path: root/addressbook/backend/pas/pas-backend-file.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Author:
 *   Nat Friedman (nat@helixcode.com)
 *
 * Copyright 2000, Helix Code, Inc.
 */

#include "config.h"  
#include <gtk/gtksignal.h>
#include <fcntl.h>
#include <time.h>
#ifdef HAVE_DB_185_H
#include <db_185.h>
#else
#include <db.h>
#endif

#include <pas-backend-file.h>
#include <pas-book.h>
#include <pas-card-cursor.h>
#include <e-card.h>
#include <e-sexp.h>

#define PAS_BACKEND_FILE_VERSION_NAME "PAS-DB-VERSION"
#define PAS_BACKEND_FILE_VERSION "0.1"

static PASBackendClass *pas_backend_file_parent_class;
typedef struct _PASBackendFileCursorPrivate PASBackendFileCursorPrivate;
typedef struct _PASBackendFileBookView PASBackendFileBookView;
typedef struct _PASBackendFileSearchContext PASBackendFileSearchContext;

struct _PASBackendFilePrivate {
    GList    *clients;
    gboolean  loaded;
    DB       *file_db;
    GList    *book_views;
};

struct _PASBackendFileCursorPrivate {
    PASBackend *backend;
    PASBook    *book;

    GList      *elements;
    guint32    num_elements;
};

struct _PASBackendFileBookView {
    PASBookView                 *book_view;
    gchar                       *search;
    ESExp                       *search_sexp;
    PASBackendFileSearchContext *search_context;
};

struct _PASBackendFileSearchContext {
    ECard *ecard;
};

static long
get_length(PASCardCursor *cursor, gpointer data)
{
    PASBackendFileCursorPrivate *cursor_data = (PASBackendFileCursorPrivate *) data;

    return cursor_data->num_elements;
}

static char *
get_nth(PASCardCursor *cursor, long n, gpointer data)
{
    PASBackendFileCursorPrivate *cursor_data = (PASBackendFileCursorPrivate *) data;
    GList *nth_item = g_list_nth(cursor_data->elements, n);

    return g_strdup((char*)nth_item->data);
}

static void
cursor_destroy(GtkObject *object, gpointer data)
{
    CORBA_Environment ev;
    Evolution_Book corba_book;
    PASBackendFileCursorPrivate *cursor_data = (PASBackendFileCursorPrivate *) data;

    corba_book = bonobo_object_corba_objref(BONOBO_OBJECT(cursor_data->book));

    CORBA_exception_init(&ev);

    Evolution_Book_unref(corba_book, &ev);
    
    if (ev._major != CORBA_NO_EXCEPTION) {
        g_warning("cursor_destroy: Exception unreffing "
              "corba book.\n");
    }

    CORBA_exception_free(&ev);

    g_list_foreach(cursor_data->elements, (GFunc)g_free, NULL);
    g_list_free (cursor_data->elements);

    g_free(cursor_data);
}

static void
view_destroy(GtkObject *object, gpointer data)
{
    CORBA_Environment ev;
    Evolution_Book    corba_book;
    PASBook           *book = (PASBook *)data;
    PASBackendFile    *bf;
    GList             *list;

    bf = PAS_BACKEND_FILE(pas_book_get_backend(book));
    for (list = bf->priv->book_views; list; list = g_list_next(list)) {
        PASBackendFileBookView *view = list->data;
        if (view->book_view == PAS_BOOK_VIEW(object)) {
            gtk_object_unref((GtkObject *)view->search_sexp);
            g_free (view->search_context);
            g_free (view->search);
            g_free (view);
            bf->priv->book_views = g_list_remove_link(bf->priv->book_views, list);
            g_list_free_1(list);
            break;
        }
    }

    corba_book = bonobo_object_corba_objref(BONOBO_OBJECT(book));

    CORBA_exception_init(&ev);

