linux 内存检测方法之-------mtrace

mtrace是glibc自带的内存检测工具。使用步骤如下:
1.在要检测内存泄露代码的开始处调用mtrace() (在mcheck.h中声明)
2.在内存泄露代码的结束处调用muntrace() 
3.设置环境变量MALLOC_TRACE,内存信息将保存在这个变量所指的路径中
4.编译时必须带上-g.
5.用perl脚本mtrace来解析MALLOC_TRACE指向的文件。

For example, 以下是一段申请内存后没有释放内存的C代码 (mtrace.c):
点击(此处)折叠或打开

#include <stdlib.h>
 int main(void) {
      int *a;
      a = malloc(sizeof(int));
      return 0;
}

采用mtrace检测后的代码如下：

#include <stdlib.h>
#include <mcheck.h>
int main(void) {
    mtrace();
    int *a;
    a = malloc(sizeof(int));
    muntrace();
    return 0;
}

一、设置环境变量：

export MALLOC_TRACE=malloc_trace.log 
二、编译代码: gcc -g mtrace.c -o mtrace.out-------------注意编译时必须带上-g选项
三、运行可执行文件
      ./mtrace.out
四、使用perl脚本mtrace将机器指令装换成易读的输出
      ./mtrace mtrace.out malloc_trace.log

linux:~/test/mtrace>./mtrace mtrace.out malloc_trace.log
Memory not freed:
-----------------
   Address     Size     Caller
0x012fe460      0x4  at /home/gwwu/test/mtrace/mtrace.c:6

从中可以明显看出mtrace.c文件的第6行内存申请后没有释放了。

附上perl脚本

#! /usr/bin/perl
#eval "exec /usr/bin/perl -S $0 $*" if 0;
# Copyright (C) 1997-2004, 2005, 2006, 2007 Free Software Foundation, Inc.
# This file is part of the GNU C Library.
# Contributed by Ulrich Drepper <[e-mail]>, 1997.
# Based on the mtrace.awk script.

# The GNU C Library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.

# The GNU C Library 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
# Lesser General Public License for more details.

# You should have received a copy of the GNU Lesser General Public
# License along with the GNU C Library; if not, write to the Free
# Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
# 02111-1307 USA.

$VERSION = "2.7";
$PACKAGE = "libc";
$progname = $0;

sub usage {
    print "Usage: mtrace [OPTION]... [Binary] MtraceData\n";
    print "  --help       print this help, then exit\n";
    print "  --version    print version number, then exit\n";
    print "\n";
    print "For bug reporting instructions, please see:\n";
    print ".\n"; exit 0;
}

# We expect two arguments:
#   #1: the complete path to the binary
#   #2: the mtrace data filename
# The usual options are also recognized.

arglist: while (@ARGV) {
             if ($ARGV[0] eq "--v" || $ARGV[0] eq "--ve" || $ARGV[0] eq "--ver" ||
                     $ARGV[0] eq "--vers" || $ARGV[0] eq "--versi" ||
                     $ARGV[0] eq "--versio" || $ARGV[0] eq "--version") {
                 print "mtrace (GNU $PACKAGE) $VERSION\n";
                 print "Copyright (C) 2007 Free Software Foundation, Inc.\n";
                 print "This is free software; see the source for copying conditions.  There is NO\n";
                 print "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n";
                 print "Written by Ulrich Drepper \n";
                 exit 0;
             } elsif ($ARGV[0] eq "--h" || $ARGV[0] eq "--he" || $ARGV[0] eq "--hel" ||
                     $ARGV[0] eq "--help") {
                 &usage;
             } elsif ($ARGV[0] =~ /^-/) {
                 print "$progname: unrecognized option `$ARGV[0]'\n";
                 print "Try `$progname --help' for more information.\n";
                 exit 1;
             } else {
                 last arglist;
             }
         }

if ($#ARGV == 0) {
    $binary="";
    $data=$ARGV[0];
} elsif ($#ARGV == 1) {
    $binary=$ARGV[0];
    $data=$ARGV[1];

    if ($binary =~ /^.*[\/].*$/) {
        $prog = $binary;
    } else {
        $prog = "./$binary";
    }
    if (open (LOCS, "env LD_TRACE_LOADED_OBJECTS=1 $prog |")) {
        while (<LOCS>) {
            chop;
            if (/^.*=> (.*) .(0x[0123456789abcdef]*).$/) {
                $locs{$1} = $2;
            }
        }
        close (LOCS);
    }
} else {
    die "Wrong number of arguments, run $progname --help for help.";
}

