libssh：简单实现中丢失的内存
libssh: Memory lost in simple implementation
我正在尝试 libssh 的一个非常简单的实现，但是 valgrind 显示内存泄漏。
代码为：
#include <libssh/libssh.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
int main()
{
ssh_session my_ssh_session = ssh_new();
int port = 22;
int rc, state;
const char *ip = "192.168.125.241";
char *password;
if (my_ssh_session == NULL)
exit(-1);
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, ip);
ssh_options_set(my_ssh_session, SSH_OPTIONS_PORT, &port);
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Error connecting to localhost: %s\n",
ssh_get_error(my_ssh_session));
exit(-1);
}
state = ssh_is_server_known(my_ssh_session);
if(state == SSH_SERVER_KNOWN_OK)
printf("already added\n");
else
printf("require addition\n");
rc = ssh_userauth_password(my_ssh_session, "rohit", "password");
if (rc != SSH_AUTH_SUCCESS)
{
fprintf(stderr, "Error authenticating with password: %s\n",
ssh_get_error(my_ssh_session));
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
exit(-1);
}
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
编译：
gcc sshex.c -lssh
VALGRIND 运行：
root@rohit-Precision-T1500:/# valgrind --tool=memcheck --leak-check=full --show-leak-kinds=all --show-reachable=no ./a.out
==1937== Memcheck, a memory error detector
==1937== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==1937== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==1937== Command: ./a.out
==1937==
yahoo
==1937==
==1937== HEAP SUMMARY:
==1937== in use at exit: 14,256 bytes in 521 blocks
==1937== total heap usage: 1,339 allocs, 818 frees, 92,442 bytes allocated
==1937==
==1937== 24 bytes in 1 blocks are indirectly lost in loss record 507 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3F07: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E6079B: pki_signature_from_blob (pki_crypto.c:1384)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== 24 bytes in 1 blocks are indirectly lost in loss record 508 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3F07: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E607EC: pki_signature_from_blob (pki_crypto.c:1405)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== 32 bytes in 1 blocks are indirectly lost in loss record 511 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E35E6: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3AD4: bn_expand2 (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3ECF: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E6079B: pki_signature_from_blob (pki_crypto.c:1384)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937==
==1937== 32 bytes in 1 blocks are indirectly lost in loss record 512 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E35E6: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3AD4: bn_expand2 (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3ECF: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E607EC: pki_signature_from_blob (pki_crypto.c:1405)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937==
==1937== 48 bytes in 2 blocks are definitely lost in loss record 513 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x574C358: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750B1A: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750BC5: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D79: ASN1_item_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E60734: pki_signature_from_blob (pki_crypto.c:1347)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937==
==1937== 128 (16 direct, 112 indirect) bytes in 1 blocks are definitely lost in loss record 516 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D0B: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D79: ASN1_item_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E60734: pki_signature_from_blob (pki_crypto.c:1347)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== LEAK SUMMARY:
==1937== definitely lost: 64 bytes in 3 blocks
==1937== indirectly lost: 112 bytes in 4 blocks
==1937== possibly lost: 0 bytes in 0 blocks
==1937== still reachable: 14,080 bytes in 514 blocks
==1937== suppressed: 0 bytes in 0 blocks
==1937== Reachable blocks (those to which a pointer was found) are not shown.
