The shmmax expected value is tricky to check because kernel clamps it
to INT_MAX in two cases:
1. Compat symbols with IPC_64, i.e, 32-bit binaries running on 64-bit
kernels.
2. Default symbol without IPC_64 (defined as IPC_OLD within Linux) and
glibc always use IPC_64 for 32-bit ABIs (to support 64-bit time_t).
It means that 32-bit binaries running on 32-bit kernels will not see
shmmax being clamped.
And finding out whether the compat symbol is used would require checking
the underlying kernel against the current ABI. The shmall and shmmni
already provided enough coverage.
Checked on x86_64-linux-gnu and i686-linux-gnu. It should fix the
tst-sysvshm-linux failures on 32-bit kernels.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
The Linux shminfo fields are '__syscall_ulong_t' (which is 64-bit
for x32). This patch fixes the test to compare againt the correct
type and to only clamp the value if '__syscall_ulong_t' is the same
size of 'unsigned long int'.
Checked on x86_64-linux-gnu-x32.
Both commands are Linux extensions where the third argument is either
a 'struct shminfo' (IPC_INFO) or a 'struct shm_info' (SHM_INFO) instead
of 'struct shmid_ds'. And their information does not contain any time
related fields, so there is no need to extra conversion for __IPC_TIME64.
The regression testcase checks for Linux specifix SysV ipc message
control extension. For SHM_INFO it tries to match the values against the
tunable /proc values and for MSG_STAT/MSG_STAT_ANY it check if the create\
shared memory is within the global list returned by the kernel.
Checked on x86_64-linux-gnu and on i686-linux-gnu (Linux v5.4 and on
Linux v4.15).
