i/prompting/requestprompts: include reason in notice data when prompt…

… resolved

A prompt may only be resolved once, and the notice recorded when that
prompt is resolved is the final notice which will be associated with
that prompt ID. Therefore, it is safe to include notice data without
risk of signal loss.

Currently, prompt clients need to query the prompting API in order to
check whether an outstanding prompt was modified (due to some but not
all of its permissions being satisfied by a new rule) or fully resolved,
either due to a direct reply, a new rule satisfying all remaining
permissions, or the prompt DB being closed.

Since the notice recorded when a prompt is resolved is the final notice
for that prompt, we can instead include the "resolved" key in the
notice data to indicate to the client that the prompt has been resolved
without the need to query the prompting API. And the value for the
"resolved" key can be "replied", "satisfied", or "cancelled", giving
additional information to the prompt client about why the prompt was
resolved.

Signed-off-by: Oliver Calder <[email protected]>

interfaces/prompting/requestprompts/requestprompts.go

@@ -103,15 +103,15 @@ type PromptDB struct {
 	maxIDPath string
 	mutex     sync.Mutex
 	// Function to issue a notice for a change in a prompt
-	notifyPrompt func(userID uint32, promptID string) error
+	notifyPrompt func(userID uint32, promptID string, data map[string]string) error
 }
 
 // New creates and returns a new prompt database.
 //
 // The given notifyPrompt closure should record a notice of type
 // "interfaces-requests-prompt" for the given user with the given
 // promptID as its key.
-func New(notifyPrompt func(userID uint32, promptID string) error) *PromptDB {
+func New(notifyPrompt func(userID uint32, promptID string, data map[string]string) error) *PromptDB {
 	pdb := PromptDB{
 		perUser:      make(map[uint32]*userPromptDB),
 		notifyPrompt: notifyPrompt,
@@ -212,7 +212,7 @@ func (pdb *PromptDB) AddOrMerge(metadata *prompting.Metadata, path string, permi
 			// have replied with a malformed response and not retried after
 			// receiving the error, so this notice encourages it to try again
 			// if the user retries the operation.
-			pdb.notifyPrompt(metadata.User, prompt.ID)
+			pdb.notifyPrompt(metadata.User, prompt.ID, nil)
 			return prompt, true
 		}
 	}
@@ -228,7 +228,7 @@ func (pdb *PromptDB) AddOrMerge(metadata *prompting.Metadata, path string, permi
 		listenerReqs: []*listener.Request{listenerReq},
 	}
 	userEntry.ByID[id] = prompt
-	pdb.notifyPrompt(metadata.User, id)
+	pdb.notifyPrompt(metadata.User, id, nil)
 	return prompt, false
 }
 
@@ -293,7 +293,9 @@ func (pdb *PromptDB) Reply(user uint32, id string, outcome prompting.OutcomeType
 		}
 	}
 	delete(userEntry.ByID, id)
-	pdb.notifyPrompt(user, id)
+	data := make(map[string]string)
+	data["resolved"] = "replied"
+	pdb.notifyPrompt(user, id, data)
 	return prompt, nil
 }
 
@@ -344,8 +346,8 @@ func (pdb *PromptDB) HandleNewRule(metadata *prompting.Metadata, constraints *pr
 		if !modified {
 			continue
 		}
-		pdb.notifyPrompt(metadata.User, id)
 		if len(prompt.Constraints.Permissions) > 0 && allow == true {
+			pdb.notifyPrompt(metadata.User, id, nil)
 			continue
 		}
 		// All permissions of prompt satisfied, or any permission denied
@@ -354,6 +356,9 @@ func (pdb *PromptDB) HandleNewRule(metadata *prompting.Metadata, constraints *pr
 		}
 		delete(userEntry.ByID, id)
 		satisfiedPromptIDs = append(satisfiedPromptIDs, id)
+		data := make(map[string]string)
+		data["resolved"] = "satisfied"
+		pdb.notifyPrompt(metadata.User, id, data)
 	}
 	return satisfiedPromptIDs, nil
 }
@@ -363,11 +368,13 @@ func (pdb *PromptDB) HandleNewRule(metadata *prompting.Metadata, constraints *pr
 // This should be called when snapd is shutting down, to notify prompt clients
 // that the given prompts are no longer awaiting a reply.
 func (pdb *PromptDB) Close() {
+	data := make(map[string]string)
+	data["resolved"] = "cancelled"
 	pdb.mutex.Lock()
 	defer pdb.mutex.Unlock()
 	for user, userEntry := range pdb.perUser {
 		for id := range userEntry.ByID {
-			pdb.notifyPrompt(user, id)
+			pdb.notifyPrompt(user, id, data)
 		}
 	}
 	// Clear all outstanding prompts