rclone/backend/s3/gen_setfrom.go
Nick Craig-Wood bda4f25baa s3: support metadata setting and mapping on server side Copy
Before this change the backend would not run the metadata mapper and
it would ignore metadata set when doing server side copies.
2024-03-07 14:44:45 +00:00

103 lines
2.8 KiB
Go

// Generate boilerplate code for setting similar structs from each other
//go:build ignore
// +build ignore
package main
import (
"flag"
"fmt"
"io"
"log"
"os"
"reflect"
"strings"
"github.com/aws/aws-sdk-go/service/s3"
)
// flags
var (
outputFile = flag.String("o", "", "Output file name, stdout if unset")
)
// globals
var (
out io.Writer = os.Stdout
)
// genSetFrom generates code to set the public members of a from b
//
// a and b should be pointers to structs
//
// a can be a different type from b
//
// Only the Fields which have the same name and assignable type on a
// and b will be set.
//
// This is useful for copying between almost identical structures that
// are frequently present in auto-generated code for cloud storage
// interfaces.
func genSetFrom(a, b interface{}) {
name := fmt.Sprintf("setFrom_%T_%T", a, b)
name = strings.Replace(name, ".", "", -1)
name = strings.Replace(name, "*", "", -1)
fmt.Fprintf(out, "\n// %s copies matching elements from a to b\n", name)
fmt.Fprintf(out, "func %s(a %T, b %T) {\n", name, a, b)
ta := reflect.TypeOf(a).Elem()
tb := reflect.TypeOf(b).Elem()
va := reflect.ValueOf(a).Elem()
vb := reflect.ValueOf(b).Elem()
for i := 0; i < tb.NumField(); i++ {
bField := vb.Field(i)
tbField := tb.Field(i)
name := tbField.Name
aField := va.FieldByName(name)
taField, found := ta.FieldByName(name)
if found && aField.IsValid() && bField.IsValid() && aField.CanSet() && tbField.Type.AssignableTo(taField.Type) {
fmt.Fprintf(out, "\ta.%s = b.%s\n", name, name)
}
}
fmt.Fprintf(out, "}\n")
}
func main() {
flag.Parse()
if *outputFile != "" {
fd, err := os.Create(*outputFile)
if err != nil {
log.Fatal(err)
}
defer func() {
err := fd.Close()
if err != nil {
log.Fatal(err)
}
}()
out = fd
}
fmt.Fprintf(out, `// Code generated by "go run gen_setfrom.go"; DO NOT EDIT.
package s3
import "github.com/aws/aws-sdk-go/service/s3"
`)
genSetFrom(new(s3.ListObjectsInput), new(s3.ListObjectsV2Input))
genSetFrom(new(s3.ListObjectsV2Output), new(s3.ListObjectsOutput))
genSetFrom(new(s3.ListObjectVersionsInput), new(s3.ListObjectsV2Input))
genSetFrom(new(s3.ObjectVersion), new(s3.DeleteMarkerEntry))
genSetFrom(new(s3.ListObjectsV2Output), new(s3.ListObjectVersionsOutput))
genSetFrom(new(s3.Object), new(s3.ObjectVersion))
genSetFrom(new(s3.CreateMultipartUploadInput), new(s3.HeadObjectOutput))
genSetFrom(new(s3.CreateMultipartUploadInput), new(s3.CopyObjectInput))
genSetFrom(new(s3.UploadPartCopyInput), new(s3.CopyObjectInput))
genSetFrom(new(s3.HeadObjectOutput), new(s3.GetObjectOutput))
genSetFrom(new(s3.CreateMultipartUploadInput), new(s3.PutObjectInput))
genSetFrom(new(s3.HeadObjectOutput), new(s3.PutObjectInput))
genSetFrom(new(s3.CopyObjectInput), new(s3.PutObjectInput))
}