Dominique Pelle wrote:
> Valgrind memory checker detects use of uninitialised value vim:
>
> ==6865== Conditional jump or move depends on uninitialised value(s)
> ==6865== at 0x814E0BA: do_xterm_trace (os_unix.c:6121)
> ==6865== by 0x814E038: start_xterm_trace (os_unix.c:6081)
> ==6865== by 0x81B25BA: check_termcode (term.c:4301)
> ==6865== by 0x80D4A58: vgetorpeek (getchar.c:2253)
> ==6865== by 0x80D3B9C: vgetc (getchar.c:1552)
> ==6865== by 0x80D4117: safe_vgetc (getchar.c:1757)
> ==6865== by 0x8121D96: normal_cmd (normal.c:625)
> ==6865== by 0x80E5A49: main_loop (main.c:1181)
> ==6865== by 0x80E5599: main (main.c:940)
>
> Steps to reproduce:
>
> 1/ Run vim with the mouse option in a terminal:
>
> $ valgrind vim -u NONE -c 'set mouse=a' 2> vg.log
>
> 2/ Left click with the mouse anywhere in the terminal to position cursor
>
> 3/ Observe the valgrind error at os_unix.c:6121 (do_xterm_trace)
> Cursor is positioned properly where I click (no apparent wrong
> behavior despite the error).
>
> Code in os_unix.c:
>
> 6118 /* Get the hints just before tracking starts. The font size
> might
> 6119 * have changed recently */
> 6120 XGetWMNormalHints(xterm_dpy, x11_window, &xterm_hints,
> &got_hints);
> 6121 if (!(got_hints & PResizeInc)
> 6122 || xterm_hints.width_inc <= 1
> 6123 || xterm_hints.height_inc <= 1)
> 6124 {
> 6125 xterm_trace = -1; /* Not enough data -- disable tracing */
> 6126 return FALSE;
> 6127 }
>
> When error happens, call to XGetWMNormalHints(...) at line 6120 fails
> somehow [i.e. it returns a 0 (error), I don't know why]. When
> XGetWMNormalHints(...) fails, it does not initialize output value
> got_hints, hence access to uninitialized value later at line 6121.
>
> Here is a snippet of the man page of XGetWMNormalHints(...):
>
> -------------------------------------------
> The XGetWMNormalHints function returns the size hints stored in the WM_NOR‐
> MAL_HINTS property on the specified window. If the property is of type
> WM_SIZE_HINTS, is of format 32, and is long enough to contain either an old
> (pre-ICCCM) or new size hints structure, XGetWMNormalHints sets the various
> fields of the XSizeHints structure, sets the supplied_return argument to the
> list of fields that were supplied by the user (whether or not they contained
> defined values), and returns a nonzero status. Otherwise, it returns a zero
> status.
>
> If XGetWMNormalHints returns successfully and a pre-ICCCM size hints property
> is read, the supplied_return argument will contain the following bits:
> -------------------------------------------
>
> I attach a patch which fixes it by checking the return value of
> XGetWMNormalHints(...). It would be interesting to know why
> XGetWMNormalHints(...) failed in the first place though.
>
> I am using vim-7.1 (Patches 1-220) built with 'configure --with-feature=huge',
> without optimizations (-g -O0) on Linux in a gnome-terminal.
Looks like a good fix. I'll include it. Thanks!
- Bram
--
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/// Bram Moolenaar -- [EMAIL PROTECTED] -- http://www.Moolenaar.net \\\
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