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MichaelRFairhurstMichaelRFairhurst
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Implement Rule 22-4-1, only assign literal 0 to errno.
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+268
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‎cpp/common/src/codingstandards/cpp/exclusions/cpp/Preconditions4.qll‎

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//** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY. **/
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import cpp
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import RuleMetadata
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import codingstandards.cpp.exclusions.RuleMetadata
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newtype Preconditions4Query = TInvalidAssignmentToErrnoQuery()
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predicate isPreconditions4QueryMetadata(Query query, string queryId, string ruleId, string category) {
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query =
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// `Query` instance for the `invalidAssignmentToErrno` query
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Preconditions4Package::invalidAssignmentToErrnoQuery() and
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queryId =
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// `@id` for the `invalidAssignmentToErrno` query
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"cpp/misra/invalid-assignment-to-errno" and
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ruleId = "RULE-22-4-1" and
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category = "required"
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}
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module Preconditions4Package {
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Query invalidAssignmentToErrnoQuery() {
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//autogenerate `Query` type
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result =
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// `Query` type for `invalidAssignmentToErrno` query
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TQueryCPP(TPreconditions4PackageQuery(TInvalidAssignmentToErrnoQuery()))
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}
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}

‎cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll‎

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@@ -44,6 +44,7 @@ import Operators
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import OrderOfEvaluation
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import OutOfBounds
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import Pointers
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import Preconditions4
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import Representation
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import Scope
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import SideEffects1
@@ -103,6 +104,7 @@ newtype TCPPQuery =
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TOrderOfEvaluationPackageQuery(OrderOfEvaluationQuery q) or
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TOutOfBoundsPackageQuery(OutOfBoundsQuery q) or
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TPointersPackageQuery(PointersQuery q) or
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TPreconditions4PackageQuery(Preconditions4Query q) or
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TRepresentationPackageQuery(RepresentationQuery q) or
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TScopePackageQuery(ScopeQuery q) or
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TSideEffects1PackageQuery(SideEffects1Query q) or
@@ -162,6 +164,7 @@ predicate isQueryMetadata(Query query, string queryId, string ruleId, string cat
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isOrderOfEvaluationQueryMetadata(query, queryId, ruleId, category) or
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isOutOfBoundsQueryMetadata(query, queryId, ruleId, category) or
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isPointersQueryMetadata(query, queryId, ruleId, category) or
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isPreconditions4QueryMetadata(query, queryId, ruleId, category) or
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isRepresentationQueryMetadata(query, queryId, ruleId, category) or
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isScopeQueryMetadata(query, queryId, ruleId, category) or
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isSideEffects1QueryMetadata(query, queryId, ruleId, category) or

‎cpp/common/src/codingstandards/cpp/standardlibrary/Errno.qll‎

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import cpp
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predicate isErrno(VariableAccess va) {
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va.getTarget().hasName("errno") or
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va.getTarget().hasName("__errno")
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}

‎cpp/common/test/includes/standard-library/errno.h‎

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@@ -2,4 +2,7 @@
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#define _GHLIBCPP_ERRNO
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int __errno;
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#define errno __errno
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#define EINVAL 22
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#define ERANGE 34
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#define EDOM 33
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#endif // _GHLIBCPP_ERRNO

‎cpp/common/test/includes/standard-library/string‎

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@@ -248,6 +248,8 @@ public:
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int compare(size_type pos1, size_type n1, const charT *s) const;
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int compare(size_type pos1, size_type n1, const charT *s, size_type n2) const;
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bool empty() const noexcept;
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void reserve(size_type new_cap = 0);
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};
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‎cpp/misra/src/rules/RULE-22-4-1/InvalidAssignmentToErrno.ql‎

