mirror of
https://git.savannah.gnu.org/git/parallel.git
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579 lines
17 KiB
Perl
579 lines
17 KiB
Perl
package Carp;
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use strict;
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use warnings;
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our $VERSION = '1.20';
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our $MaxEvalLen = 0;
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our $Verbose = 0;
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our $CarpLevel = 0;
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our $MaxArgLen = 64; # How much of each argument to print. 0 = all.
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our $MaxArgNums = 8; # How many arguments to print. 0 = all.
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require Exporter;
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our @ISA = ('Exporter');
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our @EXPORT = qw(confess croak carp);
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our @EXPORT_OK = qw(cluck verbose longmess shortmess);
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our @EXPORT_FAIL = qw(verbose); # hook to enable verbose mode
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# The members of %Internal are packages that are internal to perl.
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# Carp will not report errors from within these packages if it
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# can. The members of %CarpInternal are internal to Perl's warning
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# system. Carp will not report errors from within these packages
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# either, and will not report calls *to* these packages for carp and
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# croak. They replace $CarpLevel, which is deprecated. The
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# $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval
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# text and function arguments should be formatted when printed.
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our %CarpInternal;
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our %Internal;
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# disable these by default, so they can live w/o require Carp
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$CarpInternal{Carp}++;
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$CarpInternal{warnings}++;
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$Internal{Exporter}++;
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$Internal{'Exporter::Heavy'}++;
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# if the caller specifies verbose usage ("perl -MCarp=verbose script.pl")
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# then the following method will be called by the Exporter which knows
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# to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word
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# 'verbose'.
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sub export_fail { shift; $Verbose = shift if $_[0] eq 'verbose'; @_ }
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sub _cgc {
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no strict 'refs';
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return \&{"CORE::GLOBAL::caller"} if defined &{"CORE::GLOBAL::caller"};
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return;
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}
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sub longmess {
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# Icky backwards compatibility wrapper. :-(
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#
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# The story is that the original implementation hard-coded the
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# number of call levels to go back, so calls to longmess were off
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# by one. Other code began calling longmess and expecting this
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# behaviour, so the replacement has to emulate that behaviour.
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my $cgc = _cgc();
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my $call_pack = $cgc ? $cgc->() : caller();
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if ( $Internal{$call_pack} or $CarpInternal{$call_pack} ) {
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return longmess_heavy(@_);
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}
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else {
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local $CarpLevel = $CarpLevel + 1;
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return longmess_heavy(@_);
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}
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}
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our @CARP_NOT;
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sub shortmess {
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my $cgc = _cgc();
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# Icky backwards compatibility wrapper. :-(
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local @CARP_NOT = $cgc ? $cgc->() : caller();
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shortmess_heavy(@_);
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}
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sub croak { die shortmess @_ }
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sub confess { die longmess @_ }
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sub carp { warn shortmess @_ }
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sub cluck { warn longmess @_ }
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sub caller_info {
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my $i = shift(@_) + 1;
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my %call_info;
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my $cgc = _cgc();
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{
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package DB;
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@DB::args = \$i; # A sentinel, which no-one else has the address of
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@call_info{
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qw(pack file line sub has_args wantarray evaltext is_require) }
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= $cgc ? $cgc->($i) : caller($i);
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}
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unless ( defined $call_info{pack} ) {
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return ();
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}
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my $sub_name = Carp::get_subname( \%call_info );
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if ( $call_info{has_args} ) {
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my @args;
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if ( @DB::args == 1
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&& ref $DB::args[0] eq ref \$i
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&& $DB::args[0] == \$i ) {
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@DB::args = (); # Don't let anyone see the address of $i
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local $@;
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my $where = eval {
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my $func = $cgc or return '';
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my $gv = B::svref_2object($func)->GV;
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my $package = $gv->STASH->NAME;
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my $subname = $gv->NAME;
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return unless defined $package && defined $subname;
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# returning CORE::GLOBAL::caller isn't useful for tracing the cause:
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return if $package eq 'CORE::GLOBAL' && $subname eq 'caller';
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" in &${package}::$subname";
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} // '';
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@args
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= "** Incomplete caller override detected$where; \@DB::args were not set **";
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}
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else {
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@args = map { Carp::format_arg($_) } @DB::args;
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}
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if ( $MaxArgNums and @args > $MaxArgNums )
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{ # More than we want to show?
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$#args = $MaxArgNums;
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push @args, '...';
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}
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# Push the args onto the subroutine
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$sub_name .= '(' . join( ', ', @args ) . ')';
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}
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$call_info{sub_name} = $sub_name;
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return wantarray() ? %call_info : \%call_info;
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}
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# Transform an argument to a function into a string.