直接运行：
root@rohit-Precision-T1500:/# gcc sshex.c -lssh
root@rohit-Precision-T1500:/# ./a.out
already added
root@rohit-Precision-T1500:/#
Linux 版本：
root@rohit-Precision-T1500:/# uname -a
Linux rohit-Precision-T1500 3.13.0-43-generic #72-Ubuntu SMP Mon Dec 8 19:35:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
我已经试验过了。如果我删除函数 ssh_connect() （当然还有其他后续函数），那么我就不会得到任何泄漏。因此，泄漏一定是由这个函数引起的。但是在我的小程序中，我已经使用函数ssh_disconnect()来释放ssh_connect()分配的内存。那么，我怎样才能确保释放内存呢？
我想在我的软件中使用 SCP 功能，这将是一个长期存在的过程。因此，内存泄漏将成为一个严重的问题。
根据我的理解，泄漏与 libcrypto 库相关，这可能不是 libssh 的泄漏。如果是或不是，消除这些泄漏的解决方案是什么？
我哪里做错了？
果然如我所料。这可能是 libcrypto 中的错误。我 运行 我的程序 RHEL 6.5 和 valgrind 显示没有泄漏。
这是输出的片段：
[root@demo-hadoop test]# gcc sshex.c -lssh
[root@demo-hadoop test]# valgrind --tool=memcheck ./a.out
==23636== Memcheck, a memory error detector
==23636== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==23636== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==23636== Command: ./a.out
==23636==
already added
==23636==
==23636== HEAP SUMMARY:
==23636== in use at exit: 15,304 bytes in 532 blocks
==23636== total heap usage: 1,067 allocs, 535 frees, 82,199 bytes allocated
==23636==
==23636== LEAK SUMMARY:
==23636== definitely lost: 0 bytes in 0 blocks
==23636== indirectly lost: 0 bytes in 0 blocks
==23636== possibly lost: 0 bytes in 0 blocks
==23636== still reachable: 15,304 bytes in 532 blocks
==23636== suppressed: 0 bytes in 0 blocks
==23636== Rerun with --leak-check=full to see details of leaked memory
==23636==
==23636== For counts of detected and suppressed errors, rerun with: -v
==23636== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 6)
[root@demo-hadoop test]#
[root@demo-hadoop test]#
[root@demo-hadoop test]# uname -a
Linux demo-hadoop 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux
所以，当然，这不是 libssh 中的错误。
我正在尝试 libssh 的一个非常简单的实现，但是 valgrind 显示内存泄漏。
代码为：
#include <libssh/libssh.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
int main()
{
ssh_session my_ssh_session = ssh_new();
int port = 22;
int rc, state;
const char *ip = "192.168.125.241";
char *password;
if (my_ssh_session == NULL)
exit(-1);
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, ip);
ssh_options_set(my_ssh_session, SSH_OPTIONS_PORT, &port);
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
fprintf(stderr, "Error connecting to localhost: %s\n",
ssh_get_error(my_ssh_session));
exit(-1);
}
state = ssh_is_server_known(my_ssh_session);
if(state == SSH_SERVER_KNOWN_OK)
printf("already added\n");
else
printf("require addition\n");
rc = ssh_userauth_password(my_ssh_session, "rohit", "password");
if (rc != SSH_AUTH_SUCCESS)
{
fprintf(stderr, "Error authenticating with password: %s\n",
ssh_get_error(my_ssh_session));
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
exit(-1);
}
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
}
编译：
gcc sshex.c -lssh
VALGRIND 运行：
root@rohit-Precision-T1500:/# valgrind --tool=memcheck --leak-check=full --show-leak-kinds=all --show-reachable=no ./a.out
==1937== Memcheck, a memory error detector
==1937== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==1937== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==1937== Command: ./a.out
==1937==
yahoo
==1937==
==1937== HEAP SUMMARY:
==1937== in use at exit: 14,256 bytes in 521 blocks
==1937== total heap usage: 1,339 allocs, 818 frees, 92,442 bytes allocated
==1937==
==1937== 24 bytes in 1 blocks are indirectly lost in loss record 507 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3F07: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E6079B: pki_signature_from_blob (pki_crypto.c:1384)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== 24 bytes in 1 blocks are indirectly lost in loss record 508 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3F07: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E607EC: pki_signature_from_blob (pki_crypto.c:1405)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== 32 bytes in 1 blocks are indirectly lost in loss record 511 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E35E6: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3AD4: bn_expand2 (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3ECF: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E6079B: pki_signature_from_blob (pki_crypto.c:1384)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937==