    Evolution_Book_unref(corba_book, &ev);
    
    if (ev._major != CORBA_NO_EXCEPTION) {
        g_warning("view_destroy: Exception unreffing "
              "corba book.\n");
    }

    CORBA_exception_free(&ev);
}

static void
string_to_dbt(const char *str, DBT *dbt)
{
    dbt->data = (void*)str;
    dbt->size = strlen (str) + 1;
}

static char *
pas_backend_file_create_unique_id (char *vcard)
{
    /* use a 32 counter and the 32 bit timestamp to make an id.
       it's doubtful 2^32 id's will be created in a second, so we
       should be okay. */
    static guint c = 0;
    return g_strdup_printf ("pas-id-%08lX%08X", time(NULL), c++);
}

static gboolean
compare_email (ECard *ecard, const char *str,
           char *(*compare)(const char*, const char*))
{
    ECardList *prop_list;
    ECardIterator *iter;
    gboolean truth = FALSE;

    gtk_object_get(GTK_OBJECT(ecard),
               "email", &prop_list, NULL);

    iter = e_card_list_get_iterator(prop_list);

    while (e_card_iterator_is_valid(iter)) {
        
        if (compare((char*)e_card_iterator_get(iter), str)) {
            truth = TRUE;
            break;
        }
        else {
            e_card_iterator_next(iter);
        }
    }

    gtk_object_unref (GTK_OBJECT(iter));

    return truth;
}

static gboolean
compare_phone (ECard *ecard, const char *str,
           char *(*compare)(const char*, const char*))
{
    ECardList *prop_list;
    ECardIterator *iter;
    gboolean truth = FALSE;

    gtk_object_get(GTK_OBJECT(ecard),
               "phone", &prop_list, NULL);
                
    iter = e_card_list_get_iterator(prop_list);

    while (e_card_iterator_is_valid(iter)) {
        ECardPhone *phone = (ECardPhone*)e_card_iterator_get(iter);
        if (compare(phone->number, str)) {
            truth = TRUE;
            break;
        }
        else {
            e_card_iterator_next(iter);
        }
    }

    gtk_object_unref (GTK_OBJECT(iter));

    return truth;
}

static gboolean
compare_address (ECard *ecard, const char *str,
         char *(*compare)(const char*, const char*))
{
    g_warning("address searching not implemented\n");
    return FALSE;
}

static struct prop_info {
    const char *query_prop;
    const char *ecard_prop;
#define PROP_TYPE_NORMAL   0x01
#define PROP_TYPE_LIST     0x02
#define PROP_TYPE_LISTITEM 0x03
    int prop_type;
    gboolean (*list_compare)(ECard *ecard, const char *str,
                 char *(*compare)(const char*, const char*));

} prop_info_table[] = {
    /* query prop,  ecard prop,   type,              list compare function */
    { "full_name",  "full_name",  PROP_TYPE_NORMAL,  NULL },
    { "url",        "url",        PROP_TYPE_NORMAL,  NULL },
    { "mailer",     "mailer",     PROP_TYPE_NORMAL,  NULL },
    { "org",        "org",        PROP_TYPE_NORMAL,  NULL },
    { "title",      "title",      PROP_TYPE_NORMAL,  NULL },
    { "role",       "role",       PROP_TYPE_NORMAL,  NULL },
    { "email",      "email",      PROP_TYPE_LIST,    compare_email },
    { "phone",      "phone",      PROP_TYPE_LIST,    compare_phone },
    { "address",    "address",    PROP_TYPE_LIST,    compare_address },
    { "note",       "note",       PROP_TYPE_NORMAL,  NULL },
};
static int num_prop_infos = sizeof(prop_info_table) / sizeof(prop_info_table[0]);

static ESExpResult *
entry_compare(PASBackendFileSearchContext *ctx, struct _ESExp *f,
          int argc, struct _ESExpResult **argv,
          char *(*compare)(const char*, const char*))
{
    ESExpResult *r;
    int truth = FALSE;

