PTHREAD_COND_INITIALIZER 与 Splint

发布于 2024-11-05 23:40:22 字数 484 浏览 5 评论 0原文

我有以下代码

static pthread_mutex_t watchdogMutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t watchdogCond = PTHREAD_COND_INITIALIZER;

，并且在使用 Splint 时收到以下错误/警告

静态 watchdogCond._data._mutex 初始化为 null 值：watchdogCond._data._mutex = (void )0 没有 null 注释的引用被分配或初始化为 NULL。使用 /@null@*/ 将引用声明为可能为空指针。（使用 -nullassign 禁止警告）

这有什么问题，它是真正的危险吗？

原文

I have the following code

static pthread_mutex_t watchdogMutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t watchdogCond = PTHREAD_COND_INITIALIZER;

and I get the following errors/warnings when using Splint

Static watchdogCond._data._mutex initialized to null
value: watchdogCond._data._mutex = (void )0
A reference with no null annotation is assigned or initialized to NULL. Use
/@null@*/ to declare the reference as a possibly null pointer. (Use
-nullassign to inhibit warning)

What is the issue with this and is it a real danger?

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谁人与我共长歌 2024-11-12 23:40:22

听起来 splint 存在将指针显式初始化为 null 的问题，并且需要某种覆盖注释注释来禁用警告。我只需遵循其建议并使用 -nullassign 选项来禁用此警告。您的代码正在执行的操作或实现定义初始值设定项宏的方式没有任何不好或有害的地方。这只是夹板有非理性的恐惧。

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叶落知秋 2024-11-12 23:40:22

看起来pthread_mutex_t是一个不透明的指针（你可以跟踪typedef来找出答案）。在 Splint 中，默认情况下指针不可为空。如果你想有一个可为空的指针，你必须用语义注释/*@null@*/来声明它，例如：

char * ptr1;
/*@null@*/ char * ptr2;

ptr1 = NULL; /* warning: implicitly not-nullable pointer */
ptr2 = NULL; /* OK: explicitly nullable pointer */

根据手册，有3个关于空状态的选项：

null 可能是空指针。
notnull 非空指针。
relnull 放松空值检查。当将 NULL 分配给它或将其用作非空指针时，不会出现错误。

使用不可空指针的优点是，您无需在每次获取其中一个指针时都检查它们。例如，您可以将函数参数注释为 /*@notnull@*/，然后您就不需要检查 if(pointer == NULL)< /code> 在取消引用它之前。这减少了检查并简化了代码。

忽略这些警告的危险是，如果您告诉 Splint 特定指针不可能为空，然后您尝试分配 NULL< /code> 到它，这个空指针最终可能会被解引用，并且程序可能会崩溃。

在我看来，您的实际问题是 Splint 的策略，它认为所有指针隐式不可为空。这迫使您注释所有可能为空的指针。

It seems that pthread_mutex_t is an opaque pointer (you could track the typedef down to find out). In Splint, pointers are not-nullable by default. If you want to have a nullable pointer, you must declare it with the semantic annotation /*@null@*/, for example:

char * ptr1;
/*@null@*/ char * ptr2;

ptr1 = NULL; /* warning: implicitly not-nullable pointer */
ptr2 = NULL; /* OK: explicitly nullable pointer */

According to the manual, there are 3 options regarding null state:

null Possibly null pointer.
notnull Non-null pointer.
relnull Relax null checking. No errors when NULL is assigned to it, or when it is used as a non-null pointer.

The advantage of using not-nullable pointers is that you don't need to check them every time you get one of them. For example, you could annotate a function parameter as /*@notnull@*/ and then you are not required to check if(pointer == NULL) before you dereference it. This reduces checking and simplifies your code.

The danger of ignoring these warnings is that, if you are telling Splint that a specific pointer can't possibly be null and later on you try to assign NULL to it, this null pointer could end up being derefered and the program could crash.

In my opinion, your actual issue is Splint's policy, which considers all pointers implicitly not-nullable. This forces you to annotate all your possibly null pointers.

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