From 36b3f57b6167eb4e25d29dcb7be976d603f47d51 Mon Sep 17 00:00:00 2001
From: Jackson Owens <jackson@cockroachlabs.com>
Date: Fri, 6 Oct 2023 19:19:43 -0400
Subject: [PATCH] db: return structured errors from checkConsistency

During Open, Pebble verifies the consistency between the Version and the object
catalog. Previously if this function encountered an error or inconsistency, it
would return a new error that erased the type(s) of the original errors. This
commit modifies the function to use errors.Join and avoid the type erasure.
This is necessary for the metamorphic test's error injection, which must be
able to test an error to observe whether it is an errorfs.ErrInjected error.

Informs #1115.
---
 open.go | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/open.go b/open.go
index e021c9a1aa..83fa9dcfd5 100644
--- a/open.go
+++ b/open.go
@@ -1127,9 +1127,7 @@ func IsCorruptionError(err error) bool {
 }
 
 func checkConsistency(v *manifest.Version, dirname string, objProvider objstorage.Provider) error {
-	var buf bytes.Buffer
-	var args []interface{}
-
+	var errs []error
 	dedup := make(map[base.DiskFileNum]struct{})
 	for level, files := range v.Levels {
 		iter := files.Iter()
@@ -1153,22 +1151,18 @@ func checkConsistency(v *manifest.Version, dirname string, objProvider objstorag
 				size, err = objProvider.Size(meta)
 			}
 			if err != nil {
-				buf.WriteString("L%d: %s: %v\n")
-				args = append(args, errors.Safe(level), errors.Safe(fileNum), err)
+				errs = append(errs, errors.Wrapf(err, "L%d: %s", errors.Safe(level), fileNum))
 				continue
 			}
 
 			if size != int64(fileSize) {
-				buf.WriteString("L%d: %s: object size mismatch (%s): %d (disk) != %d (MANIFEST)\n")
-				args = append(args, errors.Safe(level), errors.Safe(fileNum), objProvider.Path(meta),
-					errors.Safe(size), errors.Safe(fileSize))
+				errs = append(errs, errors.Errorf(
+					"L%d: %s: object size mismatch (%s): %d (disk) != %d (MANIFEST)",
+					errors.Safe(level), fileNum, objProvider.Path(meta),
+					errors.Safe(size), errors.Safe(fileSize)))
 				continue
 			}
 		}
 	}
-
-	if buf.Len() == 0 {
-		return nil
-	}
-	return errors.Errorf(buf.String(), args...)
+	return errors.Join(errs...)
 }