Feat: conditional permissions behavior (#28)

* Fix: don't need sudo if we're root + other aesthetics

* Heavy refactoring, see PR #28

* Fix: avoid silent fatalities

demo: https://tcp.ac/i/JMSUc.gif

* Fix: Inverse check on `IsRoot`

* D.R.Y: check for permissions error in `common.ErrorCheck`

Reduce cognitive complexity.

* Fix: Issue with copying

* Resolve https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646535918

* Resolve https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646606680 and https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646594105

* Revert "Resolve https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646606680 and https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646594105"

This reverts commit ce15213009.

* Resolve https://github.com/HikariKnight/quickpassthrough/pull/28#discussion_r1646730751

internal/common/errors.go

@@ -0,0 +1,50 @@
+package common
+
+import (
+	"errors"
+	"os"
+	"time"
+
+	"github.com/HikariKnight/ls-iommu/pkg/errorcheck"
+	"github.com/gookit/color"
+)
+
+const PermissionNotice = `
+<yellowB>Permissions error occured during file operations.</>
+
+<blue_b>Hint</>:
+
+	If you initially ran QuickPassthrough as root or using sudo,
+	but are now running it as a normal user, this is expected behavior.
+
+	<us>Try running QuickPassthrough as root or using sudo if so.</>
+
+	If this does not work, double check your filesystem's permissions,
+	and be sure to check the debug log for more information.
+`
+
+// ErrorCheck serves as a wrapper for HikariKnight/ls-iommu/pkg/common.ErrorCheck that allows for visibile error messages
+func ErrorCheck(err error, msg ...string) {
+	_, _ = os.Stdout.WriteString("\033[H\033[2J") // clear the screen
+	if err == nil {
+		return
+	}
+	if errors.Is(err, os.ErrPermission) {
+		color.Printf(PermissionNotice)
+	}
+	oneMsg := ""
+	if len(msg) < 1 {
+		oneMsg = ""
+	} else {
+		for _, v := range msg {
+			oneMsg += v + "\n"
+		}
+	}
+	color.Printf("\n<red_b>FATAL</>: %s\n%s\nAborting", err.Error(), oneMsg)
+	for i := 0; i < 10; i++ {
+		time.Sleep(1 * time.Second)
+		print(".")
+	}
+	print("\n")
+	errorcheck.ErrorCheck(err, msg...)
+}