forked from OSchip/llvm-project
37 lines
1.2 KiB
ReStructuredText
37 lines
1.2 KiB
ReStructuredText
.. title:: clang-tidy - android-comparison-in-temp-failure-retry
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android-comparison-in-temp-failure-retry
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========================================
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Diagnoses comparisons that appear to be incorrectly placed in the argument to
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the ``TEMP_FAILURE_RETRY`` macro. Having such a use is incorrect in the vast
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majority of cases, and will often silently defeat the purpose of the
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``TEMP_FAILURE_RETRY`` macro.
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For context, ``TEMP_FAILURE_RETRY`` is `a convenience macro
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<https://www.gnu.org/software/libc/manual/html_node/Interrupted-Primitives.html>`_
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provided by both glibc and Bionic. Its purpose is to repeatedly run a syscall
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until it either succeeds, or fails for reasons other than being interrupted.
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Example buggy usage looks like:
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.. code-block:: c
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char cs[1];
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while (TEMP_FAILURE_RETRY(read(STDIN_FILENO, cs, sizeof(cs)) != 0)) {
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// Do something with cs.
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}
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Because TEMP_FAILURE_RETRY will check for whether the result *of the comparison*
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is ``-1``, and retry if so.
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If you encounter this, the fix is simple: lift the comparison out of the
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``TEMP_FAILURE_RETRY`` argument, like so:
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.. code-block:: c
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char cs[1];
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while (TEMP_FAILURE_RETRY(read(STDIN_FILENO, cs, sizeof(cs))) != 0) {
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// Do something with cs.
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}
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