    if (argc == 2
        && argv[0]->type == ESEXP_RES_STRING
        && argv[1]->type == ESEXP_RES_STRING) {
        char *propname;
        struct prop_info *info = NULL;
        int i;

        propname = argv[0]->value.string;

        for (i = 0; i < num_prop_infos; i ++) {
            if (!strcmp (prop_info_table[i].query_prop, propname)) {
                info = &prop_info_table[i];
                break;
            }
        }

        if (info) {
            if (info->prop_type == PROP_TYPE_NORMAL) {
                char *prop = NULL;
                /* searches where the query's property
                                   maps directly to an ecard property */

                gtk_object_get(GTK_OBJECT(ctx->ecard),
                           info->ecard_prop, &prop, NULL);

                if (prop && compare(prop, argv[1]->value.string)) {
                    truth = TRUE;
                }
            }
            else if (info->prop_type == PROP_TYPE_LIST) {
                /* the special searches that match any of the list elements */
                truth = info->list_compare (ctx->ecard, argv[1]->value.string, compare);
            }
        }
        
    }
    r = e_sexp_result_new(ESEXP_RES_BOOL);
    r->value.bool = truth;

    return r;
}

static ESExpResult *
func_contains(struct _ESExp *f, int argc, struct _ESExpResult **argv, void *data)
{
    PASBackendFileSearchContext *ctx = data;

    return entry_compare (ctx, f, argc, argv, strstr);
}

static char *
is_helper (const char *s1, const char *s2)
{
    if (!strcmp(s1, s2))
        return (char*)s1;
    else
        return NULL;
}

static ESExpResult *
func_is(struct _ESExp *f, int argc, struct _ESExpResult **argv, void *data)
{
    PASBackendFileSearchContext *ctx = data;

    return entry_compare (ctx, f, argc, argv, is_helper);
}

static char *
endswith_helper (const char *s1, const char *s2)
{
    char *p;
    if ((p = strstr(s1, s2))
        && (strlen(p) == strlen(s2)))
        return p;
    else
        return NULL;
}

static ESExpResult *
func_endswith(struct _ESExp *f, int argc, struct _ESExpResult **argv, void *data)
{
    PASBackendFileSearchContext *ctx = data;

    return entry_compare (ctx, f, argc, argv, endswith_helper);
}

static char *
beginswith_helper (const char *s1, const char *s2)
{
    char *p;
    if ((p = strstr(s1, s2))
        && (p == s1))
        return p;
    else
        return NULL;
}

static ESExpResult *
func_beginswith(struct _ESExp *f, int argc, struct _ESExpResult **argv, void *data)
{
    PASBackendFileSearchContext *ctx = data;

    return entry_compare (ctx, f, argc, argv, beginswith_helper);
}

/* 'builtin' functions */
static struct {
    char *name;
    ESExpFunc *func;
    int type;       /* set to 1 if a function can perform shortcut evaluation, or
                   doesn't execute everything, 0 otherwise */
} symbols[] = {
    { "contains", func_contains, 0 },
    { "is", func_is, 0 },
    { "beginswith", func_beginswith, 0 },
    { "endswith", func_endswith, 0 },
};

static gboolean
vcard_matches_search (PASBackendFileBookView *view, char *vcard_string)
{
    ESExpResult *r;
    gboolean retval;

    view->search_context->ecard = e_card_new (vcard_string);