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sub format_arg {
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my $arg = shift;
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if ( ref($arg) ) {
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$arg = defined($overload::VERSION) ? overload::StrVal($arg) : "$arg";
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}
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if ( defined($arg) ) {
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$arg =~ s/'/\\'/g;
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$arg = str_len_trim( $arg, $MaxArgLen );
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# Quote it?
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$arg = "'$arg'" unless $arg =~ /^-?[0-9.]+\z/;
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} # 0-9, not \d, as \d will try to
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else { # load Unicode tables
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$arg = 'undef';
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}
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# The following handling of "control chars" is direct from
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# the original code - it is broken on Unicode though.
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# Suggestions?
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utf8::is_utf8($arg)
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or $arg =~ s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg;
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return $arg;
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}
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# Takes an inheritance cache and a package and returns
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# an anon hash of known inheritances and anon array of
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# inheritances which consequences have not been figured
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# for.
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sub get_status {
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my $cache = shift;
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my $pkg = shift;
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$cache->{$pkg} ||= [ { $pkg => $pkg }, [ trusts_directly($pkg) ] ];
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return @{ $cache->{$pkg} };
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}
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# Takes the info from caller() and figures out the name of
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# the sub/require/eval
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sub get_subname {
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my $info = shift;
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if ( defined( $info->{evaltext} ) ) {
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my $eval = $info->{evaltext};
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if ( $info->{is_require} ) {
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return "require $eval";
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}
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else {
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$eval =~ s/([\\\'])/\\$1/g;
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return "eval '" . str_len_trim( $eval, $MaxEvalLen ) . "'";
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}
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}
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return ( $info->{sub} eq '(eval)' ) ? 'eval {...}' : $info->{sub};
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}
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# Figures out what call (from the point of view of the caller)
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# the long error backtrace should start at.
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sub long_error_loc {
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my $i;
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my $lvl = $CarpLevel;
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{
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++$i;
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my $cgc = _cgc();
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my $pkg = $cgc ? $cgc->($i) : caller($i);
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unless ( defined($pkg) ) {
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# This *shouldn't* happen.
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if (%Internal) {
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local %Internal;
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$i = long_error_loc();
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last;
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}
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else {
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# OK, now I am irritated.
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return 2;
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}
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}
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redo if $CarpInternal{$pkg};
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redo unless 0 > --$lvl;
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redo if $Internal{$pkg};
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}
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return $i - 1;
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}
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sub longmess_heavy {
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return @_ if ref( $_[0] ); # don't break references as exceptions
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my $i = long_error_loc();
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return ret_backtrace( $i, @_ );
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}
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# Returns a full stack backtrace starting from where it is
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# told.
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sub ret_backtrace {
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my ( $i, @error ) = @_;
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my $mess;
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my $err = join '', @error;
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$i++;
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my $tid_msg = '';
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if ( defined &threads::tid ) {
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my $tid = threads->tid;
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$tid_msg = " thread $tid" if $tid;
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}
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my %i = caller_info($i);
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$mess = "$err at $i{file} line $i{line}$tid_msg\n";
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while ( my %i = caller_info( ++$i ) ) {
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$mess .= "\t$i{sub_name} called at $i{file} line $i{line}$tid_msg\n";
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}
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return $mess;
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}
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sub ret_summary {
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my ( $i, @error ) = @_;
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my $err = join '', @error;
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$i++;
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my $tid_msg = '';
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if ( defined &threads::tid ) {
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my $tid = threads->tid;
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$tid_msg = " thread $tid" if $tid;
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}
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my %i = caller_info($i);
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return "$err at $i{file} line $i{line}$tid_msg\n";
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}
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sub short_error_loc {
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# You have to create your (hash)ref out here, rather than defaulting it
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# inside trusts *on a lexical*, as you want it to persist across calls.
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# (You can default it on $_[2], but that gets messy)
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my $cache = {};
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my $i = 1;
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my $lvl = $CarpLevel;
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{
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my $cgc = _cgc();
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my $called = $cgc ? $cgc->($i) : caller($i);
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$i++;
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my $caller = $cgc ? $cgc->($i) : caller($i);
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return 0 unless defined($caller); # What happened?
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redo if $Internal{$caller};
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redo if $CarpInternal{$caller};
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redo if $CarpInternal{$called};
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redo if trusts( $called, $caller, $cache );
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redo if trusts( $caller, $called, $cache );
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redo unless 0 > --$lvl;
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}
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return $i - 1;
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}
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sub shortmess_heavy {
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return longmess_heavy(@_) if $Verbose;
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return @_ if ref( $_[0] ); # don't break references as exceptions
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my $i = short_error_loc();
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if ($i) {
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ret_summary( $i, @_ );
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}
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else {
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longmess_heavy(@_);
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}
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}
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# If a string is too long, trims it with ...
