[gambit-list] Returning a byte array from C

Vijay Mathew vijay.the.lisper at gmail.com
Wed Sep 25 04:48:39 EDT 2013


Thanks for reviewing my code.

I have updated the C function as follows:

int read_bytes (int fd, size_t count, ___SCMOBJ data_vect)
   void *data = malloc (count);
   int result;

   if (data == NULL)
     result = -1;
       result = read (fd, data, count);
       if (result > 0)
         memcpy (___BODY (data_vect), data, result);
       free (data);
   return result;

A call from scheme will look like:

(read-bytes fd count (make-u8vector count 0))

I suppose now I don't have to worry about leaks or heap-overflow-exceptions.



On Tue, Sep 24, 2013 at 8:52 PM, Marc Feeley <feeley at iro.umontreal.ca>wrote:

> On 2013-09-23, at 11:14 AM, Vijay Mathew <vijay.the.lisper at gmail.com>
> wrote:
> > The following C function is a wrapper for the `read' system call.
> > It returns a pair that contains the number of bytes read and the data.
> > Is this the right way to initialize a u8vector from C?
> There are a few things I would do differently, such as heap overflow
> checking.  But for the particular task of providing a wrapper to the read
> system call I would use a different interface.  Why don't you allocate the
> buffer in Scheme before calling read?  That would simplify the C code
> (avoiding GC issues) and would be more efficient.
> Marc
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