    /* if it's not a valid vcard why is it in our db? :) */
    if (!view->search_context->ecard)
        return FALSE;

    r = e_sexp_eval(view->search_sexp);

    retval = (r && r->type == ESEXP_RES_BOOL && r->value.bool);

    gtk_object_unref(GTK_OBJECT(view->search_context->ecard));

    e_sexp_result_free(r);

    return retval;
}

static void
pas_backend_file_search (PASBackendFile     *bf,
             PASBook            *book,
             PASBackendFileBookView *view)
{
    int     db_error = 0;
    GList   *cards = NULL;
    DB      *db = bf->priv->file_db;
    DBT     id_dbt, vcard_dbt;
    int i;

    view->search_sexp = e_sexp_new();
    view->search_context = g_new0(PASBackendFileSearchContext, 1);

    for(i=0;i<sizeof(symbols)/sizeof(symbols[0]);i++) {
        if (symbols[i].type == 1) {
            e_sexp_add_ifunction(view->search_sexp, 0, symbols[i].name,
                         (ESExpIFunc *)symbols[i].func, view->search_context);
        } else {
            e_sexp_add_function(view->search_sexp, 0, symbols[i].name,
                        symbols[i].func, view->search_context);
        }
    }

    e_sexp_input_text(view->search_sexp, view->search, strlen(view->search));
    e_sexp_parse(view->search_sexp);

    db_error = db->seq(db, &id_dbt, &vcard_dbt, R_FIRST);

    while (db_error == 0) {

        /* don't include the version in the list of cards */
        if (id_dbt.size != strlen(PAS_BACKEND_FILE_VERSION_NAME + 1)
            || strcmp (id_dbt.data, PAS_BACKEND_FILE_VERSION_NAME)) {
            char *vcard_string = vcard_dbt.data;

            /* check if the vcard matches the search sexp */
            if (vcard_matches_search (view, vcard_string)) {
                cards = g_list_append (cards, strdup(vcard_string));
            }
        }
        
        db_error = db->seq(db, &id_dbt, &vcard_dbt, R_NEXT);
    }

    if (db_error == -1) {
        g_warning ("pas_backend_file_search: error building list\n");
    }
    else {
        pas_book_view_notify_add (view->book_view, cards);
    }

    /*
    ** It's fine to do this now since the data has been handed off.
    */
    g_list_foreach (cards, (GFunc)g_free, NULL);
    g_list_free (cards);
}

static void
pas_backend_file_process_create_card (PASBackend *backend,
                      PASBook    *book,
                      PASRequest *req)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);
    DB             *db = bf->priv->file_db;
    DBT            id_dbt, vcard_dbt;
    int            db_error;
    char           *id;
    GList         *list;
    ECard         *card;
    char          *vcard;

    id = pas_backend_file_create_unique_id (req->vcard);

    string_to_dbt (id, &id_dbt);
    
    card = e_card_new(req->vcard);
    e_card_set_id(card, id);
    vcard = e_card_get_vcard(card);

    string_to_dbt (vcard, &vcard_dbt);

    db_error = db->put (db, &id_dbt, &vcard_dbt, 0);

    if (0 == db_error) {
        db_error = db->sync (db, 0);
        if (db_error != 0)
            g_warning ("db->sync failed.\n");

        for (list = bf->priv->book_views; list; list = g_list_next(list)) {
            PASBackendFileBookView *view = list->data;
            if (vcard_matches_search (view, vcard))
                pas_book_view_notify_add_1 (view->book_view, req->vcard);
        }

        pas_book_respond_create (
                 book,
                 Evolution_BookListener_Success,
                 id);

    }
    else {
        /* XXX need a different call status for this case, i
                   think */
        pas_book_respond_create (
                 book,
                 Evolution_BookListener_CardNotFound,
                 "");
    }

    g_free (id);
    g_free (vcard);
    g_free (req->vcard);

    gtk_object_unref(GTK_OBJECT(card));
    card = NULL;
}

static void
pas_backend_file_process_remove_card (PASBackend *backend,
                      PASBook    *book,
                      PASRequest *req)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);
    DB             *db = bf->priv->file_db;
    DBT            id_dbt, vcard_dbt;
    int            db_error;
    GList         *list;
    char          *vcard_string;

    string_to_dbt (req->id, &id_dbt);

    db_error = db->get (db, &id_dbt, &vcard_dbt, 0);
    if (0 != db_error) {
        pas_book_respond_remove (
                 book,
                 Evolution_BookListener_CardNotFound);
        g_free (req->id);
        return;
    }
    
