diff -r 000000000000 -r 6474c204b198 tools/rb/fix-linux-stack.pl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/rb/fix-linux-stack.pl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,259 @@
+#!/usr/bin/perl
+# vim:sw=4:ts=4:et:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# $Id: fix-linux-stack.pl,v 1.16 2008/05/05 21:51:11 dbaron%dbaron.org Exp $
+#
+# This script uses addr2line (part of binutils) to process the output of
+# nsTraceRefcnt's Linux stack walking code.  This is useful for two
+# things:
+#  (1) Getting line number information out of
+#      |nsTraceRefcnt::WalkTheStack|'s output in debug builds.
+#  (2) Getting function names out of |nsTraceRefcnt::WalkTheStack|'s
+#      output on optimized builds (where it mostly prints UNKNOWN
+#      because only a handful of symbols are exported from component
+#      libraries).
+#
+# Use the script by piping output containing stacks (such as raw stacks
+# or make-tree.pl balance trees) through this script.
+
+use strict;
+use IPC::Open2;
+use File::Basename;
+
+# XXX Hard-coded to gdb defaults (works on Fedora).
+my $global_debug_dir = '/usr/lib/debug';
+
+# We record several things for each file encountered.
+#
+# - {pipe_read}, {pipe_write}: these constitute a bidirectional pipe to an
+#   addr2line process that gives symbol information for a file.
+#
+# - {cache}: this table holds the results of lookups that we've done
+#   previously for (pre-adjustment) addresses, which lets us avoid redundant
+#   calls to addr2line.
+#
+# - {address_adjustment}: addr2line wants offsets relative to the base address
+#   for shared libraries, but it wants addresses including the base address
+#   offset for executables.  This holds the appropriate address adjustment to
+#   add to an offset within file.  See bug 230336.
+#
+my %file_infos;
+
+sub set_address_adjustment($$) {
+    my ($file, $file_info) = @_;
+
+    # find out if it's an executable (as opposed to a shared library)
+    my $elftype;
+    open(ELFHDR, '-|', 'readelf', '-h', $file);
+    while (<ELFHDR>) {
+        if (/^\s*Type:\s+(\S+)/) {
+            $elftype = $1;
+            last;
+        }
+    }
+    close(ELFHDR);
+
+    # If it's an executable, make adjustment the base address.
+    # Otherwise, leave it zero.
+    my $adjustment = 0;
+    if ($elftype eq 'EXEC') {
+        open(ELFSECS, '-|', 'readelf', '-S', $file);
+        while (<ELFSECS>) {
+            if (/^\s*\[\s*\d+\]\s+\.text\s+\w+\s+(\w+)\s+(\w+)\s+/) {
+                # Subtract the .text section's offset within the
+                # file from its base address.
+                $adjustment = hex($1) - hex($2);
+                last;
+            }
+        }
+        close(ELFSECS);
+    }
+
+    $file_info->{address_adjustment} = $adjustment;
+}
+
+# Files sometimes contain a link to a separate object file that contains
+# the debug sections of the binary, removed so that a smaller file can
+# be shipped, but kept separately so that it can be obtained by those
+# who want it.
+# See http://sources.redhat.com/gdb/current/onlinedocs/gdb_16.html#SEC154
+# for documentation of debugging information in separate files.
+# On Fedora distributions, these files can be obtained by installing
+# *-debuginfo RPM packages.
+sub separate_debug_file_for($) {
+    my ($file) = @_;
+    # We can read the .gnu_debuglink section using either of:
+    #   objdump -s --section=.gnu_debuglink $file
+    #   readelf -x .gnu_debuglink $file
+    # Since readelf prints things backwards on little-endian platforms
+    # for some versions only (backwards on Fedora Core 6, forwards on
+    # Fedora 7), use objdump.
+
+    # See if there's a .gnu_debuglink section
+    my $have_debuglink = 0;
+    open(ELFSECS, '-|', 'readelf', '-S', $file);
+    while (<ELFSECS>) {
+        if (/^\s*\[\s*\d+\]\s+\.gnu_debuglink\s+\w+\s+(\w+)\s+(\w+)\s+/) {
+            $have_debuglink = 1;
+            last;
+        }
+    }
+    close(ELFSECS);
+    return '' unless ($have_debuglink);
+
+    # Determine the endianness of the shared library.
+    my $endian = '';
+    open(ELFHDR, '-|', 'readelf', '-h', $file);
+    while (<ELFHDR>) {
+        if (/^\s*Data:\s+.*(little|big) endian.*$/) {
+            $endian = $1;
+            last;
+        }
+    }
+    close(ELFHDR);
+    if ($endian ne 'little' && $endian ne 'big') {
+        print STDERR "Warning: could not determine endianness of $file.\n";
+        return '';
+    }
+
+
+    # Read the debuglink section as an array of words, in hexidecimal.
