package Carp;
+use strict;
+use warnings;
+
+our $VERSION = '1.20';
+
+our $MaxEvalLen = 0;
+our $Verbose = 0;
+our $CarpLevel = 0;
+our $MaxArgLen = 64; # How much of each argument to print. 0 = all.
+our $MaxArgNums = 8; # How many arguments to print. 0 = all.
+
+require Exporter;
+our @ISA = ('Exporter');
+our @EXPORT = qw(confess croak carp);
+our @EXPORT_OK = qw(cluck verbose longmess shortmess);
+our @EXPORT_FAIL = qw(verbose); # hook to enable verbose mode
+
+# The members of %Internal are packages that are internal to perl.
+# Carp will not report errors from within these packages if it
+# can. The members of %CarpInternal are internal to Perl's warning
+# system. Carp will not report errors from within these packages
+# either, and will not report calls *to* these packages for carp and
+# croak. They replace $CarpLevel, which is deprecated. The
+# $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval
+# text and function arguments should be formatted when printed.
+
+our %CarpInternal;
+our %Internal;
+
+# disable these by default, so they can live w/o require Carp
+$CarpInternal{Carp}++;
+$CarpInternal{warnings}++;
+$Internal{Exporter}++;
+$Internal{'Exporter::Heavy'}++;
+
+# if the caller specifies verbose usage ("perl -MCarp=verbose script.pl")
+# then the following method will be called by the Exporter which knows
+# to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word
+# 'verbose'.
+
+sub export_fail { shift; $Verbose = shift if $_[0] eq 'verbose'; @_ }
+
+sub _cgc {
+ no strict 'refs';
+ return \&{"CORE::GLOBAL::caller"} if defined &{"CORE::GLOBAL::caller"};
+ return;
+}
+
+sub longmess {
+ # Icky backwards compatibility wrapper. :-(
+ #
+ # The story is that the original implementation hard-coded the
+ # number of call levels to go back, so calls to longmess were off
+ # by one. Other code began calling longmess and expecting this
+ # behaviour, so the replacement has to emulate that behaviour.
+ my $cgc = _cgc();
+ my $call_pack = $cgc ? $cgc->() : caller();
+ if ( $Internal{$call_pack} or $CarpInternal{$call_pack} ) {
+ return longmess_heavy(@_);
+ }
+ else {
+ local $CarpLevel = $CarpLevel + 1;
+ return longmess_heavy(@_);
+ }
+}
+
+our @CARP_NOT;
+
+sub shortmess {
+ my $cgc = _cgc();
+
+ # Icky backwards compatibility wrapper. :-(
+ local @CARP_NOT = $cgc ? $cgc->() : caller();
+ shortmess_heavy(@_);
+}
+
+sub croak { die shortmess @_ }
+sub confess { die longmess @_ }
+sub carp { warn shortmess @_ }
+sub cluck { warn longmess @_ }
+
+sub caller_info {
+ my $i = shift(@_) + 1;
+ my %call_info;
+ my $cgc = _cgc();
+ {
+ package DB;
+ @DB::args = \$i; # A sentinel, which no-one else has the address of
+ @call_info{
+ qw(pack file line sub has_args wantarray evaltext is_require) }
+ = $cgc ? $cgc->($i) : caller($i);
+ }
+
+ unless ( defined $call_info{pack} ) {
+ return ();
+ }
+
+ my $sub_name = Carp::get_subname( \%call_info );
+ if ( $call_info{has_args} ) {
+ my @args;
+ if ( @DB::args == 1
+ && ref $DB::args[0] eq ref \$i
+ && $DB::args[0] == \$i ) {
+ @DB::args = (); # Don't let anyone see the address of $i
+ local $@;
+ my $where = eval {
+ my $func = $cgc or return '';
+ my $gv = B::svref_2object($func)->GV;
+ my $package = $gv->STASH->NAME;
+ my $subname = $gv->NAME;
+ return unless defined $package && defined $subname;
+
+ # returning CORE::GLOBAL::caller isn't useful for tracing the cause:
+ return if $package eq 'CORE::GLOBAL' && $subname eq 'caller';
+ " in &${package}::$subname";
+ } // '';
+ @args
+ = "** Incomplete caller override detected$where; \@DB::args were not set **";
+ }
+ else {
+ @args = map { Carp::format_arg($_) } @DB::args;
+ }
+ if ( $MaxArgNums and @args > $MaxArgNums )
+ { # More than we want to show?
