--- /dev/null
-# `1 + 2`, which embeds whitespace, is scanned as three token in shell, as well.
+ # Copyright (c) 2021-2022 Eric Sunshine <sunshine@sunshineco.com>
+ #
+ # Shared shell script parser for test lint tools. Provides Lexer,
+ # ShellParser, and ScriptParser. Subclass ScriptParser and override
+ # check_test() to implement lint checks.
+
+ use strict;
+ use warnings;
+
+ # 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 whitepaces, 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,
+ lineno => 1,
+ heretags => []
+ } => $class;
+ }
+
+ sub scan_heredoc_tag {
+ my $self = shift @_;
+ ${$self->{buff}} =~ /\G(-?)/gc;
+ my $indented = $1;
+ my $token = $self->scan_token();
+ return "<<$indented" unless $token;
+ my $tag = $token->[0];
+ $tag =~ s/['"\\]//g;
+ $$token[0] = $indented ? "\t$tag" : "$tag";
+ push(@{$self->{heretags}}, $token);
+ return "<<$indented$tag";
+ }
+
+ sub scan_op {
+ my ($self, $c) = @_;
+ my $b = $self->{buff};
+ return $c unless $$b =~ /\G(.)/sgc;
+ my $cc = $c . $1;
+ return scan_heredoc_tag($self) if $cc eq '<<';
+ return $cc if $cc =~ /^(?:&&|\|\||>>|;;|<&|>&|<>|>\|)$/;
+ pos($$b)--;
+ return $c;
+ }
+
+ sub scan_sqstring {
+ my $self = shift @_;
+ ${$self->{buff}} =~ /\G([^']*'|.*\z)/sgc;
+ my $s = $1;
+ $self->{lineno} += () = $s =~ /\n/sg;
+ return "'" . $s;
+ }
+
+ sub scan_dqstring {
+ my $self = shift @_;
+ my $b = $self->{buff};
+ my $s = '"';
+ while (1) {
+ # Slurp non-special characters; count newlines here because
+ # newlines inside $() are already counted by the recursive parse.
+ if ($$b =~ /\G([^"\$\\]+)/gc) {
+ $s .= $1;
+ $self->{lineno} += $1 =~ tr/\n//;
+ }
+ # 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;
+ $self->{lineno}++, 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;
+ }
+ $self->{lineno} += () = $s =~ /\n/sg;
+ 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; # $((...))
+ return '(' . join(' ', map {$_->[0]} $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 $start = pos($$b);
+ my $indent = $$tag[0] =~ s/^\t// ? '\\s*' : '';
+ $$b =~ /(?:\G|\n)$indent\Q$$tag[0]\E(?:\n|\z)/gc;
+ if (pos($$b) > $start) {
+ my $body = substr($$b, $start, pos($$b) - $start);
+ $self->{parser}->{heredocs}->{$$tag[0]} = {
+ content => substr($body, 0, length($body) - length($&)),
+ start_line => $self->{lineno},
+ };
+ $self->{lineno} += () = $body =~ /\n/sg;
+ next;
+ }
+ push(@{$self->{parser}->{problems}}, ['HEREDOC', $tag]);
+ $$b =~ /(?:\G|\n).*\z/gc; # consume rest of input
+ my $body = substr($$b, $start, pos($$b) - $start);
+ $self->{lineno} += () = $body =~ /\n/sg;
+ last;
+ }
+ }
+
+ sub scan_token {
+ my $self = shift @_;
+ my $b = $self->{buff};
+ my $token = '';
+ my ($start, $startln);
+ RESTART:
+ $startln = $self->{lineno};
+ $$b =~ /\G[ \t]+/gc; # skip whitespace (but not newline)
+ $start = pos($$b) || 0;
+ $self->{lineno}++, return ["\n", $start, pos($$b), $startln, $startln] 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 $$b =~ /\G(.)/sgc;
+ my $c = $1;
+ pos($$b)--, last if $c =~ /^[ \t]$/; # whitespace ends token
+ pos($$b)--, last if length($token) && $c =~ /^[;&|<>(){}\n]$/;
+ $token .= $self->scan_sqstring(), next if $c eq "'";
+ $token .= $self->scan_dqstring(), next if $c eq '"';
+ $token .= $c . $self->scan_dollar(), next if $c eq '$';
+ $self->{lineno}++, $self->swallow_heredocs(), $token = $c, last if $c eq "\n";
+ $token = $self->scan_op($c), last if $c =~ /^[;&|<>]$/;
+ $token = $c, last if $c =~ /^[(){}]$/;
+ if ($c eq '\\') {
+ $token .= '\\', last unless $$b =~ /\G(.)/sgc;
+ $c = $1;
+ $self->{lineno}++, next if $c eq "\n" && length($token); # line splice
+ $self->{lineno}++, goto RESTART if $c eq "\n"; # line splice
+ $token .= '\\' . $c;
+ next;
+ }
+ die("internal error scanning character '$c'\n");
+ }
+ return length($token) ? [$token, $start, pos($$b), $startln, $self->{lineno}] : undef;
+ }
+
+ # ShellParser parses POSIX shell scripts (with minor extensions for Bash). It
+ # is a recursive descent parser very roughly modeled after section 2.10 "Shell
+ # Grammar" of POSIX chapter 2 "Shell Command Language".
