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Support for raw ODBC DSN connections. #54

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Support for raw ODBC DSN connections. #54

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b4afdfb
Support for raw ODBC DSN connections.
blumf Jul 4, 2016
61af46b
BUG: Referencing value after it's popped off stack
blumf Jul 4, 2016
3772f38
Name changed for clarity
blumf Jul 4, 2016
cf4dbf5
Removed unused function
blumf Jul 5, 2016
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128 changes: 115 additions & 13 deletions src/ls_odbc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -576,7 +576,6 @@ static int conn_setautocommit (lua_State *L) {
return pass(L);
}


/*
** Create a new Connection object and push it on top of the stack.
*/
Expand All @@ -601,32 +600,135 @@ static int create_connection (lua_State *L, int o, env_data *env, SQLHDBC hdbc)
return 1;
}

/*
** Uses a DSN string to connect to a ODBC source dynamically
** Lua Input: {
** dsn = <DSN string>,
** }
** Lua Returns:
** connection object if successfull
** nil and error message otherwise.
*/
static int env_table_connect_DSN (lua_State *L)
{
env_data *env = getenvironment (L);
SQLCHAR *sourcename = (SQLCHAR *)luasql_table_optstring(L, 2, "dsn", NULL);

SQLHDBC hdbc;
SQLCHAR sqlOutBuf[4097];
SQLSMALLINT sqlOutLen;
SQLRETURN ret;

ret = SQLSetEnvAttr (env->henv, SQL_ATTR_ODBC_VERSION, (void *)SQL_OV_ODBC3, 0);
if (error(ret)) {
return luasql_faildirect (L, "error setting SQL version.");
}

/* tries to allocate connection handle */
ret = SQLAllocHandle (hDBC, env->henv, &hdbc);
if (error(ret)) {
return luasql_faildirect (L, "connection allocation error.");
}

/* tries to connect handle */
ret = SQLDriverConnect (hdbc, NULL, sourcename, SQL_NTS, sqlOutBuf, 4096,
&sqlOutLen, SQL_DRIVER_NOPROMPT);
if (error(ret)) {
ret = fail(L, hDBC, hdbc);
SQLFreeHandle(hDBC, hdbc);
return ret;
}

/* success, return connection object */
ret = create_connection (L, 1, env, hdbc);
if(ret == 1) {
/* Add the sqlOutBuf string to the results, for diagnostics */
lua_pushlstring(L, (char *)sqlOutBuf, sqlOutLen);
return 2;
}

return ret;
}

/*
** Creates and returns a connection object
** Lua Input: source [, user [, pass]]
** Reforms old connection style to new one
** Lua Input: source, [user, [pass]]
** source: data source
** user, pass: data source authentication information
** Lua Returns:
** new connection details table
*/
static void env_connect_convert_args_to_table (lua_State *L)
{
static const char *const opt_names[] = {
"source",
"user",
"password",
NULL
};
int i, t = lua_gettop(L)-1;

lua_newtable(L);
lua_insert(L, 2);

for(i=0; opt_names[i] != NULL && i<t; ++i) {
lua_pushstring(L, opt_names[i]);
lua_pushvalue(L, i+3);
lua_settable(L, 2);
}

lua_settop(L, 2);
}

/*
** Creates and returns a connection object
** Lua Input: {
** source = <database source/path>,
** user = <user name>,
** password = <user password>,
** or
** dsn = <DSN string>,
** }
** Lua Returns:
** connection object if successfull
** nil and error message otherwise.
*/
static int env_connect (lua_State *L) {
env_data *env = (env_data *) getenvironment (L);
SQLCHAR *sourcename = (SQLCHAR*)luaL_checkstring (L, 2);
SQLCHAR *username = (SQLCHAR*)luaL_optstring (L, 3, NULL);
SQLCHAR *password = (SQLCHAR*)luaL_optstring (L, 4, NULL);
SQLHDBC hdbc;
SQLRETURN ret;
static int env_connect (lua_State *L)
{
env_data *env = getenvironment (L);
SQLCHAR *sourcename = NULL;
SQLCHAR *username = NULL;
SQLCHAR *password = NULL;
SQLHDBC hdbc = NULL;
SQLRETURN ret = 0;

if(lua_gettop(L) < 2) {
return luasql_faildirect(L, "No connection details provided");
}

if(!lua_istable(L, 2)) {
env_connect_convert_args_to_table(L);
}

/* check for the custom DSN connection string */
if(luasql_table_optstring(L, 2, "dsn", NULL) != NULL) {
return env_table_connect_DSN(L);
}

