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| author | David Mitchell <davem@iabyn.com> | 2017-07-16 20:00:01 +0100 |
|---|---|---|
| committer | David Mitchell <davem@iabyn.com> | 2017-07-16 20:00:01 +0100 |
| commit | 978b185906e439ce6a0fcb8e90c8e3f328556a8a (patch) | |
| tree | 30340c56c37949f3a8c9bbfa6b4eb0f8ccde6bb2 /cop.h | |
| parent | ab9a6a636dbb66ae5bf3f7546a87872aa295f96d (diff) | |
| download | perl-978b185906e439ce6a0fcb8e90c8e3f328556a8a.tar.gz | |
PL_curstackinfo->si_stack_hwm: gently restore
RT #131732
With v5.27.1-66-g87058c3, I introduced a DEBUGGING-only mechanism in the
runops loop for checking whether an op extended the stack by as many slots
as values it returned on the stack. It did this by setting a
high-water-mark just before calling each pp function, and checking its
result on return.
It saved and restored the old value of PL_curstackinfo->si_stack_hwm
whenever it entered or left a runops loop or did a JMPENV_PUSH /
JMPENV_POP. However, the restoring could restore to an old value that was
smaller than the current value, leading to false-positive stack-extend
panics. So only restore if the old value was larger.
In particular this was causing false positives in DBI.
Diffstat (limited to 'cop.h')
| -rw-r--r-- | cop.h | 3 |
1 files changed, 2 insertions, 1 deletions
@@ -47,7 +47,8 @@ typedef struct jmpenv JMPENV; # define JE_OLD_STACK_HWM_save(je) \ (je).je_old_stack_hwm = PL_curstackinfo->si_stack_hwm # define JE_OLD_STACK_HWM_restore(je) \ - PL_curstackinfo->si_stack_hwm = (je).je_old_stack_hwm + if (PL_curstackinfo->si_stack_hwm < (je).je_old_stack_hwm) \ + PL_curstackinfo->si_stack_hwm = (je).je_old_stack_hwm #else # define JE_OLD_STACK_HWM_zero NOOP # define JE_OLD_STACK_HWM_save(je) NOOP |