[ObjC] Model methods from NSArray

Summary:
In particular, the method for retrieving an element from the array, this should never be nil. Also added a model for count
similar to the one for NSString length.

Reviewed By: ddino

Differential Revision: D4306655

fbshipit-source-id: 0ecb25a

infer/models/objc/src/NSArray.m

@@ -9,7 +9,13 @@
 
 #import "NSArray.h"
 
-@implementation NSArray
+void __infer_assume(bool cond);
+
+@implementation NSArray {
+
+ @private
+  id elementData[10];
+}
 
 - (NSArray*)arrayByAddingObject:(id)anObject {
   id a = ((NSObject*)anObject)->isa;
@@ -25,4 +31,18 @@
   return [NSArray alloc];
 }
 
+- (id)objectAtIndexedSubscript:(NSUInteger)idx {
+  id obj = elementData[idx];
+  __infer_assume(obj != nil);
+  return obj;
+}
+
+- (int)count {
+  if (self == nil) {
+    return 0;
+  } else {
+    sizeof(elementData);
+  }
+}
+
 @end

infer/src/clang/cField_decl.ml

@@ -88,7 +88,9 @@ let add_missing_fields tenv class_name ck missing_fields =
       Logging.out_debug " Updating info for class '%s' in tenv\n" class_name
   | _ -> ()
 
-let modelled_fields_in_classes = [("NSData", "_bytes", Typ.Tptr (Typ.Tvoid, Typ.Pk_pointer))]
+let modelled_fields_in_classes =
+  [("NSData", "_bytes", Typ.Tptr (Typ.Tvoid, Typ.Pk_pointer));
+   ("NSArray", "elementData", Typ.Tint Typ.IInt)]
 
 let modelled_field class_name_info =
   let modelled_field_in_class res (class_name, field_name, typ) =

infer/tests/codetoanalyze/objc/errors/Makefile

@@ -33,6 +33,7 @@ SOURCES_DEFAULT = \
   npe/block.m \
   npe/skip_method_with_nil_object.m \
 	npe/Nsstring_length_no_npe.m \
+	npe/No_null_from_array.m \
   procdescs/MethodCall.m \
   property/main.c \
   resource_leaks/ResourceLeakExample.m \

