[checks/scripts] [PATCH 3/4] shell script wrapper detection

["Adam D. Barratt" <adam@adam-barratt.org.uk>]

Hi,

This is the third of a series of patches updating checks/scripts
bashisms checks with some changes that have been made to checkbashisms
over the past few months.

Hopefully all the patches are self-explanatory, but please let me know
if there are any questions or issues.

Regards,

Adam

scripts_are_more_evil_and_wrong.diff
------------------------------------
 
The archive-wide checkbashisms runs have revealed more methods of
disguising something as a shell script than script_is_evil_and_wrong()
currently catches.
 
1) Match cases where just $@ is quoted, or where the whole of ${1:+$@}
is quoted.

2) Allow arguments to eval to be double- as well as single-quoted

3) Increase the number of lines scanned

Both of the above were added to match line 52 of
bastille-firewall-schedule:

        eval "exec ${PERL} -x $0 $*"

4) Match lines execing $var if $var has previously been assigned the
value of $0. /usr/bin/git-citool uses this construct:

        #!/bin/sh
        # Tcl ignores the next line -*- tcl -*- \
         if test "z$*" = zversion \
         || test "z$*" = z--version; \
         then \
                echo 'git-gui version 0.9.3.1.g21623'; \
                exit; \
         fi; \
         argv0=$0; \
         exec '/usr/bin/wish8.5' "$argv0" -- "$@"

5) Allow the exec to be preceded by && as well as a semicolon

6) Match scripts that don't pass on their parameters (i.e. re-exec
themselves and read from stdin)

--- checks/scripts.orig	2008-06-13 10:56:03.000000000 +0100
+++ checks/scripts	2008-06-13 10:58:11.000000000 +0100
@@ -738,16 +738,19 @@
     my $ret = 0;
     open (IN, '<', $filename) or fail("cannot open $filename: $!");
     my $i = 0;
+    my $var = "0";
     local $_;
     while (<IN>) {
-        chomp;
+	chomp;
 	next if /^#/o;
 	next if /^$/o;
-        last if (++$i > 20);
-        if (/(^\s*|\beval\s*\'|;\s*)exec\s*.+\s*.?\$0.?\s*(--\s*)?(\${1:?\+)?.?\$(\@|\*)/o) {
-            $ret = 1;
-            last;
-        }
+	last if (++$i > 55);
+	if (/(^\s*|\beval\s*[\'\"]|(;|&&)\s*)exec\s*.+\s*.?\$$var.?\s*(--\s*)?.?(\${1:?\+.?)?(\$(\@|\*))?/) {
+	    $ret = 1;
+	    last;
+	} elsif (/^\s*(\w+)=\$0;/) {
+	    $var = $1;
+	}
     }
     close IN;
     return $ret;