--- /dev/null
+/*
+ * Copyright (c) 2000-2002 Damien Miller. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* GCR support by Jan Tojnar <jtojnar@gmail.com> */
+
+/*
+ * This is a simple SSH passphrase grabber for GNOME. To use it, set the
+ * environment variable SSH_ASKPASS to point to the location of
+ * gnome-ssh-askpass before calling "ssh-add < /dev/null".
+ */
+
+/*
+ * Known problems:
+ * - This depends on unstable libgcr features
+ * - long key fingerprints may be truncted:
+ * https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6781
+ */
+
+/*
+ * Compile with:
+ *
+ * cc -Wall `pkg-config --cflags gcr-4 gio-2.0` \
+ * gnome-ssh-askpass4.c -o gnome-ssh-askpass \
+ * `pkg-config --libs gcr-4 gio-2.0`
+ *
+ */
+
+#include <stdio.h>
+#include <err.h>
+
+#include <gio/gio.h>
+
+#define GCR_API_SUBJECT_TO_CHANGE 1
+#include <gcr/gcr.h>
+
+typedef enum _PromptType {
+ PROMPT_ENTRY,
+ PROMPT_CONFIRM,
+ PROMPT_NONE,
+} PromptType;
+
+typedef struct _PromptState {
+ GApplication *app;
+ char* message;
+ PromptType type;
+ int exit_status;
+} PromptState;
+
+static PromptState *
+prompt_state_new(GApplication *app, char* message, PromptType type)
+{
+ PromptState *state = g_malloc(sizeof(PromptState));
+ state->app = g_object_ref(app);
+ state->message = g_strdup(message);
+ state->type = type;
+ state->exit_status = -1;
+ return state;
+}
+
+static void
+prompt_state_free(PromptState *state)
+{
+ g_clear_object(&state->app);
+ g_free(state->message);
+ g_free(state);
+}
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(PromptState, prompt_state_free)
+
+static void
+prompt_password_done(GObject *source_object, GAsyncResult *res,
+ gpointer user_data)
+{
+ GcrPrompt *prompt = GCR_PROMPT(source_object);
+ PromptState *state = user_data;
+ g_autoptr(GError) error = NULL;
+
+ /*
+ * “The returned password is valid until the next time a method
+ * is called to display another prompt.”
+ */
+ const char *pw = gcr_prompt_password_finish(prompt, res, &error);
+
+ if ((!pw && !error) || (error && error->code == G_IO_ERROR_CANCELLED)) {
+ /* Operation was cancelled or timed out. */
+ state->exit_status = -1;
+ } else if (error) {
+ warnx("Failed to prompt for ssh-askpass: %s", error->message);
+ state->exit_status = 1;
+ } else {
+ /* Report passphrase if user selected Continue. */
+ g_autofree char *local = g_locale_from_utf8(pw, strlen(pw),
+ NULL, NULL, NULL);
+
+ if (local != NULL) {
+ puts(local);
+ memset(local, '\0', strlen(local));
+ } else {
+ puts(pw);
+ }
+ state->exit_status = 0;
+ }
+
+ g_application_release(state->app);
+}
+
+static void
+prompt_confirm_done(GObject *source_object, GAsyncResult *res,
+ gpointer user_data)
+{
+ GcrPrompt *prompt = GCR_PROMPT(source_object);
+ PromptState *state = user_data;
+ g_autoptr(GError) error = NULL;
+
+ GcrPromptReply reply = gcr_prompt_confirm_finish(prompt, res, &error);
+ if (error) {
+ if (error->code == G_IO_ERROR_CANCELLED) {
+ /* Operation was cancelled or timed out. */
+ state->exit_status = -1;
+ } else {
+ state->exit_status = 1;
+ warnx("Failed to prompt for ssh-askpass: %s",
+ error->message);
+ }
+ } else if (reply == GCR_PROMPT_REPLY_CONTINUE ||
+ state->type == PROMPT_NONE) {
+ /*
+ * Since Gcr doesn’t yet support one button message
+ * boxes treat Cancel the same as Continue.
+ */
+ state->exit_status = 0;
+ } else {
+ /* GCR_PROMPT_REPLY_CANCEL */
+ state->exit_status = -1;
+ }
+
+ g_application_release(state->app);
+}
+
+static int
+command_line(GApplication* app, G_GNUC_UNUSED GApplicationCommandLine *cmdline,
+ gpointer user_data)
+{
+ PromptState *state = user_data;
+
+ /* Prevent app from exiting while waiting for the async callback. */
+ g_application_hold(app);
+
+ /* Wait indefinitely. */
+ int timeout_seconds = -1;
+ g_autoptr(GError) error = NULL;
+ GcrPrompt* prompt = gcr_system_prompt_open(timeout_seconds, NULL, &error);
+
+ if (!prompt) {
+ if (error->code == GCR_SYSTEM_PROMPT_IN_PROGRESS) {
+ /*
+ * This means the timeout elapsed, but no prompt
+ * was ever shown.
+ */
+ warnx("Timeout: the Gcr system prompter was "
+ "already in use.");
+ } else {
+ warnx("Couldn’t create prompt for ssh-askpass: %s",
+ error->message);
+ }
+
+ return 1;
+ }
+
+ gcr_prompt_set_message(prompt, "OpenSSH");
+ gcr_prompt_set_description(prompt, state->message);
+
+ /*
+ * XXX: Remove the Cancel button for PROMPT_NONE when GCR
+ * supports that.
+ */
+ if (state->type == PROMPT_ENTRY) {
+ gcr_prompt_password_async(prompt, NULL, prompt_password_done, state);
+ } else {
+ gcr_prompt_confirm_async(prompt, NULL, prompt_confirm_done, state);
+ }
+
+ /* The exit status will be changed in the async callbacks. */
+ return 1;
+}
+
+int
+main(int argc, char **argv)
+{
+ g_autoptr(GApplication) app = g_application_new(
+ "com.openssh.gnome-ssh-askpass4",
+ G_APPLICATION_HANDLES_COMMAND_LINE);
+ g_autofree char *message = NULL;
+
+ if (argc > 1) {
+ message = g_strjoinv(" ", argv + 1);
+ } else {
+ message = g_strdup("Enter your OpenSSH passphrase:");
+ }
+
+ const char *prompt_mode = getenv("SSH_ASKPASS_PROMPT");
+ PromptType type = PROMPT_ENTRY;
+ if (prompt_mode != NULL) {
+ if (strcasecmp(prompt_mode, "confirm") == 0) {
+ type = PROMPT_CONFIRM;
+ } else if (strcasecmp(prompt_mode, "none") == 0) {
+ type = PROMPT_NONE;
+ }
+ }
+
+ g_autoptr(PromptState) state = prompt_state_new(app, message, type);
+
+ g_signal_connect(app, "command-line", G_CALLBACK(command_line), state);
+
+ /*
+ * Since we are calling g_application_hold, we cannot use
+ * g_application_command_line_set_exit_status.
+ * To change the exit status returned by g_application_run:
+ * “If the commandline invocation results in the mainloop running
+ * (ie: because the use-count of the application increased to a
+ * non-zero value) then the application is considered to have been
+ * ‘successful’ in a certain sense, and the exit status is always
+ * zero.”
+ */
+ (void)(g_application_run(app, argc, argv));
+
+ return state->exit_status;
+}