    db_error = db->del (db, &id_dbt, 0);
    if (0 != db_error) {
        pas_book_respond_remove (
                 book,
                 Evolution_BookListener_CardNotFound);
        g_free (req->id);
        return;
    }

    db_error = db->sync (db, 0);
    if (db_error != 0)
        g_warning ("db->sync failed.\n");


    vcard_string = vcard_dbt.data;
    for (list = bf->priv->book_views; list; list = g_list_next(list)) {
        PASBackendFileBookView *view = list->data;
        if (vcard_matches_search (view, vcard_string))
            pas_book_view_notify_remove (view->book_view, req->id);
    }
    
    pas_book_respond_remove (
                 book,
                 Evolution_BookListener_Success);
    
    g_free (req->id);
}

static void
pas_backend_file_process_modify_card (PASBackend *backend,
                      PASBook    *book,
                      PASRequest *req)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);
    DB             *db = bf->priv->file_db;
    DBT            id_dbt, vcard_dbt;
    int            db_error;
    GList         *list;
    ECard         *card;
    char          *id;
    char          *old_vcard_string;

    /* create a new ecard from the request data */
    card = e_card_new(req->vcard);
    id = e_card_get_id(card);

    string_to_dbt (id, &id_dbt);    

    /* get the old ecard - the one that's presently in the db */
    db_error = db->get (db, &id_dbt, &vcard_dbt, 0);
    if (0 != db_error) {
        pas_book_respond_modify (
                 book,
                 Evolution_BookListener_CardNotFound);
        g_free (req->id);
        return;
    }
    old_vcard_string = g_strdup(vcard_dbt.data);

    string_to_dbt (req->vcard, &vcard_dbt); 

    db_error = db->put (db, &id_dbt, &vcard_dbt, 0);

    if (0 == db_error) {
        db_error = db->sync (db, 0);
        if (db_error != 0)
            g_warning ("db->sync failed.\n");

        for (list = bf->priv->book_views; list; list = g_list_next(list)) {
            PASBackendFileBookView *view = list->data;
            gboolean old_match, new_match;

            old_match = vcard_matches_search (view, old_vcard_string);
            new_match = vcard_matches_search (view, req->vcard);
            if (old_match && new_match)
                pas_book_view_notify_change_1 (view->book_view, req->vcard);
            else if (new_match)
                pas_book_view_notify_add_1 (view->book_view, req->vcard);
            else /* if (old_match) */
                pas_book_view_notify_remove (view->book_view, id);
        }

        pas_book_respond_modify (
                 book,
                 Evolution_BookListener_Success);
    }
    else {
        pas_book_respond_modify (
                 book,
                 Evolution_BookListener_CardNotFound);
    }

    gtk_object_unref(GTK_OBJECT(card));
    g_free (req->vcard);
}

static void
pas_backend_file_build_all_cards_list(PASBackend *backend,
                      PASBackendFileCursorPrivate *cursor_data)
{
      PASBackendFile *bf = PAS_BACKEND_FILE (backend);
      DB             *db = bf->priv->file_db;
      int            db_error;
      DBT  id_dbt, vcard_dbt;
  
      cursor_data->elements = NULL;
      
      db_error = db->seq(db, &id_dbt, &vcard_dbt, R_FIRST);

      while (db_error == 0) {

          /* don't include the version in the list of cards */
          if (id_dbt.size != strlen(PAS_BACKEND_FILE_VERSION_NAME + 1)
              || strcmp (id_dbt.data, PAS_BACKEND_FILE_VERSION_NAME)) {

              cursor_data->elements = g_list_append(cursor_data->elements,
                                g_strdup(vcard_dbt.data));

          }

          db_error = db->seq(db, &id_dbt, &vcard_dbt, R_NEXT);

