A test of this is funcs/tst.strtok.d which has this filter:
BEGIN
/(this->field = strtok(this->str, ",")) == NULL/
{
exit(1);
}The test will randomly fail with exit status of 1 indicating that this->field
was NULL even though printing it out shows it is not.
This is compiled to the DTrace instruction set:
// Pushed arguments not shown here // call strtok() and set result into %r1 07: 2f001f01 call DIF_SUBR(31), %r1 ! strtok // set thread local scalar this->field from %r1 08: 39050101 stls %r1, DT_VAR(1281) ! DT_VAR(1281) = "field" // Prepare for the == comparison // Set right side of %r2 to NULL 09: 25000102 setx DT_INTEGER[1], %r2 ! 0x0 // string compare %r1 (strtok result) to %r2 10: 27010200 scmp %r1, %r2
In this case only %r1 is loaded with a string limit set to lim1. %r2 being
NULL does not get loaded and does not set lim2. Then we call dtrace_strncmp()
with MIN(lim1, lim2) resulting in passing 0 and comparing neither side.
dtrace_strncmp() handles this case fine and it already has been while
being lucky with what lim2 was [un]initialized as.
Specifically in SCMP we are wanting to see cc_r = !0 in this case.
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