+ $#args = $MaxArgNums;
+ push @args, '...';
+ }
+
+ # Push the args onto the subroutine
+ $sub_name .= '(' . join( ', ', @args ) . ')';
+ }
+ $call_info{sub_name} = $sub_name;
+ return wantarray() ? %call_info : \%call_info;
+}
+
+# Transform an argument to a function into a string.
+sub format_arg {
+ my $arg = shift;
+ if ( ref($arg) ) {
+ $arg = defined($overload::VERSION) ? overload::StrVal($arg) : "$arg";
+ }
+ if ( defined($arg) ) {
+ $arg =~ s/'/\\'/g;
+ $arg = str_len_trim( $arg, $MaxArgLen );
+
+ # Quote it?
+ $arg = "'$arg'" unless $arg =~ /^-?[\d.]+\z/;
+ }
+ else {
+ $arg = 'undef';
+ }
+
+ # The following handling of "control chars" is direct from
+ # the original code - it is broken on Unicode though.
+ # Suggestions?
+ utf8::is_utf8($arg)
+ or $arg =~ s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg;
+ return $arg;
+}
+
+# Takes an inheritance cache and a package and returns
+# an anon hash of known inheritances and anon array of
+# inheritances which consequences have not been figured
+# for.
+sub get_status {
+ my $cache = shift;
+ my $pkg = shift;
+ $cache->{$pkg} ||= [ { $pkg => $pkg }, [ trusts_directly($pkg) ] ];
+ return @{ $cache->{$pkg} };
+}
+
+# Takes the info from caller() and figures out the name of
+# the sub/require/eval
+sub get_subname {
+ my $info = shift;
+ if ( defined( $info->{evaltext} ) ) {
+ my $eval = $info->{evaltext};
+ if ( $info->{is_require} ) {
+ return "require $eval";
+ }
+ else {
+ $eval =~ s/([\\\'])/\\$1/g;
+ return "eval '" . str_len_trim( $eval, $MaxEvalLen ) . "'";
+ }
+ }
+
+ return ( $info->{sub} eq '(eval)' ) ? 'eval {...}' : $info->{sub};
+}
+
+# Figures out what call (from the point of view of the caller)
+# the long error backtrace should start at.
+sub long_error_loc {
+ my $i;
+ my $lvl = $CarpLevel;
+ {
+ ++$i;
+ my $cgc = _cgc();
+ my $pkg = $cgc ? $cgc->($i) : caller($i);
+ unless ( defined($pkg) ) {
+
+ # This *shouldn't* happen.
+ if (%Internal) {
+ local %Internal;
+ $i = long_error_loc();
+ last;
+ }
+ else {
+
+ # OK, now I am irritated.
+ return 2;
+ }
+ }
+ redo if $CarpInternal{$pkg};
+ redo unless 0 > --$lvl;
+ redo if $Internal{$pkg};
+ }
+ return $i - 1;
+}
+
+sub longmess_heavy {
+ return @_ if ref( $_[0] ); # don't break references as exceptions
+ my $i = long_error_loc();
+ return ret_backtrace( $i, @_ );
+}
+
+# Returns a full stack backtrace starting from where it is
+# told.
+sub ret_backtrace {
+ my ( $i, @error ) = @_;
+ my $mess;
+ my $err = join '', @error;
+ $i++;
+
+ my $tid_msg = '';
+ if ( defined &threads::tid ) {
+ my $tid = threads->tid;
+ $tid_msg = " thread $tid" if $tid;
+ }
+
+ my %i = caller_info($i);
+ $mess = "$err at $i{file} line $i{line}$tid_msg\n";
+
+ while ( my %i = caller_info( ++$i ) ) {
+ $mess .= "\t$i{sub_name} called at $i{file} line $i{line}$tid_msg\n";
+ }
+
+ return $mess;
+}
+
+sub ret_summary {
+ my ( $i, @error ) = @_;
+ my $err = join '', @error;
+ $i++;
+
+ my $tid_msg = '';
+ if ( defined &threads::tid ) {
+ my $tid = threads->tid;
+ $tid_msg = " thread $tid" if $tid;
+ }
+
+ my %i = caller_info($i);
+ return "$err at $i{file} line $i{line}$tid_msg\n";
+}
+
+sub short_error_loc {
+ # You have to create your (hash)ref out here, rather than defaulting it
+ # inside trusts *on a lexical*, as you want it to persist across calls.
