git/t/chainlint.pl
Eric Sunshine fd4094c3ca chainlint.pl: complain about loops lacking explicit failure handling
Shell `for` and `while` loops do not terminate automatically just
because a command fails within the loop body. Instead, the loop
continues to iterate and eventually returns the exit status of the final
command of the final iteration, which may not be the command which
failed, thus it is possible for failures to go undetected. Consequently,
it is important for test authors to explicitly handle failure within the
loop body by terminating the loop manually upon failure. This can be
done by returning a non-zero exit code from within the loop body
(i.e. `|| return 1`) or exiting (i.e. `|| exit 1`) if the loop is within
a subshell, or by manually checking `$?` and taking some appropriate
action. Therefore, add logic to detect and complain about loops which
lack explicit `return` or `exit`, or `$?` check.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-09-01 10:07:41 -07:00

728 lines
20 KiB
Perl
Executable File

#!/usr/bin/env perl
#
# Copyright (c) 2021-2022 Eric Sunshine <sunshine@sunshineco.com>
#
# This tool scans shell scripts for test definitions and checks those tests for
# problems, such as broken &&-chains, which might hide bugs in the tests
# themselves or in behaviors being exercised by the tests.
#
# Input arguments are pathnames of shell scripts containing test definitions,
# or globs referencing a collection of scripts. For each problem discovered,
# the pathname of the script containing the test is printed along with the test
# name and the test body with a `?!FOO?!` annotation at the location of each
# detected problem, where "FOO" is a tag such as "AMP" which indicates a broken
# &&-chain. Returns zero if no problems are discovered, otherwise non-zero.
use warnings;
use strict;
use Config;
use File::Glob;
use Getopt::Long;
my $jobs = -1;
my $show_stats;
my $emit_all;
