Allow the user to open a file if the lock wasn't obtained

after going through a dialog.


git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@2962 57a11ea4-9604-0410-9ed3-97b8803252fd

src/FileDialog.c

@@ -37,78 +37,86 @@
 #include "file-history.h"
 
 /* This static indicates the debugging module that this .o belongs to.  */
-// static short module = MOD_GUI;
+/* static short module = MOD_GUI; */
 
 /** GLOBALS *********************************************************/
 static Session *current_session = NULL;
 static AccountGroup *topgroup = NULL; /* the current top of the hierarchy */
 
-/********************************************************************\
- * fileMenubarCB -- handles file menubar choices                    * 
-\********************************************************************/
 
-#define SHOW_IO_ERR_MSG(io_error) {				\
+/* ======================================================== */
-  switch (io_error) {						\
+
-     case ERR_FILEIO_NO_ERROR:					\
+static gboolean
-        break;							\
+show_file_error (int io_error, char *newfile)
-     case ERR_FILEIO_FILE_NOT_FOUND:				\
+{
-        sprintf (buf, FILE_NOT_FOUND_MSG, newfile);		\
+  gboolean uh_oh = FALSE;
-        gnc_error_dialog (buf);	                		\
+  char *buf = NULL;
-        uh_oh = 1;						\
+
-        break;							\
+  switch (io_error)
-     case ERR_FILEIO_FILE_EMPTY:				\
+  {
-        sprintf (buf, FILE_EMPTY_MSG, newfile);			\
+    case ERR_FILEIO_NO_ERROR:
-        gnc_error_dialog (buf);         			\
+      break;
-        uh_oh = 1;						\
+    case ERR_FILEIO_FILE_NOT_FOUND:
-        break;							\
+      buf = g_strdup_printf (FILE_NOT_FOUND_MSG, newfile);
-     case ERR_FILEIO_FILE_TOO_NEW:				\
+      gnc_error_dialog (buf);
-        gnc_error_dialog ( FILE_TOO_NEW_MSG);	        	\
+      uh_oh = TRUE;
-        uh_oh = 1;						\
+      break;
-        break;							\
+    case ERR_FILEIO_FILE_EMPTY:
-     case ERR_FILEIO_FILE_TOO_OLD:				\
+      buf = g_strdup_printf (FILE_EMPTY_MSG, newfile);
-        if (!gnc_verify_dialog( FILE_TOO_OLD_MSG, TRUE )) {     \
+      gnc_error_dialog (buf);
-           xaccFreeAccountGroup (newgrp);			\
+      uh_oh = TRUE;
-           newgrp = NULL;					\
+      break;
-           uh_oh = 1;						\
+    case ERR_FILEIO_FILE_TOO_NEW:
-        }							\
+      gnc_error_dialog (FILE_TOO_NEW_MSG);
-        break;							\
+      uh_oh = TRUE;
-     case ERR_FILEIO_FILE_BAD_READ:				\
+      break;
-        if (!gnc_verify_dialog( FILE_BAD_READ_MSG, TRUE )) {	\
+    case ERR_FILEIO_FILE_TOO_OLD:
-           xaccFreeAccountGroup (newgrp);			\
+      if (!gnc_verify_dialog (FILE_TOO_OLD_MSG, TRUE))
-           newgrp = NULL;					\
+        uh_oh = TRUE;
-           uh_oh = 1;						\
+      break;
-        }							\
+    case ERR_FILEIO_FILE_BAD_READ:
-        break;							\
+      if (!gnc_verify_dialog (FILE_BAD_READ_MSG, TRUE))
-     default:							\
+        uh_oh = TRUE;
-        break;							\
+      break;
-  }								\
+    default:
+      break;
+  }
+
+  g_free (buf);
+
+  return uh_oh;
 }
-      
 
