1 | package sigtrap;
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2 |
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3 | =head1 NAME
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4 |
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5 | sigtrap - Perl pragma to enable simple signal handling
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6 |
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7 | =cut
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8 |
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9 | use Carp;
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10 |
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11 | $VERSION = 1.02;
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12 | $Verbose ||= 0;
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13 |
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14 | sub import {
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15 | my $pkg = shift;
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16 | my $handler = \&handler_traceback;
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17 | my $saw_sig = 0;
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18 | my $untrapped = 0;
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19 | local $_;
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20 |
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21 | Arg_loop:
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22 | while (@_) {
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23 | $_ = shift;
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24 | if (/^[A-Z][A-Z0-9]*$/) {
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25 | $saw_sig++;
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26 | unless ($untrapped and $SIG{$_} and $SIG{$_} ne 'DEFAULT') {
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27 | print "Installing handler $handler for $_\n" if $Verbose;
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28 | $SIG{$_} = $handler;
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29 | }
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30 | }
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31 | elsif ($_ eq 'normal-signals') {
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32 | unshift @_, grep(exists $SIG{$_}, qw(HUP INT PIPE TERM));
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33 | }
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34 | elsif ($_ eq 'error-signals') {
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35 | unshift @_, grep(exists $SIG{$_},
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36 | qw(ABRT BUS EMT FPE ILL QUIT SEGV SYS TRAP));
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37 | }
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38 | elsif ($_ eq 'old-interface-signals') {
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39 | unshift @_,
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40 | grep(exists $SIG{$_},
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41 | qw(ABRT BUS EMT FPE ILL PIPE QUIT SEGV SYS TERM TRAP));
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42 | }
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43 | elsif ($_ eq 'stack-trace') {
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44 | $handler = \&handler_traceback;
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45 | }
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46 | elsif ($_ eq 'die') {
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47 | $handler = \&handler_die;
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48 | }
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49 | elsif ($_ eq 'handler') {
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50 | @_ or croak "No argument specified after 'handler'";
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51 | $handler = shift;
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52 | unless (ref $handler or $handler eq 'IGNORE'
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53 | or $handler eq 'DEFAULT') {
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54 | require Symbol;
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55 | $handler = Symbol::qualify($handler, (caller)[0]);
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56 | }
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57 | }
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58 | elsif ($_ eq 'untrapped') {
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59 | $untrapped = 1;
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60 | }
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61 | elsif ($_ eq 'any') {
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62 | $untrapped = 0;
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63 | }
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64 | elsif ($_ =~ /^\d/) {
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65 | $VERSION >= $_ or croak "sigtrap.pm version $_ required,"
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66 | . " but this is only version $VERSION";
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67 | }
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68 | else {
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69 | croak "Unrecognized argument $_";
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70 | }
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71 | }
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72 | unless ($saw_sig) {
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73 | @_ = qw(old-interface-signals);
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74 | goto Arg_loop;
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75 | }
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76 | }
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77 |
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78 | sub handler_die {
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79 | croak "Caught a SIG$_[0]";
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80 | }
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81 |
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82 | sub handler_traceback {
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83 | package DB; # To get subroutine args.
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84 | $SIG{'ABRT'} = DEFAULT;
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85 | kill 'ABRT', $$ if $panic++;
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86 | syswrite(STDERR, 'Caught a SIG', 12);
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87 | syswrite(STDERR, $_[0], length($_[0]));
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88 | syswrite(STDERR, ' at ', 4);
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89 | ($pack,$file,$line) = caller;
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90 | syswrite(STDERR, $file, length($file));
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91 | syswrite(STDERR, ' line ', 6);
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92 | syswrite(STDERR, $line, length($line));
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93 | syswrite(STDERR, "\n", 1);
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94 |
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95 | # Now go for broke.
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96 | for ($i = 1; ($p,$f,$l,$s,$h,$w,$e,$r) = caller($i); $i++) {
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97 | @a = ();
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98 | for $arg (@args) {
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99 | $_ = "$arg";
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100 | s/([\'\\])/\\$1/g;
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101 | s/([^\0]*)/'$1'/
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102 | unless /^(?: -?[\d.]+ | \*[\w:]* )$/x;
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103 | s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
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104 | s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
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105 | push(@a, $_);
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106 | }
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107 | $w = $w ? '@ = ' : '$ = ';
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108 | $a = $h ? '(' . join(', ', @a) . ')' : '';
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109 | $e =~ s/\n\s*\;\s*\Z// if $e;
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110 | $e =~ s/[\\\']/\\$1/g if $e;
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111 | if ($r) {
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112 | $s = "require '$e'";
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113 | } elsif (defined $r) {
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114 | $s = "eval '$e'";
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115 | } elsif ($s eq '(eval)') {
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116 | $s = "eval {...}";
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117 | }
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118 | $f = "file `$f'" unless $f eq '-e';
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119 | $mess = "$w$s$a called from $f line $l\n";
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120 | syswrite(STDERR, $mess, length($mess));
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121 | }
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122 | kill 'ABRT', $$;
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123 | }
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124 |
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125 | 1;
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126 |
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127 | __END__
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128 |
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129 | =head1 SYNOPSIS
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130 |
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131 | use sigtrap;
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132 | use sigtrap qw(stack-trace old-interface-signals); # equivalent
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133 | use sigtrap qw(BUS SEGV PIPE ABRT);
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134 | use sigtrap qw(die INT QUIT);
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135 | use sigtrap qw(die normal-signals);
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136 | use sigtrap qw(die untrapped normal-signals);
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137 | use sigtrap qw(die untrapped normal-signals
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138 | stack-trace any error-signals);
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139 | use sigtrap 'handler' => \&my_handler, 'normal-signals';
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140 | use sigtrap qw(handler my_handler normal-signals
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141 | stack-trace error-signals);
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142 |
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143 | =head1 DESCRIPTION
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144 |
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145 | The B<sigtrap> pragma is a simple interface to installing signal
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146 | handlers. You can have it install one of two handlers supplied by
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147 | B<sigtrap> itself (one which provides a Perl stack trace and one which
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148 | simply C<die()>s), or alternately you can supply your own handler for it
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149 | to install. It can be told only to install a handler for signals which
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150 | are either untrapped or ignored. It has a couple of lists of signals to
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151 | trap, plus you can supply your own list of signals.
