path: root/composer/e-composer-autosave.c

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 */

#include "e-composer-autosave.h"

#include <errno.h>
#include <sys/stat.h>
#include <glib/gi18n.h>
#include <glib/gstdio.h>

#include <e-util/e-alert-dialog.h>
#include <e-util/e-util.h>

#define AUTOSAVE_PREFIX     ".evolution-composer.autosave"
#define AUTOSAVE_SEED       AUTOSAVE_PREFIX "-XXXXXX"
#define AUTOSAVE_INTERVAL   60 /* seconds */

typedef struct _AutosaveState AutosaveState;

struct _AutosaveState {
    GFile *file;
    gboolean enabled;
    gboolean error_shown;
};

static GList *autosave_registry;
static guint autosave_source_id;

static EMsgComposer *
composer_autosave_registry_lookup (const gchar *basename)
{
    GList *iter;

    /* Find the composer with the given autosave filename. */
    for (iter = autosave_registry; iter != NULL; iter = iter->next) {
        EMsgComposer *composer = iter->data;
        AutosaveState *state;
        gchar *_basename;

        state = g_object_get_data (G_OBJECT (composer), "autosave");
        if (state == NULL || state->file == NULL)
            continue;

        _basename = g_file_get_basename (state->file);
        if (strcmp (_basename, basename) == 0) {
            g_free (_basename);
            return composer;
        }
        g_free (_basename);
    }

    return NULL;
}

static AutosaveState *
composer_autosave_state_new (void)
{
    AutosaveState *state;

    state = g_slice_new0 (AutosaveState);
    state->enabled = TRUE;

    return state;
}

static void
composer_autosave_state_free (AutosaveState *state)
{
    if (state->file)
        g_object_unref (state->file);
    g_slice_free (AutosaveState, state);
}

static gboolean
composer_autosave_state_open (AutosaveState *state)
{
    gchar *path;
    gint fd;

    if (state->file != NULL)
        return TRUE;

    path = g_build_filename (
        e_get_user_data_dir (), AUTOSAVE_SEED, NULL);

    /* Since GIO doesn't have support for creating temporary files
     * from a template (and in a given directory), we have to use
     * g_mkstemp(), which brings a small risk of overwriting another
     * autosave file.  The risk is, however, miniscule. */
    fd = g_mkstemp (path);
    if (fd == -1) {
        g_free (path);
        return FALSE;
    }

    close (fd);

    /* Create the GFile */
    state->file = g_file_new_for_path (path);
    g_free (path);

    return TRUE;
}

static void
composer_autosave_finish_cb (EMsgComposer *composer,
                             GAsyncResult *result)
{
    AutosaveState *state;
    GError *error = NULL;

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    g_return_if_fail (state != NULL);

    e_composer_autosave_snapshot_finish (composer, result, &error);

    if (error != NULL) {
        gchar *basename;

        if (G_IS_FILE (state->file))
            basename = g_file_get_basename (state->file);
        else
            basename = g_strdup (" ");

        /* Only show one error dialog at a
         * time to avoid cascading dialogs. */
        if (!state->error_shown) {
            state->error_shown = TRUE;
            e_alert_run_dialog_for_args (
                GTK_WINDOW (composer),
                "mail-composer:no-autosave",
                basename, error->message, NULL);
            state->error_shown = FALSE;
        } else
            g_warning ("%s: %s", basename, error->message);

        g_free (basename);
        g_error_free (error);
    }
}

static void
composer_autosave_foreach (EMsgComposer *composer)
{
    /* Make sure the composer is still alive. */
    g_return_if_fail (E_IS_MSG_COMPOSER (composer));

    if (e_composer_autosave_get_enabled (composer))
        e_composer_autosave_snapshot_async (
            composer, (GAsyncReadyCallback)
            composer_autosave_finish_cb, NULL);
}

static gboolean
composer_autosave_timeout (void)
{
    g_list_foreach (
        autosave_registry, (GFunc)
        composer_autosave_foreach, NULL);

    return TRUE;
}

static void
composer_autosave_notify (gpointer unused,
                          GObject *where_the_object_was)
{
    /* Remove the dead composer from the registry. */
    autosave_registry = g_list_remove (
        autosave_registry, where_the_object_was);

    /* Cancel timeouts if the registry is now empty. */
    if (autosave_registry == NULL && autosave_source_id != 0) {
        g_source_remove (autosave_source_id);
        autosave_source_id = 0;
    }
}

GList *
e_composer_autosave_find_orphans (GError **error)
{
    GDir *dir;
    const gchar *dirname;
    const gchar *basename;
    GList *orphans = NULL;

    dirname = e_get_user_data_dir ();
    dir = g_dir_open (dirname, 0, error);
    if (dir == NULL)
        return NULL;