-#define SHOW_LOCK_ERR_MSG(session) 				\
+/* ======================================================== */
-    {								\
+
-    int norr = xaccSessionGetError (session);			\
+static gboolean
-    if (ETXTBSY == norr)					\
+show_session_error(Session *session, char *newfile)
-      {								\
+{
-        sprintf (buf, FMB_LOCKED_MSG, newfile);			\
+  int norr = xaccSessionGetError (session);
-        gnc_error_dialog (buf);				        \
+  gboolean uh_oh = FALSE;
-        uh_oh = 1;						\
+  char *buf = NULL;
-      }								\
+
-    else 							\
+  if (ETXTBSY == norr)
-    if (ERANGE == norr)						\
+  {
-      {								\
+    uh_oh = TRUE;
-        sprintf (buf, FILE_NOT_FOUND_MSG, newfile);		\
+  }
-        gnc_error_dialog (buf);				        \
+  else if (ERANGE == norr)
-        uh_oh = 1;						\
+  {
-      }								\
+    buf = g_strdup_printf (FILE_NOT_FOUND_MSG, newfile);
-    else 							\
+    gnc_error_dialog (buf);
-    if (norr)							\
+    uh_oh = TRUE;
-      {								\
+  }
-        sprintf (buf, FMB_INVALID_MSG, newfile);		\
+  else if (norr)
-        gnc_error_dialog (buf);				        \
+  {
-        uh_oh = 1;						\
+    buf = (FMB_INVALID_MSG, newfile);
-      }								\
+    gnc_error_dialog (buf);
-    }								\
+    uh_oh = TRUE;
+  }
+
+  g_free(buf);
+
+  return uh_oh;
+}
 
 /* ======================================================== */
 
@@ -191,6 +199,29 @@ gncFileQuerySave (void)
   return TRUE;
 }
 
+/* ======================================================== */
+
+static gboolean
+gncLockFailHandler (const char *file)
+{
+  const char *format = _("Gnucash could not obtain the lock for\n"
+                         "   %s.\n"
+                         "That file may be in use by another user,\n"
+                         "in which case you should not open the file.\n"
+                         "\nDo you want to proceed with opening the file?");
+  char *message;
+  gboolean result;
+
+  if (file == NULL)
+    return FALSE;
+
+  message = g_strdup_printf (format, file);
+  result = gnc_verify_dialog (message, FALSE);
+  g_free (message);
+
+  return result;
+}
+
 /* ======================================================== */
 /* private utilities for file open; done in two stages */
 
@@ -199,16 +230,17 @@ gncPostFileOpen (const char * filename)
 {
   Session *newsess;
   AccountGroup *oldgrp;
-  int io_error, uh_oh=0;
+  gboolean uh_oh = FALSE;
-  char buf[BUFSIZE];
+  int io_error;
   AccountGroup *newgrp;
   char * newfile;
 
   if (!filename) return;
   newfile = xaccResolveFilePath (filename); 
   if (!newfile) {
-     sprintf (buf, FILE_NOT_FOUND_MSG, filename);
+     char *buf = g_strdup_printf (FILE_NOT_FOUND_MSG, filename);
      gnc_error_dialog (buf);
+     g_free(buf);
      return;
   }
 
@@ -227,26 +259,32 @@ gncPostFileOpen (const char * filename)
    * switchover is not something we want to keep in a journal.  */
   gnc_set_busy_cursor(NULL);
   xaccLogDisable();
-  newgrp = xaccSessionBeginFile (newsess, newfile);
+  newgrp = xaccSessionBeginFile (newsess, newfile, gncLockFailHandler);
   xaccLogEnable();
   gnc_unset_busy_cursor(NULL);
 
   /* check for session errors, put up appropriate dialog */
-  SHOW_LOCK_ERR_MSG (newsess);
+  uh_oh = show_session_error (newsess, newfile);
 
   if (!uh_oh)
   {
     /* check for i/o error, put up appropriate error message */
     io_error = xaccGetFileIOError();
-    SHOW_IO_ERR_MSG(io_error);
+    uh_oh = show_file_error (io_error, newfile);
+    if (uh_oh)
+    {
+      xaccFreeAccountGroup (newgrp);
+      newgrp = NULL;
+    }
 
     /* Umm, came up empty-handed, i.e. the file was not found. */
     /* This is almost certainly not what the user wanted. */
     if (!uh_oh && !newgrp && !io_error) 
     {
-      sprintf (buf, FILE_NOT_FOUND_MSG, newfile);	
+      char *buf = g_strdup_printf (FILE_NOT_FOUND_MSG, newfile);	
-      gnc_error_dialog ( buf);
+      gnc_error_dialog (buf);
-      uh_oh = 1;
+      g_free (buf);
+      uh_oh = TRUE;
     }
   }
 