# Lexer tokenizes POSIX shell scripts. It is roughly modeled after section 2.3
# "Token Recognition" of POSIX chapter 2 "Shell Command Language". Although
# similar to lexical analyzers for other languages, this one differs in a few
# substantial ways due to quirks of the shell command language.
#
# For instance, in many languages, newline is just whitespace like space or
# TAB, but in shell a newline is a command separator, thus a distinct lexical
# token. A newline is significant and returned as a distinct token even at the
# end of a shell comment.
#
# In other languages, `1+2` would typically be scanned as three tokens
# (`1`, `+`, and `2`), but in shell it is a single token. However, the similar
# `1 + 2`, which embeds whitepace, is scanned as three token in shell, as well.
# In shell, several characters with special meaning lose that meaning when not
# surrounded by whitespace. For instance, the negation operator `!` is special
# when standing alone surrounded by whitespace; whereas in `foo!uucp` it is
# just a plain character in the longer token "foo!uucp". In many other
# languages, `"string"/foo:'string'` might be scanned as five tokens ("string",
# `/`, `foo`, `:`, and 'string'), but in shell, it is just a single token.
#
# The lexical analyzer for the shell command language is also somewhat unusual
# in that it recursively invokes the parser to handle the body of `$(...)`
# expressions which can contain arbitrary shell code. Such expressions may be
# encountered both inside and outside of double-quoted strings.
#
# The lexical analyzer is responsible for consuming shell here-doc bodies which
# extend from the line following a `<<TAG` operator until a line consisting
# solely of `TAG`. Here-doc consumption begins when a newline is encountered.
# It is legal for multiple here-doc `<<TAG` operators to be present on a single
# line, in which case their bodies must be present one following the next, and
# are consumed in the (left-to-right) order the `<<TAG` operators appear on the
# line. A special complication is that the bodies of all here-docs must be
# consumed when the newline is encountered even if the parse context depth has
# changed. For instance, in `cat <<A && x=$(cat <<B &&\n`, bodies of here-docs
# "A" and "B" must be consumed even though "A" was introduced outside the
# recursive parse context in which "B" was introduced and in which the newline
# is encountered.
package Lexer;
sub new {
my ($class, $parser, $s) = @_;
bless {
parser => $parser,
buff => $s,
heretags => []
} => $class;
}
sub scan_heredoc_tag {
my $self = shift @_;
${$self->{buff}} =~ /\G(-?)/gc;
my $indented = $1;
my $tag = $self->scan_token();
$tag =~ s/['"\\]//g;
push(@{$self->{heretags}}, $indented ? "\t$tag" : "$tag");
return "<<$indented$tag";
}
sub scan_op {
my ($self, $c) = @_;
my $b = $self->{buff};
return $c unless $$b =~ /\G(.)/sgc;
my $cc = $c . $1;
return scan_heredoc_tag($self) if $cc eq '<<';
return $cc if $cc =~ /^(?:&&|\|\||>>|;;|<&|>&|<>|>\|)$/;
pos($$b)--;
return $c;
}
sub scan_sqstring {
my $self = shift @_;
${$self->{buff}} =~ /\G([^']*'|.*\z)/sgc;
return "'" . $1;
}
sub scan_dqstring {
my $self = shift @_;
my $b = $self->{buff};
my $s = '"';
while (1) {
# slurp up non-special characters
$s .= $1 if $$b =~ /\G([^"\$\\]+)/gc;
# handle special characters
last unless $$b =~ /\G(.)/sgc;
my $c = $1;
$s .= '"', last if $c eq '"';
$s .= '$' . $self->scan_dollar(), next if $c eq '$';
if ($c eq '\\') {
$s .= '\\', last unless $$b =~ /\G(.)/sgc;
$c = $1;
next if $c eq "\n"; # line splice
# backslash escapes only $, `, ", \ in dq-string
$s .= '\\' unless $c =~ /^[\$`"\\]$/;
$s .= $c;
next;
}
die("internal error scanning dq-string '$c'\n");
}
return $s;
}
sub scan_balanced {
my ($self, $c1, $c2) = @_;
my $b = $self->{buff};
my $depth = 1;
my $s = $c1;
while ($$b =~ /\G([^\Q$c1$c2\E]*(?:[\Q$c1$c2\E]|\z))/gc) {
$s .= $1;
$depth++, next if $s =~ /\Q$c1\E$/;
$depth--;
last if $depth == 0;
}
return $s;
}
sub scan_subst {
my $self = shift @_;
my @tokens = $self->{parser}->parse(qr/^\)$/);
$self->{parser}->next_token(); # closing ")"
return @tokens;
}
sub scan_dollar {
my $self = shift @_;
my $b = $self->{buff};
return $self->scan_balanced('(', ')') if $$b =~ /\G\((?=\()/gc; # $((...))
return '(' . join(' ', $self->scan_subst()) . ')' if $$b =~ /\G\(/gc; # $(...)
return $self->scan_balanced('{', '}') if $$b =~ /\G\{/gc; # ${...}
return $1 if $$b =~ /\G(\w+)/gc; # $var
return $1 if $$b =~ /\G([@*#?$!0-9-])/gc; # $*, $1, $$, etc.
return '';
}
sub swallow_heredocs {
my $self = shift @_;
my $b = $self->{buff};
my $tags = $self->{heretags};
while (my $tag = shift @$tags) {
my $indent = $tag =~ s/^\t// ? '\\s*' : '';
$$b =~ /(?:\G|\n)$indent\Q$tag\E(?:\n|\z)/gc;
}
}
sub scan_token {
my $self = shift @_;
my $b = $self->{buff};
my $token = '';
RESTART:
$$b =~ /\G[ \t]+/gc; # skip whitespace (but not newline)
return "\n" if $$b =~ /\G#[^\n]*(?:\n|\z)/gc; # comment
while (1) {
# slurp up non-special characters
$token .= $1 if $$b =~ /\G([^\\;&|<>(){}'"\$\s]+)/gc;
# handle special characters
last unless $$b =~ /\G(.)/sgc;
my $c = $1;
last if $c =~ /^[ \t]$/; # whitespace ends token
pos($$b)--, last if length($token) && $c =~ /^[;&|<>(){}\n]$/;
$token .= $self->scan_sqstring(), next if $c eq "'";
$token .= $self->scan_dqstring(), next if $c eq '"';
$token .= $c . $self->scan_dollar(), next if $c eq '$';
$self->swallow_heredocs(), $token = $c, last if $c eq "\n";
$token = $self->scan_op($c), last if $c =~ /^[;&|<>]$/;
$token = $c, last if $c =~ /^[(){}]$/;
if ($c eq '\\') {
$token .= '\\', last unless $$b =~ /\G(.)/sgc;
$c = $1;
next if $c eq "\n" && length($token); # line splice
goto RESTART if $c eq "\n"; # line splice
$token .= '\\' . $c;
next;
}
die("internal error scanning character '$c'\n");
}
return length($token) ? $token : undef;
