Re: [gentoo-user] udevil question for Helmut Jarausch

[Helmut Jarausch]

On 06/15/2015 11:56:41 PM, walt wrote:
> Hi Helmut.  sys-apps/udevil failed to compile this morning and I
> noticed you
> had already submitted a proposed fix for it (your patch worked, thank
> you).
>
> The failing code was already in the udevil package when I emerged it
> on Jan
> 21 with no problems, so some other package must have changed since Jan
> 21,
> but which one(s)?
>
> I ask the question because I want to learn to think like a developer
> (hold
> all snarky comments until the professionals get here) so could you
> describe
> how you arrived at your fix so quickly?
>
> Have you used the "stat" function so often that you didn't even need
> to think
> about how to fix it, or was it more complicated?
>
> Thanks for any wisdom you care to share with us.
>

The build log says

 device-info.c:943:33: error: implicit declaration of function 'stat' [-Werror=implicit-function-declaration]
                                 stat( mount_source, &statbuf ) == 0 &&
                                 ^
device-info.c:944:33: error: implicit declaration of function 'S_ISBLK' [-Werror=implicit-function-declaration]
                                 S_ISBLK( statbuf.st_mode ) )

which means the function stat isn't declared. Together with S_ISBLK it is clear that the C-function stat (to determine
file status) is meant. 

man lstat    (man stat doesn't work here)
shows which header files have to be included.

Furthermore

grep -rF /usr/include  S_ISBLK
shows
/usr/include/sys/stat.h:#define S_ISBLK(mode)    ....

Therefore <sys/stat.h> has to be included somewhere
.
No wisdom at all,
Helmut