infer/tests/codetoanalyze/objc/errors/issues.exp

@@ -4,6 +4,7 @@ codetoanalyze/objc/errors/initialization/compound_literal.c, init_with_compound_
 codetoanalyze/objc/errors/memory_leaks_benchmark/CADisplayLinkRetainCycle.m, testCycle, 3, RETAIN_CYCLE, [start of procedure testCycle(),start of procedure init,return from a call to CADisplay_init]
 codetoanalyze/objc/errors/memory_leaks_benchmark/RetainCycleStaticVar.m, RetainCSVycleStaticVar, 2, RETAIN_CYCLE, [start of procedure RetainCSVycleStaticVar(),start of procedure init,return from a call to RetainCSV_init,start of procedure foo,start of procedure block,start of procedure init,return from a call to RetainCSV_init,return from a call to __objc_anonymous_block_RetainCSV_foo______3,start of procedure block,start of procedure init,return from a call to RetainCSV_init,return from a call to __objc_anonymous_block_RetainCSV_foo______2,return from a call to RetainCSV_foo]
 codetoanalyze/objc/errors/npe/blockenum.m, BlockEnumA_allResultsList:, 1, MEMORY_LEAK, [start of procedure allResultsList:]
+codetoanalyze/objc/errors/npe/blockenum.m, BlockEnumA_allResultsList:, 2, RETURN_VALUE_IGNORED, [start of procedure allResultsList:,Condition is true]
 codetoanalyze/objc/errors/npe/blockenum.m, BlockEnumA_foo1:, 2, MEMORY_LEAK, [start of procedure foo1:]
 codetoanalyze/objc/errors/npe/nil_param.m, NilParamMain, 4, MEMORY_LEAK, [start of procedure NilParamMain(),start of procedure test1:,Message test2 with receiver nil returns nil.,return from a call to NilParamA_test1:]
 codetoanalyze/objc/errors/npe/null_returned_by_method.m, NullReturnedByMethodA_test1, 1, NULL_DEREFERENCE, [start of procedure test1,start of procedure test,return from a call to NullReturnedByMethodA_test]
@@ -95,6 +96,7 @@ codetoanalyze/objc/errors/npe/Fraction.m, test_virtual_call, 7, NULL_DEREFERENCE
 codetoanalyze/objc/errors/npe/NPD_core_foundation.m, NullDeref_createCloseCrossGlyphNoLeak:, 5, Assert_failure, [start of procedure createCloseCrossGlyphNoLeak:]
 codetoanalyze/objc/errors/npe/NPD_core_foundation.m, NullDeref_layoutSubviews, 4, Assert_failure, [start of procedure layoutSubviews]
 codetoanalyze/objc/errors/npe/NPD_core_foundation.m, NullDeref_measureFrameSizeForTextNoLeak, 4, Assert_failure, [start of procedure measureFrameSizeForTextNoLeak,Condition is true]
+codetoanalyze/objc/errors/npe/No_null_from_array.m, No_null_from_array_collectAvailableMaps, 5, RETURN_VALUE_IGNORED, [start of procedure collectAvailableMaps]
 codetoanalyze/objc/errors/npe/Npe_with_equal_names.m, EqualNamesTest, 3, NULL_DEREFERENCE, [start of procedure EqualNamesTest(),start of procedure meth,return from a call to EqualNamesA_meth]
 codetoanalyze/objc/errors/npe/Npe_with_equal_names.m, EqualNamesTest2, 2, UNINITIALIZED_VALUE, [start of procedure EqualNamesTest2(),start of procedure meth,return from a call to EqualNamesA_meth]
 codetoanalyze/objc/errors/npe/block.m, BlockA_doSomethingThenCallback:, 2, PARAMETER_NOT_NULL_CHECKED, [start of procedure doSomethingThenCallback:]
@@ -109,6 +111,7 @@ codetoanalyze/objc/errors/taint/sources.m, testNSHTTPCookie2, 5, TAINTED_VALUE_R
 codetoanalyze/objc/errors/taint/sources.m, testNSHTTPCookie3, 5, TAINTED_VALUE_REACHING_SENSITIVE_FUNCTION, [start of procedure testNSHTTPCookie3()]
 codetoanalyze/objc/errors/taint/sources.m, testNSHTTPCookie4, 5, TAINTED_VALUE_REACHING_SENSITIVE_FUNCTION, [start of procedure testNSHTTPCookie4()]
 codetoanalyze/objc/errors/taint/viewController.m, ExampleDelegate_application:openURL:sourceApplication:annotation:, 7, TAINTED_VALUE_REACHING_SENSITIVE_FUNCTION, [start of procedure application:openURL:sourceApplication:annotation:,start of procedure init,return from a call to VCA_init,start of procedure ExampleSanitizer(),Condition is false,return from a call to ExampleSanitizer,Condition is false,Condition is true]
+codetoanalyze/objc/shared/block/block-it.m, MyBlock_array, 3, RETURN_VALUE_IGNORED, [start of procedure array,Condition is true]
 codetoanalyze/objc/shared/block/block-it.m, __objc_anonymous_block_MyBlock_array______1, 5, UNINITIALIZED_VALUE, [start of procedure block,Condition is false]
 codetoanalyze/objc/shared/block/block-it.m, __objc_anonymous_block_MyBlock_array_trans______2, 4, UNINITIALIZED_VALUE, [start of procedure block,Condition is false]
 codetoanalyze/objc/shared/block/dispatch.m, DispatchA_dispatch_a_block_variable_from_macro_delivers_initialised_object, 3, DIVIDE_BY_ZERO, [start of procedure dispatch_a_block_variable_from_macro_delivers_initialised_object,start of procedure dispatch_a_block_variable_from_macro,start of procedure block,start of procedure init,return from a call to DispatchA_init,return from a call to __objc_anonymous_block_DispatchA_dispatch_a_block_variable_from_macro______4,return from a call to DispatchA_dispatch_a_block_variable_from_macro]

infer/tests/codetoanalyze/objc/errors/npe/No_null_from_array.m

@@ -0,0 +1,19 @@
+#import <Foundation/Foundation.h>
+
+@interface No_null_from_array : NSObject
+@end
+
+@implementation No_null_from_array {
+  NSDictionary* _maps;
+}
+
+- (void)collectAvailableMaps {
+  NSMutableDictionary* maps = [NSMutableDictionary dictionaryWithCapacity:100];
+  NSString* filename = @"";
+  NSArray* components = [filename componentsSeparatedByString:@"-"];
+  NSString* locale = components[0];
+  NSMutableDictionary* mapsForLocale = maps[locale];
+  maps[locale] = @"";
+}
+
+@end