forked from OSchip/llvm-project
55 lines
1.5 KiB
ReStructuredText
55 lines
1.5 KiB
ReStructuredText
.. title:: clang-tidy - bugprone-suspicious-memset-usage
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bugprone-suspicious-memset-usage
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================================
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This check finds ``memset()`` calls with potential mistakes in their arguments.
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Considering the function as ``void* memset(void* destination, int fill_value,
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size_t byte_count)``, the following cases are covered:
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**Case 1: Fill value is a character ``'0'``**
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Filling up a memory area with ASCII code 48 characters is not customary,
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possibly integer zeroes were intended instead.
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The check offers a replacement of ``'0'`` with ``0``. Memsetting character
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pointers with ``'0'`` is allowed.
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**Case 2: Fill value is truncated**
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Memset converts ``fill_value`` to ``unsigned char`` before using it. If
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``fill_value`` is out of unsigned character range, it gets truncated
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and memory will not contain the desired pattern.
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**Case 3: Byte count is zero**
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Calling memset with a literal zero in its ``byte_count`` argument is likely
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to be unintended and swapped with ``fill_value``. The check offers to swap
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these two arguments.
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Corresponding cpplint.py check name: ``runtime/memset``.
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Examples:
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.. code-block:: c++
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void foo() {
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int i[5] = {1, 2, 3, 4, 5};
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int *ip = i;
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char c = '1';
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char *cp = &c;
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int v = 0;
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// Case 1
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memset(ip, '0', 1); // suspicious
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memset(cp, '0', 1); // OK
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// Case 2
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memset(ip, 0xabcd, 1); // fill value gets truncated
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memset(ip, 0x00, 1); // OK
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// Case 3
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memset(ip, sizeof(int), v); // zero length, potentially swapped
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memset(ip, 0, 1); // OK
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}
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