--- Begin Message ---
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Subject: |
Unnecessary fail when XGetVisualInfo returns multiple records |
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Date: |
Mon, 12 Apr 2010 10:54:20 -0400 |
Package: emacs
Version: 23.1.50; 23.1.1; 22.2.1
When invoking emacs on a remote session using Xephyr, it responds
emacs: Can't get proper X visual info
In version 22 there is a newline after the message, in version 23
there is no newline.
I've traced the problem to the function select_visual in the file xfns.c. If
the resource database does not specify a preference, it attempts to use
the default visual by getting a screen number and visual id from the supplied
dpyinfo structure.
For some reason Xephyr returns multiple records corresponding to the
same visual id.
This shows up in xpdyinfo as well, output at the end of this email.
The default id is 0x21,
and there are two identical entries for it. Every other visual id has
a single record.
The offending code is in this block:
{
int n_visuals;
XVisualInfo *vinfo, vinfo_template;
dpyinfo->visual = DefaultVisualOfScreen (screen);
vinfo_template.visualid = XVisualIDFromVisual (dpyinfo->visual);
vinfo_template.screen = XScreenNumberOfScreen (screen);
vinfo = XGetVisualInfo (dpy, VisualIDMask | VisualScreenMask,
&vinfo_template, &n_visuals);
if (n_visuals != 1) /* PROBLEM */
fatal ("Can't get proper X visual info");
dpyinfo->n_planes = vinfo->depth;
XFree ((char *) vinfo);
}
It seems that simply checking for n_visuals>1 would be sufficient. In
this particular bug,
the 2 XVisualInfo structures returned are actually identical,
including pointing to the same
Visual structure.
output of xdpyinfo:
address@hidden /usr/local/share/doc/X11-1.4.5]$ xdpyinfo -display :1
name of display: :1.0
version number: 11.0
vendor string: The X.Org Foundation
vendor release number: 10601000
X.Org version: 1.6.1
maximum request size: 16777212 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 4, bits_per_pixel 4, scanline_pad 32
depth 8, bits_per_pixel 8, scanline_pad 32
depth 15, bits_per_pixel 16, scanline_pad 32
depth 16, bits_per_pixel 16, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x2e0ccc3, revert to Parent
number of extensions: 23
BIG-REQUESTS
Composite
DAMAGE
DOUBLE-BUFFER
DPMS
GLX
Generic Event Extension
MIT-SCREEN-SAVER
MIT-SHM
RANDR
RENDER
SGI-GLX
SHAPE
SYNC
X-Resource
XC-MISC
XFIXES
XFree86-DRI
XINERAMA
XInputExtension
XKEYBOARD
XTEST
XVideo
default screen number: 0
number of screens: 1
screen #0:
print screen: no
dimensions: 1024x768 pixels (347x260 millimeters)
resolution: 75x75 dots per inch
depths (7): 1, 4, 8, 15, 16, 24, 32
root window id: 0xdf
depth of root window: 24 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x20
default number of colormap cells: 256
preallocated pixels: black 0, white 16777215
options: backing-store NO, save-unders NO
largest cursor: 1024x768
current input event mask: 0xfa8033
KeyPressMask KeyReleaseMask EnterWindowMask
LeaveWindowMask ExposureMask StructureNotifyMask
SubstructureNotifyMask SubstructureRedirectMask FocusChangeMask
PropertyChangeMask ColormapChangeMask
number of visuals: 99
default visual id: 0x21
visual:
visual id: 0x21
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x21
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0x22
class: DirectColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0xd3
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0xd4
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
visual:
visual id: 0xd5
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
[...]
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