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check-non-portable-shell: support Perl versions older than 5.10

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For thoroughness when checking for one-shot environment variable
assignments at shell function call sites, check-non-portable-shell
stitches together incomplete lines (those ending with backslash). This
allows it to correctly flag such undesirable usage even when the
variable assignment and function call are split across lines, for
example:

    FOO=bar \
    func

where 'func' is a shell function.

The stitching is accomplished like this:

    while (<>) {
        chomp;
        # stitch together incomplete lines (those ending with "\")
        while (s/\\$//) {
            $_ .= readline;
            chomp;
        }
        # detect unportable/undesirable shell constructs
        ...
    }

Although this implementation is well supported in reasonably modern Perl
versions (5.10 and later), it fails with older versions (such as Perl
5.8 shipped with ancient Mac OS 10.5). In particular, in older Perl
versions, 'readline' is not connected to the file handle associated with
the "magic" while (<>) {...} construct, so 'readline' throws a
"readline() on unopened filehandle" error. Work around this problem by
dropping readline() and instead incorporating the stitching of
incomplete lines directly into the existing while (<>) {...} loop.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Eric Sunshine 2019-05-10 20:18:53 -04:00 committed by Junio C Hamano
parent 6a6c0f10a7
commit 142997d489
1 changed files with 5 additions and 4 deletions
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9
t/check-non-portable-shell.pl
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@ -27,14 +27,14 @@ for my $i (@ARGV) {
close $f;
}
my $line = '';
while (<>) {
chomp;
$line .= $_;
# stitch together incomplete lines (those ending with "\")
while (s/\\$//) {
$_ .= readline;
chomp;
}
next if $line =~ s/\\$//;
$_ = $line;
/\bcp\s+-a/ and err 'cp -a is not portable';
/\bsed\s+-[^efn]\s+/ and err 'sed option not portable (use only -n, -e, -f)';
/\becho\s+-[neE]/ and err 'echo with option is not portable (use printf)';
@ -48,6 +48,7 @@ while (<>) {
/\bexport\s+[A-Za-z0-9_]*=/ and err '"export FOO=bar" is not portable (use FOO=bar && export FOO)';
/^\s*([A-Z0-9_]+=(\w+|(["']).*?\3)\s+)+(\w+)/ and exists($func{$4}) and
err '"FOO=bar shell_func" assignment extends beyond "shell_func"';
$line = '';
# this resets our $. for each file
close ARGV if eof;
}