FTBFS with gcc -6 / -Werror=nonnull

[Yves-Alexis Perez]

Hi,

I got a report that lightdm was failing to build with gcc 6, where apparently -Werror=nonnull is passed:

> libsystem.c: In function 'getpwnam':
> libsystem.c:859:14: error: nonnull argument 'name' compared to NULL [-Werror=nonnull]
> if (name == NULL)

You can find more info in the downstream bug report at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=811608

I have to admit I'm a bit unsure on how to fix that.

[Robert Ancell (robert-ancell)]

From the Debian report:

The system headers define:
extern struct passwd *getpwnam (const char *__name) __attribute__ ((__nonnull__ (1)));
extern int __attribute__((__nonnull__ (1))) pam_end(pam_handle_t *pamh, int pam_status);

So the compiler considers that 'name' can never be NULL and my check is therefore an error.

In this case it's probably safe to drop these checks. because these are just mock functions.

[Yves-Alexis Perez (corsac)]

Does this mean though one is supposed to check that name is not NULL *before* calling getpwnam?