      }

      if (db_error == -1) {
          g_warning ("pas_backend_file_build_all_cards_list: error building list\n");
      }
      else {
          cursor_data->num_elements = g_list_length (cursor_data->elements);
      }
}

static void
pas_backend_file_process_get_cursor (PASBackend *backend,
                     PASBook    *book,
                     PASRequest *req)
{
    /*
      PASBackendFile *bf = PAS_BACKEND_FILE (backend);
      DB             *db = bf->priv->file_db;
      DBT            id_dbt, vcard_dbt;
    */
    CORBA_Environment ev;
    int            db_error = 0;
    PASBackendFileCursorPrivate *cursor_data;
    PASCardCursor *cursor;
    Evolution_Book corba_book;

    cursor_data = g_new(PASBackendFileCursorPrivate, 1);
    cursor_data->backend = backend;
    cursor_data->book = book;

    pas_backend_file_build_all_cards_list(backend, cursor_data);

    corba_book = bonobo_object_corba_objref(BONOBO_OBJECT(book));

    CORBA_exception_init(&ev);

    Evolution_Book_ref(corba_book, &ev);
    
    if (ev._major != CORBA_NO_EXCEPTION) {
        g_warning("pas_backend_file_process_get_cursor: Exception reffing "
              "corba book.\n");
    }

    CORBA_exception_free(&ev);
    
    cursor = pas_card_cursor_new(get_length,
                     get_nth,
                     cursor_data);

    gtk_signal_connect(GTK_OBJECT(cursor), "destroy",
               GTK_SIGNAL_FUNC(cursor_destroy), cursor_data);
    
    pas_book_respond_get_cursor (
        book,
        (db_error == 0 
         ? Evolution_BookListener_Success 
         : Evolution_BookListener_CardNotFound),
        cursor);
}

static void
pas_backend_file_process_get_book_view (PASBackend *backend,
                    PASBook    *book,
                    PASRequest *req)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);
    CORBA_Environment ev;
    PASBookView       *book_view;
    Evolution_Book    corba_book;
    PASBackendFileBookView *view;

    g_return_if_fail (req->listener != NULL);

    corba_book = bonobo_object_corba_objref(BONOBO_OBJECT(book));

    CORBA_exception_init(&ev);

    Evolution_Book_ref(corba_book, &ev);
    
    if (ev._major != CORBA_NO_EXCEPTION) {
        g_warning("pas_backend_file_process_get_book_view: Exception reffing "
              "corba book.\n");
    }

    CORBA_exception_free(&ev);

    book_view = pas_book_view_new (req->listener);

    gtk_signal_connect(GTK_OBJECT(book_view), "destroy",
               GTK_SIGNAL_FUNC(view_destroy), book);

    pas_book_respond_get_book_view (book,
           (book_view != NULL
            ? Evolution_BookListener_Success 
            : Evolution_BookListener_CardNotFound /* XXX */),
           book_view);

    view = g_new(PASBackendFileBookView, 1);
    view->book_view = book_view;
    view->search = g_strdup(req->search);

    bf->priv->book_views = g_list_prepend(bf->priv->book_views, view);

    pas_backend_file_search (bf, book, view);
}

static void
pas_backend_file_process_check_connection (PASBackend *backend,
                       PASBook    *book,
                       PASRequest *req)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);

    pas_book_report_connection (book, bf->priv->file_db != NULL);
}

static void
pas_backend_file_process_client_requests (PASBook *book)
{
    PASBackend *backend;
    PASRequest *req;

    backend = pas_book_get_backend (book);

    req = pas_book_pop_request (book);
    if (req == NULL)
        return;

    switch (req->op) {
    case CreateCard:
        pas_backend_file_process_create_card (backend, book, req);
        break;

    case RemoveCard:
        pas_backend_file_process_remove_card (backend, book, req);
        break;

    case ModifyCard:
        pas_backend_file_process_modify_card (backend, book, req);
        break;

