[PATCH] memory leak in ecpglib

Hi all

Memory leaks occur when the ecpg_update_declare_statement() is called the second time.

FILE:postgresql\src\interfaces\ecpg\ecpglib\prepare.c
void
ecpg_update_declare_statement(const char *declared_name, const char *cursor_name, const int lineno)
{
    struct declared_statement *p = NULL;

    if (!declared_name || !cursor_name)
        return;

    /* Find the declared node by declared name */
    p = ecpg_find_declared_statement(declared_name);
    if (p)
        p->cursor_name = ecpg_strdup(cursor_name, lineno);  ★
}
ecpg_strdup() returns a pointer to a null-terminated byte string, which is a duplicate of the string pointed to by
str.
The memory obtained is done dynamically using malloc and hence it can be freed using free().

When the ecpg_update_declare_statement() is called for the second time, 
the memory allocated for p->cursor_name is not freed. 

For example:

    EXEC SQL BEGIN DECLARE SECTION;
        char *selectString = "SELECT * FROM foo;";
        int FooBar;
        char DooDad[17];
    EXEC SQL END DECLARE SECTION;

    EXEC SQL CONNECT TO postgres@localhost:5432 AS con1 USER postgres;

    EXEC SQL AT con1 DECLARE stmt_1 STATEMENT;
    EXEC SQL AT con1 PREPARE stmt_1 FROM :selectString;

    EXEC SQL AT con1 DECLARE cur_1 CURSOR FOR stmt_1; //★1     ECPGopen() --> ecpg_update_declare_statement()
    EXEC SQL AT con1 OPEN cur_1;   

    EXEC SQL AT con1 DECLARE cur_2 CURSOR FOR stmt_1; //★2     ECPGopen() --> ecpg_update_declare_statement()
    EXEC SQL AT con1 OPEN cur_2;                                                  Memory leaks

    EXEC SQL FETCH cur_2 INTO:FooBar, :DooDad;
    EXEC SQL COMMIT;
    EXEC SQL DISCONNECT ALL;


We should free p->cursor_name before p->cursor_name = ecpg_strdup(cursor_name, lineno).
#############################################################################
        if(p->cursor_name)
            ecpg_free(p->cursor_name);
        p->cursor_name = ecpg_strdup(cursor_name,lineno);
###########################################################################
Here is a patch.

Best Regards!