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sub str_len_trim {
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my $str = shift;
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my $max = shift || 0;
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if ( 2 < $max and $max < length($str) ) {
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substr( $str, $max - 3 ) = '...';
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}
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return $str;
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}
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# Takes two packages and an optional cache. Says whether the
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# first inherits from the second.
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#
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# Recursive versions of this have to work to avoid certain
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# possible endless loops, and when following long chains of
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# inheritance are less efficient.
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sub trusts {
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my $child = shift;
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my $parent = shift;
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my $cache = shift;
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my ( $known, $partial ) = get_status( $cache, $child );
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# Figure out consequences until we have an answer
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while ( @$partial and not exists $known->{$parent} ) {
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my $anc = shift @$partial;
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next if exists $known->{$anc};
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$known->{$anc}++;
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my ( $anc_knows, $anc_partial ) = get_status( $cache, $anc );
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my @found = keys %$anc_knows;
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@$known{@found} = ();
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push @$partial, @$anc_partial;
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}
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return exists $known->{$parent};
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}
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# Takes a package and gives a list of those trusted directly
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sub trusts_directly {
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my $class = shift;
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no strict 'refs';
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no warnings 'once';
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return @{"$class\::CARP_NOT"}
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? @{"$class\::CARP_NOT"}
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: @{"$class\::ISA"};
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}
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1;
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__END__
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=head1 NAME
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Carp - alternative warn and die for modules
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=head1 SYNOPSIS
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use Carp;
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# warn user (from perspective of caller)
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carp "string trimmed to 80 chars";
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# die of errors (from perspective of caller)
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croak "We're outta here!";
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# die of errors with stack backtrace
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confess "not implemented";
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# cluck not exported by default
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use Carp qw(cluck);
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cluck "This is how we got here!";
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=head1 DESCRIPTION
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The Carp routines are useful in your own modules because
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they act like die() or warn(), but with a message which is more
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likely to be useful to a user of your module. In the case of
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cluck, confess, and longmess that context is a summary of every
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call in the call-stack. For a shorter message you can use C<carp>
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or C<croak> which report the error as being from where your module
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was called. There is no guarantee that that is where the error
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was, but it is a good educated guess.
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You can also alter the way the output and logic of C<Carp> works, by
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changing some global variables in the C<Carp> namespace. See the
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section on C<GLOBAL VARIABLES> below.
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Here is a more complete description of how C<carp> and C<croak> work.
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What they do is search the call-stack for a function call stack where
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they have not been told that there shouldn't be an error. If every
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call is marked safe, they give up and give a full stack backtrace
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instead. In other words they presume that the first likely looking
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potential suspect is guilty. Their rules for telling whether
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a call shouldn't generate errors work as follows:
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=over 4
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=item 1.
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Any call from a package to itself is safe.
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=item 2.
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Packages claim that there won't be errors on calls to or from
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packages explicitly marked as safe by inclusion in C<@CARP_NOT>, or
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(if that array is empty) C<@ISA>. The ability to override what
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@ISA says is new in 5.8.
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=item 3.
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The trust in item 2 is transitive. If A trusts B, and B
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trusts C, then A trusts C. So if you do not override C<@ISA>
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with C<@CARP_NOT>, then this trust relationship is identical to,
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"inherits from".
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=item 4.
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Any call from an internal Perl module is safe. (Nothing keeps
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user modules from marking themselves as internal to Perl, but
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this practice is discouraged.)
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=item 5.
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Any call to Perl's warning system (eg Carp itself) is safe.
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(This rule is what keeps it from reporting the error at the
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point where you call C<carp> or C<croak>.)
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=item 6.
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C<$Carp::CarpLevel> can be set to skip a fixed number of additional
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call levels. Using this is not recommended because it is very
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difficult to get it to behave correctly.
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=back
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=head2 Forcing a Stack Trace
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As a debugging aid, you can force Carp to treat a croak as a confess
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and a carp as a cluck across I<all> modules. In other words, force a
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detailed stack trace to be given. This can be very helpful when trying
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to understand why, or from where, a warning or error is being generated.
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This feature is enabled by 'importing' the non-existent symbol
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'verbose'. You would typically enable it by saying
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perl -MCarp=verbose script.pl
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or by including the string C<-MCarp=verbose> in the PERL5OPT
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environment variable.
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Alternately, you can set the global variable C<$Carp::Verbose> to true.
