error: argument 2 null where non-null expected [-Werror=nonnull]

[hramrach]

This looks like a logic error in the code but I don't know what the logic should be.

Other callers pass a scanf type string but this one passes NULL.

So generally some type should be passed but it's not clear what it should be.

CC src/drmgr/common.o
In function ‘get_att_prop’,
inlined from ‘get_property’ at src/drmgr/common.c:802:9,
inlined from ‘valid_platform’ at src/drmgr/common.c:1079:7:
src/drmgr/common.c:773:22: error: argument 2 null where non-null expected [-Werror=nonnull]
773 | rc = fscanf(fp, attr_type, (int *)buf);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/features.h:503,
from /usr/include/fcntl.h:25,
from src/drmgr/common.c:21:
/usr/include/stdio.h: In function ‘valid_platform’:
/usr/include/stdio.h:440:12: note: in a call to function ‘fscanf’ declared ‘nonnull’
440 | extern int __REDIRECT (fscanf, (FILE *__restrict __stream,
| ^~~~~~~~~~

[tyreld]

There is a comment in the get_att_prop code that basically mentions that its a hack. Device tree properties are always assumed to used a /proc path and aren't read with fscanf unlike device attributes which are read from /sysfs using fscanf.

We can pass an arbitrary format specifier for device tree properties just to quiet the error.

The other option is just to split get_att_prop logic into two helpers like for example get_proc_prop and get_sysfs_att.

[hramrach]

The glibc manual says:

EINVAL Not enough arguments; or format is NULL.

However, the POSIX manual omits the latter part.

It should probably be checked by the caller.

Cleaning up the hack is a separate problem.