    /* Scan the user directory for autosave files. */
    while ((basename = g_dir_read_name (dir)) != NULL) {
        const gchar *errmsg;
        gchar *filename;
        struct stat st;

        /* Is this an autosave file? */
        if (!g_str_has_prefix (basename, AUTOSAVE_PREFIX))
            continue;

        /* Is this an orphaned autosave file? */
        if (composer_autosave_registry_lookup (basename) != NULL)
            continue;

        filename = g_build_filename (dirname, basename, NULL);

        /* Try to examine the autosave file.  Failure here
         * is non-fatal; just emit a warning and move on. */
        errno = 0;
        if (g_stat (filename, &st) < 0) {
            errmsg = g_strerror (errno);
            g_warning ("%s: %s", filename, errmsg);
            g_free (filename);
            continue;
        }

        /* If the file is empty, delete it.  Failure here
         * is non-fatal; just emit a warning and move on. */
        if (st.st_size == 0) {
            errno = 0;
            if (g_unlink (filename) < 0) {
                errmsg = g_strerror (errno);
                g_warning ("%s: %s", filename, errmsg);
            }
            g_free (filename);
            continue;
        }

        orphans = g_list_prepend (orphans, filename);
    }

    g_dir_close (dir);

    return g_list_reverse (orphans);
}

void
e_composer_autosave_register (EMsgComposer *composer)
{
    g_return_if_fail (E_IS_MSG_COMPOSER (composer));

    g_object_set_data_full (
        G_OBJECT (composer), "autosave",
        composer_autosave_state_new (),
        (GDestroyNotify) composer_autosave_state_free);

    autosave_registry = g_list_prepend (autosave_registry, composer);

    g_object_weak_ref (
        G_OBJECT (composer), (GWeakNotify)
        composer_autosave_notify, NULL);

    if (autosave_source_id == 0)
        autosave_source_id = g_timeout_add_seconds (
            AUTOSAVE_INTERVAL, (GSourceFunc)
            composer_autosave_timeout, NULL);
}

void
e_composer_autosave_unregister (EMsgComposer *composer)
{
    AutosaveState *state;

    g_return_if_fail (E_IS_MSG_COMPOSER (composer));

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    if (state == NULL || state->file == NULL)
        return;

    g_file_delete (state->file, NULL, NULL);

    g_object_set_data (G_OBJECT (composer), "autosave", NULL);
}

typedef struct {
    EMsgComposer *composer;
    GSimpleAsyncResult *simple;
    AutosaveState *state;

    /* Transient data */
    GInputStream *input_stream;
} AutosaveData;

static void
autosave_data_free (AutosaveData *data)
{
    g_object_unref (data->composer);
    g_object_unref (data->simple);

    if (data->input_stream != NULL)
        g_object_unref (data->input_stream);

    g_slice_free (AutosaveData, data);
}

static gboolean
autosave_snapshot_check_for_error (AutosaveData *data,
                                   GError *error)
{
    GSimpleAsyncResult *simple;

    if (error == NULL)
        return FALSE;

    simple = data->simple;
    g_simple_async_result_set_from_error (simple, error);
    g_simple_async_result_set_op_res_gboolean (simple, FALSE);
    g_simple_async_result_complete (simple);
    g_error_free (error);

    autosave_data_free (data);

    return TRUE;
}

static void
autosave_snapshot_splice_cb (GOutputStream *output_stream,
                             GAsyncResult *result,
                             AutosaveData *data)
{
    GSimpleAsyncResult *simple;
    GError *error = NULL;

    g_output_stream_splice_finish (output_stream, result, &error);

    if (autosave_snapshot_check_for_error (data, error))
        return;

    simple = data->simple;
    g_simple_async_result_set_op_res_gboolean (simple, TRUE);
    g_simple_async_result_complete (simple);

    autosave_data_free (data);
}

static void
autosave_snapshot_cb (GFile *file,
                      GAsyncResult *result,
                      AutosaveData *data)
{
    CamelMimeMessage *message;
    GFileOutputStream *output_stream;
    GInputStream *input_stream;
    CamelStream *camel_stream;
    GByteArray *buffer;
    GError *error = NULL;

    output_stream = g_file_replace_finish (file, result, &error);

    if (autosave_snapshot_check_for_error (data, error))
        return;

    /* Extract a MIME message from the composer. */
    message = e_msg_composer_get_message_draft (data->composer);
    if (message == NULL) {
        GSimpleAsyncResult *simple;

