Re: [RFA/JVMTI] Implement GetLocalVariableTable and GetMaxLocals

[Keith Seitz <keiths at redhat dot com>]

Tom Tromey wrote:

> Ok.  One more problem I failed to notice earlier :(

Oh boy. My bad... I don't know why I didn't notice this. Or perhaps I've 
missed the point.

A long time ago (20070207), Tom wrote:

> Kyle> +  int get_local_var_table (char **name, char **sig, char 
**generic_sig,
> Kyle> +                           long *startloc, jint *length, jint 
*slot,
> Kyle> +                           int table_slot)
> Kyle> +        *name = reinterpret_cast<char *>
> Kyle> +          (_Jv_AllocBytes (strlen 
(local_var_table[table_slot].name) + 1));
>
> I don't see how memory allocated here can ever be freed.

The client is responsible for doing it:

  jint entry_count;
  jvmtiLocalVariableEntry *table;
  jvmtiError err;
  err = env->GetLocalVariableTable(method, entry_count, table);
  if (err != JVMTI_ERROR_NONE)
    // whatever

  // do something with the table

  for (jint i = 0; i < entry_count; ++i)
   {
    jvmtiLocalVaribleEntry ve = table[i];
    env->Deallocate ((unsigned char *) ve->name);
    env->Deallocate ((unsigned char *) ve->signature);
    if (ve->generic_signature != NULL)
      env->Deallocate ((unsigned char *) ve->generic_signature);
   }

  env->Deallocate ((unsigned char *) table);

Or at least that's what I get from the spec (reformatted by me):

"jvmtiLocalVariableEntry **table_ptr
  On return, points to an array of local variable table entries.

Agent passes a pointer to a jvmtiLocalVariableEntry*. On return, the 
jvmtiLocalVariableEntry* points to a newly allocated array of size 
*entry_count_ptr. The array should be freed with Deallocate. The 
pointers returned in the field name of jvmtiLocalVariableEntry are newly 
allocated arrays. The arrays should be freed with Deallocate. The 
pointers returned in the field signature of jvmtiLocalVariableEntry are 
newly allocated arrays. The arrays should be freed with Deallocate. The 
pointers returned in the field generic_signature of 
jvmtiLocalVariableEntry are newly allocated arrays. The arrays should be 
freed with Deallocate."

??
Keith