# -*- cperl -*-
# Copyright (C) 2008 MySQL AB, 2009 Sun Microsystems, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

package My::CoreDump;

use strict;
use Carp;
use My::Platform;

use File::Temp qw/ tempfile tempdir /;

my $hint_mysqld;		# Last resort guess for executable path

# If path in core file is 79 chars we assume it's been truncated
# Looks like we can still find the full path using 'strings'
# If that doesn't work, use the hint (mysqld path) as last resort.

sub _verify_binpath {
  my ($binary, $core_name)= @_;
  my $binpath;

  if (length $binary != 79) {
    $binpath= $binary;
    print "Core generated by '$binpath'\n";
  } else {
    # Last occurrence of path ending in /mysql*, cut from first /
    if (`strings '$core_name' | grep "/mysql[^/. ]*\$" | tail -1` =~ /(\/.*)/) {
      $binpath= $1;
      print "Guessing that core was generated by '$binpath'\n";
    } else {
      return unless $hint_mysqld;
      $binpath= $hint_mysqld;
      print "Wild guess that core was generated by '$binpath'\n";
    }
  }
  return $binpath;
}

sub _gdb {
  my ($core_name)= @_;

  print "\nTrying 'gdb' to get a backtrace\n";

  return unless -f $core_name;

  # Find out name of binary that generated core
  `gdb -c '$core_name' --batch 2>&1` =~
    /Core was generated by `([^\s\'\`]+)/;
  my $binary= $1 or return;

  $binary= _verify_binpath ($binary, $core_name) or return;

  # Create tempfile containing gdb commands
  my ($tmp, $tmp_name) = tempfile();
  print $tmp
    "bt\n",
    "thread apply all bt\n",
    "quit\n";
  close $tmp or die "Error closing $tmp_name: $!";

  # Run gdb
  my $gdb_output=
    `gdb '$binary' -c '$core_name' -x '$tmp_name' --batch 2>&1`;

  unlink $tmp_name or die "Error removing $tmp_name: $!";

  return if $? >> 8;
  return unless $gdb_output;

  print <<EOF, $gdb_output, "\n";
Output from gdb follows. The first stack trace is from the failing thread.
The following stack traces are from all threads (so the failing one is
duplicated).
--------------------------
EOF
  return 1;
}


sub _dbx {
  my ($core_name)= @_;

  print "\nTrying 'dbx' to get a backtrace\n";

  return unless -f $core_name;

  # Find out name of binary that generated core
  `echo | dbx - '$core_name' 2>&1` =~
    /Corefile specified executable: "([^"]+)"/;
  my $binary= $1 or return;

  $binary= _verify_binpath ($binary, $core_name) or return;

  # Find all threads
  my @thr_ids = `echo threads | dbx '$binary' '$core_name' 2>&1` =~ /t@\d+/g;

  # Create tempfile containing dbx commands
  my ($tmp, $tmp_name) = tempfile();
  foreach my $thread (@thr_ids) {
    print $tmp "where $thread\n";
  }
  print $tmp "exit\n";
  close $tmp or die "Error closing $tmp_name: $!";

  # Run dbx
  my $dbx_output=
    `cat '$tmp_name' | dbx '$binary' '$core_name' 2>&1`;

  unlink $tmp_name or die "Error removing $tmp_name: $!";

  return if $? >> 8;
  return unless $dbx_output;

  print <<EOF, $dbx_output, "\n";
Output from dbx follows. Stack trace is printed for all threads in order,
above this you should see info about which thread was the failing one.
----------------------------
EOF
  return 1;
}


# Check that Debugging tools for Windows are installed
sub cdb_check {
   `cdb -? 2>&1`;
  if ($? >> 8)
  {
    print "Cannot find cdb. Please Install Debugging tools for Windows\n";
    print "from http://www.microsoft.com/whdc/devtools/debugging/";
    if($ENV{'ProgramW6432'})
    {
      print "install64bit.mspx (native x64 version)\n";
    }
    else
   {
      print "installx86.mspx\n";
   }
  }
}


sub _cdb {
  my ($core_name)= @_;
  print "\nTrying 'cdb' to get a backtrace\n";
  return unless -f $core_name;
  
