From 5fbcc2ece0f279dcae1c6bc684179d38491a2bdc Mon Sep 17 00:00:00 2001
From: "Andrew E. Torda" <torda@zbh.uni-hamburg.de>
Date: Tue, 31 May 2022 11:06:24 +0200
Subject: [PATCH] Not really fixed, but I have a verbose error message for file
creation failures which happen under windows.
---
mc_work/dorun.go | 41 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
diff --git a/mc_work/dorun.go b/mc_work/dorun.go
index 5ae5460..a6d4f7e 100644
--- a/mc_work/dorun.go
+++ b/mc_work/dorun.go
@@ -4,8 +4,10 @@ package mcwork
import (
"bufio"
"bytes"
+ "errors"
"fmt"
"io"
+ "io/fs"
"math"
"math/rand"
"os"
@@ -62,6 +64,43 @@ func isNotSane(mcPrm *McPrm) error {
return nil
}
+// fExists returns true if the file exists.
+// It is part of the exercise, working around file permissions on windows
+func fExists (name string) bool {
+ var err error
+ if _, err := os.Stat (name); err == nil {
+ return true
+ }
+ if errors.Is (err, fs.ErrNotExist) {
+ return false
+ }
+ return true
+}
+
+
+// createFix is a wrapper around os.Create() which I seem to need for windows.
+// On windows, I cannot overwrite an existing file. To be very exact, the
+// O_CREATE fails if a file exists. O_TRUNC also fails.
+func createFix (name string) (*os.File, error) {
+ var rErr = `Remove the file %s and try again. This only happens on windows: %w`
+ var f *os.File
+ var err error
+ if f, err = os.Create(name); err == nil {
+ return f, nil // Most common path (no problem)
+ }
+
+ if !fExists(name) { // does not exist, but we have a real error.
+ return nil, err // Return original error
+ } // Next step try to remove original file
+ if e := os.Remove (name); e != nil {
+ return nil, fmt.Errorf (rErr, name, e)
+ }
+ if f, err = os.Create(name); err == nil { // second attempt, after removing name
+ return f, nil
+ }
+ return nil, err
+}
+
// setupRun does things like get the cooling rate, seed the random numbers.
func setupRun(mcPrm *McPrm, cprm *cprm) error {
var err error
@@ -83,7 +122,7 @@ func setupRun(mcPrm *McPrm, cprm *cprm) error {
if mcPrm.fOutName, err = setSuffix(mcPrm.fOutName, ".csv"); err != nil {
return err
}
- if cprm.fOutRaw, err = os.Create(mcPrm.fOutName); err != nil {
+ if cprm.fOutRaw, err = createFix(mcPrm.fOutName); err != nil {
return err
}
cprm.fOut = bufio.NewWriter(cprm.fOutRaw)
--
GitLab