@@ -258,9 +296,9 @@ gncPostFileOpen (const char * filename)
 
     /* well, no matter what, I think its a good idea to have 
      * a topgroup around.  For example, early in the gnucash startup
-     * sequence, the user opens a file ... if this open fails for any 
+     * sequence, the user opens a file; if this open fails for any 
      * reason, we don't want to leave them high & dry without a topgroup,
-     * because if user continues, then bad things will happen ...
+     * because if the user continues, then bad things will happen.
      */
     if (NULL == topgroup) 
     {
@@ -343,7 +381,6 @@ gncFileSave (void)
 {
   AccountGroup *newgrp = NULL;
   char * newfile;
-  char buf[BUFSIZE];
   int io_error, norr, uh_oh = 0;
 
   /* hack alert -- Somehow make sure all in-progress edits get committed! */
@@ -392,7 +429,13 @@ gncFileSave (void)
   io_error = xaccGetFileIOError();
   newfile = xaccSessionGetFilePath(current_session);
   gnc_history_add_file(newfile);
-  SHOW_IO_ERR_MSG(io_error);
+
+  uh_oh = show_file_error (io_error, newfile);
+  if (uh_oh)
+  {
+    xaccFreeAccountGroup (newgrp);
+    newgrp = NULL;
+  }
 
   /* going down -- abandon ship */
   if (uh_oh) return;
@@ -411,8 +454,8 @@ gncFileSaveAs (void)
   char *newfile;
   AccountGroup *newgrp;
   char * oldfile;
-  char buf[BUFSIZE];
+  int io_error;
-  int io_error, uh_oh = 0;
+  gboolean uh_oh = FALSE;
 
   filename = fileBox(SAVE_STR, "*.gnc");
   if (!filename) return;
@@ -424,8 +467,9 @@ gncFileSaveAs (void)
    */
   newfile = xaccResolveFilePath (filename);
   if (!newfile) {
-     sprintf (buf, FILE_NOT_FOUND_MSG, filename);
+     char *buf = g_strdup_printf (FILE_NOT_FOUND_MSG, filename);
      gnc_error_dialog (buf);
+     g_free (buf);
      return;
   }
   oldfile = xaccSessionGetFilePath (current_session);
@@ -449,17 +493,22 @@ gncFileSaveAs (void)
    * edit; the mass deletetion of accounts and transactions during
    * switchover is not something we want to keep in a journal.  */
   xaccLogDisable();
-  newgrp = xaccSessionBeginFile (newsess, newfile);
+  newgrp = xaccSessionBeginFile (newsess, newfile, gncLockFailHandler);
   xaccLogEnable();
 
   /* check for session errors (e.g. file locked by another user) */
-  SHOW_LOCK_ERR_MSG (newsess);
+  uh_oh = show_session_error (newsess, newfile);
 
   if (!uh_oh)
   {
     /* check for i/o error, put up appropriate error message */
     io_error = xaccGetFileIOError();
-    SHOW_IO_ERR_MSG(io_error);
+    uh_oh = show_file_error (io_error, newfile);
+    if (uh_oh)
+    {
+      xaccFreeAccountGroup (newgrp);
+      newgrp = NULL;
+    }
   }
 
   /* going down -- abandon ship */
@@ -496,10 +545,15 @@ gncFileSaveAs (void)
   if (newgrp) 
   {
     char *tmpmsg;
-    tmpmsg = alloca (strlen (FMB_EEXIST_MSG) + strlen (newfile));
+    gboolean result;
-    sprintf (tmpmsg, FMB_EEXIST_MSG, newfile);
+
+    tmpmsg = g_strdup_printf (FMB_EEXIST_MSG, newfile);
+    result = gnc_verify_dialog (tmpmsg, FALSE);
+    g_free (tmpmsg);
+
     /* if user says cancel, we should break out */
-    if (! gnc_verify_dialog (tmpmsg, FALSE)) return;
+    if (!result)
+      return;
 
