Make every not exist error unwrappable to a fs.ErrNotExist (#20891)

A lot of our code is repeatedly testing if individual errors are
specific types of Not Exist errors. This is repetitative and unnecesary.
`Unwrap() error` provides a common way of labelling an error as a
NotExist error and we can/should use this.

This PR has chosen to use the common `io/fs` errors e.g.
`fs.ErrNotExist` for our errors. This is in some ways not completely
correct as these are not filesystem errors but it seems like a
reasonable thing to do and would allow us to simplify a lot of our code
to `errors.Is(err, fs.ErrNotExist)` instead of
`package.IsErr...NotExist(err)`

I am open to suggestions to use a different base error - perhaps
`models/db.ErrNotExist` if that would be felt to be better.


Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: delvh <dev.lh@web.de>

1 files changed, 18 insertions, 2 deletions

diff --git a/models/git/lfs.go b/models/git/lfs.go
index 179da3120a..1dab31d5f9 100644
--- a/models/git/lfs.go
+++ b/models/git/lfs.go
@@ -6,7 +6,6 @@ package git
 
 import (
 	"context"
-	"errors"
 	"fmt"
 
 	"code.gitea.io/gitea/models/db"
@@ -17,6 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/lfs"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 )
@@ -38,6 +38,10 @@ func (err ErrLFSLockNotExist) Error() string {
 	return fmt.Sprintf("lfs lock does not exist [id: %d, rid: %d, path: %s]", err.ID, err.RepoID, err.Path)
 }
 
+func (err ErrLFSLockNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrLFSUnauthorizedAction represents a "LFSUnauthorizedAction" kind of error.
 type ErrLFSUnauthorizedAction struct {
 	RepoID   int64
@@ -58,6 +62,10 @@ func (err ErrLFSUnauthorizedAction) Error() string {
 	return fmt.Sprintf("User %s doesn't have read access for lfs lock [rid: %d]", err.UserName, err.RepoID)
 }
 
+func (err ErrLFSUnauthorizedAction) Unwrap() error {
+	return util.ErrPermissionDenied
+}
+
 // ErrLFSLockAlreadyExist represents a "LFSLockAlreadyExist" kind of error.
 type ErrLFSLockAlreadyExist struct {
 	RepoID int64
@@ -74,6 +82,10 @@ func (err ErrLFSLockAlreadyExist) Error() string {
 	return fmt.Sprintf("lfs lock already exists [rid: %d, path: %s]", err.RepoID, err.Path)
 }
 
+func (err ErrLFSLockAlreadyExist) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
 // ErrLFSFileLocked represents a "LFSFileLocked" kind of error.
 type ErrLFSFileLocked struct {
 	RepoID   int64
@@ -91,6 +103,10 @@ func (err ErrLFSFileLocked) Error() string {
 	return fmt.Sprintf("File is lfs locked [repo: %d, locked by: %s, path: %s]", err.RepoID, err.UserName, err.Path)
 }
 
+func (err ErrLFSFileLocked) Unwrap() error {
+	return util.ErrPermissionDenied
+}
+
 // LFSMetaObject stores metadata for LFS tracked files.
 type LFSMetaObject struct {
 	ID           int64 `xorm:"pk autoincr"`
@@ -114,7 +130,7 @@ type LFSTokenResponse struct {
 
 // ErrLFSObjectNotExist is returned from lfs models functions in order
 // to differentiate between database and missing object errors.
-var ErrLFSObjectNotExist = errors.New("LFS Meta object does not exist")
+var ErrLFSObjectNotExist = db.ErrNotExist{Resource: "LFS Meta object"}
 
 // NewLFSMetaObject stores a given populated LFSMetaObject structure in the database
 // if it is not already present.