[PATCH V6] checkpatch: add command-line option for TAB size

[Antonio Borneo <borneo.antonio@gmail.com>]

Linux kernel coding style requires a size of 8 characters for
both TAB and indentation, and such value is embedded as magic
value allover the checkpatch script.
This makes hard to reuse the script by other projects with
different requirements in their coding style (e.g. OpenOCD [1]
requires TAB size of 4 characters [2]).

Replace the magic value 8 with a variable.

Add a command-line option "--tab-size" to let the user select a
TAB size value other than 8.

[1] http://openocd.org/
[2] http://openocd.org/doc/doxygen/html/stylec.html#styleformat

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Erik Ahlén <erik.ahlen@avalonenterprise.com>
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>

---

v1 -> v2
        add the command line option

v2 -> v3
        rewrite commit msg to remove script readability issue

v3 -> v4
        check for command line value positive

v4 -> v5
        exclude --tab-size=1

v5 -> v6
	rebased

---
 scripts/checkpatch.pl | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4c1be774b0ed..8bac825665ef 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -64,6 +64,7 @@ my $color = "auto";
 my $allow_c99_comments = 1; # Can be overridden by --ignore C99_COMMENT_TOLERANCE
 # git output parsing needs US English output, so first set backtick child process LANGUAGE
 my $git_command ='export LANGUAGE=en_US.UTF-8; git';
+my $tabsize = 8;
 
 sub help {
 	my ($exitcode) = @_;
@@ -98,6 +99,7 @@ Options:
   --show-types               show the specific message type in the output
   --max-line-length=n        set the maximum line length, if exceeded, warn
   --min-conf-desc-length=n   set the min description length, if shorter, warn
+  --tab-size=n               set the number of spaces for tab (default 8)
   --root=PATH                PATH to the kernel tree root
   --no-summary               suppress the per-file summary
   --mailback                 only produce a report in case of warnings/errors
@@ -215,6 +217,7 @@ GetOptions(
 	'list-types!'	=> \$list_types,
 	'max-line-length=i' => \$max_line_length,
 	'min-conf-desc-length=i' => \$min_conf_desc_length,
+	'tab-size=i'	=> \$tabsize,
 	'root=s'	=> \$root,
 	'summary!'	=> \$summary,
 	'mailback!'	=> \$mailback,
@@ -267,6 +270,9 @@ if ($color =~ /^[01]$/) {
 	die "Invalid color mode: $color\n";
 }
 
+# skip TAB size 1 to avoid additional checks on $tabsize - 1
+die "Invalid TAB size: $tabsize\n" if ($tabsize < 2);
+
 sub hash_save_array_words {
 	my ($hashRef, $arrayRef) = @_;
 
@@ -1217,7 +1223,7 @@ sub expand_tabs {
 		if ($c eq "\t") {
 			$res .= ' ';
 			$n++;
-			for (; ($n % 8) != 0; $n++) {
+			for (; ($n % $tabsize) != 0; $n++) {
 				$res .= ' ';
 			}
 			next;
@@ -2230,7 +2236,7 @@ sub string_find_replace {
 sub tabify {
 	my ($leading) = @_;
 
-	my $source_indent = 8;
+	my $source_indent = $tabsize;
 	my $max_spaces_before_tab = $source_indent - 1;
 	my $spaces_to_tab = " " x $source_indent;
 
@@ -3198,7 +3204,7 @@ sub process {
 		next if ($realfile !~ /\.(h|c|pl|dtsi|dts)$/);
 
 # at the beginning of a line any tabs must come first and anything
-# more than 8 must use tabs.
+# more than $tabsize must use tabs.
 		if ($rawline =~ /^\+\s* \t\s*\S/ ||
 		    $rawline =~ /^\+\s*        \s*/) {
 			my $herevet = "$here\n" . cat_vet($rawline) . "\n";
@@ -3217,7 +3223,7 @@ sub process {
 				"please, no space before tabs\n" . $herevet) &&
 			    $fix) {
 				while ($fixed[$fixlinenr] =~
-					   s/(^\+.*) {8,8}\t/$1\t\t/) {}
+					   s/(^\+.*) {$tabsize,$tabsize}\t/$1\t\t/) {}
 				while ($fixed[$fixlinenr] =~
 					   s/(^\+.*) +\t/$1\t/) {}
 			}
@@ -3239,11 +3245,11 @@ sub process {
 		if ($perl_version_ok &&
 		    $sline =~ /^\+\t+( +)(?:$c90_Keywords\b|\{\s*$|\}\s*(?:else\b|while\b|\s*$)|$Declare\s*$Ident\s*[;=])/) {
 			my $indent = length($1);
-			if ($indent % 8) {
+			if ($indent % $tabsize) {
 				if (WARN("TABSTOP",
 					 "Statements should start on a tabstop\n" . $herecurr) &&
 				    $fix) {
-					$fixed[$fixlinenr] =~ s@(^\+\t+) +@$1 . "\t" x ($indent/8)@e;
+					$fixed[$fixlinenr] =~ s@(^\+\t+) +@$1 . "\t" x ($indent/$tabsize)@e;
 				}
 			}
 		}
@@ -3261,8 +3267,8 @@ sub process {
 				my $newindent = $2;
 
 				my $goodtabindent = $oldindent .
-					"\t" x ($pos / 8) .
-					" "  x ($pos % 8);
+					"\t" x ($pos / $tabsize) .
+					" "  x ($pos % $tabsize);
 				my $goodspaceindent = $oldindent . " "  x $pos;
 
 				if ($newindent ne $goodtabindent &&
@@ -3733,11 +3739,11 @@ sub process {
 			#print "line<$line> prevline<$prevline> indent<$indent> sindent<$sindent> check<$check> continuation<$continuation> s<$s> cond_lines<$cond_lines> stat_real<$stat_real> stat<$stat>\n";
 
 			if ($check && $s ne '' &&
-			    (($sindent % 8) != 0 ||
+			    (($sindent % $tabsize) != 0 ||
 			     ($sindent < $indent) ||
 			     ($sindent == $indent &&
 			      ($s !~ /^\s*(?:\}|\{|else\b)/)) ||
-			     ($sindent > $indent + 8))) {
+			     ($sindent > $indent + $tabsize))) {
 				WARN("SUSPECT_CODE_INDENT",
 				     "suspect code indent for conditional statements ($indent, $sindent)\n" . $herecurr . "$stat_real\n");
 			}
-- 
2.25.0