     /* Whoa-ok. Blow away the previous file. 
      * Do not disable logging ... we want to capture the 
@@ -537,7 +591,6 @@ gncFileQuit (void)
   xaccSessionEnd (current_session);
   xaccSessionDestroy (current_session);
   current_session = NULL;
-  //  xaccGroupWindowDestroy (grp);
   xaccFreeAccountGroup (grp);
   topgroup = NULL;
 }

src/engine/Session.c

@@ -1,15 +1,3 @@
-/*
- * FILE:
- * Session.c
- *
- * FUNCTION:
- * Provide wrappers for initiating/concluding a file-editing session.
- *
- * HISTORY:
- * Created by Linas Vepstas December 1998
- * Copyright (c) 1998-2000 Linas Vepstas
- */
-
 /********************************************************************\
  * This program is free software; you can redistribute it and/or    *
  * modify it under the terms of the GNU General Public License as   *
@@ -29,6 +17,18 @@
  * Boston, MA  02111-1307,  USA       gnu@gnu.org                   *
 \********************************************************************/
 
+/*
+ * FILE:
+ * Session.c
+ *
+ * FUNCTION:
+ * Provide wrappers for initiating/concluding a file-editing session.
+ *
+ * HISTORY:
+ * Created by Linas Vepstas December 1998
+ * Copyright (c) 1998-2000 Linas Vepstas
+ */
+
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
@@ -81,7 +81,7 @@ Session *
 xaccMallocSession (void)
 {
    Session *sess;
-   sess =  (Session *) malloc (sizeof (Session));
+   sess = g_new(Session, 1);
 
    xaccInitSession (sess);
    return sess;
@@ -179,7 +179,7 @@ xaccSessionBegin (Session *sess, const char * sid)
    }
 
    /* add 5 to space past 'file:' */
-   retval = xaccSessionBeginFile (sess, sid+5);
+   retval = xaccSessionBeginFile (sess, sid+5, NULL);
 
    return retval;
 }
@@ -217,12 +217,79 @@ extern Backend * pgendNew (void);
 
 /* ============================================================== */
 
+static gboolean
+xaccSessionGetFileLock (Session *sess)
+{
+  struct stat statbuf;
+  char pathbuf[PATH_MAX];
+  char *path = NULL;
+  int rc;
+
+  rc = stat (sess->lockfile, &statbuf);
+  if (!rc) {
+    /* oops .. file is all locked up  .. */
+    sess->errtype = ETXTBSY;  
+    return FALSE;
+  }
+
+  sess->lockfd = open (sess->lockfile, O_RDWR | O_CREAT | O_EXCL , 0);
+  if (0 > sess->lockfd) {
+    /* oops .. file is all locked up  .. */
+    sess->errtype = ETXTBSY;
+    return FALSE;
+  }
+
+  /* OK, now work around some NFS atomic lock race condition 
+   * mumbo-jumbo.  We do this by linking a unique file, and 
+   * then examing the link count.  At least that's what the 
+   * NFS programmers guide suggests. 
+   * Note: the "unique filename" must be unique for the
+   * triplet filename-host-process, otherwise accidental 
+   * aliases can occur.
+   */
+
+  /* apparently, even this code may not work for some NFS
+   * implementations. In the long run, I am told that 
+   *  ftp.debian.org
+   * /pub/debian/dists/unstable/main/source/libs/liblockfile_0.1-6.tar.gz
+   * provides a better long-term solution.
+   */
+
+  strcpy (pathbuf, sess->lockfile);
+  path = strrchr (pathbuf, '.');
+  sprintf (path, ".%lx.%d.LNK", gethostid(), getpid());
+  link (sess->lockfile, pathbuf);
+  rc = stat (sess->lockfile, &statbuf);
+  if (rc) {
+    /* oops .. stat failed!  This can't happen! */
+    sess->errtype = ETXTBSY;
+    unlink (pathbuf);
+    close (sess->lockfd);
+    unlink (sess->lockfile);
+    return FALSE;
+  }
+
+  if (2 != statbuf.st_nlink) {
+    /* oops .. stat failed!  This can't happen! */
+    sess->errtype = ETXTBSY;
+    unlink (pathbuf);
+    close (sess->lockfd);
+    unlink (sess->lockfile);
+    return FALSE;
+  }
+
+  sess->linkfile = g_strdup (pathbuf);
+
+  return TRUE;
+}
+
+/* ============================================================== */
+
 AccountGroup *
-xaccSessionBeginFile (Session *sess, const char * filefrag)
+xaccSessionBeginFile (Session *sess, const char * filefrag,
+                      SessionLockFailHandler handler)
 {
    struct stat statbuf;
-   char pathbuf[PATH_MAX];
-   char *path = NULL;
    int rc;
 
    if (!sess) return NULL;
@@ -252,87 +319,27 @@ xaccSessionBeginFile (Session *sess, const char * filefrag)
    }
 
