I'm sure you've looked up clearerr() in gl...

2011-08-26T18:49:59.822-07:00

I'm sure you've looked up clearerr() in glibc.
The 2.14 version looks like this:

void
clearerr (fp)
FILE *fp;
{
CHECK_FILE (fp, /*nothing*/);
_IO_flockfile (fp);
_IO_clearerr (fp);
_IO_funlockfile (fp);
}

Your analysis is correct, first magic is checked, then lock is held, flags cleared, and lock released.

I've failed to find the definition of _IO_flockfile() in glibc's sources though.

Comments on Tsuna's blog: JVM u24 segfault in clearerr on Jaunty

I'm sure you've looked up clearerr() in gl...