There is nothing wrong with this one lonely line of code you gave us to judge.

Maybe you need to check your call to GetAttr. opg_Storage is basically the third argument you give to GetAttr.

Also make sure that the string remains valid after you forwarded its pointer.

char *text_in  = "my text";
*msg->opg_Storage = (uint32) text_in;
 
...
 
char *text_out = NULL;
GetAttr (GA_Whatever,object,(uint32 *)&text_out);
Printf ("%s\n",text_out);

Transferring boolean values is a bit tricky because OM_GET always overwrites 32 bits of storage, so you cannot let GetAttr point directly to a BOOL variable, you have to let it write to a 32 bit integer first and then assign it to the BOOL variable.

BOOL check_in = TRUE;
*msg->opg_Storage = (uint32) check_in;
 
...
 
BOOL check_out;
uint32 temp_var = 0;
GetAttr (GA_Whatever,object,&temp_var);
check_out = temp_var;
Printf ("%lu\n",check_out);