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>

11 files changed, 80 insertions, 3 deletions

diff --git a/models/issues/comment.go b/models/issues/comment.go
index a71afda9e0..9ab6cab7d0 100644
--- a/models/issues/comment.go
+++ b/models/issues/comment.go
@@ -28,6 +28,7 @@ import (
 	"code.gitea.io/gitea/modules/references"
 	"code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 	"xorm.io/xorm"
@@ -49,6 +50,10 @@ func (err ErrCommentNotExist) Error() string {
 	return fmt.Sprintf("comment does not exist [id: %d, issue_id: %d]", err.ID, err.IssueID)
 }
 
+func (err ErrCommentNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // CommentType defines whether a comment is just a simple comment, an action (like close) or a reference.
 type CommentType int
 
diff --git a/models/issues/content_history.go b/models/issues/content_history.go
index 3e321784bd..f5cfa65b8f 100644
--- a/models/issues/content_history.go
+++ b/models/issues/content_history.go
@@ -12,6 +12,7 @@ import (
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 )
@@ -201,6 +202,10 @@ func (err ErrIssueContentHistoryNotExist) Error() string {
 	return fmt.Sprintf("issue content history does not exist [id: %d]", err.ID)
 }
 
+func (err ErrIssueContentHistoryNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // GetIssueContentHistoryByID get issue content history
 func GetIssueContentHistoryByID(dbCtx context.Context, id int64) (*ContentHistory, error) {
 	h := &ContentHistory{}
diff --git a/models/issues/dependency.go b/models/issues/dependency.go
index d664c0758e..4754ed0f5f 100644
--- a/models/issues/dependency.go
+++ b/models/issues/dependency.go
@@ -11,6 +11,7 @@ import (
 	"code.gitea.io/gitea/models/db"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 )
 
 // ErrDependencyExists represents a "DependencyAlreadyExists" kind of error.
@@ -29,6 +30,10 @@ func (err ErrDependencyExists) Error() string {
 	return fmt.Sprintf("issue dependency does already exist [issue id: %d, dependency id: %d]", err.IssueID, err.DependencyID)
 }
 
+func (err ErrDependencyExists) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
 // ErrDependencyNotExists represents a "DependencyAlreadyExists" kind of error.
 type ErrDependencyNotExists struct {
 	IssueID      int64
@@ -45,6 +50,10 @@ func (err ErrDependencyNotExists) Error() string {
 	return fmt.Sprintf("issue dependency does not exist [issue id: %d, dependency id: %d]", err.IssueID, err.DependencyID)
 }
 
+func (err ErrDependencyNotExists) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrCircularDependency represents a "DependencyCircular" kind of error.
 type ErrCircularDependency struct {
 	IssueID      int64
@@ -91,6 +100,10 @@ func (err ErrUnknownDependencyType) Error() string {
 	return fmt.Sprintf("unknown dependency type [type: %d]", err.Type)
 }
 
+func (err ErrUnknownDependencyType) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
 // IssueDependency represents an issue dependency
 type IssueDependency struct {
 	ID           int64              `xorm:"pk autoincr"`
diff --git a/models/issues/issue.go b/models/issues/issue.go
index 786c969522..e56e43bd1a 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -52,6 +52,10 @@ func (err ErrIssueNotExist) Error() string {
 	return fmt.Sprintf("issue does not exist [id: %d, repo_id: %d, index: %d]", err.ID, err.RepoID, err.Index)
 }
 
+func (err ErrIssueNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrIssueIsClosed represents a "IssueIsClosed" kind of error.
 type ErrIssueIsClosed struct {
 	ID     int64
diff --git a/models/issues/label.go b/models/issues/label.go
index 667a608687..be97454e26 100644
--- a/models/issues/label.go
+++ b/models/issues/label.go
@@ -38,6 +38,10 @@ func (err ErrRepoLabelNotExist) Error() string {
 	return fmt.Sprintf("label does not exist [label_id: %d, repo_id: %d]", err.LabelID, err.RepoID)
 }
 
+func (err ErrRepoLabelNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrOrgLabelNotExist represents a "OrgLabelNotExist" kind of error.
 type ErrOrgLabelNotExist struct {
 	LabelID int64
@@ -54,6 +58,10 @@ func (err ErrOrgLabelNotExist) Error() string {
 	return fmt.Sprintf("label does not exist [label_id: %d, org_id: %d]", err.LabelID, err.OrgID)
 }
 
+func (err ErrOrgLabelNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrLabelNotExist represents a "LabelNotExist" kind of error.
 type ErrLabelNotExist struct {
 	LabelID int64
@@ -69,6 +77,10 @@ func (err ErrLabelNotExist) Error() string {
 	return fmt.Sprintf("label does not exist [label_id: %d]", err.LabelID)
 }
 
+func (err ErrLabelNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // LabelColorPattern is a regexp witch can validate LabelColor
 var LabelColorPattern = regexp.MustCompile("^#?(?:[0-9a-fA-F]{6}|[0-9a-fA-F]{3})$")
 
diff --git a/models/issues/milestone.go b/models/issues/milestone.go
index 1021938b20..3ccade7411 100644
--- a/models/issues/milestone.go
+++ b/models/issues/milestone.go
@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 )
@@ -39,6 +40,10 @@ func (err ErrMilestoneNotExist) Error() string {
 	return fmt.Sprintf("milestone does not exist [id: %d, repo_id: %d]", err.ID, err.RepoID)
 }
 
