Was tun die meisten Programmierer, wenn sie feststellen, dass in ihrem Programm Speicherplatz verloren geht? Nichts, lassen Sie den Benutzer mehr RAM kaufen.Ich wage anzunehmen, dass sie ein zuverlässiges, bewährtes Tool wie Valgrind oder Libasan verwenden, es ausführen und den Bericht ansehen. Es heißt normalerweise, dass Objekte, die in dieser und jener Zeile des Programms dieser und jener Datei erstellt wurden, nicht freigegeben wurden. Und warum? Dies ist nirgendwo geschrieben.

Dieser Beitrag konzentriert sich auf den Leckanzeiger, das zugrunde liegende statistische Analysekonzept und dessen Anwendung.

Ich habe bereits über topleaked on habr geschrieben, . - , . , . , , — . C++ vtbl . , . , , , valgrind , . topleaked , . , , — . , . " ", , , — . topleaked.

#include <iostream>
#include <assert.h>
#include <unistd.h>

class A {
    size_t val = 12345678910;
    virtual ~A(){}
};

int main() {
    for (size_t i =0; i < 1000000; i++) {
        new A();
    }
    std::cout << getpid() << std::endl;
    abort();
}

./toleaked leak.core

0x0000000000000000 : 1050347
0x0000000000000021 : 1000003
0x00000002dfdc1c3e : 1000000
0x0000558087922d90 : 1000000
0x0000000000000002 : 198
0x0000000000000001 : 180
0x00007f4247c6a000 : 164
0x0000000000000008 : 160
0x00007f4247c5c438 : 153
0xffffffffffffffff : 141

$ ./topleaked -n10 -ogdb /home/core/leak.1002.core | gdb leak /home/core/leak.1002.core
...<   gdb  >
#0  0x00007f424784e6f4 in __GI___nanosleep (requested_time=requested_time@entry=0x7ffcfffedb50, remaining=remaining@entry=0x7ffcfffedb50) at ../sysdeps/unix/sysv/linux/nanosleep.c:28
28      ../sysdeps/unix/sysv/linux/nanosleep.c: No such file or directory.
(gdb) $1 = 1050347
(gdb) 0x0:      Cannot access memory at address 0x0
(gdb) No symbol matches 0x0000000000000000.
(gdb) $2 = 1000003
(gdb) 0x21:     Cannot access memory at address 0x21
(gdb) No symbol matches 0x0000000000000021.
(gdb) $3 = 1000000
(gdb) 0x2dfdc1c3e:      Cannot access memory at address 0x2dfdc1c3e
(gdb) No symbol matches 0x00000002dfdc1c3e.
(gdb) $4 = 1000000
(gdb) 0x558087922d90 <_ZTV1A+16>:       0x87721bfa
(gdb) vtable for A + 16 in section .data.rel.ro of /home/g.smorkalov/dlang/topleaked/leak
(gdb) $5 = 198
(gdb) 0x2:      Cannot access memory at address 0x2
(gdb) No symbol matches 0x0000000000000002.
(gdb) $6 = 180
(gdb) 0x1:      Cannot access memory at address 0x1
(gdb) No symbol matches 0x0000000000000001.
(gdb) $7 = 164
(gdb) 0x7f4247c6a000:   0x47ae6000
(gdb) No symbol matches 0x00007f4247c6a000.
(gdb) $8 = 160
(gdb) 0x8:      Cannot access memory at address 0x8
(gdb) No symbol matches 0x0000000000000008.
(gdb) $9 = 153
(gdb) 0x7f4247c5c438 <_ZTVN10__cxxabiv120__si_class_type_infoE+16>:     0x47b79660
(gdb) vtable for __cxxabiv1::__si_class_type_info + 16 in section .data.rel.ro of /usr/lib/x86_64-linux-gnu/libstdc++.so.6
(gdb) $10 = 141
(gdb) 0xffffffffffffffff:       Cannot access memory at address 0xffffffffffffffff
(gdb) No symbol matches 0xffffffffffffffff.
(gdb) quit

. , , 15. , .

, ?

— ? , , . topleaked . , , , . ? , , . , , .

…

. , . — . 3 . , . 3 , - . , 2-3 — . . , — , . C++ . , . C, D, Rust, Go NodeJS. , js .

. , , , , close. , . ( ), , fd (512000 ) . . . , , .

topleaked — . , , . , , . : . state — enum, . : , , websocket, . , , .

. Topleaked , , 8 8- . - , , , - . - , . , vtbl, . , , “ ”. vtbl - state. , . .

C++ — ABI - . POD trivial C. , , . . , linux gcc , vtbl — . offsetof(state) . :

struct Base {
    virtual void foo() = 0;
};

struct Der : Base {
    size_t a = 15;
    void foo() override {

    }
};
int main()
{
    for (size_t i = 0; i < 10000; ++i) {
        new Der;
    }
    auto d = new Der;
    cout << offsetof(Der, a) << endl;
    abort();
    return 0;
}

offsetof Der::a, “” 10000 . topleaked

topleaked  my_core.core
0x0000000000000000 : 50124
0x000000000000000f : 10005
0x0000000000000021 : 10004
0x000055697c45cd78 : 10002
0x0000000000000002 : 195
0x0000000000000001 : 182
0x00007fe9cbd6c000 : 167
0x0000000000000008 : 161
0x00007fe9cbd5e438 : 154
0x0000000000001000 : 112

0x000055697c45cd78 vtbl Der. offsetof 8. , 8 . topleaked — . -f , , --memberOffset — -f, --memberType — . uint8, uint16, uint32 uint64.

topleaked my_core.core -f0x55697c45cd78 --memberOffset=8 --memberType=uint64

:

0x000000000000000f : 10001
0x000055697ccaa080 : 1

10000 0x0f, , .

Happy End

. , , , . , . , . , , . , TCP, — websocket upgrade, - . . — , . , (, ) TCP. , , . . , , — TCP Keep Alive. https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/

, . , . websocket . , .

D

, . , , (uint 8/16/32/64) :

readFile(name, offset, limit)
    .findMember!uint64_t(pattern, memberOffset)
    .findMostFrequent(size).printResult(format);

findMember — , , findMostFrequent — , . (ranges) . , , , .

dub fetch topleaked

dub run topleaked -brelease-nobounds -- <filename> [<options>...]

dub build -brelease-nobounds

c

P.S. Crazy Panda , . , topleaked.