    case CheckConnection:
        pas_backend_file_process_check_connection (backend, book, req);
        break;
        
    case GetCursor:
        pas_backend_file_process_get_cursor (backend, book, req);
        break;
        
    case GetBookView:
        pas_backend_file_process_get_book_view (backend, book, req);
        break;
    }

    g_free (req);
}

static void
pas_backend_file_book_destroy_cb (PASBook *book)
{
    PASBackendFile *backend;

    backend = PAS_BACKEND_FILE (pas_book_get_backend (book));

    pas_backend_remove_client (PAS_BACKEND (backend), book);
}

static char *
pas_backend_file_get_vcard (PASBook *book, const char *id)
{
    PASBackendFile *bf;
    DBT            id_dbt, vcard_dbt;
    DB             *db;
    int            db_error;

    bf = PAS_BACKEND_FILE (pas_book_get_backend (book));
    db = bf->priv->file_db;

    string_to_dbt (id, &id_dbt);

    db_error = db->get (db, &id_dbt, &vcard_dbt, 0);
    if (db_error == 0) {
        /* success */
        return g_strdup (vcard_dbt.data);
    }
    else if (db_error == 1) {
        /* key was not in file */
        return g_strdup (""); /* XXX */
    }
    else /* if (db_error < 0)*/ {
        /* error */
        return g_strdup (""); /* XXX */
    }
}

static char *
pas_backend_file_extract_path_from_uri (const char *uri)
{
    g_assert (strncasecmp (uri, "file:", 5) == 0);

    return g_strdup (uri + 5);
}

static gboolean
pas_backend_file_upgrade_db (PASBackendFile *bf, char *old_version)
{
    if (!strcmp (old_version, "0.0")) {
        /* 0.0 is the same as 0.1, we just need to add the version */
        DB  *db = bf->priv->file_db;
        DBT version_name_dbt, version_dbt;
        int db_error;

        string_to_dbt (PAS_BACKEND_FILE_VERSION_NAME, &version_name_dbt);
        string_to_dbt (PAS_BACKEND_FILE_VERSION, &version_dbt);

        db_error = db->put (db, &version_name_dbt, &version_dbt, 0);
        if (db_error == 0)
            return TRUE;
        else
            return FALSE;
    }
    else {
        g_warning ("unsupported version '%s' found in PAS backend file\n",
               old_version);
        return FALSE;
    }
}

static gboolean
pas_backend_file_maybe_upgrade_db (PASBackendFile *bf)
{
    DB   *db = bf->priv->file_db;
    DBT  version_name_dbt, version_dbt;
    int  db_error;
    char *version;
    gboolean ret_val = TRUE;

    string_to_dbt (PAS_BACKEND_FILE_VERSION_NAME, &version_name_dbt);

    db_error = db->get (db, &version_name_dbt, &version_dbt, 0);
    if (db_error == 0) {
        /* success */
        version = g_strdup (version_dbt.data);
    }
    else {
        /* key was not in file */
        version = g_strdup ("0.0");
    }

    if (strcmp (version, PAS_BACKEND_FILE_VERSION))
        ret_val = pas_backend_file_upgrade_db (bf, version);

    g_free (version);

    return ret_val;
}

static void
pas_backend_file_load_uri (PASBackend             *backend,
               const char             *uri)
{
    PASBackendFile *bf = PAS_BACKEND_FILE (backend);
    char           *filename;

    g_assert (bf->priv->loaded == FALSE);

    filename = pas_backend_file_extract_path_from_uri (uri);

    bf->priv->file_db = dbopen (filename, O_RDWR | O_CREAT, 0666, DB_HASH, NULL);

    if (bf->priv->file_db != NULL) {
        if (pas_backend_file_maybe_upgrade_db (bf))
            bf->priv->loaded = TRUE;
        /* XXX what if we fail to upgrade it? */
    }
    else
        g_warning ("pas_backend_file_load_uri failed for '%s'\n", filename);