}
# ShellParser parses POSIX shell scripts (with minor extensions for Bash). It
# is a recursive descent parser very roughly modeled after section 2.10 "Shell
# Grammar" of POSIX chapter 2 "Shell Command Language".
package ShellParser;
sub new {
my ($class, $s) = @_;
my $self = bless {
buff => [],
stop => [],
output => []
} => $class;
$self->{lexer} = Lexer->new($self, $s);
return $self;
}
sub next_token {
my $self = shift @_;
return pop(@{$self->{buff}}) if @{$self->{buff}};
return $self->{lexer}->scan_token();
}
sub untoken {
my $self = shift @_;
push(@{$self->{buff}}, @_);
}
sub peek {
my $self = shift @_;
my $token = $self->next_token();
return undef unless defined($token);
$self->untoken($token);
return $token;
}
sub stop_at {
my ($self, $token) = @_;
return 1 unless defined($token);
my $stop = ${$self->{stop}}[-1] if @{$self->{stop}};
return defined($stop) && $token =~ $stop;
}
sub expect {
my ($self, $expect) = @_;
my $token = $self->next_token();
return $token if defined($token) && $token eq $expect;
push(@{$self->{output}}, "?!ERR?! expected '$expect' but found '" . (defined($token) ? $token : "<end-of-input>") . "'\n");
$self->untoken($token) if defined($token);
return ();
}
sub optional_newlines {
my $self = shift @_;
my @tokens;
while (my $token = $self->peek()) {
last unless $token eq "\n";
push(@tokens, $self->next_token());
}
return @tokens;
}
sub parse_group {
my $self = shift @_;
return ($self->parse(qr/^}$/),
$self->expect('}'));
}
sub parse_subshell {
my $self = shift @_;
return ($self->parse(qr/^\)$/),
$self->expect(')'));
}
sub parse_case_pattern {
my $self = shift @_;
my @tokens;
while (defined(my $token = $self->next_token())) {
push(@tokens, $token);
last if $token eq ')';
}
return @tokens;
}
sub parse_case {
my $self = shift @_;
my @tokens;
push(@tokens,
$self->next_token(), # subject
$self->optional_newlines(),
$self->expect('in'),
$self->optional_newlines());
while (1) {
my $token = $self->peek();
last unless defined($token) && $token ne 'esac';
push(@tokens,
$self->parse_case_pattern(),
$self->optional_newlines(),
$self->parse(qr/^(?:;;|esac)$/)); # item body
$token = $self->peek();
last unless defined($token) && $token ne 'esac';
push(@tokens,
$self->expect(';;'),
$self->optional_newlines());
}
push(@tokens, $self->expect('esac'));
return @tokens;
}
sub parse_for {
my $self = shift @_;
my @tokens;
push(@tokens,
$self->next_token(), # variable
$self->optional_newlines());
my $token = $self->peek();
if (defined($token) && $token eq 'in') {
push(@tokens,
$self->expect('in'),
$self->optional_newlines());
}
push(@tokens,
$self->parse(qr/^do$/), # items
$self->expect('do'),
$self->optional_newlines(),
$self->parse_loop_body(),
$self->expect('done'));
return @tokens;
}
sub parse_if {
my $self = shift @_;
my @tokens;
while (1) {
push(@tokens,
$self->parse(qr/^then$/), # if/elif condition
$self->expect('then'),
$self->optional_newlines(),
$self->parse(qr/^(?:elif|else|fi)$/)); # if/elif body
my $token = $self->peek();
last unless defined($token) && $token eq 'elif';
push(@tokens, $self->expect('elif'));
}
my $token = $self->peek();
if (defined($token) && $token eq 'else') {
push(@tokens,
$self->expect('else'),
$self->optional_newlines(),