+
+ package ShellParser;
+
+ sub new {
+ my ($class, $s) = @_;
+ my $self = bless {
+ buff => [],
+ stop => [],
+ output => [],
+ heredocs => {},
+ insubshell => 0,
+ } => $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->[0] =~ $stop;
+ }
+
+ sub expect {
+ my ($self, $expect) = @_;
+ my $token = $self->next_token();
+ return $token if defined($token) && $token->[0] eq $expect;
+ push(@{$self->{output}}, "?!ERR?! expected '$expect' but found '" . (defined($token) ? $token->[0] : "<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->[0] 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 @_;
+ $self->{insubshell}++;
+ my @tokens = ($self->parse(qr/^\)$/),
+ $self->expect(')'));
+ $self->{insubshell}--;
+ return @tokens;
+ }
+
+ sub parse_case_pattern {
+ my $self = shift @_;
+ my @tokens;
+ while (defined(my $token = $self->next_token())) {
+ push(@tokens, $token);
+ last if $token->[0] 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->[0] 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->[0] 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->[0] 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->[0] eq 'elif';
+ push(@tokens, $self->expect('elif'));
+ }
+ my $token = $self->peek();
+ if (defined($token) && $token->[0] 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->[0] 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->[0] eq "\n";
+
+ my $token;
+ my @tokens = $cmd;
+ if ($cmd->[0] eq '!') {
+ push(@tokens, $self->parse_cmd());
+ return @tokens;
+ } elsif (my $f = $compound{$cmd->[0]}) {
+ push(@tokens, $self->$f());
+ } elsif (defined($token = $self->peek()) && $token->[0] eq '(') {
+ if ($cmd->[0] !~ /\w=$/) {
+ push(@tokens, $self->parse_func());
+ return @tokens;
+ }
+ my @array = $self->parse_bash_array_assignment();
+ $tokens[-1]->[0] .= join(' ', map {$_->[0]} @array);
+ $tokens[-1]->[2] = $array[$#array][2] if @array;
+ }
+
+ while (defined(my $token = $self->next_token())) {
+ $self->untoken($token), last if $self->stop_at($token);
+ push(@tokens, $token);
+ last if $token->[0] =~ /^(?:[;&\n|]|&&|\|\|)$/;
+ }
+ push(@tokens, $self->next_token()) if $tokens[-1]->[0] ne "\n" && defined($token = $self->peek()) && $token->[0] eq "\n";
+ return @tokens;
+ }
+
+ sub accumulate {
+ my ($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;
+ }
+
+ # ScriptParser is a subclass of ShellParser which identifies individual test
+ # definitions within test scripts and passes each test body to check_test().
+ # ScriptParser 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;
+
+ our @ISA = ('ShellParser');
+
+ sub new {
+ my $class = shift @_;
+ my $self = $class->SUPER::new(@_);
+ $self->{ntests} = 0;
+ $self->{nerrs} = 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 @_ : $_)->[0];
+ # 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 {
+ # no-op; subclass and override to implement lint checks
+ }
+
+ sub parse_cmd {
+ my $self = shift @_;
+ my @tokens = $self->SUPER::parse_cmd();
+ return @tokens unless @tokens && $tokens[0]->[0] =~ /^test_expect_(?:success|failure)$/;
+ my $n = $#tokens;
+ $n-- while $n >= 0 && $tokens[$n]->[0] =~ /^(?:[;&\n|]|&&|\|\|)$/;
+ my $herebody;
+ if ($n >= 2 && $tokens[$n-1]->[0] eq '-' && $tokens[$n]->[0] =~ /^<<-?(.+)$/) {
+ $herebody = $self->{heredocs}->{$1};
+ $n--;
+ }
+ $self->check_test($tokens[1], $tokens[2], $herebody) if $n == 2; # title body
+ $self->check_test($tokens[2], $tokens[3], $herebody) if $n > 2; # prereq title body
+ return @tokens;
+ }
+
+ 1;
projects / thirdparty / git.git / commitdiff
