71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
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package sa4030
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import (
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"fmt"
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"honnef.co/go/tools/analysis/code"
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"honnef.co/go/tools/analysis/lint"
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"honnef.co/go/tools/analysis/report"
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"honnef.co/go/tools/pattern"
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"golang.org/x/tools/go/analysis"
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)
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var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
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Analyzer: &analysis.Analyzer{
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Name: "SA4030",
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Run: run,
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Requires: code.RequiredAnalyzers,
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},
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Doc: &lint.RawDocumentation{
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Title: "Ineffective attempt at generating random number",
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Text: `
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Functions in the \'math/rand\' package that accept upper limits, such
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as \'Intn\', generate random numbers in the half-open interval [0,n). In
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other words, the generated numbers will be \'>= 0\' and \'< n\' – they
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don't include \'n\'. \'rand.Intn(1)\' therefore doesn't generate \'0\'
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or \'1\', it always generates \'0\'.`,
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Since: "2022.1",
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Severity: lint.SeverityWarning,
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MergeIf: lint.MergeIfAny,
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},
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})
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var Analyzer = SCAnalyzer.Analyzer
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var ineffectiveRandIntQ = pattern.MustParse(`
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(CallExpr
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(Symbol
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name@(Or
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"math/rand.Int31n"
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"math/rand.Int63n"
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"math/rand.Intn"
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"(*math/rand.Rand).Int31n"
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"(*math/rand.Rand).Int63n"
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"(*math/rand.Rand).Intn"
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"math/rand/v2.Int32N"
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"math/rand/v2.Int64N"
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"math/rand/v2.IntN"
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"math/rand/v2.N"
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"math/rand/v2.Uint32N"
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"math/rand/v2.Uint64N"
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"math/rand/v2.UintN"
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"(*math/rand/v2.Rand).Int32N"
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"(*math/rand/v2.Rand).Int64N"
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"(*math/rand/v2.Rand).IntN"
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"(*math/rand/v2.Rand).Uint32N"
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"(*math/rand/v2.Rand).Uint64N"
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"(*math/rand/v2.Rand).UintN"))
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[(IntegerLiteral "1")])`)
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func run(pass *analysis.Pass) (any, error) {
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for node, m := range code.Matches(pass, ineffectiveRandIntQ) {
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report.Report(pass, node,
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fmt.Sprintf("%s(n) generates a random value 0 <= x < n; that is, the generated values don't include n; %s therefore always returns 0",
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m.State["name"], report.Render(pass, node)))
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}
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return nil, nil
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}
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