The POSIX call access() seems to behave not as expected on QNX. According to the doc, access() uses the *real* user ID 
to check if a file can be accessed. The Linux call effectively does this. But on QNX, it seems to use the *effective* 
user ID.

Test environment: QNX 7.1.0

Setup (a file only readable by root, 2 versions of the tool readable, one suid, one not) (the tool readable is the 
example from the access() documentation with some printf() statements for the different IDs):
$ ls -al
total 55
drwxr-xr-x   2 root      root           4096 Jun 12 01:36 .
drwxr-xr-x   6 root      root           4096 Jun 12 01:36 ..
-rw-------   1 root      root             74 Jun 12 01:36 data
-rwxr-xr-x   1 root      root           9696 Jun 12 01:31 readable
-rwsr-xr-x   1 root      root           9696 Jun 12 01:35 readable_suid

Test output:
$ ./readable data
geteuid(): 1000 - effective user ID
getegid(): 4004 - effective group ID
getuid():  1000 - user ID
getgid():  4004 - group ID
data: Permission denied
=> as expected

$ ./readable_suid data
geteuid(): 0 - effective user ID
getegid(): 4004 - effective group ID
getuid():  1000 - user ID
getgid():  4004 - group ID
ok to read data

=> The last response ("ok to read data") is unexpected because the code is running with real user ID 1000. When doing a 
similar test on Linux, I get "permission denied".

Is my understanding of access() wrong, or is this a bug in QNX or my configuration?