+func (err ErrMilestoneNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // Milestone represents a milestone of repository.
 type Milestone struct {
 	ID              int64                  `xorm:"pk autoincr"`
diff --git a/models/issues/pull.go b/models/issues/pull.go
index 69259c269f..18b67eb305 100644
--- a/models/issues/pull.go
+++ b/models/issues/pull.go
@@ -46,6 +46,10 @@ func (err ErrPullRequestNotExist) Error() string {
 		err.ID, err.IssueID, err.HeadRepoID, err.BaseRepoID, err.HeadBranch, err.BaseBranch)
 }
 
+func (err ErrPullRequestNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrPullRequestAlreadyExists represents a "PullRequestAlreadyExists"-error
 type ErrPullRequestAlreadyExists struct {
 	ID         int64
@@ -68,6 +72,10 @@ func (err ErrPullRequestAlreadyExists) Error() string {
 		err.ID, err.IssueID, err.HeadRepoID, err.BaseRepoID, err.HeadBranch, err.BaseBranch)
 }
 
+func (err ErrPullRequestAlreadyExists) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
 // ErrPullRequestHeadRepoMissing represents a "ErrPullRequestHeadRepoMissing" error
 type ErrPullRequestHeadRepoMissing struct {
 	ID         int64
diff --git a/models/issues/reaction.go b/models/issues/reaction.go
index ccda10be2c..02cffad3ba 100644
--- a/models/issues/reaction.go
+++ b/models/issues/reaction.go
@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 )
@@ -34,6 +35,10 @@ func (err ErrForbiddenIssueReaction) Error() string {
 	return fmt.Sprintf("'%s' is not an allowed reaction", err.Reaction)
 }
 
+func (err ErrForbiddenIssueReaction) Unwrap() error {
+	return util.ErrPermissionDenied
+}
+
 // ErrReactionAlreadyExist is used when a existing reaction was try to created
 type ErrReactionAlreadyExist struct {
 	Reaction string
@@ -49,6 +54,10 @@ func (err ErrReactionAlreadyExist) Error() string {
 	return fmt.Sprintf("reaction '%s' already exists", err.Reaction)
 }
 
+func (err ErrReactionAlreadyExist) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
 // Reaction represents a reactions on issues and comments.
 type Reaction struct {
 	ID               int64              `xorm:"pk autoincr"`
diff --git a/models/issues/review.go b/models/issues/review.go
index 5835900801..26fcea9eef 100644
--- a/models/issues/review.go
+++ b/models/issues/review.go
@@ -39,6 +39,10 @@ func (err ErrReviewNotExist) Error() string {
 	return fmt.Sprintf("review does not exist [id: %d]", err.ID)
 }
 
+func (err ErrReviewNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrNotValidReviewRequest an not allowed review request modify
 type ErrNotValidReviewRequest struct {
 	Reason string
@@ -59,6 +63,10 @@ func (err ErrNotValidReviewRequest) Error() string {
 		err.RepoID)
 }
 
+func (err ErrNotValidReviewRequest) Unwrap() error {
+	return util.ErrInvalidArgument
+}
+
 // ReviewType defines the sort of feedback a review gives
 type ReviewType int
 
diff --git a/models/issues/stopwatch.go b/models/issues/stopwatch.go
index 0a7ad41f9c..a87fbfafa2 100644
--- a/models/issues/stopwatch.go
+++ b/models/issues/stopwatch.go
@@ -25,6 +25,10 @@ func (err ErrIssueStopwatchNotExist) Error() string {
 	return fmt.Sprintf("issue stopwatch doesn't exist[uid: %d, issue_id: %d", err.UserID, err.IssueID)
 }
 
+func (err ErrIssueStopwatchNotExist) Unwrap() error {
+	return util.ErrNotExist
+}
+
 // ErrIssueStopwatchAlreadyExist represents an error that stopwatch is already exist
 type ErrIssueStopwatchAlreadyExist struct {
 	UserID  int64
@@ -35,6 +39,10 @@ func (err ErrIssueStopwatchAlreadyExist) Error() string {
 	return fmt.Sprintf("issue stopwatch already exists[uid: %d, issue_id: %d", err.UserID, err.IssueID)
 }
 
+func (err ErrIssueStopwatchAlreadyExist) Unwrap() error {
+	return util.ErrAlreadyExist
+}
+
 // Stopwatch represents a stopwatch for time tracking.
 type Stopwatch struct {
 	ID          int64              `xorm:"pk autoincr"`
diff --git a/models/issues/tracked_time.go b/models/issues/tracked_time.go
index 9f8767362f..ca21eb5149 100644
--- a/models/issues/tracked_time.go
+++ b/models/issues/tracked_time.go
@@ -236,7 +236,7 @@ func DeleteIssueUserTimes(issue *Issue, user *user_model.User) error {
 		return err
 	}
 	if removedTime == 0 {
-		return db.ErrNotExist{}
+		return db.ErrNotExist{Resource: "tracked_time"}
 	}
 
 	if err := issue.LoadRepo(ctx); err != nil {
@@ -296,7 +296,7 @@ func deleteTimes(ctx context.Context, opts FindTrackedTimesOptions) (removedTime
 
 func deleteTime(ctx context.Context, t *TrackedTime) error {
 	if t.Deleted {
-		return db.ErrNotExist{ID: t.ID}
+		return db.ErrNotExist{Resource: "tracked_time", ID: t.ID}
 	}
 	t.Deleted = true
 	_, err := db.GetEngine(ctx).ID(t.ID).Cols("deleted").Update(t)
@@ -310,7 +310,7 @@ func GetTrackedTimeByID(id int64) (*TrackedTime, error) {
 	if err != nil {
 		return nil, err
 	} else if !has {
-		return nil, db.ErrNotExist{ID: id}
+		return nil, db.ErrNotExist{Resource: "tracked_time", ID: id}
 	}
 	return time, nil
 }