stash/pkg/fsutil/fs.go

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// Package fsutil provides filesystem utility functions for the application.
package fsutil
import (
"fmt"
"os"
"path/filepath"
"strings"
"unicode"
)
// IsFsPathCaseSensitive checks the fs of the given path to see if it is case sensitive
// if the case sensitivity can not be determined false and an error != nil are returned
func IsFsPathCaseSensitive(path string) (bool, error) {
// The case sensitivity of the fs of "path" is determined by case flipping
// the first letter rune from the base string of the path
// If the resulting flipped path exists then the fs should not be case sensitive
// ( we check the file mod time to avoid matching an existing path )
fi, err := os.Stat(path)
if err != nil { // path cannot be stat'd
return false, err
}
base := filepath.Base(path)
fBase, err := flipCaseSingle(base)
if err != nil { // cannot be case flipped
return false, err
}
i := strings.LastIndex(path, base)
if i < 0 { // shouldn't happen
return false, fmt.Errorf("could not case flip path %s", path)
}
flipped := []byte(path)
for _, c := range []byte(fBase) { // replace base of path with the flipped one ( we need to flip the base or last dir part )
flipped[i] = c
i++
}
fiCase, err := os.Stat(string(flipped))
if err != nil { // cannot stat the case flipped path
return true, nil // fs of path should be case sensitive
}
if fiCase.ModTime() == fi.ModTime() { // file path exists and is the same
return false, nil // fs of path is not case sensitive
}
return false, fmt.Errorf("can not determine case sensitivity of path %s", path)
}
// flipCaseSingle flips the case ( lower<->upper ) of a single char from the string s
// If the string cannot be flipped, the original string value and an error are returned
func flipCaseSingle(s string) (string, error) {
rr := []rune(s)
for i, r := range rr {
if unicode.IsLetter(r) { // look for a letter to flip
if unicode.IsUpper(r) {
rr[i] = unicode.ToLower(r)
return string(rr), nil
}
rr[i] = unicode.ToUpper(r)
return string(rr), nil
}
}
return s, fmt.Errorf("could not case flip string %s", s)
}