Apply environment expansion to options in .stowrc files

Expand environment variables used in stowrc, as requested in

    https://savannah.gnu.org/bugs/?41826

This is achieved by creating a new function expand_environment() that
replaces any substring of the form '$VAR' or '${VAR}' with contents of
environment variable $VAR.  Literal '$' can be given by '\$'.

N.B. The function is only applied to the --target and --dir options,
and only for options specified in .stowrc; cli options are left
untouched.

Undefined variables are expanded to the empty string, as they would be
in normal shell parameter expansion.

Unit tests added accordingly:

  - Test expand_environment():
    * Expand $HOME
    * Expand ${HOME}
    * Expand ${WITH SPACE}
    * Expand '\$HOME'. Expected is '$HOME'
    * Expand ${UNDEFINED}. Expected is ''.

  - Test that it's applied to the correct options.

  - Test that CLI options are not expanded.
This commit is contained in:
Charles LeDoux 2016-07-14 11:37:42 -05:00 committed by Adam Spiers
parent 4d1167ffd7
commit 9674738792
3 changed files with 123 additions and 4 deletions

View file

@ -632,7 +632,8 @@ sub check_packages {
# Returns : (\%rc_options, \@rc_pkgs_to_unstow, \@rc_pkgs_to_stow)
# Throws : a fatal error if a bad option is given
# Comments : Parses the contents of '~/.stowrc' and '.stowrc' with the same
# parser as the command line options.
# parser as the command line options. Additionally expands any
# environment variables in --target or --dir options.
#=============================================================================
sub get_config_file_options {
my @defaults = ();
@ -647,7 +648,56 @@ sub get_config_file_options {
close $FILE or die "Could not close open file: $file\n";
}
}
return parse_options(@defaults);
# Parse the options
my ($rc_options, $rc_pkgs_to_unstow, $rc_pkgs_to_stow) = parse_options(@defaults);
# Expand environment variables and glob characters.
if (exists $rc_options->{target}) {
$rc_options->{target} =
expand_environment($rc_options->{target}, '--target option');
}
if (exists $rc_options->{dir}) {
$rc_options->{dir} =
expand_environment($rc_options->{dir}, '--dir option');
}
return ($rc_options, $rc_pkgs_to_unstow, $rc_pkgs_to_stow);
}
#===== SUBROUTINE ============================================================
# Name : expand_environment()
# Purpose : Expands evironment variables.
# Parameters: $path => string to perform expansion on.
# : $source => where the string came from
# Returns : String with replacements performed.
# Throws : n/a
# Comments : Variable replacement mostly based on SO answer
# : http://stackoverflow.com/a/24675093/558820
#=============================================================================
sub expand_environment {
my ($path, $source) = @_;
# Replace non-escaped $VAR and ${VAR} with $ENV{VAR}
# If $ENV{VAR} does not exist, perl will raise a warning
# and then happily treat it as an empty string.
$path =~ s/(?<!\\)\$\{((?:\w|\s)+)\}/
_safe_expand_env_var($1, $source)
/ge;
$path =~ s/(?<!\\)\$(\w+)/
_safe_expand_env_var($1, $source)
/ge;
# Remove \$ escapes.
$path =~ s/\\\$/\$/g;
return $path;
}
sub _safe_expand_env_var {
my ($var, $source) = @_;
unless (exists $ENV{$var}) {
die "$source references undefined environment variable \$$var; " .
"aborting!\n";
}
return $ENV{$var};
}
#===== SUBROUTINE ===========================================================

View file

@ -7,7 +7,7 @@
use strict;
use warnings;
use Test::More tests => 9;
use Test::More tests => 10;
use testutil;
@ -82,5 +82,16 @@ local @ARGV = (
($options, $pkgs_to_delete, $pkgs_to_stow) = process_options();
is_deeply($options->{ignore}, [ qr(~\z), qr(\.#.*\z) ] => 'ignore temp files');
#
# Check that expansion not applied.
#
local @ARGV = (
"--target=$OUT_DIR/".'$HOME',
'dummy'
);
make_dir("$OUT_DIR/".'$HOME');
($options, $pkgs_to_delete, $pkgs_to_stow) = process_options();
is($options->{target}, "$OUT_DIR/".'$HOME', 'no expansion');
remove_dir("$OUT_DIR/".'$HOME');
# vim:ft=perl

View file

@ -7,7 +7,7 @@
use strict;
use warnings;
use Test::More tests => 4;
use Test::More tests => 15;
use testutil;
@ -72,6 +72,64 @@ make_file($RC_FILE, $rc_contents);
is_deeply($options->{defer}, [qr(\Ainfo), qr(\Aman)],
'defer man and info');
# ======== Filepath Expansion Tests ========
# Test proper filepath expansion in rc file.
# Expansion is only applied to options that
# take a filepath, namely target and dir.
# ==========================================
#
# Test environment variable expansion function.
#
# Basic expansion
is(expand_environment('$HOME/stow'), "$OUT_DIR/stow", 'expand $HOME');
is(expand_environment('${HOME}/stow'), "$OUT_DIR/stow", 'expand ${HOME}');
delete $ENV{UNDEFINED}; # just in case
foreach my $var ('$UNDEFINED', '${UNDEFINED}') {
eval {
expand_environment($var, "--foo option");
};
is(
$@,
"--foo option references undefined environment variable \$UNDEFINED; " .
"aborting!\n",
"expand $var"
);
}
# Expansion with an underscore.
$ENV{'WITH_UNDERSCORE'} = 'test string';
is(expand_environment('${WITH_UNDERSCORE}'), 'test string',
'expand ${WITH_UNDERSCORE}');
delete $ENV{'WITH_UNDERSCORE'};
# Expansion with escaped $
is(expand_environment('\$HOME/stow'), '$HOME/stow', 'expand \$HOME');
#
# Test that environment variable expansion is applied.
#
$rc_contents = <<'HERE';
--dir=$HOME/stow
--target=$HOME/stow
--ignore=\$HOME
--defer=\$HOME
--override=\$HOME
HERE
make_file($RC_FILE, $rc_contents);
($options, $pkgs_to_delete, $pkgs_to_stow) = get_config_file_options();
is($options->{dir}, "$OUT_DIR/stow",
"apply environment expansion on stowrc --dir");
is($options->{target}, "$OUT_DIR/stow",
"apply environment expansion on stowrc --target");
is_deeply($options->{ignore}, [qr(\$HOME\z)],
"environment expansion not applied on --ignore");
is_deeply($options->{defer}, [qr(\A\$HOME)],
"environment expansion not applied on --defer");
is_deeply($options->{override}, [qr(\A\$HOME)],
"environment expansion not applied on --override");
# Clean up files used for testing.
#
unlink $RC_FILE or die "Unable to clean up $RC_FILE.\n";