/* get the standard connection details */
sourcename = (SQLCHAR *)luasql_table_optstring(L, 2, "source", NULL);
username = (SQLCHAR *)luasql_table_optstring(L, 2, "user", NULL);
password = (SQLCHAR *)luasql_table_optstring(L, 2, "password", NULL);
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@hishamhm hishamhm Jul 4, 2016 •
edited
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I would just avoid the extra function altogether (and creating a table just to extract its values later), doing this:

    if(lua_istable(L, 2)) {
        /* check for the custom DSN connection string */
        if(luasql_table_optstring(L, 2, "dsn", NULL) != NULL) {
            return env_table_connect_DSN(L);    
        }
        /* get the standard connection details */
        sourcename = (SQLCHAR *)luasql_table_optstring(L, 2, "source", NULL);
        if (!sourcename) {
            return luasql_faildirect (L, "no source given.");
        }
        username = (SQLCHAR *)luasql_table_optstring(L, 2, "user", NULL);
        password = (SQLCHAR *)luasql_table_optstring(L, 2, "password", NULL);
    } else {
        sourcename = (SQLCHAR*)luaL_checkstring (L, 2);
        username = (SQLCHAR*)luaL_optstring (L, 3, NULL);
        password = (SQLCHAR*)luaL_optstring (L, 4, NULL);
    }

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I'd suggest it provides an easy pattern for conversion of the other drivers to the more flexible named parameter style (which this patch shows a good case for)

There's likely going to be additional params added here at some point (e.g. #36) and giving a clear, single place the values are picked up (along with a clear place for backward compatibility) seems a logical arrangement. The function inlines and the overhead of a table is nothing compared to the actual job of connecting to a DB.

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In any case, note that the first argument used luaL_checkstring and in your code it just defaults to NULL. I don't know if this breaks the code that follows below, but I supposed checkstring was used there for a reason.

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The code still works fine (as in the connection fails as expected)


/* tries to allocate connection handle */
ret = SQLAllocHandle (hDBC, env->henv, &hdbc);
if (error(ret))
if (error(ret)) {
return luasql_faildirect (L, "connection allocation error.");
}

/* tries to connect handle */
ret = SQLConnect (hdbc, sourcename, SQL_NTS,
username, SQL_NTS, password, SQL_NTS);
ret = SQLConnect (hdbc, sourcename, SQL_NTS, username, SQL_NTS, password,
SQL_NTS);
if (error(ret)) {
ret = fail(L, hDBC, hdbc);
SQLFreeHandle(hDBC, hdbc);
Expand Down
15 changes: 15 additions & 0 deletions src/luasql.c
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Original file line number Diff line number Diff line change
Expand Up @@ -131,3 +131,18 @@ LUASQL_API void luasql_set_info (lua_State *L) {
lua_pushliteral (L, "LuaSQL 2.3.0");
lua_settable (L, -3);
}

/*
** Pulls an optional string value from the table at idx
*/
LUASQL_API const char* luasql_table_optstring(lua_State *L, int idx, const char* name, const char* def) {
const char* res = NULL;

lua_pushstring(L, name);
lua_gettable(L, idx);

res = lua_tostring(L, -1);
lua_pop(L, 1);

return (res != NULL) ? res : def;
}
3 changes: 3 additions & 0 deletions src/luasql.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,9 @@ LUASQL_API int luasql_createmeta (lua_State *L, const char *name, const luaL_Reg
LUASQL_API void luasql_setmeta (lua_State *L, const char *name);
LUASQL_API void luasql_set_info (lua_State *L);

LUASQL_API const char* luasql_table_optstring(lua_State *L, int idx, const char* name, const char* def);
LUASQL_API lua_Number luasql_table_optnumber(lua_State *L, int idx, const char* name, lua_Number def);

#if !defined LUA_VERSION_NUM || LUA_VERSION_NUM==501
void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);
#endif
Expand Down