+ # (You can default it on $_[2], but that gets messy)
+ my $cache = {};
+ my $i = 1;
+ my $lvl = $CarpLevel;
+ {
+ my $cgc = _cgc();
+ my $called = $cgc ? $cgc->($i) : caller($i);
+ $i++;
+ my $caller = $cgc ? $cgc->($i) : caller($i);
+
+ return 0 unless defined($caller); # What happened?
+ redo if $Internal{$caller};
+ redo if $CarpInternal{$caller};
+ redo if $CarpInternal{$called};
+ redo if trusts( $called, $caller, $cache );
+ redo if trusts( $caller, $called, $cache );
+ redo unless 0 > --$lvl;
+ }
+ return $i - 1;
+}
+
+sub shortmess_heavy {
+ return longmess_heavy(@_) if $Verbose;
+ return @_ if ref( $_[0] ); # don't break references as exceptions
+ my $i = short_error_loc();
+ if ($i) {
+ ret_summary( $i, @_ );
+ }
+ else {
+ longmess_heavy(@_);
+ }
+}
+
+# If a string is too long, trims it with ...
+sub str_len_trim {
+ my $str = shift;
+ my $max = shift || 0;
+ if ( 2 < $max and $max < length($str) ) {
+ substr( $str, $max - 3 ) = '...';
+ }
+ return $str;
+}
+
+# Takes two packages and an optional cache. Says whether the
+# first inherits from the second.
+#
+# Recursive versions of this have to work to avoid certain
+# possible endless loops, and when following long chains of
+# inheritance are less efficient.
+sub trusts {
+ my $child = shift;
+ my $parent = shift;
+ my $cache = shift;
+ my ( $known, $partial ) = get_status( $cache, $child );
+
+ # Figure out consequences until we have an answer
+ while ( @$partial and not exists $known->{$parent} ) {
+ my $anc = shift @$partial;
+ next if exists $known->{$anc};
+ $known->{$anc}++;
+ my ( $anc_knows, $anc_partial ) = get_status( $cache, $anc );
+ my @found = keys %$anc_knows;
+ @$known{@found} = ();
+ push @$partial, @$anc_partial;
+ }
+ return exists $known->{$parent};
+}
+
+# Takes a package and gives a list of those trusted directly
+sub trusts_directly {
+ my $class = shift;
+ no strict 'refs';
+ no warnings 'once';
+ return @{"$class\::CARP_NOT"}
+ ? @{"$class\::CARP_NOT"}
+ : @{"$class\::ISA"};
+}
+
+1;
+
+__END__
+
=head1 NAME
-carp - warn of errors (from perspective of caller)
+carp - warn of errors (from perspective of caller)
+
+cluck - warn of errors with stack backtrace
+ (not exported by default)
-croak - die of errors (from perspective of caller)
+croak - die of errors (from perspective of caller)
confess - die of errors with stack backtrace
use Carp;
croak "We're outta here!";
+ use Carp qw(cluck);
+ cluck "This is how we got here!";
+
=head1 DESCRIPTION
The Carp routines are useful in your own modules because
-they act like die() or warn(), but report where the error
-was in the code they were called from. Thus if you have a
-routine Foo() that has a carp() in it, then the carp()
-will report the error as occurring where Foo() was called,
-not where carp() was called.
+they act like die() or warn(), but with a message which is more
+likely to be useful to a user of your module. In the case of
+cluck, confess, and longmess that context is a summary of every
+call in the call-stack. For a shorter message you can use C<carp>
+or C<croak> which report the error as being from where your module
+was called. There is no guarantee that that is where the error
+was, but it is a good educated guess.
-=cut
+You can also alter the way the output and logic of C<Carp> works, by
+changing some global variables in the C<Carp> namespace. See the
+section on C<GLOBAL VARIABLES> below.