    /* Store the sessionid URL also ... */
-   strcpy (pathbuf, "file:");
+   sess->sessionid = g_strconcat ("file:", filefrag, NULL);
-   strcat (pathbuf, filefrag);
-   sess->sessionid = strdup (pathbuf);
 
    /* ---------------------------------------------------- */
    /* We should now have a fully resolved path name.
-    * Lets see if we can get a lock on it. 
+    * Lets see if we can get a lock on it. */
-    */
 
-   sess->lockfile = malloc (strlen (sess->fullpath) + 5);
+   sess->lockfile = g_strconcat(sess->fullpath, ".LCK", NULL);
-   strcpy (sess->lockfile, sess->fullpath);
-   strcat (sess->lockfile, ".LCK");
-  
-   rc = stat (sess->lockfile, &statbuf);
-   if (!rc) {
-      /* oops .. file is all locked up  .. */
-      sess->errtype = ETXTBSY;  
-      free (sess->sessionid); sess->sessionid = NULL;
-      free (sess->fullpath);  sess->fullpath = NULL;
-      free (sess->lockfile);  sess->lockfile = NULL;
-      return NULL;    
-   }
-   sess->lockfd = open (sess->lockfile, O_RDWR | O_CREAT | O_EXCL , 0);
-   if (0 > sess->lockfd) {
-      /* oops .. file is all locked up  .. */
-      sess->errtype = ETXTBSY;  
-      free (sess->sessionid); sess->sessionid = NULL;
-      free (sess->fullpath);  sess->fullpath = NULL;
-      free (sess->lockfile);  sess->lockfile = NULL;
-      return NULL;    
-   }
 
-   /* OK, now work around some NFS atomic lock race condition 
+   if (!xaccSessionGetFileLock (sess)) {
-    * mumbo-jumbo.  We do this by linking a unique file, and 
+      if (!handler || !handler (sess->fullpath)) {
-    * then examing the link count.  At least that's what the 
+        g_free (sess->sessionid); sess->sessionid = NULL;
-    * NFS programmers guide suggests. 
+        g_free (sess->fullpath);  sess->fullpath = NULL;
-    * Note: the "unique filename" must be unique for the
+        g_free (sess->lockfile);  sess->lockfile = NULL;
-    * triplet filename-host-process, otherwise accidental 
+        return NULL;
-    * aliases can occur.
+      }
-    */
-   /* appearently, even this code may not work for some NFS
-    * implementations.  In the long run, I am told that 
-    *  ftp.debian.org
-    * /pub/debian/dists/unstable/main/source/libs/liblockfile_0.1-6.tar.gz
-    * provides a better long-term solution.
-    */
-   strcpy (pathbuf, sess->lockfile);
-   path = strrchr (pathbuf, '.');
-   sprintf (path, ".%lx.%d.LNK", gethostid(), getpid());
-   link (sess->lockfile, pathbuf);
-   rc = stat (sess->lockfile, &statbuf);
-   if (rc) {
-      /* oops .. stat failed!  This can't happen! */
-      sess->errtype = ETXTBSY;  
-      unlink (pathbuf);
-      close (sess->lockfd);
-      unlink (sess->lockfile);
-      free (sess->sessionid); sess->sessionid = NULL;
-      free (sess->fullpath);  sess->fullpath = NULL;
-      free (sess->lockfile);  sess->lockfile = NULL;
-      return NULL;    
    }
 
-   if (2 != statbuf.st_nlink) {
-      /* oops .. stat failed!  This can't happen! */
-      sess->errtype = ETXTBSY;  
-      unlink (pathbuf);
-      close (sess->lockfd);
-      unlink (sess->lockfile);
-      free (sess->sessionid); sess->sessionid = NULL;
-      free (sess->fullpath);  sess->fullpath = NULL;
-      free (sess->lockfile);  sess->lockfile = NULL;
-      return NULL;    
-   }
-   sess->linkfile = strdup (pathbuf);
-
    /* ---------------------------------------------------- */
    /* OK, if we've gotten this far, then we've succesfully obtained 
-    * an atomic lock on the file.  Go read the file contents ... 
+    * an atomic lock on the file.  Go read the file contents if it
-    * well, read it only if it exists ... 
+    * exists. */
-    */
 
