This is the mail archive of the mailing list for the glibc project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [RFC][PATCH] Add reallocarray function.

On 09/01/2014 07:24 PM, Rich Felker wrote:

I'm not sure if this is still on the table, but experience shows
that the realloc interface is error-prone for another reason: The
straight way to write an a reallocation,

   ptr = realloc(ptr, new_size);

leads to a memory leak on error.  It would be less error-prone to
have reallocarray to update the pointer directly on success, e.g.:

   if (reallocarray(&ptr, new_count, sizeof(T)) < 0) {
     // handle error

No, allocation functions which take void** are an extremely bad idiom
because they encourage UB.

That's why I wrote that reallocarray has to be a macro.

On the other hand, I'm not particularly worried about the aliasing violation because according to one reading of the standard, realloc returns a pointer to untyped (but partially initialized) memory, which needs out-of-language support anyway.

Also, reallocarray is already defined by OpenBSD and perhaps others
with a particular signature.

We'd have to give the fixed version a separate name, to avoid another strerror_r-like fiasco.

Florian Weimer / Red Hat Product Security

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]