Bug#611232: libx11-6: XrmSetDatabase is documented to not free the database, but frees it, causing crashes

[Marc Lehmann <debian-reportbug@plan9.de>]

Package: libx11-6
Version: 2:1.3.3-4
Severity: normal


The documentation for XrmSetDatabase says:

   "The database previously associated with the display (if any) is not
   destroyed."

Consequently, to avoid memory leaks, rxvt-unicode uses this to replace it:

   XrmDestroyDatabase (XrmGetDatabase (dpy));
   XrmSetDatabase (dpy, get_resources (true));

This works almost always. However, sometimes, some third-party library
calls XGetDefault itself, and this causes the undocumented behaviour of
freeing the resource database in XrmSetDatabase.

    LockDisplay(display);
    /* destroy database if set up imlicitely by XGetDefault() */
    if (display->db && (display->flags & XlibDisplayDfltRMDB)) {
        XrmDestroyDatabase(display->db);
        display->flags &= ~XlibDisplayDfltRMDB;
    }
    display->db = database;
    UnlockDisplay(display);

This makes it basically impossible to both avoid a memory leak AND not
crashing on a double free.

And either the manpage is wrong (which claims the database isn't freed) or
the code.

-- System Information:
Debian Release: squeeze/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.37-trunk-amd64 (SMP w/4 CPU cores)
Locale: LANG=C, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages libx11-6 depends on:
hi  libc6                         2.11.2-7   Embedded GNU C Library: Shared lib
ii  libx11-data                   2:1.3.3-4  X11 client-side library
ii  libxcb1                       1.6-1      X C Binding

libx11-6 recommends no packages.

libx11-6 suggests no packages.

-- debconf information excluded