Re: Wrong guile-bytestructures description for gnunet progress-info struct with unions

[Amirouche Boubekki]

Thanks for the reply.

On 2018-01-07 19:39, address@hidden wrote:
> Amirouche Boubekki <address@hidden> writes:
>
> Here are some possibilities I can think of, wildly speculatively.
>
> - %time-relative is defined wrong (I couldn't find the corresponding
>   GNUNET_TIME_Relative definition to compare)

Here is the definition in C of GNUNET_TIME_Relative:

struct GNUNET_TIME_Relative
{
  uint64_t rel_value_us;
};

Here is the definition in Guile:

(define %time-relative (bs:struct `((rel-value-us ,uint64))))

> - %crypto-ecdsa-public-key is defined wrong (I couldn't find the
>   corresponding GNUNET_CRYPTO_EcdsaPublicKey definition to compare)

Here is the definition in C:

struct GNUNET_CRYPTO_EcdsaPublicKey
{
  unsigned char q_y[256 / 8];
};

Here is the definition in Guile:

(define %crypto-ecdsa-public-key (bs:struct `((q-y ,(bs:vector (/ 256 8) 
uint8)))))


> If both of those are correct, further possibilities would be:
>
> - Some or all of the structs in the C code are "packed".
>
> - There's a bug in bytestructures.
>
> To rule out these two, you can use a simple test case: write a tiny C
> lib with a function that allocates a GNUNET_FS_ProgressInfo struct,
> writes to its status field, and returns a pointer to it.  Load the lib
> from Scheme, call the function through FFI... you know the rest; see if
> you get the correct value when you read the status field from Scheme.

I get the wrong result.

FWIW, you can reproduce following those steps:

$ git clone git://gnunet.org/gnunet-guile2.git
$ cd gnunet-guile2
$ guix package -f guix.scm
$ ./bootstrap && ./configure
$ c99 
-I/gnu/store/nfaljkxhj0hgxkzxbd4pgmm70h9niq7q-gnunet-git-0.10.1-2.477e0de/include/gnunet/ 
-c example.c -o libexample.o && gcc -shared libexample.o -o 
libexample.so
$ ./pre-inst-env guile example.scm

The expected output is 42.