Attachment 54750 Details for Bug 127552

motif bug known for years- with solution

openmotif-bug-solution.txt (text/plain), 6.67 KB, created by Forgotten User PZ4wA53Xsq on 2005-10-19 11:55:39 UTC

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Creator: Forgotten User PZ4wA53Xsq

Created: 2005-10-19 11:55:39 UTC

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>   Home | Bazaar | The Motif Developer | Motif Help | Bug Home  	sponsored by ICS 
>Full Text Bug Listing
>	  	
>XmTextField: "Character xxx not supported in font" errors, bug in multibyte code
>Bug#: 1257 	Product: OpenMotif 	Version: 2.2.2 	Platform: x86
>OS/Version: Linux 	Status: RESOLVED 	Severity: major 	Priority: High
>Resolution: FIXED 	Assigned To: openmotif-devel@motifzone.net 	Reported By: brad@sd.aonix.com
>Component: MotifCode
>URL: 
>Summary: XmTextField: "Character xxx not supported in font" errors, bug in multibyte code
>Description:
>
>RedHat Enterprise Linux 3.0 with Motif 2.2.3 gets the following errors all over
>the place:
>    Warning:                                                
>       Name: textField                                     
>       Class: XmTextField                                  
>       Character '\163' not supported in font.  Discarded. 
>
>Below I have included a C file and a Makefile for a test case.
>Also I provided a suggested fix for the problem.
>
>
>--------------------------------------------------------------------------------
>README
>--------------------------------------------------------------------------------
>
>Test case to illustrate bug in PrintableString in TextF.c in Motif 2.2.3.
>
>How to test:
>  make
>  setenv LANG en_US.UTF-8 (or another multibyte lang)
>  textf_bug
>
>  The following error messages will appear:
>
>    Warning:                                                
>       Name: textField                                     
>       Class: XmTextField                                  
>       Character '\163' not supported in font.  Discarded. 
>                                                     
>    Warning:                                                
>       Name: textField                                     
>       Class: XmTextField                                  
>       Character '\157' not supported in font.  Discarded. 
>    ...
>
>  If you do not see the errors, try setting LANG to another multibyte encoding,
>  such as ja_JP.ujis.
>
>The test case makes a simple GUI with a XmTextField widget and
>puts a regular single-byte string into it.
>The bug causes the text field to reject the string character by character
>and print the error messages.
>
>
>The bug is new for Motif 2.2 and was not present in Motif 2.1.
>The error lies in a new block of code added to the end of PrintableString in
>TextF.c:
>
>    tmp_str = (wchar_t *)str;
>    ret_val = wctomb(tmp, *tmp_str);
>    count = 0;
>    while ( (ret_val > 0)&& (buf_size >= MB_CUR_MAX) && (count < n) )
>      {
>        count += 1;
>        tmp += ret_val;
>        buf_size -= ret_val;
>        tmp_str
>        ret_val = wctomb(tmp, *tmp_str);
>      }
>    if (ret_val == -1)    /* bad character */
>      return (False);
>    is_printable = XTextWidth(TextF_Font(tf), cache_ptr, tmp - cache_ptr);
>
>The problem is that ValidateString passes the address of a single wchar_t tmp.
>The str parameter in PrintableString is consequently set to &tmp.
>n is passed in as 1.
>str is copied to tmp_str.
>The code runs wctomb on *tmp_str, increments tmp_str and then calls wctomb
>on *tmp_str again.
>At this point tmp_str points to other stuff on the stack - whatever happens to
>occupy &tmp+1.
>
>I (think I) fixed the problem by changing the code to:
>
>   tmp_str = (wchar_t *)str;
