c - 尝试检索值时，将指针传递给函数会导致段错误

Question

我在使用以下代码时遇到段错误。我很确定这是因为函数试图使用变量的地址而不是它的值。我对指针有点陌生。

int main(int argc, char *argv[])
{

    EVP_PKEY        priv_key_p;
    X509_REQ        req_p;
    X509            cert;
    PKCS7           pkcs7;

        /*Need to store value in req_p and priv_key_p*/
    makecsr(&req_p, &priv_key_p, passphrase);

        /*Need to use value of req_p and priv_key_p*/
    create_cert(&req_p, &cert, &priv_key_p, passphrase);
}


int create_cert(X509_REQ *req_p, X509 *cert, EVP_PKEY *priv_key_p, char *passphrase)
{
    int i;
    long serial = 1;
    EVP_PKEY *pkey;
    const EVP_MD *digest;
    X509_NAME *name;
    X509V3_CTX ctx;

    /* verify signature on the request */
    if (!(pkey = X509_REQ_get_pubkey (req_p))) <--- Segmentation fault here!
        int_error ("Error getting public key from request");
    ....
}

使用GDB，makecsr执行后，我可以毫无问题地打印priv_key_p和req_p的值。

但是，在 create_cert 函数内部，我只能通过写入 p *priv_key_p/*req_p 来打印该值

错误

Program received signal SIGSEGV, Segmentation fault.
0xb7ebb747 in X509_REQ_get_pubkey ()
   from /lib/i386-linux-gnu/libcrypto.so.1.0.0

Answer 1

你的代码:

if (!(pkey = X509_REQ_get_pubkey (req_p))) <--- Segementation fault here!
    int_error ("Error getting public key from request");
    ....

试试这个:

if (!(pkey == X509_REQ_get_pubkey (req_p))) <--- Segementation fault here!
    int_error ("Error getting public key from request");
    ....