Config - don't allow setting key-paths inside of strings, arrays, etc

spec/config-spec.coffee

@@ -1142,8 +1142,8 @@ describe "Config", ->
           type: 'integer'
           default: 12
 
-        expect(atom.config.getSchema('foo.baz')).toBeUndefined()
-        expect(atom.config.getSchema('foo.bar.anInt.baz')).toBeUndefined()
+        expect(atom.config.getSchema('foo.baz')).toBe(null)
+        expect(atom.config.getSchema('foo.bar.anInt.baz')).toBe(false)
 
       it "respects the schema for scoped settings", ->
         schema =
@@ -1380,6 +1380,10 @@ describe "Config", ->
           expect(atom.config.set('foo.bar.aString', nope: 'nope')).toBe false
           expect(atom.config.get('foo.bar.aString')).toBe 'ok'
 
+        it 'does not allow setting children of that key-path', ->
+          expect(atom.config.set('foo.bar.aString.something', 123)).toBe false
+          expect(atom.config.get('foo.bar.aString')).toBe 'ok'
+
         describe 'when the schema has a "maximumLength" key', ->
           it "trims the string to be no longer than the specified maximum", ->
             schema =
@@ -1438,6 +1442,11 @@ describe "Config", ->
           atom.config.set 'foo.bar', ['2', '3', '4']
           expect(atom.config.get('foo.bar')).toEqual  [2, 3, 4]
 
+        it 'does not allow setting children of that key-path', ->
+          expect(atom.config.set('foo.bar.child', 123)).toBe false
+          expect(atom.config.set('foo.bar.child.grandchild', 123)).toBe false
+          expect(atom.config.get('foo.bar')).toEqual [1, 2, 3]
+
       describe 'when the value has a "color" type', ->
         beforeEach ->
           schema =

src/config.coffee

@@ -665,12 +665,18 @@ class Config
   #
   # Returns an {Object} eg. `{type: 'integer', default: 23, minimum: 1}`.
   # Returns `null` when the keyPath has no schema specified.
+  # Returns `false` when the key-path is not accessible from the root schema.
   getSchema: (keyPath) ->
     keys = splitKeyPath(keyPath)
     schema = @schema
     for key in keys
-      break unless schema?
-      schema = schema.properties?[key]
+      if schema.type is 'object'
+        childSchema = schema.properties?[key]
+        unless childSchema?
+          return null
+      else
+        return false
+      schema = childSchema
     schema
 
   # Extended: Get the {String} path to the config file being used.
@@ -948,7 +954,9 @@ class Config
       catch e
         undefined
     else
-      value = @constructor.executeSchemaEnforcers(keyPath, value, schema) if schema = @getSchema(keyPath)
+      if (schema = @getSchema(keyPath))?
+        throw new Error("Illegal key path #{keyPath}") if schema is false
+        value = @constructor.executeSchemaEnforcers(keyPath, value, schema)
       value
 
   # When the schema is changed / added, there may be values set in the config