mysql_init(NULL) 分段错误 [英] mysql_init(NULL) segmentation fault

问题描述

我有以下功能:

int get_tcounter(char *meterType, int *error) {
    MYSQL *conn = mysql_init(NULL);
    get_connection(conn, DB_HOST, DB_USER, DB_PW, DB); 

    MYSQL_STMT *stmt = mysql_stmt_init(conn);
    if (!stmt) {
        log_to_console("Init stmt failed: %s\n", mysql_error(conn));
        exit(1);
    }
    prepare_stmt(conn, stmt, GET_TCOUNTER_SQL);

    MYSQL_BIND param[1], res[1];
    memset(param, 0, sizeof(param));
    memset(res, 0, sizeof(res));

    char *paramBuff;
    int tcBuff;
    my_bool isNullParam[] = {0}, isNullRes[] = {0};

    paramBuff = meterType;

    bind_string_param(&param[0], strlen(meterType), paramBuff, &isNullParam[0], (unsigned long *) 0);
    bind_result(&res[0], MYSQL_TYPE_LONG, (char *) &tcBuff, &isNullRes[0], (unsigned long *) 0);

    execute_statement(stmt, param, res);

    *error = TRUE;
    int ret = 0;
    if (!mysql_stmt_fetch(stmt)) {
        ret = tcBuff;
        *error = FALSE;
    }

    mysql_stmt_close(stmt);
    mysql_close(conn);

    return ret;
}

第一次执行该函数时，一切都按预期工作，但第二次，mysql_init 行抛出分段错误.

First time I execute the function all is working as expected, but the second time around, mysql_init line throws Segmentation Fault.

这是核心转储:

Program terminated with signal 11, Segmentation fault.
#0  0x00007fe23ee22f08 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) down
Bottom (innermost) frame selected; you cannot go down.
(gdb) up
#1  0x00007fe23ee24536 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) up
#2  0x00007fe23ee270b5 in malloc () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) up
#3  0x00007fe23fa951d2 in my_malloc () from /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
(gdb) up
#4  0x00007fe23fa788df in mysql_init () from /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
(gdb) up
#5  0x0000000000403ed4 in get_tcounter (meterType=0x24bcbd0 "M-9669-8", error=0x7fff6b57a8a8) at database/data_access.c:284
284     MYSQL *conn = mysql_init(NULL);

奇怪的是，第一次调用 conn 在 init 之前是 0x0，但第二次它是一些任意的 0x7fff... 地址.

The strange thing is that in first call conn is 0x0 before init, but the second time it's some arbitrary 0x7fff... address.

将 NULL 分配给 conn 并在 init 之前释放 conn 无效.

Tied assigning NULL to conn and freeing conn before init to no avail.

推荐答案

这很有可能是内存损坏导致 MySQL 中设置了一些错误状态.尝试在 Valgrind 下运行它，看看是否存在双重 free 或某种无效访问.

There's a good chance this is memory corruption that sets up some bad state in MySQL. Try running this under Valgrind to see if there is a double free or invalid access of some kind.

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