sub location {
    my $str = pop(@_);
    return $str if ($str eq "");
    if ($str =~ /.*[[](0x[^]]*)]:(.)*/) {
        my $addr = $1;
        my $fct = $2;
        return $cache{$addr} if (exists $cache{$addr});
        if ($binary ne "" && open (ADDR, "addr2line -e $binary $addr|")) {
            my $line = <ADDR>;
            chomp $line;
            close (ADDR);
            if ($line ne '??:0') {
                $cache{$addr} = $line;
                return $cache{$addr};
            }
        }
        $cache{$addr} = $str = "$fct @ $addr";
    } elsif ($str =~ /^(.*):.*[[](0x[^]]*)]$/) {
        my $prog = $1;
        my $addr = $2;
        my $searchaddr;
        return $cache{$addr} if (exists $cache{$addr});
        if ($locs{$prog} ne "") {
            $searchaddr = sprintf "%#x", $addr - $locs{$prog};
        } else {
            $searchaddr = $addr;
            $prog = $binary;
        }
        if ($binary ne "" && open (ADDR, "addr2line -e $prog $searchaddr|")) {
            my $line = <ADDR>;
            chomp $line;
            close (ADDR);
            if ($line ne '??:0') {
                $cache{$addr} = $line;
                return $cache{$addr};
            }
        }
        $cache{$addr} = $str = $addr;
    } elsif ($str =~ /^.*[[](0x[^]]*)]$/) {
        my $addr = $1;
        return $cache{$addr} if (exists $cache{$addr});
        if ($binary ne "" && open (ADDR, "addr2line -e $binary $addr|")) {
            my $line = <ADDR>;
            chomp $line;
            close (ADDR);
            if ($line ne '??:0') {
                $cache{$addr} = $line;
                return $cache{$addr};
            }
        }
        $cache{$addr} = $str = $addr;
    }
    return $str;
}

$nr=0;
open(DATA, "<$data") || die "Cannot open mtrace data file";
while (<DATA>) {
    my @cols = split (' ');
    my $n, $where;
    if ($cols[0] eq "@") {
# We have address and/or function name.
        $where=$cols[1];
        $n=2;
    } else {
        $where="";
        $n=0;
    }

    $allocaddr=$cols[$n + 1];
    $howmuch=hex($cols[$n + 2]);

    ++$nr;
SWITCH: {
            if ($cols[$n] eq "+") {
                if (defined $allocated{$allocaddr}) {
                    printf ("+ %#010x Alloc %d duplicate: %s %s\n",
                            hex($allocaddr), $nr, &location($addrwas{$allocaddr}),
                            $where);
                } else {
                    $allocated{$allocaddr}=$howmuch;
                    $addrwas{$allocaddr}=$where;
                }
                last SWITCH;
            }
            if ($cols[$n] eq "-") {
                if (defined $allocated{$allocaddr}) {
                    undef $allocated{$allocaddr};
                    undef $addrwas{$allocaddr};
                } else {
                    printf ("- %#010x Free %d was never alloc'd %s\n",
                            hex($allocaddr), $nr, &location($where));
                }
                last SWITCH;
            }
            if ($cols[$n] eq "<") {
                if (defined $allocated{$allocaddr}) {
                    undef $allocated{$allocaddr};
                    undef $addrwas{$allocaddr};
                } else {
                    printf ("- %#010x Realloc %d was never alloc'd %s\n",
                            hex($allocaddr), $nr, &location($where));
                }
                last SWITCH;
            }
            if ($cols[$n] eq ">") {
                if (defined $allocated{$allocaddr}) {
                    printf ("+ %#010x Realloc %d duplicate: %#010x %s %s\n",
                            hex($allocaddr), $nr, $allocated{$allocaddr},
                            &location($addrwas{$allocaddr}), &location($where));
                } else {
                    $allocated{$allocaddr}=$howmuch;
                    $addrwas{$allocaddr}=$where;
                }
                last SWITCH;
            }
            if ($cols[$n] eq "=") {
# Ignore "= Start".
                last SWITCH;
            }
            if ($cols[$n] eq "!") {
# Ignore failed realloc for now.
                last SWITCH;
            }
        }
}
close (DATA);

# Now print all remaining entries.
@addrs= keys %allocated;
$anything=0;
if ($#addrs >= 0) {
    foreach $addr (sort @addrs) {
        if (defined $allocated{$addr}) {
            if ($anything == 0) {
                print "\nMemory not freed:\n-----------------\n";
                print ' ' x (10 - 7), "Address     Size     Caller\n";
                $anything=1;
            }
            printf ("%#010x %#8x  at %s\n", hex($addr), $allocated{$addr},
                    &location($addrwas{$addr}));
        }
    }
}
print "No memory leaks.\n" if ($anything == 0);

exit $anything != 0;