Ignore result of EvalSymlinks on ENOENT

When the path does not exist, filepath.EvalSymlinks returns an
empty string - so we can't just ignore ENOENT, we have to discard
the result if an ENOENT is returned.

Should fix Jira issue RHEL-37948

Signed-off-by: Matt Heon <mheon@redhat.com>

libpod/boltdb_state_internal.go

@@ -3,9 +3,7 @@
 package libpod
 
 import (
-	"errors"
 	"fmt"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -237,20 +235,18 @@ func readOnlyValidateConfig(bucket *bolt.Bucket, toCheck dbConfigValidation) (bo
 	// which is symlinked to /var/home.
 	if toCheck.isPath {
 		if dbValue != "" {
-			// Ignore ENOENT on both, on a fresh system some paths
-			// may not exist this early in Libpod init.
-			dbVal, err := filepath.EvalSymlinks(dbValue)
-			if err != nil && !errors.Is(err, fs.ErrNotExist) {
+			checkedVal, err := evalSymlinksIfExists(dbValue)
+			if err != nil {
 				return false, fmt.Errorf("evaluating symlinks on DB %s path %q: %w", toCheck.name, dbValue, err)
 			}
-			dbValue = dbVal
+			dbValue = checkedVal
 		}
 		if ourValue != "" {
-			ourVal, err := filepath.EvalSymlinks(ourValue)
-			if err != nil && !errors.Is(err, fs.ErrNotExist) {
+			checkedVal, err := evalSymlinksIfExists(ourValue)
+			if err != nil {
 				return false, fmt.Errorf("evaluating symlinks on configured %s path %q: %w", toCheck.name, ourValue, err)
 			}
-			ourValue = ourVal
+			ourValue = checkedVal
 		}
 	}
 

libpod/sqlite_state.go

@@ -6,7 +6,6 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
-	"io/fs"
 	"os"
 	"path/filepath"
 	goruntime "runtime"
@@ -379,21 +378,24 @@ func (s *SQLiteState) ValidateDBConfig(runtime *Runtime) (defErr error) {
 
 	checkField := func(fieldName, dbVal, ourVal string, isPath bool) error {
 		if isPath {
-			// Evaluate symlinks. Ignore ENOENT. No guarantee all
-			// directories exist this early in Libpod init.
+			// Tolerate symlinks when possible - most relevant for OStree systems
+			// and rootless containers, where we want to put containers in /home,
+			// which is symlinked to /var/home.
+			// Ignore ENOENT as reasonable, as some paths may not exist in early Libpod
+			// init.
 			if dbVal != "" {
-				dbValClean, err := filepath.EvalSymlinks(dbVal)
-				if err != nil && !errors.Is(err, fs.ErrNotExist) {
+				checkedVal, err := evalSymlinksIfExists(dbVal)
+				if err != nil {
 					return fmt.Errorf("cannot evaluate symlinks on DB %s path %q: %w", fieldName, dbVal, err)
 				}
-				dbVal = dbValClean
+				dbVal = checkedVal
 			}
 			if ourVal != "" {
-				ourValClean, err := filepath.EvalSymlinks(ourVal)
-				if err != nil && !errors.Is(err, fs.ErrNotExist) {
+				checkedVal, err := evalSymlinksIfExists(ourVal)
+				if err != nil {
 					return fmt.Errorf("cannot evaluate symlinks on our %s path %q: %w", fieldName, ourVal, err)
 				}
-				ourVal = ourValClean
+				ourVal = checkedVal
 			}
 		}
 

libpod/util.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -288,3 +289,22 @@ func writeStringToPath(path, contents, mountLabel string, uid, gid int) error {
 
 	return nil
 }
+
+// If the given path exists, evaluate any symlinks in it. If it does not, clean
+// the path and return it. Used to try and verify path equality in a somewhat
+// sane fashion.
+func evalSymlinksIfExists(toCheck string) (string, error) {
+	checkedVal, err := filepath.EvalSymlinks(toCheck)
+	if err != nil {
+		// If the error is not ENOENT, something more serious has gone
+		// wrong, return it.
+		if !errors.Is(err, fs.ErrNotExist) {
+			return "", err
+		}
+		// This is an ENOENT. On ENOENT, EvalSymlinks returns "".
+		// We don't want that. Return a cleaned version of the original
+		// path.
+		return filepath.Clean(toCheck), nil
+	}
+	return checkedVal, nil
+}