$self->parse(qr/^fi$/)); # else body
}
push(@tokens, $self->expect('fi'));
return @tokens;
}
sub parse_loop_body {
my $self = shift @_;
return $self->parse(qr/^done$/);
}
sub parse_loop {
my $self = shift @_;
return ($self->parse(qr/^do$/), # condition
$self->expect('do'),
$self->optional_newlines(),
$self->parse_loop_body(),
$self->expect('done'));
}
sub parse_func {
my $self = shift @_;
return ($self->expect('('),
$self->expect(')'),
$self->optional_newlines(),
$self->parse_cmd()); # body
}
sub parse_bash_array_assignment {
my $self = shift @_;
my @tokens = $self->expect('(');
while (defined(my $token = $self->next_token())) {
push(@tokens, $token);
last if $token eq ')';
}
return @tokens;
}
my %compound = (
'{' => \&parse_group,
'(' => \&parse_subshell,
'case' => \&parse_case,
'for' => \&parse_for,
'if' => \&parse_if,
'until' => \&parse_loop,
'while' => \&parse_loop);
sub parse_cmd {
my $self = shift @_;
my $cmd = $self->next_token();
return () unless defined($cmd);
return $cmd if $cmd eq "\n";
my $token;
my @tokens = $cmd;
if ($cmd eq '!') {
push(@tokens, $self->parse_cmd());
return @tokens;
} elsif (my $f = $compound{$cmd}) {
push(@tokens, $self->$f());
} elsif (defined($token = $self->peek()) && $token eq '(') {
if ($cmd !~ /\w=$/) {
push(@tokens, $self->parse_func());
return @tokens;
}
$tokens[-1] .= join(' ', $self->parse_bash_array_assignment());
}
while (defined(my $token = $self->next_token())) {
$self->untoken($token), last if $self->stop_at($token);
push(@tokens, $token);
last if $token =~ /^(?:[;&\n|]|&&|\|\|)$/;
}
push(@tokens, $self->next_token()) if $tokens[-1] ne "\n" && defined($token = $self->peek()) && $token eq "\n";
return @tokens;
}
sub accumulate {
my ($self, $tokens, $cmd) = @_;
push(@$tokens, @$cmd);
}
sub parse {
my ($self, $stop) = @_;
push(@{$self->{stop}}, $stop);
goto DONE if $self->stop_at($self->peek());
my @tokens;
while (my @cmd = $self->parse_cmd()) {
$self->accumulate(\@tokens, \@cmd);
last if $self->stop_at($self->peek());
}
DONE:
pop(@{$self->{stop}});
return @tokens;
}
# TestParser is a subclass of ShellParser which, beyond parsing shell script
# code, is also imbued with semantic knowledge of test construction, and checks
# tests for common problems (such as broken &&-chains) which might hide bugs in
# the tests themselves or in behaviors being exercised by the tests. As such,
# TestParser is only called upon to parse test bodies, not the top-level
# scripts in which the tests are defined.
package TestParser;
use base 'ShellParser';
sub find_non_nl {
my $tokens = shift @_;
my $n = shift @_;
$n = $#$tokens if !defined($n);
$n-- while $n >= 0 && $$tokens[$n] eq "\n";
return $n;
}
sub ends_with {
my ($tokens, $needles) = @_;
my $n = find_non_nl($tokens);
for my $needle (reverse(@$needles)) {
return undef if $n < 0;
$n = find_non_nl($tokens, $n), next if $needle eq "\n";
return undef if $$tokens[$n] !~ $needle;
$n--;
}
return 1;
}
sub match_ending {
my ($tokens, $endings) = @_;
for my $needles (@$endings) {
next if @$tokens < scalar(grep {$_ ne "\n"} @$needles);
return 1 if ends_with($tokens, $needles);
}
return undef;
}
sub parse_loop_body {
my $self = shift @_;
my @tokens = $self->SUPER::parse_loop_body(@_);
