manager as store.
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4. pass: Provides a helper to use `pass` as credentials store.
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- gopass: Provides a helper to use `gopass` as credentials store.
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- osxkeychain: Provides a helper to use the OS X keychain as credentials store.
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- pass: Provides a helper to use `pass` as credentials store.
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- secretservice: Provides a helper to use the D-Bus secret service as credentials store.
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- wincred: Provides a helper to use Windows credentials manager as store.
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#### Note
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#### Note regarding `gopass`
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87-
`pass` needs to be configured for `docker-credential-pass` to work properly.
88-
It must be initialized with a `gpg2` key ID. Make sure your GPG key exists is in `gpg2` keyring as `pass` uses `gpg2` instead of the regular `gpg`.
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`gopass` requires manual intervention in order for `docker-credential-gopass` to
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work properly: a password store must be initialized. Please ensure to review the
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upstream [quick start guide][gopass-quick-start] for more information.
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[gopass-quick-start]: https://github.com/gopasspw/gopass#quick-start-guide
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#### Note regarding `pass`
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96+
`pass` requires manual interview in order for `docker-credential-pass` to
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work properly. It must be initialized with a `gpg2` key ID. Make sure your GPG
98+
key exists is in `gpg2` keyring as `pass` uses `gpg2` instead of the regular
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`gpg`.
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## Development
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gopass/cmd/main.go

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@@ -0,0 +1,10 @@
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package main
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import (
4+
"github.com/docker/docker-credential-helpers/credentials"
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"github.com/docker/docker-credential-helpers/gopass"
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)
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func main() {
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credentials.Serve(gopass.Gopass{})
10+
}

