Avoid memcpy(dst, NULL, 0) in forder.c
#7055
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During thread contention, it's possible for a thread to not call push() even once, leaving gs_thread[me] unallocated. The resulting call to memcpy() was noticed by a sanitizer during additional CRAN checks.
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #7055 +/- ##
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Coverage 98.69% 98.69%
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Files 79 79
Lines 14676 14676
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Hits 14485 14485
Misses 191 191 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Generated via commit ac7ac01 Download link for the artifact containing the test results: ↓ atime-results.zip
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LGTM (needs a test); I'll let Jan review based on how it will fit into the ongoing froll workstream. |
jangorecki
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Jun 9, 2025
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LGTM, could have nocov marker because codecov now complaints about added line
Currently, the condition is only encountered during thread contention, which is prohibitively expensive to test or at least requires non-portable tricks.
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Thanks! Currently I don't know any way besides adding the # nocov. I
can reproduce the issue either by running cat /dev/urandom > /dev/null
on every CPU core or by pinning all data.table threads to one CPU core
prior to running the R script, and neither seems appropriate for an R
package test.
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TysonStanley
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Jun 15, 2025
* flush(): avoid memcpy(<dst>, NULL, 0) During thread contention, it's possible for a thread to not call push() even once, leaving gs_thread[me] unallocated. The resulting call to memcpy() was noticed by a sanitizer during additional CRAN checks. * NEWS item * Add nocov to the hard-to-test branch Currently, the condition is only encountered during thread contention, which is prohibitively expensive to test or at least requires non-portable tricks. * Explain why the branch is #nocov
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Closes: #7051. Tested manually by running the reproducer in the same configuration that previously showed the warning. The NEWS item is technically correct but may be overly detailed.
Looking at the remaining
memcpy()calls, I wasn't able to find any definite examples of the same thing happening; there's usually a way to prove that the size is above 0. Possible issues in the newfrollcode are tracked in #7054.