-# This package implements handy routines for modules that wish to throw
-# exceptions outside of the current package.
+Here is a more complete description of how C<carp> and C<croak> work.
+What they do is search the call-stack for a function call stack where
+they have not been told that there shouldn't be an error. If every
+call is marked safe, they give up and give a full stack backtrace
+instead. In other words they presume that the first likely looking
+potential suspect is guilty. Their rules for telling whether
+a call shouldn't generate errors work as follows:
-$CarpLevel = 0; # How many extra package levels to skip on carp.
-$MaxEvalLen = 0; # How much eval '...text...' to show. 0 = all.
-$MaxArgLen = 64; # How much of each argument to print. 0 = all.
-$MaxArgNums = 8; # How many arguments to print. 0 = all.
+=over 4
-require Exporter;
-@ISA = Exporter;
-@EXPORT = qw(confess croak carp);
+=item 1.
-sub longmess {
- my $error = join '', @_;
- my $mess = "";
- my $i = 1 + $CarpLevel;
- my ($pack,$file,$line,$sub,$hargs,$eval,$require);
- my (@a);
- while (do { { package DB; @a = caller($i++) } } ) {
- ($pack,$file,$line,$sub,$hargs,undef,$eval,$require) = @a;
- if ($error =~ m/\n$/) {
- $mess .= $error;
- } else {
- if (defined $eval) {
- if ($require) {
- $sub = "require $eval";
- } else {
- $eval =~ s/([\\\'])/\\$1/g;
- if ($MaxEvalLen && length($eval) > $MaxEvalLen) {
- substr($eval,$MaxEvalLen) = '...';
- }
- $sub = "eval '$eval'";
- }
- } elsif ($sub eq '(eval)') {
- $sub = 'eval {...}';
- }
- if ($hargs) {
- @a = @DB::args; # must get local copy of args
- if ($MaxArgNums and @a > $MaxArgNums) {
- $#a = $MaxArgNums;
- $a[$#a] = "...";
- }
- for (@a) {
- $_ = "undef", next unless defined $_;
- if (ref $_) {
- $_ .= '';
- s/'/\\'/g;
- }
- else {
- s/'/\\'/g;
- substr($_,$MaxArgLen) = '...'
- if $MaxArgLen and $MaxArgLen < length;
- }
- $_ = "'$_'" unless /^-?[\d.]+$/;
- s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
- s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
- }
- $sub .= '(' . join(', ', @a) . ')';
- }
- $mess .= "\t$sub " if $error eq "called";
- $mess .= "$error at $file line $line\n";
- }
- $error = "called";
- }
- # this kludge circumvents die's incorrect handling of NUL
- my $msg = \($mess || $error);
- $$msg =~ tr/\0//d;
- $$msg;
-}
-
-sub shortmess { # Short-circuit &longmess if called via multiple packages
- my $error = join '', @_;
- my ($prevpack) = caller(1);
- my $extra = $CarpLevel;
- my $i = 2;
- my ($pack,$file,$line);
- my %isa = ($prevpack,1);
-
- @isa{@{"${prevpack}::ISA"}} = ()
- if(defined @{"${prevpack}::ISA"});
-
- while (($pack,$file,$line) = caller($i++)) {
- if(defined @{$pack . "::ISA"}) {
- my @i = @{$pack . "::ISA"};
- my %i;
- @i{@i} = ();
- @isa{@i,$pack} = ()
- if(exists $i{$prevpack} || exists $isa{$pack});
- }
-
- next
- if(exists $isa{$pack});
-
- if ($extra-- > 0) {
- %isa = ($pack,1);
- @isa{@{$pack . "::ISA"}} = ()
- if(defined @{$pack . "::ISA"});
- }
- else {
- # this kludge circumvents die's incorrect handling of NUL
- (my $msg = "$error at $file line $line\n") =~ tr/\0//d;
- return $msg;
- }
- }
- continue {
- $prevpack = $pack;
- }
-
- goto &longmess;
-}
-
-sub confess { die longmess @_; }
-sub croak { die shortmess @_; }
-sub carp { warn shortmess @_; }
+Any call from a package to itself is safe.