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See the C<GLOBAL VARIABLES> section below.
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=head1 GLOBAL VARIABLES
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=head2 $Carp::MaxEvalLen
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This variable determines how many characters of a string-eval are to
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be shown in the output. Use a value of C<0> to show all text.
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Defaults to C<0>.
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=head2 $Carp::MaxArgLen
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This variable determines how many characters of each argument to a
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function to print. Use a value of C<0> to show the full length of the
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argument.
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Defaults to C<64>.
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=head2 $Carp::MaxArgNums
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This variable determines how many arguments to each function to show.
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Use a value of C<0> to show all arguments to a function call.
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Defaults to C<8>.
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=head2 $Carp::Verbose
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This variable makes C<carp> and C<croak> generate stack backtraces
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just like C<cluck> and C<confess>. This is how C<use Carp 'verbose'>
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is implemented internally.
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Defaults to C<0>.
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=head2 @CARP_NOT
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This variable, I<in your package>, says which packages are I<not> to be
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considered as the location of an error. The C<carp()> and C<cluck()>
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functions will skip over callers when reporting where an error occurred.
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NB: This variable must be in the package's symbol table, thus:
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# These work
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our @CARP_NOT; # file scope
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use vars qw(@CARP_NOT); # package scope
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@My::Package::CARP_NOT = ... ; # explicit package variable
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# These don't work
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sub xyz { ... @CARP_NOT = ... } # w/o declarations above
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my @CARP_NOT; # even at top-level
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Example of use:
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package My::Carping::Package;
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use Carp;
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our @CARP_NOT;
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sub bar { .... or _error('Wrong input') }
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sub _error {
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# temporary control of where'ness, __PACKAGE__ is implicit
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local @CARP_NOT = qw(My::Friendly::Caller);
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carp(@_)
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}
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This would make C<Carp> report the error as coming from a caller not
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in C<My::Carping::Package>, nor from C<My::Friendly::Caller>.
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Also read the L</DESCRIPTION> section above, about how C<Carp> decides
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where the error is reported from.
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Use C<@CARP_NOT>, instead of C<$Carp::CarpLevel>.
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Overrides C<Carp>'s use of C<@ISA>.
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=head2 %Carp::Internal
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This says what packages are internal to Perl. C<Carp> will never
|
|
report an error as being from a line in a package that is internal to
|
|
Perl. For example:
|
|
|
|
$Carp::Internal{ (__PACKAGE__) }++;
|
|
# time passes...
|
|
sub foo { ... or confess("whatever") };
|
|
|
|
would give a full stack backtrace starting from the first caller
|
|
outside of __PACKAGE__. (Unless that package was also internal to
|
|
Perl.)
|
|
|
|
=head2 %Carp::CarpInternal
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|
|
|
This says which packages are internal to Perl's warning system. For
|
|
generating a full stack backtrace this is the same as being internal
|
|
to Perl, the stack backtrace will not start inside packages that are
|
|
listed in C<%Carp::CarpInternal>. But it is slightly different for
|
|
the summary message generated by C<carp> or C<croak>. There errors
|
|
will not be reported on any lines that are calling packages in
|
|
C<%Carp::CarpInternal>.
|
|
|
|
For example C<Carp> itself is listed in C<%Carp::CarpInternal>.
|
|
Therefore the full stack backtrace from C<confess> will not start
|
|
inside of C<Carp>, and the short message from calling C<croak> is
|
|
not placed on the line where C<croak> was called.
|
|
|
|
=head2 $Carp::CarpLevel
|
|
|
|
This variable determines how many additional call frames are to be
|
|
skipped that would not otherwise be when reporting where an error
|
|
occurred on a call to one of C<Carp>'s functions. It is fairly easy
|
|
to count these call frames on calls that generate a full stack
|
|
backtrace. However it is much harder to do this accounting for calls
|
|
that generate a short message. Usually people skip too many call
|
|
frames. If they are lucky they skip enough that C<Carp> goes all of
|
|
the way through the call stack, realizes that something is wrong, and
|
|
then generates a full stack backtrace. If they are unlucky then the
|
|
error is reported from somewhere misleading very high in the call
|
|
stack.
|
|
|
|
Therefore it is best to avoid C<$Carp::CarpLevel>. Instead use
|
|
C<@CARP_NOT>, C<%Carp::Internal> and C<%Carp::CarpInternal>.
|
|
|
|
Defaults to C<0>.
|
|
|
|
=head1 BUGS
|
|
|
|
The Carp routines don't handle exception objects currently.
|
|
If called with a first argument that is a reference, they simply
|
|
call die() or warn(), as appropriate.
|
|
|