    sess->errtype = 0;
    sess->topgroup = NULL;
@@ -387,13 +394,20 @@ xaccSessionEnd (Session *sess)
    if (sess->linkfile) unlink (sess->linkfile);
    if (0 < sess->lockfd) close (sess->lockfd);
    if (sess->lockfile) unlink (sess->lockfile);
-   if (sess->sessionid) free (sess->sessionid); sess->sessionid = NULL;
-   if (sess->fullpath) free (sess->fullpath);  sess->fullpath = NULL;
-   if (sess->lockfile) free (sess->lockfile);  sess->lockfile = NULL;
-   if (sess->linkfile) free (sess->linkfile);  sess->linkfile = NULL;
-   sess->topgroup = NULL;
 
-   return;    
+   g_free (sess->sessionid);
+   sess->sessionid = NULL;
+
+   g_free (sess->fullpath);
+   sess->fullpath = NULL;
+
+   g_free (sess->lockfile);
+   sess->lockfile = NULL;
+
+   g_free (sess->linkfile);
+   sess->linkfile = NULL;
+
+   sess->topgroup = NULL;
 }
 
 void 
@@ -401,7 +415,7 @@ xaccSessionDestroy (Session *sess)
 {
    if (!sess) return;
    xaccSessionEnd (sess);
-   free (sess);
+   g_free (sess);
 }
 
 
@@ -415,29 +429,32 @@ MakeHomeDir (void)
 {
    int rc;
    struct stat statbuf;
-   char *home, *path;
+   char *home;
+   char *path;
+   char *data;
 
    /* Punt. Can't figure out where home is. */
    home = getenv ("HOME");
    if (!home) return;
 
-   path = alloca (strlen (home) +50);
+   path = g_strconcat(home, "/.gnucash", NULL);
-   strcpy (path, home);
-   strcat (path, "/.gnucash");
 
    rc = stat (path, &statbuf);
    if (rc) {
       /* assume that the stat failed only because the dir is absent,
        * and not because its read-protected or other error.
        * Go ahead and make it. Don't bother much with checking mkdir 
-       * for errors; seems pointless ...  */
+       * for errors; seems pointless. */
       mkdir (path, S_IRWXU);   /* perms = S_IRWXU = 0700 */
    }
 
-   strcat (path, "/data");
+   data = g_strconcat (path, "/data");
-   rc = stat (path, &statbuf);
+   rc = stat (data, &statbuf);
    if (rc)
-      mkdir (path, S_IRWXU);
+      mkdir (data, S_IRWXU);
+
+   g_free (path);
+   g_free (data);
 }
 
 /* ============================================================== */

src/engine/Session.h

@@ -88,7 +88,12 @@ void       xaccSessionDestroy (Session *);
  *
  * The xaccSessionBeginFile() routine is identical to the xaccSessionBegin()
  *    routine, except that the argument is a filename (i.e. the five
- *    letters "file:" should not be prepended).
+ *    letters "file:" should not be prepended) and there is an additional
+ *    function argument. This function is called if xaccSessionBeginFile
+ *    fails to obtain a lock for the file. If it returns true, the file
+ *    is loaded anyway. If it returns false, or the handler is NULL, a
+ *    failed lock attempt will abort the load. The lock fail handler is
+ *    passed the filename of the data file being loaded.
  *
  * The xaccSessionGetFilePath() routine returns the fully-qualified file
  *    path for the session.  That is, if a relative or partial filename
@@ -168,8 +173,11 @@ void       xaccSessionDestroy (Session *);
  *    xaccSessionDestroy (sess);
  * */
 
+typedef gboolean (*SessionLockFailHandler)(const char *file);
+
 AccountGroup * xaccSessionBegin       (Session *, const char * sessionid);
-AccountGroup * xaccSessionBeginFile   (Session *, const char * filename);
+AccountGroup * xaccSessionBeginFile   (Session *, const char * filename,
+                                       SessionLockFailHandler handler);
 int            xaccSessionGetError    (Session *);
 AccountGroup * xaccSessionGetGroup    (Session *);
 void           xaccSessionSetGroup    (Session *, AccountGroup *topgroup);