+
+=item 2.
+
+Packages claim that there won't be errors on calls to or from
+packages explicitly marked as safe by inclusion in C<@CARP_NOT>, or
+(if that array is empty) C<@ISA>. The ability to override what
+@ISA says is new in 5.8.
+
+=item 3.
+
+The trust in item 2 is transitive. If A trusts B, and B
+trusts C, then A trusts C. So if you do not override C<@ISA>
+with C<@CARP_NOT>, then this trust relationship is identical to,
+"inherits from".
+
+=item 4.
+
+Any call from an internal Perl module is safe. (Nothing keeps
+user modules from marking themselves as internal to Perl, but
+this practice is discouraged.)
+
+=item 5.
+
+Any call to Perl's warning system (eg Carp itself) is safe.
+(This rule is what keeps it from reporting the error at the
+point where you call C<carp> or C<croak>.)
+
+=item 6.
+
+C<$Carp::CarpLevel> can be set to skip a fixed number of additional
+call levels. Using this is not recommended because it is very
+difficult to get it to behave correctly.
+
+=back
+
+=head2 Forcing a Stack Trace
+
+As a debugging aid, you can force Carp to treat a croak as a confess
+and a carp as a cluck across I<all> modules. In other words, force a
+detailed stack trace to be given. This can be very helpful when trying
+to understand why, or from where, a warning or error is being generated.
+
+This feature is enabled by 'importing' the non-existent symbol
+'verbose'. You would typically enable it by saying
+
+ perl -MCarp=verbose script.pl
+
+or by including the string C<-MCarp=verbose> in the PERL5OPT
+environment variable.
+
+Alternately, you can set the global variable C<$Carp::Verbose> to true.
+See the C<GLOBAL VARIABLES> section below.
+
+=head1 GLOBAL VARIABLES
+
+=head2 $Carp::MaxEvalLen
+
+This variable determines how many characters of a string-eval are to
+be shown in the output. Use a value of C<0> to show all text.
+
+Defaults to C<0>.
+
+=head2 $Carp::MaxArgLen
+
+This variable determines how many characters of each argument to a
+function to print. Use a value of C<0> to show the full length of the
+argument.
+
+Defaults to C<64>.
+
+=head2 $Carp::MaxArgNums
+
+This variable determines how many arguments to each function to show.
+Use a value of C<0> to show all arguments to a function call.
+
+Defaults to C<8>.
+
+=head2 $Carp::Verbose
+
+This variable makes C<carp> and C<croak> generate stack backtraces
+just like C<cluck> and C<confess>. This is how C<use Carp 'verbose'>
+is implemented internally.
+
+Defaults to C<0>.
+
+=head2 @CARP_NOT
+
+This variable, I<in your package>, says which packages are I<not> to be
+considered as the location of an error. The C<carp()> and C<cluck()>
+functions will skip over callers when reporting where an error occurred.
+
+NB: This variable must be in the package's symbol table, thus:
+
+ # These work
+ our @CARP_NOT; # file scope
+ use vars qw(@CARP_NOT); # package scope
+ @My::Package::CARP_NOT = ... ; # explicit package variable
+
+ # These don't work
+ sub xyz { ... @CARP_NOT = ... } # w/o declarations above
+ my @CARP_NOT; # even at top-level
+
+Example of use:
+
+ package My::Carping::Package;
+ use Carp;
+ our @CARP_NOT;
+ sub bar { .... or _error('Wrong input') }
+ sub _error {
+ # temporary control of where'ness, __PACKAGE__ is implicit
+ local @CARP_NOT = qw(My::Friendly::Caller);
+ carp(@_)
+ }
+
+This would make C<Carp> report the error as coming from a caller not
+in C<My::Carping::Package>, nor from C<My::Friendly::Caller>.
+
+Also read the L</DESCRIPTION> section above, about how C<Carp> decides
+where the error is reported from.
+
+Use C<@CARP_NOT>, instead of C<$Carp::CarpLevel>.
+
+Overrides C<Carp>'s use of C<@ISA>.
+
+=head2 %Carp::Internal
+
+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
+
+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.
-1;
https://perl5.git.perl.org / perl5.git / blobdiff