strdup(NULL) supposed to create SIGSEGV?

[Bernard van Gastel]

Op 23 apr 2008, om 08:50 heeft Mike Meyer het volgende geschreven:
> On Tue, 22 Apr 2008 22:40:21 -0700
> "Garrett Cooper" <yanefbsd at gmail.com> wrote:
>
>> Hi all,
>>     I made an oops in a program, which uncovered "feature" in  
>> strdup(2)
>> that I wasn't aware of before. So I was wondering, is  
>> strdup(pointer = NULL)
>> supposed to segfault should this just return NULL and set errno?
>
> Yes, it's supposed to segfault. Check out what, say, strcpy does if
> you ask it to copy a NULL pointer. And this is an improvement from the
> bad old days, when they would happily walk through memory starting at
> 0.....

I don't like it this way. I would like:

strdup(NULL) = NULL
strdup(string) = copy of string

strcpy(NULL, NULL) = NULL
strcpy(s1, NULL) = ERROR
strcpy(NULL, s2) = NULL (with s2 unchanged)
strcpy(s1, s2) = normal

But I am not sure of the implications. Maybe in some situation it is  
bad... Anyone?

>
> Besides, errno is used to signal errors from system calls. strdup
> isn't a system call, it's a library function (says so at the top of
> the man page).

But strdup uses malloc, which is a system call (from the strdup  
manual: If insufficient memory is available, NULL is returned and  
errno is set to ENOMEM.)

Regards,
	Bernard