[英]Suspicious memory leak when using getopt lib in MySQL?
我代表我的大学张贴这篇文章。
当使用handle_option(MySQL getopt lib)读取配置文件(/etc/my.cnf)时,他发现了可疑的内存泄漏。
他在malloc host_name(用户名)之后执行以下源代码:
char* host_name;
char* user_name;
struct my_option mysql_confgs[] =
{
{"host", "h", "MySQL Server", (uchar**) & host_name, NULL, NULL, GET_STR,
REQUIRED_ARG, 0,0,0,0,0,0},
{"user", "u", "userID", "h",(uchar**) & user_name, NULL, NULL, GET_STR,
REQUIRED_ARG, 0,0,0,0,0,0}
}
handle_options(&argc, &argv, mysql_configs, aux_config_reader);
他提到上述方法是使用Error(Segment)而不是使用free(host_name)和free(user_name)吗? 那么这是导致内存泄漏的可能原因吗?
好吧..我对MySQL的基础知识为零,所以我可能无法交付100%的问题描述。 因此,随时对此进行查询,我将根据查询更新问题描述的详细信息。
我的大学有语言障碍,所以我代表他发布。
Valgrind报告:
480 bytes in 1 blocks are possibly lost in loss record 26 of 43
at 0x4A068FE: malloc (vg_replace_malloc.c:270)
by 0x33E4E293C1: my_malloc (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2C974: alloc_root (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2E620: ??? (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2F838: my_load_defaults (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x408BF1: MS_MYSQL_init (MS_MYSQL_O.h:109)
by 0x438A39: main_proc (AccLab.c:221)
by 0x437F8A: main (AccLab.c:67)
75,840 bytes in 158 blocks are definitely lost in loss record 41 of 43
at 0x4A068FE: malloc (vg_replace_malloc.c:270)
by 0x33E4E293C1: my_malloc (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2C974: alloc_root (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2E620: ??? (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x33E4E2F838: my_load_defaults (in /usr/lib64/mysql/libmysqlclient.so.16.0.0)
by 0x408BF1: MS_MYSQL_init (MS_MYSQL_O.h:109)
by 0x438A39: main_proc (AccLab.c:221)
by 0x437F8A: main (AccLab.c:67)
泄漏摘要:
definitely lost: 75,840 bytes in 158 blocks
indirectly lost: 0 bytes in 0 blocks
possibly lost: 2,304 bytes in 7 blocks
still reachable: 9,675,408 bytes in 2,387 blocks
suppressed: 0 bytes in 0 blocks
Reachable blocks (those to which a pointer was found) are not shown.
To see them, rerun with: --leak-check=full --show-reachable=yes
For counts of detected and suppressed errors, rerun with: -v
ERROR SUMMARY: 8 errors from 8 contexts (suppressed: 4 from 4)
把printf("user_name: %p; host_name: %p\\n", (void *) user_name, (void *) host_name);
调用handle_options之前和之后并运行您的代码。 结果打印的另外两行是否彼此不同? 如果是这样,则您的诊断是正确的,并且handle_options更改了user_name和host_name,并且可能不适合使用使用malloc指针的函数。
否则,您的诊断不正确,并且内存泄漏在其他地方。 您需要按顺序查看MS_MYSQL_init,main_proc和main的源代码,这是valgrind从您的项目中列出的三个函数。 让我知道您是否需要我的帮助...
我想说分配内存指针的组合my_option.value
指向与使用沿着GET_STR
是导致漏水什么已分配给my_option.value
,作为GET_PTR
initalises什么my_option.value
指向,指向有权移至以argv
传递到handle_options
,而无需释放先前指向的my_option.value
所指向的值。
为了解决这个问题,要么不分配任何内存什么my_option.value
将其传递给指向之前handle_options
或使用分配它my_alloc()
并使用GET_PTR_ALLOC
为价值型,为GET_PTR_ALLOC
意味着调用my_free()
什么my_option.value
在重新初始化它指向之前指向。
出于好奇:什么是uchar
,为什么要转换为my_option.value
类型的uchar **
而不是void *
?
还有这个
"user", "u", "userID", "h",(uchar**) & user_name ...
应该读
"user", "u", "userID", (uchar**) & user_name ...
不是吗
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