        /* FIXME Need to set a GError here. */
        simple = data->simple;
        g_simple_async_result_set_op_res_gboolean (simple, FALSE);
        g_simple_async_result_complete (simple);
        g_object_unref (output_stream);
        autosave_data_free (data);
        return;
    }

    /* Decode the MIME part to an in-memory buffer.  We have to do
     * this because CamelStream is synchronous-only, and using threads
     * is dangerous because CamelDataWrapper is not reentrant. */
    buffer = g_byte_array_new ();
    camel_stream = camel_stream_mem_new ();
    camel_stream_mem_set_byte_array (
        CAMEL_STREAM_MEM (camel_stream), buffer);
    camel_data_wrapper_decode_to_stream (
        CAMEL_DATA_WRAPPER (message), camel_stream);
    g_object_unref (message);
    g_object_unref (camel_stream);

    /* Load the buffer into a GMemoryInputStream.
     * But watch out for zero length MIME parts. */
    input_stream = g_memory_input_stream_new ();
    if (buffer->len > 0)
        g_memory_input_stream_add_data (
            G_MEMORY_INPUT_STREAM (input_stream),
            buffer->data, (gssize) buffer->len,
            (GDestroyNotify) g_free);
    g_byte_array_free (buffer, FALSE);
    data->input_stream = input_stream;

    /* Splice the input and output streams */
    g_output_stream_splice_async (
        G_OUTPUT_STREAM (output_stream), input_stream,
        G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE |
        G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET,
        G_PRIORITY_DEFAULT, NULL, (GAsyncReadyCallback)
        autosave_snapshot_splice_cb, data);

    g_object_unref (output_stream);
}

void
e_composer_autosave_snapshot_async (EMsgComposer *composer,
                                    GAsyncReadyCallback callback,
                                    gpointer user_data)
{
    AutosaveData *data;
    AutosaveState *state;
    GSimpleAsyncResult *simple;

    g_return_if_fail (E_IS_MSG_COMPOSER (composer));

    simple = g_simple_async_result_new (
        G_OBJECT (composer), callback, user_data,
        e_composer_autosave_snapshot_async);

    /* If the contents are unchanged, exit early. */
    if (!gtkhtml_editor_get_changed (GTKHTML_EDITOR (composer))) {
        g_simple_async_result_set_op_res_gboolean (simple, TRUE);
        g_simple_async_result_complete (simple);
        return;
    }

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    g_return_if_fail (state != NULL);

    /* Open the autosave file on-demand. */
    errno = 0;
    if (!composer_autosave_state_open (state)) {
        g_simple_async_result_set_error (
            simple, G_FILE_ERROR,
            g_file_error_from_errno (errno),
            "%s", g_strerror (errno));
        g_simple_async_result_set_op_res_gboolean (simple, FALSE);
        g_simple_async_result_complete (simple);
        return;
    }

    /* Overwrite the file */
    data = g_slice_new (AutosaveData);
    data->composer = g_object_ref (composer);
    data->simple = simple;
    data->state = state;

    g_file_replace_async (
        state->file, NULL, FALSE, G_FILE_CREATE_PRIVATE,
        G_PRIORITY_DEFAULT, NULL, (GAsyncReadyCallback)
        autosave_snapshot_cb, data);
}

gboolean
e_composer_autosave_snapshot_finish (EMsgComposer *composer,
                                     GAsyncResult *result,
                                     GError **error)
{
    GSimpleAsyncResult *simple;
    gboolean success;

    g_return_val_if_fail (E_IS_MSG_COMPOSER (composer), FALSE);
    g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (result), FALSE);
    g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

    simple = G_SIMPLE_ASYNC_RESULT (result);
    success = g_simple_async_result_get_op_res_gboolean (simple);
    g_simple_async_result_propagate_error (simple, error);

    return success;
}

gchar *
e_composer_autosave_get_filename (EMsgComposer *composer)
{
    AutosaveState *state;

    g_return_val_if_fail (E_IS_MSG_COMPOSER (composer), NULL);

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    g_return_val_if_fail (state != NULL, NULL);

    return g_file_get_path (state->file);
}

gboolean
e_composer_autosave_get_enabled (EMsgComposer *composer)
{
    AutosaveState *state;

    g_return_val_if_fail (E_IS_MSG_COMPOSER (composer), FALSE);

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    g_return_val_if_fail (state != NULL, FALSE);

    return state->enabled;
}

void
e_composer_autosave_set_enabled (EMsgComposer *composer,
                                 gboolean enabled)
{
    AutosaveState *state;

    g_return_if_fail (E_IS_MSG_COMPOSER (composer));

    state = g_object_get_data (G_OBJECT (composer), "autosave");
    g_return_if_fail (state != NULL);

    state->enabled = enabled;
}