x/simulation: (*StandardLogWriter).PrintLogs() creates files but never closes them, but also the os.Create should check that error

[odeke-em]

Problems

• Noticed via an audit, the code from (*StandardLogWriter).PrintLogs() requests for *os.File but never closes it
  

  cosmos-sdk/x/simulation/log.go

  Lines 36 to 47 in 13b5a8d

  	func (lw *StandardLogWriter) PrintLogs() {
  	f := createLogFile()
  	for i := 0; i < len(lw.OpEntries); i++ {
  	writeEntry := fmt.Sprintf("%s\n", (lw.OpEntries[i]).MustMarshal())
  	_, err := f.WriteString(writeEntry)
  	if err != nil {
  	panic("Failed to write logs to file")
  	}
  	}
  	}

• We should be checking that the error returned after os.Create(filepath) checks an error and panics if non-nil
  

  cosmos-sdk/x/simulation/log.go

  Lines 61 to 64 in 13b5a8d

  	f, _ = os.Create(filePath)
  	fmt.Printf("Logs to writing to %s\n", filePath)
  	return f

We need to fix that code in the 2 places as

// PrintLogs - print the logs to a simulation file
func (lw *StandardLogWriter) PrintLogs() {
        f := createLogFile()
        defer  f.Close()

        for i := 0; i < len(lw.OpEntries); i++ {
                writeEntry := fmt.Sprintf("%s\n", (lw.OpEntries[i]).MustMarshal())
                _, err := f.WriteString(writeEntry)

                if err != nil {
                        panic("Failed to write logs to file")
                }
        }
}

func createLogFile() *os.File {
        fileName := fmt.Sprintf("%s.log", time.Now().Format("2006-01-02_15:04:05"))
        folderPath := os.ExpandEnv("$HOME/.simapp/simulations")
        filePath := path.Join(folderPath, fileName)

        if err := os.MkdirAll(folderPath, os.ModePerm); err != nil {
                panic(err)
        }

        f, err := os.Create(filePath)
        if err != nil {
                panic(err)
        }
        fmt.Printf("Logs to writing to %s\n", filePath)

        return f
}

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For Admin Use

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• Appropriate labels applied
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[odeke-em]

Even better, perhaps we need to remove that harded "/" separators to make it

folderPath := filepath.Join(os.ExpandEnv("$HOME"), ".simapp", "simulations")