str_buf safety

[Charles Mills]

Is it safe so set the length of a String Buffer like so:
{
VALUE str_buf;
long len = len_of_ext_data_source;
unsigned char *buf = ptr_to_ext_data_source;

str_buf = rb_str_buf_new(len);
/* bug: Dangerous to set Ruby String fields directly? */
MEMCPY(RSTRING(str_buf)->ptr, buf, unsigned char, len);
RSTRING(str_buf)->len = len;
return str_buf;
}
Where len is the length of some buffer and buf is a pointer to that
buffer.
-Charlie

 

[Charles Mills]

Is it safe so set the length of a String Buffer like so:
{
VALUE str_buf;
long len = len_of_ext_data_source;
unsigned char *buf = ptr_to_ext_data_source;

str_buf = rb_str_buf_new(len);
/* bug: Dangerous to set Ruby String fields directly? */
MEMCPY(RSTRING(str_buf)->ptr, buf, unsigned char, len);
RSTRING(str_buf)->len = len;
return str_buf;
}
Where len is the length of some buffer and buf is a pointer to that
buffer.
-Charlie

I just realized this example suggests I should use:
VALUE str = rb_str_new(buf, len);
Unfortunately I cannot do that (without allocating 2 buffers) since I
have a routine pack() which packs an object into a buffer.
I was hoping I could do the following:
{
long len = pack_size(obj);
VALUE str_buf = rb_str_buf_new(len);
pack(obj, RSTRING(str_buf)->ptr, len);
RSTRING(str_buf)->len = len;
return str_buf;
}

I am sure something similar is done with the read() system call in
io.c, ... I will look there.
-Charlie