[PATCH v3] 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

 scripts/checkpatch.pl | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 916a3fbd4d47..90f641bf1895 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -62,6 +62,7 @@ my $conststructsfile = "$D/const_structs.checkpatch";
 my $typedefsfile = "";
 my $color = "auto";
 my $allow_c99_comments = 1; # Can be overridden by --ignore C99_COMMENT_TOLERANCE
+my $tabsize = 8;
 
 sub help {
 	my ($exitcode) = @_;
@@ -96,6 +97,7 @@ Options:
   --show-types               show the specific message type in the output
   --max-line-length=n        set the maximum line length, if exceeded, warn
   --min-conf-desc-length=n   set the min description length, if shorter, warn
+  --tab-size=n               set the number of spaces for tab (default 8)
   --root=PATH                PATH to the kernel tree root
   --no-summary               suppress the per-file summary
   --mailback                 only produce a report in case of warnings/errors
@@ -213,6 +215,7 @@ GetOptions(
 	'list-types!'	=> \$list_types,
 	'max-line-length=i' => \$max_line_length,
 	'min-conf-desc-length=i' => \$min_conf_desc_length,
+	'tab-size=i'	=> \$tabsize,
 	'root=s'	=> \$root,
 	'summary!'	=> \$summary,
 	'mailback!'	=> \$mailback,
@@ -1211,7 +1214,7 @@ sub expand_tabs {
 		if ($c eq "\t") {
 			$res .= ' ';
 			$n++;
-			for (; ($n % 8) != 0; $n++) {
+			for (; ($n % $tabsize) != 0; $n++) {
 				$res .= ' ';
 			}
 			next;
@@ -2224,7 +2227,7 @@ sub string_find_replace {
 sub tabify {
 	my ($leading) = @_;
 
-	my $source_indent = 8;
+	my $source_indent = $tabsize;
 	my $max_spaces_before_tab = $source_indent - 1;
 	my $spaces_to_tab = " " x $source_indent;
 
@@ -3153,7 +3156,7 @@ 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";
@@ -3172,7 +3175,7 @@ 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/$1\t/) {}
 			}
@@ -3194,11 +3197,11 @@ sub process {
 		if ($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;
 				}
 			}
 		}
@@ -3216,8 +3219,8 @@ 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 $goodtabindent &&
@@ -3688,11 +3691,11 @@ sub process {
 			#print "line<$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");
 			}
-- 
2.21.0