    g_free (filename);
}

static void
pas_backend_file_add_client (PASBackend             *backend,
                 Evolution_BookListener  listener)
{
    PASBackendFile *bf;
    PASBook        *book;

    g_assert (backend != NULL);
    g_assert (PAS_IS_BACKEND_FILE (backend));

    bf = PAS_BACKEND_FILE (backend);

    book = pas_book_new (
        backend, listener,
        pas_backend_file_get_vcard);

    g_assert (book != NULL);

    gtk_signal_connect (GTK_OBJECT (book), "destroy",
            pas_backend_file_book_destroy_cb, NULL);

    gtk_signal_connect (GTK_OBJECT (book), "requests_queued",
            pas_backend_file_process_client_requests, NULL);

    bf->priv->clients = g_list_prepend (
        bf->priv->clients, book);

    if (bf->priv->loaded) {
        pas_book_respond_open (
            book, Evolution_BookListener_Success);
    } else {
        /* Open the book. */
        pas_book_respond_open (
            book, Evolution_BookListener_Success);
    }
}

static void
pas_backend_file_remove_client (PASBackend             *backend,
                PASBook                *book)
{
    g_return_if_fail (backend != NULL);
    g_return_if_fail (PAS_IS_BACKEND (backend));
    g_return_if_fail (book != NULL);
    g_return_if_fail (PAS_IS_BOOK (book));

    g_warning ("pas_backend_file_remove_client: Unimplemented!\n");
}

static gboolean
pas_backend_file_construct (PASBackendFile *backend)
{
    g_assert (backend != NULL);
    g_assert (PAS_IS_BACKEND_FILE (backend));

    if (! pas_backend_construct (PAS_BACKEND (backend)))
        return FALSE;

    return TRUE;
}

/**
 * pas_backend_file_new:
 */
PASBackend *
pas_backend_file_new (void)
{
    PASBackendFile *backend;

    backend = gtk_type_new (pas_backend_file_get_type ());

    if (! pas_backend_file_construct (backend)) {
        gtk_object_unref (GTK_OBJECT (backend));

        return NULL;
    }

    return PAS_BACKEND (backend);
}

static void
pas_backend_file_destroy (GtkObject *object)
{
    GTK_OBJECT_CLASS (pas_backend_file_parent_class)->destroy (object); 
}

static void
pas_backend_file_class_init (PASBackendFileClass *klass)
{
    GtkObjectClass  *object_class = (GtkObjectClass *) klass;
    PASBackendClass *parent_class;

    pas_backend_file_parent_class = gtk_type_class (pas_backend_get_type ());

    parent_class = PAS_BACKEND_CLASS (klass);

    /* Set the virtual methods. */
    parent_class->load_uri      = pas_backend_file_load_uri;
    parent_class->add_client    = pas_backend_file_add_client;
    parent_class->remove_client = pas_backend_file_remove_client;

    object_class->destroy = pas_backend_file_destroy;
}

static void
pas_backend_file_init (PASBackendFile *backend)
{
    PASBackendFilePrivate *priv;

    priv             = g_new0 (PASBackendFilePrivate, 1);
    priv->loaded     = FALSE;
    priv->clients    = NULL;
    priv->book_views = NULL;

    backend->priv = priv;
}

/**
 * pas_backend_file_get_type:
 */
GtkType
pas_backend_file_get_type (void)
{
    static GtkType type = 0;

    if (! type) {
        GtkTypeInfo info = {
            "PASBackendFile",
            sizeof (PASBackendFile),
            sizeof (PASBackendFileClass),
            (GtkClassInitFunc)  pas_backend_file_class_init,
            (GtkObjectInitFunc) pas_backend_file_init,
            NULL, /* reserved 1 */
            NULL, /* reserved 2 */
            (GtkClassInitFunc) NULL
        };

        type = gtk_type_unique (pas_backend_get_type (), &info);
    }

    return type;
}