22 Dec
2017
22 Dec
'17
8:55 a.m.
On Thu, Dec 21, 2017, at 20:51, William Corcoran wrote:
Okay, I think I am on to something…
Whenever tar or cpio dumps core, it is always when 32769 bytes have been
written to stdout.
Is that 32769 bytes to the tape (which is not stdout in your tar invocation), or 32769
bytes of printed output? Is it exactly 32769, or just some value above 32768 by some small
amount?
I looked at fprintf and there is a register int called
“count.”
Your crash is in _strout, two calls deep before that variable is written since the adjust
parameter is 0, the only thing of note in _strout is a putc loop. putc is a macro so it
won't appear in the stack trace - that _flsbuf does not appear in the stack trace
means this is happening in the 'ordinary' buffered I/O case.
Strange, though, I can't see anything inside putc/flsbuf that seems like anything
should be any different on the 32770th character than the 514th or 1026th.
What are the strings being printed? (second argument to printf, and first argument to
strout)?