Is argv[0] guaranteed to be a valid pointer?

[August Derleth]

What does the C Standard (any of them) say about this issue? Can a
conformant implementation allow argv[0] == NULL? Can a conformant
implementation allow argv[0] to cause the machine to segfault if it is
dereferenced?

I understand, I think, the difference between hosted implementations and
freestanding ones (as in microcontrollers). I just want to know if a
program to be compiled by a conformant compiler needs to be careful with
argv[0].

 

[Kevin Easton]

What does the C Standard (any of them) say about this issue? Can a
conformant implementation allow argv[0] == NULL? Can a conformant
implementation allow argv[0] to cause the machine to segfault if it is
dereferenced?

argc can be 0, which case argv[0] == NULL.

argv[0] must be either NULL, or a pointer to a string. If argc is
non-zero, argv[0] cannot be NULL.

- Kevin.

 

[Russell Hanneken]

What does the C Standard (any of them) say about this issue? Can a
conformant implementation allow argv[0] == NULL? Can a conformant
implementation allow argv[0] to cause the machine to segfault if it is
dereferenced?

argv[0] can be NULL only if argc is 0. If argc is greater than 0, argv[0]
must be a valid string, although it might be an empty string (i.e.,
argv[0][0] might be '\0').

I'm looking at the C99 standard. I don't know what C89 says.