# did loop signal failure via "|| return" or "|| exit"?
return @tokens if !@tokens || grep(/^(?:return|exit|\$\?)$/, @tokens);
# flag missing "return/exit" handling explicit failure in loop body
my $n = find_non_nl(\@tokens);
splice(@tokens, $n + 1, 0, '?!LOOP?!');
return @tokens;
}
my @safe_endings = (
[qr/^(?:&&|\|\||\||&)$/],
[qr/^(?:exit|return)$/, qr/^(?:\d+|\$\?)$/],
[qr/^(?:exit|return)$/, qr/^(?:\d+|\$\?)$/, qr/^;$/],
[qr/^(?:exit|return|continue)$/],
[qr/^(?:exit|return|continue)$/, qr/^;$/]);
sub accumulate {
my ($self, $tokens, $cmd) = @_;
goto DONE unless @$tokens;
goto DONE if @$cmd == 1 && $$cmd[0] eq "\n";
# did previous command end with "&&", "|", "|| return" or similar?
goto DONE if match_ending($tokens, \@safe_endings);
# if this command handles "$?" specially, then okay for previous
# command to be missing "&&"
for my $token (@$cmd) {
goto DONE if $token =~ /\$\?/;
}
# if this command is "false", "return 1", or "exit 1" (which signal
# failure explicitly), then okay for all preceding commands to be
# missing "&&"
if ($$cmd[0] =~ /^(?:false|return|exit)$/) {
@$tokens = grep(!/^\?!AMP\?!$/, @$tokens);
goto DONE;
}
# flag missing "&&" at end of previous command
my $n = find_non_nl($tokens);
splice(@$tokens, $n + 1, 0, '?!AMP?!') unless $n < 0;
DONE:
$self->SUPER::accumulate($tokens, $cmd);
}
# ScriptParser is a subclass of ShellParser which identifies individual test
# definitions within test scripts, and passes each test body through TestParser
# to identify possible problems. ShellParser detects test definitions not only
# at the top-level of test scripts but also within compound commands such as
# loops and function definitions.
package ScriptParser;
use base 'ShellParser';
sub new {
my $class = shift @_;
my $self = $class->SUPER::new(@_);
$self->{ntests} = 0;
return $self;
}
# extract the raw content of a token, which may be a single string or a
# composition of multiple strings and non-string character runs; for instance,
# `"test body"` unwraps to `test body`; `word"a b"42'c d'` to `worda b42c d`
sub unwrap {
my $token = @_ ? shift @_ : $_;
# simple case: 'sqstring' or "dqstring"
return $token if $token =~ s/^'([^']*)'$/$1/;
return $token if $token =~ s/^"([^"]*)"$/$1/;
# composite case
my ($s, $q, $escaped);
while (1) {
# slurp up non-special characters
$s .= $1 if $token =~ /\G([^\\'"]*)/gc;
# handle special characters
last unless $token =~ /\G(.)/sgc;
my $c = $1;
$q = undef, next if defined($q) && $c eq $q;
$q = $c, next if !defined($q) && $c =~ /^['"]$/;
if ($c eq '\\') {
last unless $token =~ /\G(.)/sgc;
$c = $1;
$s .= '\\' if $c eq "\n"; # preserve line splice
}
$s .= $c;
}
return $s
}
sub check_test {
my $self = shift @_;
my ($title, $body) = map(unwrap, @_);
$self->{ntests}++;
my $parser = TestParser->new(\$body);
my @tokens = $parser->parse();
return unless $emit_all || grep(/\?![^?]+\?!/, @tokens);
my $checked = join(' ', @tokens);
$checked =~ s/^\n//;
$checked =~ s/^ //mg;
$checked =~ s/ $//mg;
$checked .= "\n" unless $checked =~ /\n$/;
push(@{$self->{output}}, "# chainlint: $title\n$checked");
}
sub parse_cmd {
my $self = shift @_;
my @tokens = $self->SUPER::parse_cmd();
return @tokens unless @tokens && $tokens[0] =~ /^test_expect_(?:success|failure)$/;
my $n = $#tokens;
$n-- while $n >= 0 && $tokens[$n] =~ /^(?:[;&\n|]|&&|\|\|)$/;
$self->check_test($tokens[1], $tokens[2]) if $n == 2; # title body
$self->check_test($tokens[2], $tokens[3]) if $n > 2; # prereq title body
return @tokens;
