91 lines
2.6 KiB
Go
91 lines
2.6 KiB
Go
package sa5005
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import (
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"fmt"
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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/go/ir"
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"honnef.co/go/tools/internal/passes/buildir"
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"honnef.co/go/tools/knowledge"
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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: "SA5005",
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Run: run,
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Requires: []*analysis.Analyzer{buildir.Analyzer},
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},
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Doc: &lint.RawDocumentation{
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Title: `The finalizer references the finalized object, preventing garbage collection`,
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Text: `A finalizer is a function associated with an object that runs when the
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garbage collector is ready to collect said object, that is when the
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object is no longer referenced by anything.
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If the finalizer references the object, however, it will always remain
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as the final reference to that object, preventing the garbage
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collector from collecting the object. The finalizer will never run,
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and the object will never be collected, leading to a memory leak. That
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is why the finalizer should instead use its first argument to operate
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on the object. That way, the number of references can temporarily go
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to zero before the object is being passed to the finalizer.`,
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Since: "2017.1",
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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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func run(pass *analysis.Pass) (any, error) {
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cb := func(caller *ir.Function, site ir.CallInstruction, callee *ir.Function) {
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if callee.RelString(nil) != "runtime.SetFinalizer" {
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return
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}
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arg0 := site.Common().Args[knowledge.Arg("runtime.SetFinalizer.obj")]
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if iface, ok := arg0.(*ir.MakeInterface); ok {
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arg0 = iface.X
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}
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load, ok := arg0.(*ir.Load)
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if !ok {
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return
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}
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v, ok := load.X.(*ir.Alloc)
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if !ok {
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return
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}
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arg1 := site.Common().Args[knowledge.Arg("runtime.SetFinalizer.finalizer")]
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if iface, ok := arg1.(*ir.MakeInterface); ok {
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arg1 = iface.X
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}
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mc, ok := arg1.(*ir.MakeClosure)
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if !ok {
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return
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}
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for _, b := range mc.Bindings {
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if b == v {
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pos := report.DisplayPosition(pass.Fset, mc.Fn.Pos())
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report.Report(pass, site, fmt.Sprintf("the finalizer closes over the object, preventing the finalizer from ever running (at %s)", pos))
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}
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}
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}
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for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
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eachCall(fn, cb)
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}
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return nil, nil
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}
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func eachCall(fn *ir.Function, cb func(caller *ir.Function, site ir.CallInstruction, callee *ir.Function)) {
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for _, b := range fn.Blocks {
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for _, instr := range b.Instrs {
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if site, ok := instr.(ir.CallInstruction); ok {
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if g := site.Common().StaticCallee(); g != nil {
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cb(fn, site, g)
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}
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}
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}
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}
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}
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