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package Carp;
# This package is heavily used. Be small. Be fast. Be good.
# Comments added by Andy Wardley <abw@kfs.org> 09-Apr-98, based on an
# _almost_ complete understanding of the package. Corrections and
# comments are welcome.
# longmess() crawls all the way up the stack reporting on all the function
# calls made. The error string, $error, is originally constructed from the
# arguments passed into longmess() via confess(), cluck() or shortmess().
# This gets appended with the stack trace messages which are generated for
# each function call on the stack.
sub longmess_heavy {
return @_ if ref $_[0];
my $error = join '', @_;
my $mess = "";
my $i = 1 + $CarpLevel;
my ($pack,$file,$line,$sub,$hargs,$eval,$require);
my (@a);
#
# crawl up the stack....
#
while (do { { package DB; @a = caller($i++) } } ) {
# get copies of the variables returned from caller()
($pack,$file,$line,$sub,$hargs,undef,$eval,$require) = @a;
#
# if the $error error string is newline terminated then it
# is copied into $mess. Otherwise, $mess gets set (at the end of
# the 'else {' section below) to one of two things. The first time
# through, it is set to the "$error at $file line $line" message.
# $error is then set to 'called' which triggers subsequent loop
# iterations to append $sub to $mess before appending the "$error
# at $file line $line" which now actually reads "called at $file line
# $line". Thus, the stack trace message is constructed:
#
# first time: $mess = $error at $file line $line
# subsequent times: $mess .= $sub $error at $file line $line
# ^^^^^^
# "called"
if ($error =~ m/\n$/) {
$mess .= $error;
} else {
# Build a string, $sub, which names the sub-routine called.
# This may also be "require ...", "eval '...' or "eval {...}"
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 there are any arguments in the sub-routine call, format
# them according to the format variables defined earlier in
# this file and join them onto the $sub sub-routine string
if ($hargs) {
# we may trash some of the args so we take a copy
@a = @DB::args; # must get local copy of args
# don't print any more than $MaxArgNums
if ($MaxArgNums and @a > $MaxArgNums) {
# cap the length of $#a and set the last element to '...'
$#a = $MaxArgNums;
$a[$#a] = "...";
}
for (@a) {
# set args to the string "undef" if undefined
$_ = "undef", next unless defined $_;
if (ref $_) {
# dunno what this is for...
$_ .= '';
s/'/\\'/g;
}
else {
s/'/\\'/g;
# terminate the string early with '...' if too long
substr($_,$MaxArgLen) = '...'
if $MaxArgLen and $MaxArgLen < length;
}
# 'quote' arg unless it looks like a number
$_ = "'$_'" unless /^-?[\d.]+$/;
# print high-end chars as 'M-<char>'
s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
# print remaining control chars as ^<char>
s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
}
# append ('all', 'the', 'arguments') to the $sub string
$sub .= '(' . join(', ', @a) . ')';
}
# here's where the error message, $mess, gets constructed
$mess .= "\t$sub " if $error eq "called";
$mess .= "$error at $file line $line";
if (defined &Thread::tid) {
my $tid = Thread->self->tid;
$mess .= " thread $tid" if $tid;
}
$mess .= "\n";
}
# we don't need to print the actual error message again so we can
# change this to "called" so that the string "$error at $file line
# $line" makes sense as "called at $file line $line".
$error = "called";
}
# this kludge circumvents die's incorrect handling of NUL
my $msg = \($mess || $error);
$$msg =~ tr/\0//d;
$$msg;
}
# shortmess() is called by carp() and croak() to skip all the way up to
# the top-level caller's package and report the error from there. confess()
# and cluck() generate a full stack trace so they call longmess() to
# generate that. In verbose mode shortmess() calls longmess() so
# you always get a stack trace
sub shortmess_heavy { # Short-circuit &longmess if called via multiple packages
goto &longmess_heavy if $Verbose;
return @_ if ref $_[0];
my $error = join '', @_;
my ($prevpack) = caller(1);
my $extra = $CarpLevel;
my $i = 2;
my ($pack,$file,$line);
# when reporting an error, we want to report it from the context of the
# calling package. So what is the calling package? Within a module,
# there may be many calls between methods and perhaps between sub-classes
# and super-classes, but the user isn't interested in what happens
# inside the package. We start by building a hash array which keeps
# track of all the packages to which the calling package belongs. We
# do this by examining its @ISA variable. Any call from a base class
# method (one of our caller's @ISA packages) can be ignored
my %isa = ($prevpack,1);
# merge all the caller's @ISA packages into %isa.
@isa{@{"${prevpack}::ISA"}} = ()
if(@{"${prevpack}::ISA"});
# now we crawl up the calling stack and look at all the packages in
# there. For each package, we look to see if it has an @ISA and then
# we see if our caller features in that list. That would imply that
# our caller is a derived class of that package and its calls can also
# be ignored
while (($pack,$file,$line) = caller($i++)) {
if(@{$pack . "::ISA"}) {
my @i = @{$pack . "::ISA"};
my %i;
@i{@i} = ();
# merge any relevant packages into %isa
@isa{@i,$pack} = ()
if(exists $i{$prevpack} || exists $isa{$pack});
}
# and here's where we do the ignoring... if the package in
# question is one of our caller's base or derived packages then
# we can ignore it (skip it) and go onto the next (but note that
# the continue { } block below gets called every time)
next
if(exists $isa{$pack});
# Hey! We've found a package that isn't one of our caller's
# clan....but wait, $extra refers to the number of 'extra' levels
# we should skip up. If $extra > 0 then this is a false alarm.
# We must merge the package into the %isa hash (so we can ignore it
# if it pops up again), decrement $extra, and continue.
if ($extra-- > 0) {
%isa = ($pack,1);
@isa{@{$pack . "::ISA"}} = ()
if(@{$pack . "::ISA"});
}
else {
# OK! We've got a candidate package. Time to construct the
# relevant error message and return it. die() doesn't like
# to be given NUL characters (which $msg may contain) so we
# remove them first.
my $msg;
$msg = "$error at $file line $line";
if (defined &Thread::tid) {
my $tid = Thread->self->tid;
$mess .= " thread $tid" if $tid;
}
$msg .= "\n";
$msg =~ tr/\0//d;
return $msg;
}
}
continue {
$prevpack = $pack;
}
# uh-oh! It looks like we crawled all the way up the stack and
# never found a candidate package. Oh well, let's call longmess
# to generate a full stack trace. We use the magical form of 'goto'
# so that this shortmess() function doesn't appear on the stack
# to further confuse longmess() about it's calling package.
goto &longmess_heavy;
}
1;
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