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/**
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* @id cpp/misra/invalid-assignment-to-errno
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* @name RULE-22-4-1: The literal value zero shall be the only value assigned to errno
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* @description C++ provides better options for error handling than the use of errno. Errno should
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* not be used for reporting errors within project code.
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* @kind problem
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* @precision very-high
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* @problem.severity error
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* @tags external/misra/id/rule-22-4-1
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* scope/single-translation-unit
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* maintainability
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* external/misra/enforcement/decidable
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* external/misra/obligation/required
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*/
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import cpp
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import codingstandards.cpp.misra
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import codingstandards.cpp.standardlibrary.Errno
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import codingstandards.cpp.Literals
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from Assignment assign, VariableAccess errno, Expr rvalue, string message
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where
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not isExcluded(assign, Preconditions4Package::invalidAssignmentToErrnoQuery()) and
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assign.getLValue() = errno and
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isErrno(errno) and
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assign.getRValue().getExplicitlyConverted() = rvalue and
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(
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not rvalue instanceof LiteralZero and
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message = "Assignment to 'errno' with non-zero literal value '" + rvalue.toString() + "'."
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or
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assign instanceof AssignOperation and
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message =
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"Compound assignment to 'errno' with operator '" + assign.getOperator() + "' is not allowed."
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)
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select assign, message

‎cpp/misra/test/rules/RULE-22-4-1/InvalidAssignmentToErrno.expected‎

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| test.cpp:26:3:26:13 | ... = ... | Assignment to 'errno' with non-zero literal value '0.0'. |
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| test.cpp:27:3:27:14 | ... = ... | Assignment to 'errno' with non-zero literal value '0.0'. |
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| test.cpp:31:3:31:11 | ... = ... | Assignment to 'errno' with non-zero literal value '1'. |
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| test.cpp:32:3:32:12 | ... = ... | Assignment to 'errno' with non-zero literal value '42'. |
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| test.cpp:33:3:33:12 | ... = ... | Assignment to 'errno' with non-zero literal value '- ...'. |
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| test.cpp:39:3:39:22 | ... = ... | Assignment to 'errno' with non-zero literal value '42'. |
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| test.cpp:49:3:49:12 | ... = ... | Assignment to 'errno' with non-zero literal value 'l1'. |
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| test.cpp:50:3:50:12 | ... = ... | Assignment to 'errno' with non-zero literal value 'l2'. |
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| test.cpp:51:3:51:12 | ... = ... | Assignment to 'errno' with non-zero literal value 'l3'. |
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| test.cpp:52:3:52:12 | ... = ... | Assignment to 'errno' with non-zero literal value 'l4'. |
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| test.cpp:53:3:53:12 | ... = ... | Assignment to 'errno' with non-zero literal value 'l5'. |
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| test.cpp:57:3:57:16 | ... = ... | Assignment to 'errno' with non-zero literal value '22'. |
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| test.cpp:58:3:58:16 | ... = ... | Assignment to 'errno' with non-zero literal value '34'. |
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| test.cpp:59:3:59:14 | ... = ... | Assignment to 'errno' with non-zero literal value '33'. |
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| test.cpp:63:3:63:15 | ... = ... | Assignment to 'errno' with non-zero literal value '... + ...'. |
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| test.cpp:64:3:64:15 | ... = ... | Assignment to 'errno' with non-zero literal value '... - ...'. |
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| test.cpp:65:3:65:15 | ... = ... | Assignment to 'errno' with non-zero literal value '... * ...'. |
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| test.cpp:66:3:66:35 | ... = ... | Assignment to 'errno' with non-zero literal value '... - ...'. |
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| test.cpp:70:3:70:11 | ... = ... | Assignment to 'errno' with non-zero literal value '5'. |
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| test.cpp:71:3:71:12 | ... += ... | Compound assignment to 'errno' with operator '+=' is not allowed. |
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| test.cpp:72:3:72:12 | ... -= ... | Assignment to 'errno' with non-zero literal value '5'. |
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| test.cpp:72:3:72:12 | ... -= ... | Compound assignment to 'errno' with operator '-=' is not allowed. |
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| test.cpp:73:3:73:12 | ... *= ... | Compound assignment to 'errno' with operator '*=' is not allowed. |
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| test.cpp:74:3:74:12 | ... /= ... | Assignment to 'errno' with non-zero literal value '1'. |
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| test.cpp:74:3:74:12 | ... /= ... | Compound assignment to 'errno' with operator '/=' is not allowed. |
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| test.cpp:81:3:81:14 | ... = ... | Assignment to 'errno' with non-zero literal value 'call to operator()'. |
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| test.cpp:82:3:82:14 | ... = ... | Assignment to 'errno' with non-zero literal value 'call to operator()'. |
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| test.cpp:86:3:86:29 | ... = ... | Assignment to 'errno' with non-zero literal value 'static_cast<int>...'. |
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| test.cpp:87:3:87:31 | ... = ... | Assignment to 'errno' with non-zero literal value 'static_cast<int>...'. |
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| test.cpp:88:3:88:16 | ... = ... | Assignment to 'errno' with non-zero literal value '(int)...'. |
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| test.cpp:89:3:89:16 | ... = ... | Assignment to 'errno' with non-zero literal value '(int)...'. |
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| test.cpp:108:3:108:40 | ... = ... | Assignment to 'errno' with non-zero literal value 'reinterpret_cast<int>...'. |
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| test.cpp:110:3:110:35 | ... = ... | Assignment to 'errno' with non-zero literal value 'reinterpret_cast<int>...'. |
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| test.cpp:111:3:111:35 | ... = ... | Assignment to 'errno' with non-zero literal value 'reinterpret_cast<int>...'. |
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| test.cpp:113:3:113:40 | ... = ... | Assignment to 'errno' with non-zero literal value 'reinterpret_cast<int>...'. |
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| test.cpp:122:3:122:13 | ... = ... | Assignment to 'errno' with non-zero literal value '48'. |
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| test.cpp:128:3:128:14 | ... = ... | Assignment to 'errno' with non-zero literal value '1'. |

