[ka-Map-users] Segmentation fault in tile.php
steve.lime at dnr.state.mn.us
Wed Mar 1 14:38:27 EST 2006
What happens when you render the mapfile outside of ka-map and
outside of mapscript? That is, using shp2img or mapserv CGI?
>>> David Badke <dbadke at uvic.ca> 03/01/06 1:14 PM >>>
The only thing I've seen was from the MapServer list (see below). The
systems guys here applied the patch, but it didn't help. I have since
run a test generating TrueType text using only GD/FreeType, which
worked, and ka-Map tile.php with TYPE BITMAP in my .map file, which
worked. Setting TYPE TRUETYPE causes the segmentation fault, and no one
knows why... We are assuming it is some problem -- possibly
configuration -- with PHP MapScript --> GD --> FreeType; it doesn't look
like a problem in tile.php itself. MapScript is not generating any
error, just crashing, so it is proving hard to track down.
Since no one else has reported a similar problem here, I guess no one
else has seen this error... :'(
>From the MapServer mailing list (14 Feb 2006):
Hi all: There have been a number of users reporting issues with 1 pixel
seg. faults and version 4.8. There is a problem with GD. The library
does not properly
check pixel values against the image size which can result in a buffer
overflow in some
cases. The GD author is aware of the problem but has not released a fix
yet- no idea
why since it is a pretty severe error.
Anyway, to use 1 pixel-wide antialiasing you *MUST* apply a small fix to
the fix is a one-liner.
In gd.c, function gdImageSetAAPixelColor() change:
p = gdImageGetPixel(im,x,y);
if (!gdImageBoundsSafeMacro (im, x, y)) return;
p = gdImageGetPixel(im,x,y);
Jon Fatula wrote:
> Hi, David,
> No insights, just commiseration: after struggling mightily with 4.8/gd
> under RedHat ES3, I gave up and dropped back to 4.6.2... Have you seen
> any off-list patches or suggestions?
> Jon Fatula
> jonf at cruzio.com
> -----Original Message-----
> From: ka-map-users-bounces at lists.maptools.org
> [mailto:ka-map-users-bounces at lists.maptools.org]On Behalf Of David Badke
> Sent: Monday, February 27, 2006 11:29 AM
> To: ka-map-users at lists.maptools.org
> Subject: [ka-Map-users] Segmentation fault in tile.php
> I am running ka-Map on a local Windows XP system, and now on a remote
> Linux server. Both systems are running the same ka-Map code (version 0.2
> with mods) and version 4.8 of MapServer/ PHP MapScript. On the Windows
> system, everything is working; on Linux, everything is working except a
> label layer. All of the relevant files are the same on both systems. The
> layer is:
> NAME "Labels"
> GROUP "Labels"
> STATUS OFF
> DATA "vicbird1878"
> TYPE ANNOTATION
> LABELITEM "LABEL"
> MAXSCALE 150
> SYMBOLSCALE 71
> TYPE TRUETYPE
> FONT "lucida-sans"
> SIZE 9
> POSITION UC
> OFFSET 0 8
> COLOR 0 0 0
> BACKGROUNDCOLOR 255 255 255
> MINSIZE 8
> MAXSIZE 10
> BUFFER 1
> There is also a raster layer and a point layer; the point layer uses the
> same shape file as the annotation layer, and displays correctly on both
> With TYPE TRUETYPE, I get no labels on Linux (I do on Windows). If I run
> tile.php directly (on the Linux server) in Firefox (with appropriate t,
> l, g, s, etc. parameters) I get an "internal server error (500)"
> response in the browser, and the server log reports a segmentation fault
> (the same tile.php URL produces the correct label on the Windows
> system). If I change the layer to TYPE BITMAP, I get no error but still
> get no labels -- the tiles are created but are blank (white). If I use
> TrueType but change the FONT to something nonexistent ("xxxxx"), there
> is also no error (and of course no label), which suggests that my font
> set file is OK and the "lucida-sans" font file is being found.
> I noticed a problem report on the MapServer list about segmentation
> faults with MS 4.8 and GD, but that had to do with antialiasing, which I
> have not turned on (the server guys are looking into the bug anyway, in
> case there is some antialiasing going on that I don't know about).
> Anyone have any idea what might be going wrong on the Linux server? I am
> getting nowhere on this...
Humanities Computing and Media Center
University of Victoria, BC, Canada
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