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152 |
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153 | The arguments passed to the C<use> statement which invokes B<sigtrap>
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154 | are processed in order. When a signal name or the name of one of
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155 | B<sigtrap>'s signal lists is encountered a handler is immediately
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156 | installed, when an option is encountered it affects subsequently
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157 | installed handlers.
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158 |
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159 | =head1 OPTIONS
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160 |
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161 | =head2 SIGNAL HANDLERS
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162 |
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163 | These options affect which handler will be used for subsequently
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164 | installed signals.
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165 |
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166 | =over 4
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167 |
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168 | =item B<stack-trace>
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169 |
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170 | The handler used for subsequently installed signals outputs a Perl stack
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171 | trace to STDERR and then tries to dump core. This is the default signal
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172 | handler.
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173 |
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174 | =item B<die>
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175 |
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176 | The handler used for subsequently installed signals calls C<die>
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177 | (actually C<croak>) with a message indicating which signal was caught.
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178 |
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179 | =item B<handler> I<your-handler>
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180 |
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181 | I<your-handler> will be used as the handler for subsequently installed
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182 | signals. I<your-handler> can be any value which is valid as an
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183 | assignment to an element of C<%SIG>.
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184 |
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185 | =back
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186 |
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187 | =head2 SIGNAL LISTS
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188 |
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189 | B<sigtrap> has a few built-in lists of signals to trap. They are:
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190 |
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191 | =over 4
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192 |
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193 | =item B<normal-signals>
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194 |
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195 | These are the signals which a program might normally expect to encounter
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196 | and which by default cause it to terminate. They are HUP, INT, PIPE and
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197 | TERM.
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198 |
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199 | =item B<error-signals>
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200 |
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201 | These signals usually indicate a serious problem with the Perl
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202 | interpreter or with your script. They are ABRT, BUS, EMT, FPE, ILL,
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203 | QUIT, SEGV, SYS and TRAP.
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204 |
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205 | =item B<old-interface-signals>
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206 |
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207 | These are the signals which were trapped by default by the old
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208 | B<sigtrap> interface, they are ABRT, BUS, EMT, FPE, ILL, PIPE, QUIT,
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209 | SEGV, SYS, TERM, and TRAP. If no signals or signals lists are passed to
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210 | B<sigtrap>, this list is used.
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211 |
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212 | =back
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213 |
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214 | For each of these three lists, the collection of signals set to be
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215 | trapped is checked before trapping; if your architecture does not
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216 | implement a particular signal, it will not be trapped but rather
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217 | silently ignored.
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218 |
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219 | =head2 OTHER
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220 |
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221 | =over 4
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222 |
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223 | =item B<untrapped>
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224 |
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225 | This token tells B<sigtrap> to install handlers only for subsequently
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226 | listed signals which aren't already trapped or ignored.
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227 |
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228 | =item B<any>
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229 |
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230 | This token tells B<sigtrap> to install handlers for all subsequently
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231 | listed signals. This is the default behavior.
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232 |
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233 | =item I<signal>
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234 |
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235 | Any argument which looks like a signal name (that is,
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236 | C</^[A-Z][A-Z0-9]*$/>) indicates that B<sigtrap> should install a
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237 | handler for that name.
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238 |
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239 | =item I<number>
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240 |
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241 | Require that at least version I<number> of B<sigtrap> is being used.
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242 |
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243 | =back
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244 |
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245 | =head1 EXAMPLES
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246 |
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247 | Provide a stack trace for the old-interface-signals:
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248 |
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249 | use sigtrap;
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250 |
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251 | Ditto:
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252 |
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253 | use sigtrap qw(stack-trace old-interface-signals);
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254 |
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255 | Provide a stack trace on the 4 listed signals only:
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256 |
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257 | use sigtrap qw(BUS SEGV PIPE ABRT);
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258 |
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259 | Die on INT or QUIT:
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260 |
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261 | use sigtrap qw(die INT QUIT);
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262 |
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263 | Die on HUP, INT, PIPE or TERM:
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264 |
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265 | use sigtrap qw(die normal-signals);
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266 |
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267 | Die on HUP, INT, PIPE or TERM, except don't change the behavior for
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268 | signals which are already trapped or ignored:
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269 |
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270 | use sigtrap qw(die untrapped normal-signals);
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271 |
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272 | Die on receipt one of an of the B<normal-signals> which is currently
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273 | B<untrapped>, provide a stack trace on receipt of B<any> of the
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274 | B<error-signals>:
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275 |
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276 | use sigtrap qw(die untrapped normal-signals
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277 | stack-trace any error-signals);
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278 |
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279 | Install my_handler() as the handler for the B<normal-signals>:
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280 |
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281 | use sigtrap 'handler', \&my_handler, 'normal-signals';
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282 |
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283 | Install my_handler() as the handler for the normal-signals, provide a
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284 | Perl stack trace on receipt of one of the error-signals:
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285 |
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286 | use sigtrap qw(handler my_handler normal-signals
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287 | stack-trace error-signals);
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288 |
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289 | =cut
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