+    open(DEBUGLINK, '-|', 'objdump', '-s', '--section=.gnu_debuglink', $file);
+    my @words;
+    while (<DEBUGLINK>) {
+        if ($_ =~ /^ [0-9a-f]* ([0-9a-f ]{8}) ([0-9a-f ]{8}) ([0-9a-f ]{8}) ([0-9a-f ]{8}).*/) {
+            push @words, $1, $2, $3, $4;
+        }
+    }
+    close(DEBUGLINK);
+
+    while (@words[$#words] eq '        ') {
+        pop @words;
+    }
+
+    if ($#words < 1) {
+        print STDERR "Warning: .gnu_debuglink section in $file too short.\n";
+        return '';
+    }
+
+    my @chars;
+    while ($#words >= 0) {
+        my $w = shift @words;
+        if ($w =~ /^([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})$/) {
+            push @chars, $1, $2, $3, $4;
+        } else {
+            print STDERR "Warning: malformed objdump output for $file.\n";
+            return '';
+        }
+    }
+
+    my @hash_bytes = map(hex, @chars[$#chars - 3 .. $#chars]);
+    $#chars -= 4;
+
+    my $hash;
+    if ($endian eq 'little') {
+        $hash = ($hash_bytes[3] << 24) | ($hash_bytes[2] << 16) | ($hash_bytes[1] << 8) | $hash_bytes[0];
+    } else {
+        $hash = ($hash_bytes[0] << 24) | ($hash_bytes[1] << 16) | ($hash_bytes[2] << 8) | $hash_bytes[3];
+    }
+
+    # The string ends with a null-terminator and then 0 to three bytes
+    # of padding to fill the current 32-bit unit.  (This padding is
+    # usually null bytes, but I've seen null-null-H, on Ubuntu x86_64.)
+    my $terminator = 1;
+    while ($chars[$terminator] ne '00') {
+        if ($terminator == $#chars) {
+            print STDERR "Warning: missing null terminator in " .
+                         ".gnu_debuglink section of $file.\n";
+            return '';
+        }
+        ++$terminator;
+    }
+    if ($#chars - $terminator > 3) {
+        print STDERR "Warning: Excess padding in .gnu_debuglink section " .
+                     "of $file.\n";
+        return '';
+    }
+    $#chars = $terminator - 1;
+
+    my $basename = join('', map { chr(hex($_)) } @chars);
+
+    # Now $basename and $hash represent the information in the
+    # .gnu_debuglink section.
+    #printf STDERR "%x: %s\n", $hash, $basename;
+
+    my @possible_results = (
+        dirname($file) . $basename,
+        dirname($file) . '.debug/' . $basename,
+        $global_debug_dir . dirname($file) . '/' . $basename
+    );
+    foreach my $result (@possible_results) {
+        if (-f $result) {
+            # XXX We should check the hash.
+            return $result;
+        }
+    }
+
+    return '';
+}
+
+sub get_file_info($) {
+    my ($file) = @_;
+    my $file_info = $file_infos{$file};
+    unless (defined $file_info) {
+        my $debug_file = separate_debug_file_for($file);
+        $debug_file = $file if ($debug_file eq '');
+
+        my $pid = open2($file_info->{pipe_read}, $file_info->{pipe_write},
+                        '/usr/bin/addr2line', '-C', '-f', '-e', $debug_file);
+
+        set_address_adjustment($file, $file_info);
+
+        $file_infos{$file} = $file_info;
+    }
+    return $file_info;
+}
+
+# Ignore SIGPIPE as a workaround for addr2line crashes in some situations.
+$SIG{PIPE} = 'IGNORE';
+
+select STDOUT; $| = 1; # make STDOUT unbuffered
+while (<>) {
+    my $line = $_;
+    if ($line =~ /^([ \|0-9-]*)(.*) ?\[([^ ]*) \+(0x[0-9A-F]{1,8})\](.*)$/) {
+        my $before = $1; # allow preservation of balance trees
+        my $badsymbol = $2;
+        my $file = $3;
+        my $address = hex($4);
+        my $after = $5; # allow preservation of counts
+
+        if (-f $file) {
+            my $file_info = get_file_info($file);
+            my $result = $file_info->{cache}->{$address};
+            if (not defined $result) {
+                my $address2 = $address + $file_info->{address_adjustment};
+                my $out = $file_info->{pipe_write};
+                my $in = $file_info->{pipe_read};
+                printf {$out} "0x%X\n", $address2;
+                chomp(my $symbol = <$in>);
+                chomp(my $fileandline = <$in>);
+                if (!$symbol || $symbol eq '??') { $symbol = $badsymbol; }
+                if (!$fileandline || $fileandline eq '??:0') {
+                    $fileandline = $file;
+                }
+                $result = "$symbol ($fileandline)";
+                $file_info->{cache}->{$address} = $result;
+            }
+            print "$before$result$after\n";
+        } else {
+            print STDERR "Warning: File \"$file\" does not exist.\n";
+            print $line;
+        }
+
+    } else {
+        print $line;
+    }
+}