==1937== 32 bytes in 1 blocks are indirectly lost in loss record 512 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E35E6: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3AD4: bn_expand2 (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3ECF: BN_bin2bn (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E607EC: pki_signature_from_blob (pki_crypto.c:1405)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937==
==1937== 48 bytes in 2 blocks are definitely lost in loss record 513 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x56E3A59: BN_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x574C358: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750B1A: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750BC5: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D79: ASN1_item_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E60734: pki_signature_from_blob (pki_crypto.c:1347)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937==
==1937== 128 (16 direct, 112 indirect) bytes in 1 blocks are definitely lost in loss record 516 of 520
==1937== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==1937== by 0x56AAD32: CRYPTO_malloc (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D0B: ??? (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x5750D79: ASN1_item_new (in /lib/x86_64-linux-gnu/libcrypto.so.1.0.0)
==1937== by 0x4E60734: pki_signature_from_blob (pki_crypto.c:1347)
==1937== by 0x4E599F9: ssh_pki_import_signature_blob (pki.c:1262)
==1937== by 0x4E59A77: ssh_pki_signature_verify_blob (pki.c:1281)
==1937== by 0x4E578DE: ssh_packet_newkeys (packet_cb.c:186)
==1937== by 0x4E56E6F: ssh_packet_process (packet.c:422)
==1937== by 0x4E57374: ssh_packet_socket_callback (packet.c:326)
==1937== by 0x4E573B3: ssh_packet_socket_callback (packet.c:336)
==1937== by 0x4E5D951: ssh_socket_pollcallback (socket.c:290)
==1937==
==1937== LEAK SUMMARY:
==1937== definitely lost: 64 bytes in 3 blocks
==1937== indirectly lost: 112 bytes in 4 blocks
==1937== possibly lost: 0 bytes in 0 blocks
==1937== still reachable: 14,080 bytes in 514 blocks
==1937== suppressed: 0 bytes in 0 blocks
==1937== Reachable blocks (those to which a pointer was found) are not shown.
直接运行：
root@rohit-Precision-T1500:/# gcc sshex.c -lssh
root@rohit-Precision-T1500:/# ./a.out
already added
root@rohit-Precision-T1500:/#
Linux 版本：
root@rohit-Precision-T1500:/# uname -a
Linux rohit-Precision-T1500 3.13.0-43-generic #72-Ubuntu SMP Mon Dec 8 19:35:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
我已经试验过了。如果我删除函数 ssh_connect() （当然还有其他后续函数），那么我就不会得到任何泄漏。因此，泄漏一定是由这个函数引起的。但是在我的小程序中，我已经使用函数ssh_disconnect()来释放ssh_connect()分配的内存。那么，我怎样才能确保释放内存呢？
我想在我的软件中使用 SCP 功能，这将是一个长期存在的过程。因此，内存泄漏将成为一个严重的问题。
根据我的理解，泄漏与 libcrypto 库相关，这可能不是 libssh 的泄漏。如果是或不是，消除这些泄漏的解决方案是什么？
我哪里做错了？
果然如我所料。这可能是 libcrypto 中的错误。我 运行 我的程序 RHEL 6.5 和 valgrind 显示没有泄漏。
这是输出的片段：
[root@demo-hadoop test]# gcc sshex.c -lssh
[root@demo-hadoop test]# valgrind --tool=memcheck ./a.out
==23636== Memcheck, a memory error detector
==23636== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==23636== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==23636== Command: ./a.out
==23636==
already added
==23636==
==23636== HEAP SUMMARY:
==23636== in use at exit: 15,304 bytes in 532 blocks
==23636== total heap usage: 1,067 allocs, 535 frees, 82,199 bytes allocated
==23636==
==23636== LEAK SUMMARY:
==23636== definitely lost: 0 bytes in 0 blocks
==23636== indirectly lost: 0 bytes in 0 blocks
==23636== possibly lost: 0 bytes in 0 blocks
==23636== still reachable: 15,304 bytes in 532 blocks
==23636== suppressed: 0 bytes in 0 blocks
==23636== Rerun with --leak-check=full to see details of leaked memory
==23636==
==23636== For counts of detected and suppressed errors, rerun with: -v
==23636== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 6)
[root@demo-hadoop test]#
[root@demo-hadoop test]#
[root@demo-hadoop test]# uname -a
Linux demo-hadoop 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux
所以，当然，这不是 libssh 中的错误。