4.4.2

Author: molicechen

QMUIKit/UIKitExtensions/QMUIStringPrivate.m

@@ -160,7 +160,7 @@ + (void)qmuisafety_NSString {
 
             // index 越界
             {
-                BOOL isValidddatedIndex = index < selfObject.length;
+                BOOL isValidddatedIndex = index <= selfObject.length;
                 if (!isValidddatedIndex) {
                     NSString *logString = [NSString stringWithFormat:@"%@ 传入了一个超过字符串长度的 index: %@，原字符串为: %@(%@)", NSStringFromSelector(originCMD), @(index), selfObject, @(selfObject.length)];
                     NSAssert(NO, logString);
@@ -171,13 +171,15 @@ + (void)qmuisafety_NSString {
 
             // 保护从 emoji 等 ComposedCharacterSequence 中间裁剪的场景
             {
-                NSRange range = [selfObject rangeOfComposedCharacterSequenceAtIndex:index];
-                BOOL isValidddatedIndex = range.location == index || NSMaxRange(range) == index;
-                if (!isValidddatedIndex) {
-                    NSString *logString = [NSString stringWithFormat:@"试图在 ComposedCharacterSequence 中间用 %@ 裁剪字符串，可能导致乱码、crash。原字符串为“%@”(%@)，index 为 %@，命中的 ComposedCharacterSequence range 为 %@", NSStringFromSelector(originCMD), selfObject, @(selfObject.length), @(index), NSStringFromRange(range)];
-                    NSAssert(NO, logString);
-                    QMUILogWarn(@"QMUIStringSafety", @"%@", logString);
-                    index = range.location;
+                if (index < selfObject.length) {
+                    NSRange range = [selfObject rangeOfComposedCharacterSequenceAtIndex:index];
+                    BOOL isValidddatedIndex = range.location == index || NSMaxRange(range) == index;
+                    if (!isValidddatedIndex) {
+                        NSString *logString = [NSString stringWithFormat:@"试图在 ComposedCharacterSequence 中间用 %@ 裁剪字符串，可能导致乱码、crash。原字符串为“%@”(%@)，index 为 %@，命中的 ComposedCharacterSequence range 为 %@", NSStringFromSelector(originCMD), selfObject, @(selfObject.length), @(index), NSStringFromRange(range)];
+                        NSAssert(NO, logString);
+                        QMUILogWarn(@"QMUIStringSafety", @"%@", logString);
+                        index = range.location;
+                    }
                 }
             }
 

QMUIKitTests/UIKitExtensions/NSStringTests.m

@@ -33,7 +33,8 @@ - (void)testStringSafety {
     NSString *string = @"A😊B";
 
     XCTAssertNoThrow([string substringFromIndex:0]);
-    XCTAssertThrows([string substringFromIndex:string.length]); // 越界的识别
+    XCTAssertNoThrow([string substringFromIndex:string.length]); // 系统自身对 length 的参数做了保护，返回空字符串
+    XCTAssertThrows([string substringFromIndex:5]); // 越界的识别
     XCTAssertNoThrow([string substringFromIndex:1]);
     XCTAssertThrows([string substringFromIndex:2]); // emoji 中间裁剪的识别
     XCTAssertNoThrow([string substringFromIndex:3]);