1 files changed, 45 insertions, 0 deletions
diff --git a/lib/pinentry/ttyname.go b/lib/pinentry/ttyname.go
new file mode 100644
index 00000000..053cff74
--- /dev/null
+++ b/lib/pinentry/ttyname.go
@@ -0,0 +1,45 @@
+package pinentry
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/lib/log"
+)
+
+var missingGPGTTYmsg = `
+You need to set GPG_TTY manually before starting aerc. Add the following to your
+.bashrc or whatever initialization file is used for shell invocations:
+
+	GPG_TTY=$(tty)
+	export GPG_TTY
+
+Further information can be found here:
+https://www.gnupg.org/documentation/manuals/gnupg/Invoking-GPG_002dAGENT.html
+`
+
+// ttyname returns current name of the pty. This is necessary in order to tell
+// pinentry where to ask for the passphrase.
+//
+// If there is a GPG_TTY environment variable set, use this one. Otherwise, try
+// readline() on /proc/<pid>/fd/0.
+//
+// If both approaches fail, the user's only option is to set GPG_TTY manually.
+//
+// If tty name could not be determined, an empty string is returned.
+func ttyname() string {
+	if s := os.Getenv("GPG_TTY"); s != "" {
+		return s
+	}
+
+	// try readlink or else show missing GPG_TTY warning msg
+	tty, err := os.Readlink(fmt.Sprintf("/proc/%d/fd/0", os.Getpid()))
+	if err != nil {
+		log.Debugf("readlink: '%s' with err: %v", tty, err)
+		log.Warnf(missingGPGTTYmsg)
+		return ""
+	}
+
+	return strings.TrimSpace(tty)
+}