Replace "new" variable

[hirotakaster]

Description

• Type: Enhancement
• Priority: Minor

---

Enhancement

I would like to replace variable "*new" to "*new_cert" in ssl_append_key_cert function at ssl_tls.c like a following, because of my build with arm-none-eabi-gcc(c++) will fail on this "new" variable.

now

static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
                                mbedtls_x509_crt *cert,
                                mbedtls_pk_context *key )
{
    mbedtls_ssl_key_cert *new;

    new = mbedtls_calloc( 1, sizeof( mbedtls_ssl_key_cert ) );
    if( new == NULL )
        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );

    new->cert = cert;
    new->key  = key;
    new->next = NULL;

    /* Update head is the list was null, else add to the end */
    if( *head == NULL )
    {
        *head = new;
    }
    else
    {
        mbedtls_ssl_key_cert *cur = *head;
        while( cur->next != NULL )
            cur = cur->next;
        cur->next = new;
    }

    return( 0 );
}

to

static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
                                mbedtls_x509_crt *cert,
                                mbedtls_pk_context *key )
{
    mbedtls_ssl_key_cert *new_cert;

    new_cert = mbedtls_calloc( 1, sizeof( mbedtls_ssl_key_cert ) );
    if( new_key_cert == NULL )
        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );

    new_cert->cert = cert;
    new_cert->key  = key;
    new_cert->next = NULL;

    /* Update head is the list was null, else add to the end */
    if( *head == NULL )
    {
        *head = new_cert;
    }
    else
    {
        mbedtls_ssl_key_cert *cur = *head;
        while( cur->next != NULL )
            cur = cur->next;
        cur->next = new_cert;
    }

    return( 0 );
}

[hanno-becker]

Hi @hirotakaster, thank you for your report!

I don't see a reason not to perform the suggested renaming if the current naming causes problems on some build systems. Do you have time to open a PR with the change?

Thank you,
Hanno, Mbed TLS team member

[hirotakaster]

Hi @hanno-arm ,

Okay, I would send a PR with this change.

Thank you,
Hirotaka Niisato

[hanno-becker]

Hi @hirotakaster,

great, thank you!

Best,
Hanno

[RonEld]

@hirotakaster Since this causes your build to fail, I would consider this a bug, rather than an enhancement.

[ciarmcom]

ARM Internal Ref: IOTSSL-2374

[gilles-peskine-arm]

@hirotakaster Could you please let us know what compiler options you're using? Note that Mbed TLS is a C library. It must be compiled with a C compiler. If you use a combined C/C++ compiler, make sure that you're using it in the correct mode. This should be automatic for a file name with the extension .c.

There are more differences between C and C++ than the addition of new as a reserved identifier, for example the size of some integral expressions. Compiling Mbed TLS source files with a C++ compiler is not supported and may lead to subtle bugs. It is fine to use Mbed TLS headers in C++ programs and to link the library in C++ programs, but the library itself must be compiled with a C compiler.

[hirotakaster]

@gilles-peskine-arm
yes, I build with my C++ source code with build option is included arm-none-eabi-gcc -std=gnu++11.
so if this proposal not suitable and supported in mbedTLS, please revoke this issue and pull request.
Thank you.

[irwir]

@gilles-peskine-arm

It must be compiled with a C compiler.

According to an old issue #447

Compiling under C++ should be tested, and whatever issues are found, should be fixed.

In that case, none of C++ reserved words could be used as identifiers.

[gilles-peskine-arm]

@irwir Thanks for mentioning this old issue! But I'm with Guido Vranken on this one: shoehorning C code into being compilable C++ is risky, and it is not needed to link C code into an application that is otherwise written in C++.

[hirotakaster]

@gilles-peskine-arm Thank you, then I should revoke & close this issue&PR? I understood your points and risk, and I see mbedTLS support/maintain under C language written in tutorial.

[irwir]

@gilles-peskine-arm

But I'm with Guido Vranken on this one

Interesting example, though.
That was C99 standard allowing variable sized local arrays, while all C++ implementations were non-standard extensions.

Giving more meaningful name to variables is a positive change, not a risky one.

[simonbutcher]

All PR's, #1783 for development, #1819 for mbedtls-2.7, and #1820 for mbedtls-2.1 have been merged, fixing the issue, so this can now be closed.