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ccollins pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-newtmgr.git
commit 0d6802eb80b5277936052d5117168d7cd90c7cd8
Author: Christopher Collins <ccoll...@apache.org>
AuthorDate: Wed Feb 19 08:53:23 2020 -0800
res: Use zero payload when no args specified
This command:
newtmgr res get /my/res
should send a CoAP GET request with *no* payload. An optional payload
can be specified with extra arguments after the resource name. Since
there are no extra arguments, there should be no payload.
Prior to this commit, newtmgr was including an empty map as the payload
in such requests.
The bug was caused by this quirk in Go:
https://forum.golangbridge.org/t/a-nil-a-b-b-nil-with-pointers-and-interface/10593
In short, if `nil` is assigned to a variable of type `interface{}`, the
variable will *not* compare equal to `nil`. An interface variable
contains two pieces of information: 1) its type, and 2) its value. The
variable is not equal to `nil` because `nil` is an *untyped* nil value.
The solution is to return the untyped `nil` rather than the nil
interface{}.
---
newtmgr/cli/res.go | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/newtmgr/cli/res.go b/newtmgr/cli/res.go
index 7f2e39e..51ff7c8 100644
--- a/newtmgr/cli/res.go
+++ b/newtmgr/cli/res.go
@@ -259,17 +259,25 @@ func parsePayload(args []string) ([]byte, error) {
if len(args) == 0 {
return nil, nil
}
- val, err = parsePayloadJson(args[0])
+ itf, err := parsePayloadJson(args[0])
+ if err != nil {
+ return nil, err
+ }
+ // Check for zero payload. Need to return nil explicitly;
don't wrap
+ // in interface{}.
+ if itf == nil {
+ return nil, nil
+ }
} else {
- val, err = parsePayloadMap(args)
- }
- if err != nil {
- return nil, err
- }
-
- if val == nil {
- // No payload.
- return nil, nil
+ itf, err := parsePayloadMap(args)
+ if err != nil {
+ return nil, err
+ }
+ // Check for zero payload. Need to return nil explicitly;
don't wrap
+ // in interface{}.
+ if itf == nil {
+ return nil, nil
+ }
}
b, err := nmxutil.EncodeCbor(val)
