kvm/internal/usbgadget/utils.go

64 lines
1.7 KiB
Go

package usbgadget
import (
"bytes"
"fmt"
"os"
"path/filepath"
)
// Helper function to get absolute value of float64
func abs(x float64) float64 {
if x < 0 {
return -x
}
return x
}
func joinPath(basePath string, paths []string) string {
pathArr := append([]string{basePath}, paths...)
return filepath.Join(pathArr...)
}
func ensureSymlink(linkPath string, target string) error {
if _, err := os.Lstat(linkPath); err == nil {
currentTarget, err := os.Readlink(linkPath)
if err != nil || currentTarget != target {
err = os.Remove(linkPath)
if err != nil {
return fmt.Errorf("failed to remove existing symlink %s: %w", linkPath, err)
}
}
} else if !os.IsNotExist(err) {
return fmt.Errorf("failed to check if symlink exists: %w", err)
}
if err := os.Symlink(target, linkPath); err != nil {
return fmt.Errorf("failed to create symlink from %s to %s: %w", linkPath, target, err)
}
return nil
}
func (u *UsbGadget) writeIfDifferent(filePath string, content []byte, permMode os.FileMode) error {
if _, err := os.Stat(filePath); err == nil {
oldContent, err := os.ReadFile(filePath)
if err == nil {
if bytes.Equal(oldContent, content) {
u.log.Tracef("skipping writing to %s as it already has the correct content", filePath)
return nil
}
if len(oldContent) == len(content)+1 &&
bytes.Equal(oldContent[:len(content)], content) &&
oldContent[len(content)] == 10 {
u.log.Tracef("skipping writing to %s as it already has the correct content", filePath)
return nil
}
u.log.Tracef("writing to %s as it has different content old%v new%v", filePath, oldContent, content)
}
}
return os.WriteFile(filePath, content, permMode)
}