>   count = 0;
>   do {
>     ret_val = wctomb(tmp, *tmp_str);
>     count += 1;
>     tmp += ret_val;
>     buf_size -= ret_val;
>     tmp_str++;
>   } while ( (ret_val > 0)&& (buf_size >= MB_CUR_MAX) && (count < n) ) ;
>   if (ret_val == -1)    /* bad character */
>     return (False);
>   is_printable =
>     ( XTextWidth(TextF_Font(tf), cache_ptr, tmp - cache_ptr) != 0 ) ;
>
>Apparently RedHat does not define SUPPORT_ZERO_WIDTH in their version of Motif.
>
>The bug does not always show itself.
>Depending on the libXm build, sometimes the address at &tmp+1 is another
>variable, and other times it is just uninitialized junk.
>This test case attempts to write gibberish to the stack area, so that the
>bug will show up in the case that &tmp+1 is not used by another variable.
>If another variable lands on &tmp+1, then the problem is revealed only if
>this other variable is set to something that wctomb doesn''t like.
>I built Motif 2.2.2 on RHLinux8 and the &tmp+1 address was given to the
>start_tmp variable.
>The pointer value given to start_tmp did not cause wctomb to complain,
>so this test case didn''t reveal the problem on RH8.
>The test case shows the problem with RedHat Enterprise Linux 3.0.
>
>This test case is intended to run on a 32 bit Intel platform.
>It may not work on other platforms.
>
>Brad Despres
>Aonix
>
>--------------------------------------------------------------------------------
>Makefile
>--------------------------------------------------------------------------------
>all: textf_bug
>
>textf_bug: textf_bug.c
>	cc -g -Wall \
>		-I/usr/X11R6/include \
>		textf_bug.c \
>		-o textf_bug \
>		-L/usr/X11R6/lib \
>		-lXm \
>		-lXp \
>		-lXt \
>		-lXext \
>		-lXpm \
>		-lSM \
>		-lICE \
>		-lX11 \
>		-lpthread
>
>
>clean:
>	-rm -f textf_bug textf_bug.o
>
>--------------------------------------------------------------------------------
>textf_bug.c
>--------------------------------------------------------------------------------
>#include <locale.h>
>#include <Xm/TextF.h>
>  
>int main (
>  int argc ,
>  char * argv []
>)
>{
>  Widget toplevel , textf ;
>  XtAppContext app ;
>  int i , fill_size = 1024 ;
>  unsigned char fill_byte = 0xA5 ;
>  unsigned fill_pattern ;
>  unsigned * pu ;
>
>  /* Read the locale env variables. */
>  setlocale ( LC_ALL , "" ) ;
>
>  toplevel = XtVaAppInitialize ( & app , "TestCase" , NULL , 0 ,
>    & argc , argv , NULL , NULL ) ;
>
>  textf = XtVaCreateWidget ( "textField" ,
>    xmTextFieldWidgetClass , toplevel ,
>    NULL ) ;
>  
>  XtManageChild ( textf ) ;
>
>  { /*
>     * Write jibberish into the unused area below the stack.
>     * Hopefully this will cause the bug to show up.
>     */
>
>    /* Push a variable so we know where the sp is. */
>    unsigned u ;
>
>    /* Set up the fill pattern, e.g. 0xA5A5A5A5 */
>    memset ( ( void * ) & fill_pattern , fill_byte , sizeof ( u ) ) ;
>
>    /* Fill the unused stack area with this pattern. */
>    for ( i = 0 , pu = & u ; i < fill_size ; i ++ , pu -- ) {
>      * pu = fill_pattern ;
>      /* The problem is masked if you fill it with zeros instead. */
>    }
>  }
>  XmTextFieldSetString ( textf , "some text" ) ;
>  XtRealizeWidget ( toplevel ) ;
>  XtAppMainLoop ( app ) ;
>
>  /* Not reached. */
>  return ( 0 ) ;
>}
>
>
>
>------- Additional Comments From brad@sd.aonix.com 2004-05-27 11:33 -------
>
>Created an attachment (id=45)
>Tar file containing test case for bug.
>
>
>
>------- Additional Comments From yura@ics.com 2004-06-30 05:28 -------
>
>Fixed as proposed. Thanks for the report and patch.
>
>
>
>Update this bug
>Submit a Patch for this bug
>Note: All patches are submitted under the MIT License.

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