scripts/sphinx-pre-install: don't use LaTeX with CentOS 7

There aren't enough texlive packages for LaTeX-based builds
to work on CentOS/RHEL <= 7.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

scripts/sphinx-pre-install

@@ -83,6 +83,17 @@ sub check_missing(%)
 	foreach my $prog (sort keys %missing) {
 		my $is_optional = $missing{$prog};
 
+		# At least on some LTS distros like CentOS 7, texlive doesn't
+		# provide all packages we need. When such distros are
+		# detected, we have to disable PDF output.
+		#
+		# So, we need to ignore the packages that distros would
+		# need for LaTeX to work
+		if ($is_optional == 2 && !$pdf) {
+			$optional--;
+			next;
+		}
+
 		if ($is_optional) {
 			print "Warning: better to also install \"$prog\".\n";
 		} else {
@@ -333,10 +344,10 @@ sub give_debian_hints()
 
 	if ($pdf) {
 		check_missing_file("/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
-				   "fonts-dejavu", 1);
+				   "fonts-dejavu", 2);
 	}
 
-	check_program("dvipng", 1) if ($pdf);
+	check_program("dvipng", 2) if ($pdf);
 	check_missing(\%map);
 
 	return if (!$need && !$optional);
@@ -371,22 +382,40 @@ sub give_redhat_hints()
 	#
 	# Checks valid for RHEL/CentOS version 7.x.
 	#
+	my $old = 0;
+	my $rel;
+	$rel = $1 if ($system_release =~ /release\s+(\d+)/);
+
 	if (!($system_release =~ /Fedora/)) {
 		$map{"virtualenv"} = "python-virtualenv";
-	}
 
-	my $release;
+		if ($rel && $rel < 8) {
+			$old = 1;
+			$pdf = 0;
 
-	$release = $1 if ($system_release =~ /Fedora\s+release\s+(\d+)/);
+			printf("Note: texlive packages on RHEL/CENTOS <= 7 are incomplete. Can't support PDF output\n");
+			printf("If you want to build PDF, please read:\n");
+			printf("\thttps://www.systutorials.com/241660/how-to-install-tex-live-on-centos-7-linux/\n");
+		}
+	} else {
+		if ($rel && $rel < 26) {
+			$old = 1;
+		}
+	}
+	if (!$rel) {
+		printf("Couldn't identify release number\n");
+		$old = 1;
+		$pdf = 0;
+	}
 
-	check_rpm_missing(\@fedora26_opt_pkgs, 1) if ($pdf && $release >= 26);
-	check_rpm_missing(\@fedora_tex_pkgs, 1) if ($pdf);
-	check_missing_tex(1) if ($pdf);
+	check_rpm_missing(\@fedora26_opt_pkgs, 2) if ($pdf && !$old);
+	check_rpm_missing(\@fedora_tex_pkgs, 2) if ($pdf);
+	check_missing_tex(2) if ($pdf);
 	check_missing(\%map);
 
 	return if (!$need && !$optional);
 
-	if ($release >= 18) {
+	if (!$old) {
 		# dnf, for Fedora 18+
 		printf("You should run:\n\n\tsudo dnf install -y $install\n");
 	} else {
@@ -425,8 +454,8 @@ sub give_opensuse_hints()
 		"texlive-zapfding",
 	);
 
-	check_rpm_missing(\@suse_tex_pkgs, 1) if ($pdf);
-	check_missing_tex(1) if ($pdf);
+	check_rpm_missing(\@suse_tex_pkgs, 2) if ($pdf);
+	check_missing_tex(2) if ($pdf);
 	check_missing(\%map);
 
 	return if (!$need && !$optional);
@@ -450,7 +479,7 @@ sub give_mageia_hints()
 		"texlive-fontsextra",
 	);
 
-	check_rpm_missing(\@tex_pkgs, 1) if ($pdf);
+	check_rpm_missing(\@tex_pkgs, 2) if ($pdf);
 	check_missing(\%map);
 
 	return if (!$need && !$optional);
@@ -473,7 +502,8 @@ sub give_arch_linux_hints()
 		"texlive-latexextra",
 		"ttf-dejavu",
 	);
-	check_pacman_missing(\@archlinux_tex_pkgs, 1) if ($pdf);
+	check_pacman_missing(\@archlinux_tex_pkgs, 2) if ($pdf);
+
 	check_missing(\%map);
 
 	return if (!$need && !$optional);
@@ -492,7 +522,7 @@ sub give_gentoo_hints()
 	);
 
 	check_missing_file("/usr/share/fonts/dejavu/DejaVuSans.ttf",
-			   "media-fonts/dejavu", 1) if ($pdf);
+			   "media-fonts/dejavu", 2) if ($pdf);
 
 	check_missing(\%map);
 
@@ -560,7 +590,7 @@ sub check_distros()
 	my %map = (
 		"sphinx-build" => "sphinx"
 	);
-	check_missing_tex(1) if ($pdf);
+	check_missing_tex(2) if ($pdf);
 	check_missing(\%map);
 	print "I don't know distro $system_release.\n";
 	print "So, I can't provide you a hint with the install procedure.\n";
@@ -589,11 +619,13 @@ sub check_needs()
 	check_program("make", 0);
 	check_program("gcc", 0);
 	check_python_module("sphinx_rtd_theme", 1) if (!$virtualenv);
-	check_program("xelatex", 1) if ($pdf);
 	check_program("dot", 1);
 	check_program("convert", 1);
-	check_program("rsvg-convert", 1) if ($pdf);
-	check_program("latexmk", 1) if ($pdf);
+
+	# Extra PDF files - should use 2 for is_optional
+	check_program("xelatex", 2) if ($pdf);
+	check_program("rsvg-convert", 2) if ($pdf);
+	check_program("latexmk", 2) if ($pdf);
 
 	check_distros();