Skip python magic expectation on RHEL 8

RHEL 8 carries an older libmagic behavior for /usr/bin/python3 scripts. The file_type_detect_test expected text/x-script.python from the system magic database, but RHEL 8 reports text/x-python, which made the test fail even though that platform-specific result is acceptable for an old extended-support platform.

Configure now detects RHEL 8 from /etc/os-release in a subshell and defines FAPOLICYD_RHEL8. Keeping the os-release variables contained matters because os-release also defines VERSION, and clobbering Automake's VERSION breaks make dist on newer Fedora hosts.

The file type detection test includes config.h and skips only the full-python-usr-bin system-libmagic assertion when FAPOLICYD_RHEL8 is present, leaving the newer-platform expectation active everywhere else.

Author: stevegrubb

configure.ac

@@ -11,6 +11,31 @@ AM_INIT_AUTOMAKE(foreign subdir-objects)
 LT_INIT
 AC_SUBST(LIBTOOL_DEPS)
 
+AC_MSG_CHECKING([whether build host is RHEL 8])
+fapolicyd_rhel8=no
+if test -r /etc/os-release; then
+	fapolicyd_rhel8=`(
+		. /etc/os-release
+		if test "x$ID" = xrhel; then
+			case "$VERSION_ID" in
+			8|8.*)
+				echo yes
+				;;
+			*)
+				echo no
+				;;
+			esac
+		else
+			echo no
+		fi
+	)`
+fi
+AC_MSG_RESULT([$fapolicyd_rhel8])
+if test "x$fapolicyd_rhel8" = xyes; then
+	AC_DEFINE([FAPOLICYD_RHEL8], [1],
+		[Define if the build host is Red Hat Enterprise Linux 8])
+fi
+
 echo .
 echo Checking for programs
 AC_PROG_CC

src/tests/file_type_detect_test.c

@@ -3,6 +3,8 @@
  */
 
 #define _GNU_SOURCE
+#include "config.h"
+
 #include <errno.h>
 #include <error.h>
 #include <fcntl.h>
@@ -271,10 +273,17 @@ int main(void)
 		"text/x-perl");
 	close(fd);
 
+#ifndef FAPOLICYD_RHEL8
+	/*
+	 * RHEL 8 libmagic reports this as text/x-python. Keep the current
+	 * expectation for newer systems and drop this guard when RHEL 8
+	 * support is no longer needed.
+	 */
 	fd = create_tmp_file("#!/usr/bin/python3\nprint(1)\n");
 	expect_magic_descriptor("full-python-usr-bin", magic_full, fd,
 		"text/x-script.python");
 	close(fd);
+#endif
 
 	fd = create_tmp_file("#!/usr/bin/R\nprint(1)\n");
 	expect_magic_descriptor("full-r-usr-bin", magic_full, fd, "text/plain");