  # Try to set environment for debugging tools for Windows
  if ($ENV{'PATH'} !~ /Debugging Tools/)
  {
    if ($ENV{'ProgramW6432'})
    {
      # On x64 computer
      $ENV{'PATH'}.= ";".$ENV{'ProgramW6432'}."\\Debugging Tools For Windows (x64)";
    }
    else
    {
     # On x86 computer. Newest versions of Debugging tools are installed in the  
     # directory with (x86) suffix, older versions did not have this suffix.
     $ENV{'PATH'}.= ";".$ENV{'ProgramFiles'}."\\Debugging Tools For Windows (x86)";
     $ENV{'PATH'}.= ";".$ENV{'ProgramFiles'}."\\Debugging Tools For Windows";
    }
  }
  
  
  # Read module list, find out the name of executable and 
  # build symbol path (required by cdb if executable was built on 
  # different machine)
  my $tmp_name= $core_name.".cdb_lmv";
  `cdb -z $core_name -c \"lmv;q\" > $tmp_name 2>&1`;
  if ($? >> 8)
  {
    unlink($tmp_name);
    # check if cdb is installed and complain if not
    cdb_check();
    return;
  }
  
  open(temp,"< $tmp_name");
  my %dirhash=();
  while(<temp>)
  {
    if($_ =~ /Image path\: (.*)/)
    {
      if (rindex($1,'\\') != -1)
      {
        my $dir= substr($1, 0, rindex($1,'\\'));
        $dirhash{$dir}++;
      }
    }
  }
  close(temp);
  unlink($tmp_name);
  
  my $image_path= join(";", (keys %dirhash),".");

  # For better callstacks, setup _NT_SYMBOL_PATH to include
  # OS symbols. Note : Dowloading symbols for the first time 
  # can take some minutes
  if (!$ENV{'_NT_SYMBOL_PATH'})
  {
    my $windir= $ENV{'windir'};
    my $symbol_cache= substr($windir ,0, index($windir,'\\'))."\\cdb_symbols";

    print "OS debug symbols will be downloaded and stored in $symbol_cache.\n";
    print "You can control the location of symbol cache with _NT_SYMBOL_PATH\n";
    print "environment variable. Please refer to Microsoft KB article\n";
    print "http://support.microsoft.com/kb/311503  for details about _NT_SYMBOL_PATH\n";
    print "-------------------------------------------------------------------------\n";

    $ENV{'_NT_SYMBOL_PATH'}.= 
      "srv*".$symbol_cache."*http://msdl.microsoft.com/download/symbols";
  }
  
  my $symbol_path= $image_path.";".$ENV{'_NT_SYMBOL_PATH'};
  
  
  # Run cdb. Use "analyze" extension to print crashing thread stacktrace
  # and "uniqstack" to print other threads

  my $cdb_cmd = "!sym prompts off; !analyze -v; .ecxr; !for_each_frame dv /t;!uniqstack -p;q";
  my $cdb_output=
    `cdb -c "$cdb_cmd" -z $core_name -i "$image_path" -y "$symbol_path" -t 0 -lines 2>&1`;
  return if $? >> 8;
  return unless $cdb_output;
  
  # Remove comments (lines starting with *), stack pointer and frame 
  # pointer adresses and offsets to function to make output better readable
  $cdb_output=~ s/^\*.*\n//gm;   
  $cdb_output=~ s/^([\:0-9a-fA-F\`]+ )+//gm; 
  $cdb_output=~ s/^ChildEBP RetAddr//gm;
  $cdb_output=~ s/^Child\-SP          RetAddr           Call Site//gm;
  $cdb_output=~ s/\+0x([0-9a-fA-F]+)//gm;
  
  print <<EOF, $cdb_output, "\n";
Output from cdb follows. Faulting thread is printed twice,with and without function parameters
Search for STACK_TEXT to see the stack trace of 
the faulting thread. Callstacks of other threads are printed after it.
EOF
  return 1;
}


sub show {
  my ($class, $core_name, $exe_mysqld)= @_;
  $hint_mysqld= $exe_mysqld;

  # On Windows, rely on cdb to be there...
  if (IS_WINDOWS)
  {
    _cdb($core_name);
    return;
  }
  
  # We try dbx first; gdb itself may coredump if run on a Sun Studio
  # compiled binary on Solaris.

  my @debuggers =
    (
     \&_dbx,
     \&_gdb,
     # TODO...
   );

  # Try debuggers until one succeeds

  foreach my $debugger (@debuggers){
    if ($debugger->($core_name)){
      return;
    }
  }
  return;
}


1;