EXP30-PL. Do not use deprecated or obsolete functions

Do not use deprecated or obsolescent functions when more secure equivalent functions are available.

Here is a list of deprecated functions along with their recommended alternatives if available:

Noncompliant Code Example (die())

This noncompliant code example tries to open a file and invokes the obsolete die() method if it fails.

my $file;
open(FILE, "<", $file) or die "error opening $file: stopped";
# work with FILE

The die() method is considered deprecated because it prints the file name and line number in which it was invoked. This might be sensitive information.

Compliant Solution (croak())

This compliant solution uses the croak() function instead of die().

use Carp;

my $file;
open(FILE, "<", $file) or croak "error opening $file: stopped";
# work with FILE

Unlike die(), croak() provides the file name and line number of the function that invoked the function that invoked croak(). This is more useful for application code that invokes library code; in this case, croak() and carp() also will reveal the file name and line number of the application code rather than the library code.

Exceptions

EXP30:EX0: The -t function should not be used for determining if input is interactive, but it is perfectly valid to determine if output is interactive. So it may be used on *STDOUT or *STDERR.

EXP30:EX1: The behavior of the croak() and carp() functions when invoked inside a signal handler are not documented. Consequently, die() and warn() should be used instead.

Risk Assessment

Using deprecated or obsolete classes or methods in program code can lead to erroneous behavior.

Automated Detection

Related Guidelines

CERT C Secure Coding Standard: MSC34-C. Do not use deprecated or obsolete functions

The CERT Oracle Secure Coding Standard for Java: MET02-J. Do not use deprecated or obsolete classes or methods

Bibliography

[CPAN] Elliot Shank, Perl-Critic-1.116 RequireCarping, InteractiveTest, ProhibitFormats
[Conway 2005]

      02. Expressions      EXP31-PL. Do not use the two-argument form of open()