Show line with syntax error when parsing JSON files

config.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+ "camlistore.org/pkg/errorutil"
  "encoding/json"
+ "fmt"
  "github.com/miekg/dns"
  "io/ioutil"
  "log"
@@ -102,7 +104,20 @@ func readZoneFile(zoneName, fileName string) (*Zone, error) {
  if err == nil {
  var objmap map[string]interface{}
  decoder := json.NewDecoder(fh)
- err := decoder.Decode(&objmap)
+ if err = decoder.Decode(&objmap); err != nil {
+ extra := ""
+ if serr, ok := err.(*json.SyntaxError); ok {
+ if _, serr := fh.Seek(0, os.SEEK_SET); serr != nil {
+ log.Fatalf("seek error: %v", serr)
+ }
+ line, col, highlight := errorutil.HighlightBytePosition(fh, serr.Offset)
+ extra = fmt.Sprintf(":\nError at line %d, column %d (file offset %d):\n%s",
+ line, col, serr.Offset, highlight)
+ }
+ return nil, fmt.Errorf("error parsing JSON object in config file %s%s\n%v",
+ fh.Name(), extra, err)
+ }
+
  if err != nil {
  panic(err)
  }