honnef.co/go/tools@v0.5.0-0.dev.0.20240520180541-dcae280a5e87/staticcheck/sa1023/sa1023.go (about)

     1  package sa1023
     2  
     3  import (
     4  	"go/types"
     5  
     6  	"honnef.co/go/tools/analysis/lint"
     7  	"honnef.co/go/tools/analysis/report"
     8  	"honnef.co/go/tools/go/ir"
     9  	"honnef.co/go/tools/go/ir/irutil"
    10  	"honnef.co/go/tools/internal/passes/buildir"
    11  	"honnef.co/go/tools/knowledge"
    12  
    13  	"golang.org/x/tools/go/analysis"
    14  )
    15  
    16  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
    17  	Analyzer: &analysis.Analyzer{
    18  		Name:     "SA1023",
    19  		Run:      run,
    20  		Requires: []*analysis.Analyzer{buildir.Analyzer},
    21  	},
    22  	Doc: &lint.Documentation{
    23  		Title:    `Modifying the buffer in an \'io.Writer\' implementation`,
    24  		Text:     `\'Write\' must not modify the slice data, even temporarily.`,
    25  		Since:    "2017.1",
    26  		Severity: lint.SeverityError,
    27  		MergeIf:  lint.MergeIfAny,
    28  	},
    29  })
    30  
    31  var Analyzer = SCAnalyzer.Analyzer
    32  
    33  func run(pass *analysis.Pass) (interface{}, error) {
    34  	// TODO(dh): this might be a good candidate for taint analysis.
    35  	// Taint the argument as MUST_NOT_MODIFY, then propagate that
    36  	// through functions like bytes.Split
    37  
    38  	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
    39  		sig := fn.Signature
    40  		if fn.Name() != "Write" || sig.Recv() == nil {
    41  			continue
    42  		}
    43  		if !types.Identical(sig, knowledge.Signatures["(io.Writer).Write"]) {
    44  			continue
    45  		}
    46  
    47  		for _, block := range fn.Blocks {
    48  			for _, ins := range block.Instrs {
    49  				switch ins := ins.(type) {
    50  				case *ir.Store:
    51  					addr, ok := ins.Addr.(*ir.IndexAddr)
    52  					if !ok {
    53  						continue
    54  					}
    55  					if addr.X != fn.Params[1] {
    56  						continue
    57  					}
    58  					report.Report(pass, ins, "io.Writer.Write must not modify the provided buffer, not even temporarily")
    59  				case *ir.Call:
    60  					if !irutil.IsCallTo(ins.Common(), "append") {
    61  						continue
    62  					}
    63  					if ins.Common().Args[0] != fn.Params[1] {
    64  						continue
    65  					}
    66  					report.Report(pass, ins, "io.Writer.Write must not modify the provided buffer, not even temporarily")
    67  				}
    68  			}
    69  		}
    70  	}
    71  	return nil, nil
    72  }