RE: Seg Fault while using /dev/clipboard

["Dave Korn" <dave dot korn at artimi dot com>]

----Original Message----
>From: Igor Pechtchanski
>Sent: 04 March 2005 16:55

> On Fri, 4 Mar 2005, Pat Kane wrote:

>> To duplicate the problem try:       cat  /dev/clipboard
>> first with a text selection and then after using Windows to copy a
>> program (right click, copy), or after taking a screen  snapshot
>> (cntrl-alt-prntScrn). 

> Ok, I can reproduce this on WinXP Pro SP1.  The last few lines of strace
> before the exception[*] show a read call that executes normally, and then
> a SEGV.  Someone with a debug version of Cygwin [...snip!...]

<wakes up>Grmbmmgf?  Huh?  did someone call my name?  Here's the results
from the .stackdump file:

Exception: STATUS_ACCESS_VIOLATION at eip=610AB771
eax=00000000 ebx=00000400 ecx=FFFFFFFF edx=00000000 esi=00000000
edi=00000000
ebp=0022ED60 esp=0022ED5C program=C:\cygwin\bin\cat.exe, pid 4224, thread
main
cs=001B ds=0023 es=0023 fs=0038 gs=0000 ss=0023
Stack trace:
Frame     Function  Args
0022ED60  610AB771  (00000000, 00000002, 0000000F, 610ABD58)
../../../../../../src/newlib/libc/machine/i386/strlen.S:27
0022EDC0  6101B28F  (0022EE78, 00000001, 0022EDF0, 61045C38)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/fh
andler_clipboard.cc:228
0022EDF0  61019508  (617E1458, 0022EE78, 00000001, 00000400)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/fh
andler.cc:948
0022EE60  6107CC95  (00000003, 0022EE78, 00000001, 6107DF7F)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/cy
gheap.h:326
0022EE80  6107CABD  (00000003, 0A0501F8, 00000400, 00000000)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/sy
scalls.cc:388
0022EEB0  6107348F  (00000003, 0A0501F8, 00000400, 2CF91218)
??:0
0022EEE0  00401672  (0A0501F8, 00000400, 0022EFA0, 00402022)
??:0
0022EFA0  0040202E  (00000002, 617E2CB8, 0A0500A8, 0022EFF8)
??:0
0022EFE0  610054DD  (0022EFF8, 00000000, 00000002, 00000003)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/dc
rt0.cc:861
0022FF60  61005603  (00000000, 00000000, 00000000, 00000000)
/usr/build/obj/i686-pc-cygwin/winsup/cygwin/../../../../src/winsup/cygwin/dc
rt0.cc:916
End of stack trace


  Hmmph.  Calling strlen on a NULL pointer.  D'oh!

void __stdcall
fhandler_dev_clipboard::read (void *ptr, size_t& len)
{
  HGLOBAL hglb;
  size_t ret;
  UINT formatlist[2];
  UINT format;
  if (eof)
    len = 0;
  else
    {
      formatlist[0] = cygnativeformat;
      formatlist[1] = current_codepage == ansi_cp ? CF_TEXT : CF_OEMTEXT;
      OpenClipboard (0);
      if ((format = GetPriorityClipboardFormat (formatlist, 2)) <= 0)
	{
	  CloseClipboard ();
#if 0
	  system_printf ("a non-accepted format! %d", format);
#endif
	  len = 0;
	}
      else
	{
	  hglb = GetClipboardData (format);
	  if (format == cygnativeformat)
	    {
	      unsigned char *buf = (unsigned char *) GlobalLock (hglb);
	      size_t buflen = (*(size_t *) buf);
	      ret = ((len > (buflen - pos)) ? (buflen - pos) : len);
	      memcpy (ptr, buf + sizeof (size_t)+ pos , ret);
	      pos += ret;
	      if (pos + len - ret >= buflen)
		eof = true;
	      GlobalUnlock (hglb);
	    }
	  else
	    {
	      LPSTR lpstr;
	      lpstr = (LPSTR) GlobalLock (hglb);

	      ret = ((len > (strlen (lpstr) - pos)) ? (strlen (lpstr) - pos)
		     : len);

  So, GetClipboardData is failing and returning NULL.


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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