‎cpp/misra/test/rules/RULE-22-4-1/InvalidAssignmentToErrno.qlref‎

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rules/RULE-22-4-1/InvalidAssignmentToErrno.ql

‎cpp/misra/test/rules/RULE-22-4-1/test.cpp‎

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#include <cerrno>
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#include <cstdint>
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#include <optional>
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#include <string>
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void errnoSettingFunction();
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void handleError();
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void f();
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#define OK 0
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#define CUSTOM_ERROR 42
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#define ZERO_MACRO 0
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void test_literal_zero_assignment() {
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errno = 0; // COMPLIANT
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}
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void test_different_zero_literal_formats() {
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errno = 0; // COMPLIANT - decimal zero literal
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errno = 0x0; // COMPLIANT - hexadecimal zero literal
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errno = 00; // COMPLIANT - octal zero literal
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errno = 0b0; // COMPLIANT - binary zero literal
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}
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void test_floating_point_zero_literals() {
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errno = 0.0; // NON_COMPLIANT - floating point literal, not integer literal
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errno = 0.0f; // NON_COMPLIANT - floating point literal, not integer literal
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}
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void test_non_zero_literal_assignment() {
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errno = 1; // NON_COMPLIANT
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errno = 42; // NON_COMPLIANT
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errno = -1; // NON_COMPLIANT
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}
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void test_macro_assignments() {
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errno = OK; // COMPLIANT - expands to literal 0
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errno = ZERO_MACRO; // COMPLIANT - expands to literal 0
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errno = CUSTOM_ERROR; // NON_COMPLIANT - expands to non-zero literal
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}
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void test_variable_assignments() {
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std::uint32_t l1 = 0;
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const std::uint32_t l2 = 0;
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constexpr std::uint32_t l3 = 0;
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std::uint32_t l4 = 42;
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const std::uint32_t l5 = 42;
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errno = l1; // NON_COMPLIANT - variable, not literal
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errno = l2; // NON_COMPLIANT - constant variable, not literal
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errno = l3; // NON_COMPLIANT - constexpr variable, not literal
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errno = l4; // NON_COMPLIANT - variable with non-zero value
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errno = l5; // NON_COMPLIANT - constant variable with non-zero value
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}
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void test_standard_error_macros() {
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errno = EINVAL; // NON_COMPLIANT - standard error macro
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errno = ERANGE; // NON_COMPLIANT - standard error macro
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errno = EDOM; // NON_COMPLIANT - standard error macro
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}
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void test_expressions() {
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errno = 0 + 0; // NON_COMPLIANT - expression, not literal
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errno = 1 - 1; // NON_COMPLIANT - expression, not literal
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errno = 0 * 5; // NON_COMPLIANT - expression, not literal
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errno = sizeof(int) - sizeof(int); // NON_COMPLIANT - expression, not literal
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}
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void test_compound_assignments() {
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errno = 5; // NON_COMPLIANT - initial assignment to non-zero value
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errno += 0; // NON_COMPLIANT - compound assignment, not simple assignment
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errno -= 5; // NON_COMPLIANT - compound assignment, not simple assignment
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errno *= 0; // NON_COMPLIANT - compound assignment, not simple assignment
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errno /= 1; // NON_COMPLIANT - compound assignment, not simple assignment
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}
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void test_function_return_values() {
