如何修复Perl中的多行失控字符串错误？

我的Perl脚本中有一些错误,我查看了源代码,但找不到问题.

#Tool: decoding shell codes/making shell codes

use strict;
use Getopt::Std;

my %opts=();
getopts("f:xa", \%opts);

my($infile, $hex);
my($gen_hex, $gen_ascii);

sub usage() {
print "$0 -f  [-x | -a] \n\t";
print '-p '."\n\t";
print '-x convert "\nxXX" hex to readable ascii'."\n\t";
print '-a convert ascii to "\xXX" hex'."\n\t";
print "\n";
exit;
}

$infile = $opts{f};

$gen_hex = $opts{a};
$gen_ascii = $opts{x};use


if((!opts{f} || (!$gen_hex && !$gen_ascii)) {
usage();
exit;
}

if($infile) {
open(INFILE,$infile) || die "Error Opening '$infile': $!\n"; 
while() {
#Strips newlines
s/\n/g;
#Strips tabs
s/\t//g;
#Strips quotes
s/"//g;
$hex .= $_;
}
}

if($gen_ascii) {

# \xXX hex style to ASCII
$hex =~ s/\\x([a-fA-F0-9]{2,2})/chr(hex($1)/eg;
}
elsif ($gen_hex) {
$hex =~ s/([\W|\w)/"\\x" . uc(sprintf("%2.2x",ord($1)))/eg;
} 

print "\n$hex\n";
if($infile) {
close(INFILE);
}

给了我错误

Backslash found where operator expected at 2.txt line 36, near "s/\"
(Might be runaway multi-line // string starting on line 34) 
syntax error at 2.txt line 25, near ") {"
syntax error at 2.txt line 28, near "}"
syntax error at 2.txt line 36, near "s/\"
syntax error at 2.txt line 41. nar "}"
Execution of 2.txt aborted due to compilation errors

你看到了问题吗？

#Strips newlines
s/\n/g;

是错的.你忘记了一个额外的/:

#Strips newlines
s/\n//g;

此外,这里的括号太少:

if((!opts{f} || (!$gen_hex && !$gen_ascii)) {

你可能看起来只有一个额外的,而不是添加一些.把它拿出来吧.

作为旁注,请尽可能尝试use warnings;.这是一件好事.

编辑:虽然我在这,你可能要小心你的open()s:

open(INPUT,$input);

可以被滥用.如果$input是的话">file.txt"？然后open()会尝试打开文件进行写作 - 而不是你想要的.试试这个:

open(INPUT, "<", $input);

有许多错误:尾随use,失踪/的s操作,不平衡的括号if表达.有点整理:

use strict;
use Getopt::Std;

my %opts = ();
getopts( "f:xa", \%opts );

my ( $gen_hex, $gen_ascii );

sub usage() {
    print < [-x | -a]
    -p 
    -x convert "\\xXX" hex to readable ascii
    -a convert ascii to "\\xXX" hex
EOU
}

@ARGV = ( $opts{f} ) if exists $opts{f};

$gen_hex   = $opts{a};
$gen_ascii = $opts{x};

if ( not( $gen_hex xor $gen_ascii ) ) {
    usage();
    exit;
}

my $transform = $gen_ascii
    ? sub {
    s/\\x([a-fA-F0-9]{2,2})/pack'H2', $1/eg;
    }
    : sub {
    s/([^[:print:]])/'\\x'.uc unpack'H2', $1/eg;
    };

while (<>) {
    s/\n    #Strips newlines
    | \t    #Strips tabs
    | "     #Strips quotes
    //xg;
    &$transform;
    print;
}