}
# main contains high-level functionality for processing command-line switches,
# feeding input test scripts to ScriptParser, and reporting results.
package main;
my $getnow = sub { return time(); };
my $interval = sub { return time() - shift; };
if (eval {require Time::HiRes; Time::HiRes->import(); 1;}) {
$getnow = sub { return [Time::HiRes::gettimeofday()]; };
$interval = sub { return Time::HiRes::tv_interval(shift); };
}
sub ncores {
# Windows
return $ENV{NUMBER_OF_PROCESSORS} if exists($ENV{NUMBER_OF_PROCESSORS});
# Linux / MSYS2 / Cygwin / WSL
do { local @ARGV='/proc/cpuinfo'; return scalar(grep(/^processor\s*:/, <>)); } if -r '/proc/cpuinfo';
# macOS & BSD
return qx/sysctl -n hw.ncpu/ if $^O =~ /(?:^darwin$|bsd)/;
return 1;
}
sub show_stats {
my ($start_time, $stats) = @_;
my $walltime = $interval->($start_time);
my ($usertime) = times();
my ($total_workers, $total_scripts, $total_tests, $total_errs) = (0, 0, 0, 0);
for (@$stats) {
my ($worker, $nscripts, $ntests, $nerrs) = @$_;
print(STDERR "worker $worker: $nscripts scripts, $ntests tests, $nerrs errors\n");
$total_workers++;
$total_scripts += $nscripts;
$total_tests += $ntests;
$total_errs += $nerrs;
}
printf(STDERR "total: %d workers, %d scripts, %d tests, %d errors, %.2fs/%.2fs (wall/user)\n", $total_workers, $total_scripts, $total_tests, $total_errs, $walltime, $usertime);
}
sub check_script {
my ($id, $next_script, $emit) = @_;
my ($nscripts, $ntests, $nerrs) = (0, 0, 0);
while (my $path = $next_script->()) {
$nscripts++;
my $fh;
unless (open($fh, "<", $path)) {
$emit->("?!ERR?! $path: $!\n");
next;
}
my $s = do { local $/; <$fh> };
close($fh);
my $parser = ScriptParser->new(\$s);
1 while $parser->parse_cmd();
if (@{$parser->{output}}) {
my $s = join('', @{$parser->{output}});
$emit->("# chainlint: $path\n" . $s);
$nerrs += () = $s =~ /\?![^?]+\?!/g;
}
$ntests += $parser->{ntests};
}
return [$id, $nscripts, $ntests, $nerrs];
}
sub exit_code {
my $stats = shift @_;
for (@$stats) {
my ($worker, $nscripts, $ntests, $nerrs) = @$_;
return 1 if $nerrs;
}
return 0;
}
Getopt::Long::Configure(qw{bundling});
GetOptions(
"emit-all!" => \$emit_all,
"jobs|j=i" => \$jobs,
"stats|show-stats!" => \$show_stats) or die("option error\n");
$jobs = ncores() if $jobs < 1;
my $start_time = $getnow->();
my @stats;
my @scripts;
push(@scripts, File::Glob::bsd_glob($_)) for (@ARGV);
unless (@scripts) {
show_stats($start_time, \@stats) if $show_stats;
exit;
}
unless ($Config{useithreads} && eval {
require threads; threads->import();
require Thread::Queue; Thread::Queue->import();
1;
}) {
push(@stats, check_script(1, sub { shift(@scripts); }, sub { print(@_); }));
show_stats($start_time, \@stats) if $show_stats;
exit(exit_code(\@stats));
}
my $script_queue = Thread::Queue->new();
my $output_queue = Thread::Queue->new();
sub next_script { return $script_queue->dequeue(); }
sub emit { $output_queue->enqueue(@_); }
sub monitor {
while (my $s = $output_queue->dequeue()) {
print($s);
}
}
my $mon = threads->create({'context' => 'void'}, \&monitor);
threads->create({'context' => 'list'}, \&check_script, $_, \&next_script, \&emit) for 1..$jobs;
$script_queue->enqueue(@scripts);
$script_queue->end();
for (threads->list()) {
push(@stats, $_->join()) unless $_ == $mon;
}
$output_queue->end();
$mon->join();
show_stats($start_time, \@stats) if $show_stats;
exit(exit_code(\@stats));