Warn when throw-keyids is set (gopasspw#1759)

Fixes gopasspw#1756

RELEASE_NOTES=[BUGFIX] Warn about --throw-keyids

Signed-off-by: Dominik Schulz <dominik.schulz@gauner.org>

internal/backend/crypto/age/unsupported.go

@@ -73,7 +73,7 @@ func (a *Age) ReadNamesFromKey(ctx context.Context, buf []byte) ([]string, error
 	return nil, fmt.Errorf("not implemented")
 }
 
-// RecipientIDs is TODO
+// RecipientIDs is not supported by design
 func (a *Age) RecipientIDs(ctx context.Context, buf []byte) ([]string, error) {
-	return nil, fmt.Errorf("not supported by backend")
+	return nil, fmt.Errorf("reading recipient IDs is not supported by the age backend by design")
 }

internal/backend/crypto/gpg/cli/gpg.go

@@ -33,6 +33,7 @@ type GPG struct {
 	pubKeys   gpg.KeyList
 	privKeys  gpg.KeyList
 	listCache *lru.TwoQueueCache
+	throwKids bool
 }
 
 // Config is the gpg wrapper config
@@ -56,8 +57,9 @@ func New(ctx context.Context, cfg Config) (*GPG, error) {
 	}
 
 	g := &GPG{
-		binary: "gpg",
-		args:   append(defaultArgs, cfg.Args...),
+		binary:    "gpg",
+		args:      append(defaultArgs, cfg.Args...),
+		throwKids: fileContains(gpgConfigLoc(), "throw-keyids"),
 	}
 
 	debug.Log("initializing LRU cache")
@@ -111,6 +113,10 @@ func (g *GPG) RecipientIDs(ctx context.Context, buf []byte) ([]string, error) {
 		}
 	}
 
+	if g.throwKids {
+		// TODO shouldn't log here
+		out.Warning(ctx, "gpg option throw-keyids is set. some features might not work.")
+	}
 	return recp, nil
 }
 

internal/backend/crypto/gpg/cli/gpgcfg.go

@@ -0,0 +1,36 @@
+package cli
+
+import (
+	"bufio"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/gopasspw/gopass/pkg/debug"
+)
+
+func gpgConfigLoc() string {
+	if sv := os.Getenv("GNUPGHOME"); sv != "" {
+		return filepath.Join(sv, "gpg.conf")
+	}
+
+	uhd, _ := os.UserHomeDir()
+	return filepath.Join(uhd, ".gnupg", "gpg.conf")
+}
+
+func fileContains(path, needle string) bool {
+	fh, err := os.Open(path)
+	if err != nil {
+		debug.Log("failed to open %q for reading: %s", path, err)
+		return false
+	}
+	defer fh.Close()
+
+	s := bufio.NewScanner(fh)
+	for s.Scan() {
+		if strings.Contains(s.Text(), needle) {
+			return true
+		}
+	}
+	return false
+}