testing/ostest: test process capabilities

[royzah]

Note: Please adhere to Contributing Guidelines.

Summary

ostest coverage for process capabilities, apache/nuttx#20417 (PR_CAPS_GET, PR_CAPS_DROP; PR_CAP_SPAWN, PR_CAP_RAWIO, PR_CAP_ADMIN).

Step	Checks
child	starts with all caps
child drops ADMIN, spawns	the grandchild inherits the reduced set
child drops SPAWN	task_create() fails with EPERM
child drops RAWIO	mount() fails with EPERM; ENOSYS when the build has no mountable fs, since there is nothing to guard
parent	keeps its full set

Built only with CONFIG_SCHED_CAPABILITIES, CONFIG_SCHED_WAITPID and a flat or protected build (task_create()). The option comes with apache/nuttx#20417, so this compiles to nothing until that merges, and on boards that turn it off.

Impact

testing/ostest only. No change where CONFIG_SCHED_CAPABILITIES is unset.

Testing

Host: Ubuntu 24.04.3, x86_64. Builds and runs in ghcr.io/apache/nuttx/apache-nuttx-ci-linux (GCC 12.3). sim:ostest, CONFIG_TESTING_OSTEST_LOOPS=1.

nuttx	Config	Result
apache/nuttx#20417	sim:ostest	caps_test: PASSED; ostest exits 0
apache/nuttx#20417	sim:ostest + CONFIG_FS_TMPFS	caps_test: PASSED; with a mountable fs, mount() reaches the RAWIO check; ostest exits 0
master	sim:ostest	caps.c not built; ostest exits 0

tools/checkpatch.sh -c -u -m -g clean. The logs below are cut to the boot, the caps test and the end; each full run is about 4,200 lines, happy to post them.

apache/nuttx#20417, sim:ostest + CONFIG_FS_TMPFS

stdio_test: write fd=1
stdio_test: Standard I/O Check: printf
stdio_test: write fd=2
ostest_main: putenv(Variable1=BadValue3)
ostest_main: setenv(Variable1, GoodValue1, TRUE)
ostest_main: setenv(Variable2, BadValue1, FALSE)
ostest_main: setenv(Variable2, GoodValue2, TRUE)
ostest_main: setenv(Variable3, GoodValue3, FALSE)
ostest_main: setenv(Variable3, BadValue2, FALSE)
show_variable: Variable=Variable1 has value=GoodValue1
show_variable: Variable=Variable2 has value=GoodValue2
show_variable: Variable=Variable3 has value=GoodValue3
...

user_main: caps test
caps_test: Starting test
caps_test: PASSED

End of test memory usage:
VARIABLE  BEFORE   AFTER
======== ======== ========
arena     3effff8  3effff8
ordblks         2        2
mxordblk  3eaac88  3eaac88
uordblks    45078    45078
fordblks  3ebaf80  3ebaf80

...
Final memory usage:
VARIABLE  BEFORE   AFTER
======== ======== ========
arena     3effff8  3effff8
ordblks         2        5
mxordblk  3eaac88  3eaac88
uordblks    450f0    453a8
fordblks  3ebaf08  3ebac50
user_main: Exiting
ostest_main: Exiting with status 0

apache/nuttx#20417, sim:ostest

stdio_test: write fd=1
stdio_test: Standard I/O Check: printf
stdio_test: write fd=2
ostest_main: putenv(Variable1=BadValue3)
ostest_main: setenv(Variable1, GoodValue1, TRUE)
ostest_main: setenv(Variable2, BadValue1, FALSE)
ostest_main: setenv(Variable2, GoodValue2, TRUE)
ostest_main: setenv(Variable3, GoodValue3, FALSE)
ostest_main: setenv(Variable3, BadValue2, FALSE)
show_variable: Variable=Variable1 has value=GoodValue1
show_variable: Variable=Variable2 has value=GoodValue2
show_variable: Variable=Variable3 has value=GoodValue3
...

user_main: caps test
caps_test: Starting test
caps_test: PASSED

End of test memory usage:
VARIABLE  BEFORE   AFTER
======== ======== ========
arena     3effff8  3effff8
ordblks         2        2
mxordblk  3eaad78  3eaad78
uordblks    44f88    44f88
fordblks  3ebb070  3ebb070

...
Final memory usage:
VARIABLE  BEFORE   AFTER
======== ======== ========
arena     3effff8  3effff8
ordblks         2        5
mxordblk  3eaad78  3eaad78
uordblks    45000    452b8
fordblks  3ebaff8  3ebad40
user_main: Exiting
ostest_main: Exiting with status 0

master, sim:ostest

stdio_test: write fd=1
stdio_test: Standard I/O Check: printf
stdio_test: write fd=2
ostest_main: putenv(Variable1=BadValue3)
ostest_main: setenv(Variable1, GoodValue1, TRUE)
ostest_main: setenv(Variable2, BadValue1, FALSE)
ostest_main: setenv(Variable2, GoodValue2, TRUE)
ostest_main: setenv(Variable3, GoodValue3, FALSE)
ostest_main: setenv(Variable3, BadValue2, FALSE)
show_variable: Variable=Variable1 has value=GoodValue1
show_variable: Variable=Variable2 has value=GoodValue2
show_variable: Variable=Variable3 has value=GoodValue3
...
Final memory usage:
VARIABLE  BEFORE   AFTER
======== ======== ========
arena     3effff8  3effff8
ordblks         2        5
mxordblk  3eaad78  3eaad78
uordblks    45000    452b8
fordblks  3ebaff8  3ebad40
user_main: Exiting
ostest_main: Exiting with status 0