[XForms] infrequent address exception in XCreatePixmap, FYI

[Peter Rowat]

My program runs successfully 90% of the time, but about every 10th run there is an address exception appearing in XCreatePixmap.

Here is the lldb output:

Process 4581 launched: '/Users/prowat/BioPrep/N2Prep/Izh2p2/mod' (x86_64)

......

......

Process 4581 stopped

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x968)

    frame #0: 0x000000010012b52b libX11.6.dylib`XCreatePixmap + 29

libX11.6.dylib`XCreatePixmap:

->  0x10012b52b <+29>: movq   0x968(%rbx), %rax

    0x10012b532 <+36>: testq  %rax, %rax

    0x10012b535 <+39>: je     0x10012b53c               ; <+46>

    0x10012b537 <+41>: movq   %rbx, %rdi

Target 0: (mod) stopped.

(lldb) bt

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x968)

  * frame #0: 0x000000010012b52b libX11.6.dylib`XCreatePixmap + 29

    frame #1: 0x000000010012a589 libX11.6.dylib`XCreateBitmapFromData + 53

    frame #2: 0x000000010029f593 libforms.2.dylib`fli_init_stipples + 67

    frame #3: 0x0000000100250046 libforms.2.dylib`fli_init_colormap + 198

    frame #4: 0x0000000100258546 libforms.2.dylib`fl_initialize + 5334

    frame #5: 0x0000000100001577 mod`main(argc=1, argv=0x00007ffeefbff888) at runit1.c:315:2

    frame #6: 0x00007fff674a07fd libdyld.dylib`start + 1

    frame #7: 0x00007fff674a07fd libdyld.dylib`start + 1

(end of lldb print)===========

Frame #5: is at statement: `fl_initialize( &argc, argv, "BioPrep", 0, 0 );’

It was not the first executable statement  but was before any other XForms statement.

I’ve moved the fl_initialize statement to be the first executable, in case this stops the address exceptions.  None so far after 2 runs.  If I get no more address exceptions after another 20-30 runs, I’ll write again.

— Peter Rowat