For the storage management, we can use free() function, but the storage management functions might have bugs, like accidentally freeing a section of memory twice, or overwriting an array. Some of these bugs will result in infinite loops or crashes. How to define a function to check the list is freed? like detect is a missing free block that is a block that's been freed that doesn't appear in the free list. Can anyone give some idea for that? Thanks!!!
Since free(NULL) has no effect it's fine if you free it again.Code:free(ptr); ptr = NULL;
Unless I've missed what you're asking?
you can use some external program that will make such checks for you like Boundschecker
or you can write your own memory manager - that will allocate a big memory pool at the beginning of the program and then allocate and deallocate memory ranges from this pool - adding necessary checks
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
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Originally Posted by zacs7
just like you said after freed ptr then assign prt = NULL, it work fine. do we have any other method that checks the consistency of the free list?
Keep track, programmatically, what has been freed and what has not. For example, only free the memory for something in one function.
Given a pointer, there's no way to tell if it's pointing to allocated memory or not -- unless you set the pointer to NULL when it is not allocated (i.e., before malloc() and after free()). Then you can just compare the pointer against NULL.How to define a function to check the list is freed? like detect is a missing free block that is a block that's been freed that doesn't appear in the free list. Can anyone give some idea for that?
dwk
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