gopass/gopass.go

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// Package gopass implements a `gopass` based credential helper. Passwords are
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// stored as arguments to gopass of the form:
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//
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// "$GOPASS_FOLDER/base64-url(serverURL)/username"
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//
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// We base64-url encode the serverURL, because under the hood gopass uses files
7+
// and folders, so /s will get translated into additional folders.
8+
package gopass
9+
10+
import (
11+
"bytes"
12+
"encoding/base64"
13+
"errors"
14+
"fmt"
15+
"io/fs"
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"os"
17+
"os/exec"
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"path"
19+
"strings"
20+
"sync"
21+
22+
"github.com/docker/docker-credential-helpers/credentials"
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)
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// GOPASS_FOLDER contains the directory where credentials are stored
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const GOPASS_FOLDER = "docker-credential-helpers" //nolint:revive
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// Gopass handles secrets using gopass as a store.
29+
type Gopass struct{}
30+
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// Ideally these would be stored as members of Gopass, but since all of Gopass's
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// methods have value receivers, not pointer receivers, and changing that is
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// backwards incompatible, we assume that all Gopass instances share the same
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// configuration
35+
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// initializationMutex is held while initializing so that only one 'gopass'
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// round-tripping is done to check that gopass is functioning.
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var initializationMutex sync.Mutex
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var gopassInitialized bool
40+
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// CheckInitialized checks whether the password helper can be used. It
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// internally caches and so may be safely called multiple times with no impact
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// on performance, though the first call may take longer.
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func (g Gopass) CheckInitialized() bool {
45+
return g.checkInitialized() == nil
46+
}
47+
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func (g Gopass) checkInitialized() error {
49+
initializationMutex.Lock()
50+
defer initializationMutex.Unlock()
51+
if gopassInitialized {
52+
return nil
53+
}
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55+
// We just run a `gopass ls`, if it fails then gopass is not initialized.
56+
_, err := g.runGopassHelper("", "ls", "--flat")
57+
if err != nil {
58+
return fmt.Errorf("gopass is not initialized: %v", err)
59+
}
60+
gopassInitialized = true
61+
return nil
62+
}
63+
64+
func (g Gopass) runGopass(stdinContent string, args ...string) (string, error) {
65+
if err := g.checkInitialized(); err != nil {
66+
return "", err
67+
}
68+
return g.runGopassHelper(stdinContent, args...)
69+
}
70+
71+
func (g Gopass) runGopassHelper(stdinContent string, args ...string) (string, error) {
72+
var stdout, stderr bytes.Buffer
73+
cmd := exec.Command("gopass", args...)
74+
cmd.Stdin = strings.NewReader(stdinContent)
75+
cmd.Stdout = &stdout
76+
cmd.Stderr = &stderr
77+
78+
err := cmd.Run()
79+
if err != nil {
80+
return "", fmt.Errorf("%s: %s", err, stderr.String())
81+
}
82+
83+
// trim newlines; gopass includes a newline at the end of `show` output
84+
return strings.TrimRight(stdout.String(), "\n\r"), nil
85+
}
86+
87+
// Add adds new credentials to the keychain.
88+
func (g Gopass) Add(creds *credentials.Credentials) error {
89+
if creds == nil {
90+
return errors.New("missing credentials")
91+
}
92+
93+
encoded := base64.URLEncoding.EncodeToString([]byte(creds.ServerURL))
94+
95+
_, err := g.runGopass(creds.Secret, "insert", "-f", path.Join(GOPASS_FOLDER, encoded, creds.Username))
96+
return err
97+
}
98+
99+
// Delete removes credentials from the store.
100+
func (g Gopass) Delete(serverURL string) error {
101+
if serverURL == "" {
102+
return errors.New("missing server url")
103+
}
104+
105+
encoded := base64.URLEncoding.EncodeToString([]byte(serverURL))
106+
_, err := g.runGopass("", "rm", "-rf", path.Join(GOPASS_FOLDER, encoded))
107+
return err
108+
}
109+
110+
func (g Gopass) getGopassDir() (string, error) {
111+
gopassDir, err := g.runGopass("", "config", "mounts.path")
112+
113+
if err != nil {
114+
return "", fmt.Errorf("error getting gopass dir: %v", err)
115+
}
116+
117+
gopassDir = os.ExpandEnv(gopassDir)
118+
119+
if strings.HasPrefix(gopassDir, "~/") {
120+
d, err := os.UserHomeDir()
121+
122+
if err != nil {
123+
message := fmt.Sprintf("unable to get user home directory: %v", err.Error())
124+
return "", errors.New(message)
125+
}
126+
127+
gopassDir = path.Join(d, gopassDir[2:])
128+
}
129+
130+
return gopassDir, nil
131+
}
132+
133+
// listGopassDir lists all the contents of a directory in the password store.
134+
// Gopass uses fancy unicode to emit stuff to stdout, so rather than try
135+
// and parse this, let's just look at the directory structure instead.
136+
func (g Gopass) listGopassDir(args ...string) ([]os.FileInfo, error) {
137+
gopassDir, err := g.getGopassDir()
138+
if err != nil {
139+
return nil, err
140+
}
141+
142+
p := os.ExpandEnv(path.Join(append([]string{gopassDir, GOPASS_FOLDER}, args...)...))
143+
144+
entries, err := os.ReadDir(p)
145+
if err != nil {
146+
if os.IsNotExist(err) {
147+
return []os.FileInfo{}, nil
148+
}
149+
return nil, err
150+
}
151+
152+
infos := make([]fs.FileInfo, 0, len(entries))
153+
for _, entry := range entries {
154+
info, err := entry.Info()
155+
if err != nil {
156+
return nil, err
157+
}
158+
infos = append(infos, info)
159+
}
160+
return infos, nil
161+
}
162+
163+
// Get returns the username and secret to use for a given registry server URL.
164+
func (g Gopass) Get(serverURL string) (string, string, error) {
165+
if serverURL == "" {
166+
return "", "", errors.New("missing server url")
167+
}
168+
169+
gopassDir, err := g.getGopassDir()
170+
if err != nil {
171+
return "", "", err
172+
}
173+
174+
encoded := base64.URLEncoding.EncodeToString([]byte(serverURL))
175+
176+
if _, err := os.Stat(path.Join(gopassDir, GOPASS_FOLDER, encoded)); err != nil {
177+
if os.IsNotExist(err) {
178+
return "", "", credentials.NewErrCredentialsNotFound()
179+
}
180+
181+
return "", "", err
182+
}
183+
184+
usernames, err := g.listGopassDir(encoded)
185+
if err != nil {
186+
return "", "", err
187+
}
188+
189+
if len(usernames) < 1 {
190+
return "", "", fmt.Errorf("no usernames for %s", serverURL)
191+
}
192+
193+
actual := strings.TrimSuffix(usernames[0].Name(), ".gpg")
194+
secret, err := g.runGopass("", "show", "-o", path.Join(GOPASS_FOLDER, encoded, actual))
195+
196+
return actual, secret, err
197+
}
198+
199+
// List returns the stored URLs and corresponding usernames for a given credentials label
200+
func (g Gopass) List() (map[string]string, error) {
201+
servers, err := g.listGopassDir()
202+
if err != nil {
203+
return nil, err
204+
}
205+
206+
resp := map[string]string{}
207+
208+
for _, server := range servers {
209+
if !server.IsDir() {
210+
continue
211+
}
212+
213+
serverURL, err := base64.URLEncoding.DecodeString(server.Name())
214+
if err != nil {
215+
return nil, err
216+
}
217+
218+
usernames, err := g.listGopassDir(server.Name())
219+
if err != nil {
220+
return nil, err
221+
}
222+
223+
if len(usernames) < 1 {
224+
return nil, fmt.Errorf("no usernames for %s", serverURL)
225+
}
226+
227+
resp[string(serverURL)] = strings.TrimSuffix(usernames[0].Name(), ".gpg")
228+
}
229+
230+
return resp, nil
231+
}

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