checkpatch: check for incorrect permissions

Throw an error when a source file has been given execute permissions using
the mode change line present in git diffs.  Also alow the filename
matching to use the "diff" line in addition to the "+++" line, since the
mode change lines appear before any "+++" lines.

[apw@canonical.com: simplified filename logic slightly, added tests]
Cc: Andy Whitcroft <apw@canonical.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -1315,7 +1315,11 @@ sub process {
 		$here = "#$realline: " if ($file);
 
 		# extract the filename as it passes
-		if ($line=~/^\+\+\+\s+(\S+)/) {
+		if ($line =~ /^diff --git.*?(\S+)$/) {
+			$realfile = $1;
+			$realfile =~ s@^([^/]*)/@@;
+
+		} elsif ($line =~ /^\+\+\+\s+(\S+)/) {
 			$realfile = $1;
 			$realfile =~ s@^([^/]*)/@@;
 
@@ -1339,6 +1343,14 @@ sub process {
 
 		$cnt_lines++ if ($realcnt != 0);
 
+# Check for incorrect file permissions
+		if ($line =~ /^new (file )?mode.*[7531]\d{0,2}$/) {
+			my $permhere = $here . "FILE: $realfile\n";
+			if ($realfile =~ /(Makefile|Kconfig|\.c|\.h|\.S|\.tmpl)$/) {
+				ERROR("do not set execute permissions for source files\n" . $permhere);
+			}
+		}
+
 #check the patch for a signoff:
 		if ($line =~ /^\s*signed-off-by:/i) {
 			# This is a signoff, if ugly, so do not double report.