feat: Prevent SEGFAULT in Cast operations

Author: Gu1nness

pbm/config/config_test.go

@@ -3,6 +3,7 @@ package config
 import (
 	"testing"
 
+	"github.com/percona/percona-backup-mongodb/pbm/storage"
 	"github.com/percona/percona-backup-mongodb/pbm/storage/azure"
 	"github.com/percona/percona-backup-mongodb/pbm/storage/gcs"
 	"github.com/percona/percona-backup-mongodb/pbm/storage/s3"
@@ -125,6 +126,18 @@ func TestIsSameStorage(t *testing.T) {
 	})
 }
 
+func TestCastError(t *testing.T) {
+	t.Run("S3", func(t *testing.T) {
+		cfg := StorageConf{Type: storage.S3}
+
+		err := cfg.Cast()
+		if err == nil {
+			t.Errorf("Cast did not raise an error")
+		}
+
+	})
+}
+
 func boolPtr(b bool) *bool {
 	return &b
 }

pbm/storage/fs/fs.go

@@ -47,6 +47,9 @@ func (cfg *Config) Equal(other *Config) bool {
 }
 
 func (cfg *Config) Cast() error {
+	if cfg == nil {
+		return errors.New("Missing blackhole configuration with blackhole storage type.")
+	}
 	if cfg.Path == "" {
 		return errors.New("path can't be empty")
 	}

pbm/storage/s3/s3.go

@@ -44,7 +44,7 @@ const (
 //nolint:lll
 type Config struct {
 	Provider             string            `bson:"provider,omitempty" json:"provider,omitempty" yaml:"provider,omitempty"`
-	Region               string            `bson:"region" json:"region" yaml:"region"`
+	Region               string            `bson:"region,omitempty" json:"region,omitempty" yaml:"region,omitempty"`
 	EndpointURL          string            `bson:"endpointUrl,omitempty" json:"endpointUrl" yaml:"endpointUrl,omitempty"`
 	EndpointURLMap       map[string]string `bson:"endpointUrlMap,omitempty" json:"endpointUrlMap,omitempty" yaml:"endpointUrlMap,omitempty"`
 	ForcePathStyle       *bool             `bson:"forcePathStyle,omitempty" json:"forcePathStyle,omitempty" yaml:"forcePathStyle,omitempty"`
@@ -207,6 +207,9 @@ func (cfg *Config) IsSameStorage(other *Config) bool {
 }
 
 func (cfg *Config) Cast() error {
+	if cfg == nil {
+		return errors.New("Missing S3 configuration with S3 storage type.")
+	}
 	if cfg.Region == "" {
 		cfg.Region = defaultS3Region
 	}

pbm/storage/s3/s3_test.go

@@ -149,6 +149,17 @@ func TestConfig(t *testing.T) {
 			t.Error("expected not to be equal when updating credentials")
 		}
 	})
+
+	t.Run("Cast succeeds", func(t *testing.T) {
+		if opts.Region != "" {
+			t.Error("Start value is not ''")
+		}
+		opts.Cast()
+
+		if opts.Region != "us-east-1" {
+			t.Error("Default value should be set on Cast")
+		}
+	})
 }
 
 func TestRetryer(t *testing.T) {