Issue during compilation with glibc >= 2.30

[forrest96]

On Linux systems which use glibc ≥2.30 the following will be logged
during compilation:

In file included from arch/arch_info.c:52:0: /usr/include/sys/sysctl.h:21:2: error: #warning "The <sys/sysctl.h> header is deprecated and will be removed." [-Werror=cpp] #warning "The <sys/sysctl.h> header is deprecated and will be removed." ^~~~~~~ cc1: all warnings being treated as errors

The release notes for glibc 2.30 read:

“The Linux-specific <sys/sysctl.h> header and the sysctl function have
been deprecated and will be removed from a future version of glibc.
Application should directly access /proc instead. For obtaining
random bits, the getentropy function can be used.”

(See also https://sourceware.org/ml/libc-alpha/2019-08/msg00029.html for
the full release notes.)

To Reproduce

1 install glibc and glibc-dev / glibc-devel >= 2.30

2 compile ltfs v. 2.4.5.0 :
./autogen.sh
./configure --prefix=$1 --enable-message-checker --enable-warning-as-error
make

Solution

Because of the deprecated sysctl() function, sysconf() should be used instead.

Source file src/libltfs/arch/arch_info.c

[piste-jp-ibm]

It's not mandatory at this time because the main target is RHEL8 and RHEL7.

But it is good to move the API to sysconf() before reconsidering the main target OSs, because RHEL7 and RHEL8 support the API already.