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auto l1 = []() { return 0; };
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auto l2 = []() { return 42; };
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errno = l1(); // NON_COMPLIANT - function return value, not literal
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errno = l2(); // NON_COMPLIANT - function return value, not literal
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}
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void test_cast_expressions() {
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errno = static_cast<int>(0); // NON_COMPLIANT - cast expression
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errno = static_cast<int>(0.0); // NON_COMPLIANT - cast expression
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errno = (int)0; // NON_COMPLIANT - C-style cast
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errno = int(0); // NON_COMPLIANT - functional cast
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}
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void test_reading_errno_is_allowed() {
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std::uint32_t l1 = errno; // COMPLIANT - reading errno is allowed
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if (errno != 0) { // COMPLIANT - reading errno is allowed
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handleError();
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}
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errnoSettingFunction();
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std::uint32_t l2 = 0;
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if (errno != l2) { // COMPLIANT - reading errno is allowed
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handleError();
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}
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}
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void test_pointer_and_null_assignments() {
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label:
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static const int x = 0;
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errno = reinterpret_cast<int>(nullptr); // NON_COMPLIANT - nullptr is
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// not an integer literal
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errno = reinterpret_cast<int>(&x); // NON_COMPLIANT - pointer cast to integer
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errno = reinterpret_cast<int>(&f); // NON_COMPLIANT - pointer cast to
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// integer
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errno = reinterpret_cast<int>(&&label); // NON_COMPLIANT - pointer
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// cast to integer
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errno = NULL; // NON_COMPLIANT[FALSE_NEGATIVE] - NULL may expand to 0 but not
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// literal
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}
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void test_character_literals() {
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errno = '\0'; // NON_COMPLIANT[FALSE_NEGATIVE] - character literal, not
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// integer literal
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errno = '0'; // NON_COMPLIANT - character '0' has value 48
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}
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void test_boolean_literals() {
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errno = false; // NON_COMPLIANT[FALSE_NEGATIVE] - boolean literal, not integer
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// literal
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errno = true; // NON_COMPLIANT - boolean literal with non-zero value
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}

‎rule_packages/cpp/Preconditions4.json‎

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{
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"MISRA-C++-2023": {
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"RULE-22-4-1": {
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"properties": {
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"enforcement": "decidable",
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"obligation": "required"
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},
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"queries": [
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{
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"description": "C++ provides better options for error handling than the use of errno. Errno should not be used for reporting errors within project code.",
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"kind": "problem",
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"name": "The literal value zero shall be the only value assigned to errno",
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"precision": "very-high",
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"severity": "error",
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"short_name": "InvalidAssignmentToErrno",
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"tags": [
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"scope/single-translation-unit",
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"maintainability"
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]
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}
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],
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"title": "The literal value zero shall be the only value assigned to errno"
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}
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}
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}

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