Tk Toolkit

8.6a1, but code is same as now and long before.

Some of my users are getting a crash in CFStringGetCString invoked
from GetFontFamilyName (tkMacOSXFont.c). (There is a comment above
these lines about a possible crash.) I cannot replicate it, and the
circumstances are strange: when MS Word 2008 is running, application
startup will crash, otherwise not. My rough guess is that additional
fonts or font manager are made available when this app is running,
with some characteristics that trigger the crash.

I am attaching a user-generated trace. Looking at the code in
GetFontFamilyName, several things seem suspicious. I'm not a
Carbon programmer so I am not sure though. I have made a patch
that addresses the most obvious ones and am sending it off for
user testing.

If someone who knows more about Carbon font handling and data types
could take a look, that would be great.

Things That Seem Strange But I'm Not A Carbon Programmer:

1) FontFamilyEnumCallback:
err = ChkErr(GetFontFamilyName, family, name, sizeof(name));
!!! converts ATSFontFamilyRef (UInt32) to FMFontFamily (SInt16)
lossy conversion, and anyway are semantics the same?
in my trace, this conversion is lossy: 4294961600 -> -5696

2) GetFontFamilyName:
encoding = kTextEncodingMacRoman;
!!! This shouldn't be needed unless next line fails, in which case the
rest
of the function should be aborted.

ChkErr(FMGetFontFamilyTextEncoding, fontFamily, &encoding);
!!! This function is deprecated as of 10.4, though no replacement
advice
seems to be given.

nameencoding = encoding;
!!! encoding is UInt32 while nameencoding is SInt16
furthermore are the semantics the same?

ChkErr(RevertTextEncodingToScriptInfo, encoding, &nameencoding, NULL,
NULL);
!!! nameencoding is ScriptCode (SInt16), CFStringEncoding (UInt32)
expected

CFStringGetCString(
cfString, name, numBytes, kCFStringEncodingUTF8);
!!! cfString returned is not checked for NULL after previous call


Stack Trace (some proprietary info removed):

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x00000000
0x962de133 in CFStringGetCString ()
(gdb) bt
#0 0x962de133 in CFStringGetCString ()
#1 0x0b106c4d in GetFontFamilyName (fontFamily=-5696, name=0xbffff0a4 "",
numBytes=260) at ../macosx/tkMacOSXFont.c:2136
#2 0x0b1069b4 in FontFamilyEnumCallback (family=4294961600, refCon=0x0) at
../macosx/tkMacOSXFont.c:2064
#3 0x9031fe98 in ATSFontFamilyApplyFunction ()
#4 0x0b10680c in InitFontFamilies () at ../macosx/tkMacOSXFont.c:2018
#5 0x0b10477b in TkpFontPkgInit (mainPtr=0xf2d10) at
../macosx/tkMacOSXFont.c:288
#6 0x0b019c6f in TkFontPkgInit (mainPtr=0xf2d10) at
../generic/tkFont.c:389
#7 0x0b03d646 in TkCreateMainWindow (interp=0xd6c10, screenName=0xb132b54
"", baseName=0xbffff6df "Foo") at ../generic/tkWindow.c:907
#8 0x0b04b63b in CreateFrame (clientData=0x0, interp=0xd6c10, objc=4,
objv=0x30a150, type=TYPE_TOPLEVEL, appName=0xbffff6df "Foo") at
../generic/tkFrame.c:555
#9 0x0b04b011 in TkCreateFrame (clientData=0x0, interp=0xd6c10, argc=4,
argv=0xbffff7a0, toplevel=1, appName=0xbffff6df "Foo") at
../generic/tkFrame.c:437
#10 0x0b0402e6 in Initialize (interp=0xd6c10) at
../generic/tkWindow.c:3160
#11 0x0b03fb33 in Tk_Init (interp=0xd6c10) at ../generic/tkWindow.c:2852
#12 0x0000322b in Tk_myMain (argc=1, argv=0xbffff9fc, myappInitProc=0x33e4
<Tcl_UnixAppInit>) at ../src/myMain.c:160
#13 0x00003030 in main (argc=1, argv=0xbffff9fc) at ../src/myMain.c:120


Patch against trunk (though I'm using 8.6a1):

Index: macosx/tkMacOSXFont.c
===================================================================
RCS file: /cvsroot/tktoolkit/tk/macosx/tkMacOSXFont.c,v
retrieving revision 1.43
diff -u -p -r1.43 tkMacOSXFont.c
--- macosx/tkMacOSXFont.c 10 Dec 2008 05:02:52 -0000 1.43
+++ macosx/tkMacOSXFont.c 30 Jan 2009 10:32:49 -0000
@@ -2194,10 +2194,16 @@ GetFontFamilyName(
*/

encoding = kTextEncodingMacRoman;
- ChkErr(FMGetFontFamilyTextEncoding, fontFamily, &encoding);
+ err = ChkErr(FMGetFontFamilyTextEncoding, fontFamily, &encoding);
+ if (err != noErr) {
+ return err;
+ }
nameencoding = encoding;
- ChkErr(RevertTextEncodingToScriptInfo, encoding, &nameencoding, NULL,
+ err = ChkErr(RevertTextEncodingToScriptInfo, encoding, &nameencoding,
NULL,
NULL);
+ if (err != noErr) {
+ return err;
+ }

/*
* Note: We could use Tcl facilities to do the re-encoding here. We'd
@@ -2211,6 +2217,9 @@ GetFontFamilyName(

cfString = CFStringCreateWithPascalStringNoCopy(
NULL, nativeName, nameencoding, kCFAllocatorNull);
+ if (cfString == NULL) {
+ return noErr-1; /* I have no idea here, just make it not noErr
*/
+ }
CFStringGetCString(
cfString, name, numBytes, kCFStringEncodingUTF8);
CFRelease(cfString);