db-lib
for self-help.
More...Functions | |
int | _dblib_client_msg (DBPROCESS *dbproc, int dberr, int severity, const char *dberrstr) |
Pass a server-generated error message to the client's installed handler. | |
RETCODE | dbcmdrow (DBPROCESS *dbproc) |
See if the current command can return rows. | |
DBINT | dbcount (DBPROCESS *dbproc) |
Get count of rows processed. | |
int | dbcurcmd (DBPROCESS *dbproc) |
Get number of the row just returned. | |
DBINT | dbcurrow (DBPROCESS *dbproc) |
Get number of the row currently being read. | |
DBBOOL | dbdead (DBPROCESS *dbproc) |
Check if dbproc is an ex-parrot. | |
DBINT | dbfirstrow (DBPROCESS *dbproc) |
Get number of the first row in the row buffer. | |
int | dbiordesc (DBPROCESS *dbproc) |
Get file descriptor of the socket used by a DBPROCESS to read data coming from the server. (!). | |
int | dbiowdesc (DBPROCESS *dbproc) |
Get file descriptor of the socket used by a DBPROCESS to write data coming to the server. (!). | |
DBINT | dblastrow (DBPROCESS *dbproc) |
Get number of the last row in the row buffer. | |
int | dbperror (DBPROCESS *dbproc, DBINT msgno, int errnum) |
Call client-installed error handler. | |
RETCODE | dbrows (DBPROCESS *dbproc) |
Indicate whether a query returned rows. | |
STATUS | dbrowtype (DBPROCESS *dbproc) |
Get returned row's type. | |
void | dbsetavail (DBPROCESS *dbproc) |
Mark a DBPROCESS as "available". | |
int | dbtds (DBPROCESS *dbproc) |
Get the TDS version in use for dbproc. | |
DBPROCESS * | tdsdbopen (LOGINREC *login, char *server, int msdblib) |
Form a connection with the server. |
db-lib
for self-help.
These functions are of interest only to people hacking on the FreeTDS db-lib implementation.
int _dblib_client_msg | ( | DBPROCESS * | dbproc, | |
int | dberr, | |||
int | severity, | |||
const char * | dberrstr | |||
) |
Pass a server-generated error message to the client's installed handler.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. | |
dberr | error number | |
severity | severity level | |
dberrstr | null-terminated ASCII string, the error message. |
RETCODE dbcmdrow | ( | DBPROCESS * | dbproc | ) |
See if the current command can return rows.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
SUCCEED | Yes, it can. | |
FAIL | No, it can't. |
DBINT dbcount | ( | DBPROCESS * | dbproc | ) |
Get count of rows processed.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
int dbcurcmd | ( | DBPROCESS * | dbproc | ) |
Get number of the row just returned.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
DBINT dbcurrow | ( | DBPROCESS * | dbproc | ) |
Get number of the row currently being read.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
0 | Always. |
DBBOOL dbdead | ( | DBPROCESS * | dbproc | ) |
Check if dbproc is an ex-parrot.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
TRUE | process has been marked dead. | |
FALSE | process is OK. |
FALSE
. DBINT dbfirstrow | ( | DBPROCESS * | dbproc | ) |
Get number of the first row in the row buffer.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
int dbiordesc | ( | DBPROCESS * | dbproc | ) |
Get file descriptor of the socket used by a DBPROCESS
to read data coming from the server. (!).
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
int dbiowdesc | ( | DBPROCESS * | dbproc | ) |
Get file descriptor of the socket used by a DBPROCESS
to write data coming to the server. (!).
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
DBINT dblastrow | ( | DBPROCESS * | dbproc | ) |
Get number of the last row in the row buffer.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
int dbperror | ( | DBPROCESS * | dbproc, | |
DBINT | msgno, | |||
int | errnum | |||
) |
Call client-installed error handler.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. | |
msgno | identifies the error message to be passed to the client's handler. | |
errnum | identifies the OS error (errno), if any. Use 0 if not applicable. |
Instead of sprinkling error text all over db-lib, we consolidate it here, where it can be translated (one day), and where it can be mapped to the TDS error number. The libraries don't use consistent error numbers or messages, so when libtds has to emit an error message, it can't include the text. It can pass its error number to a client-library function, which will interpret it, add the text, call the application's installed handler (if any) and return the handler's return code back to the caller.
The call stack may look something like this:
The error handling in this case is unambiguous: the caller invokes this function, the client's handler returns its instruction, which the caller receives. Quite often the caller will get INT_CANCEL, in which case it should put its house in order and return FAIL.
The call stack may otherwise look something like this:
Here libtds invokes the client's handler. Because different client libraries specify their handler semantics differently, and because libtds doesn't know which client library is in charge of any given connection, it cannot interpret the raw return code. Similarly, the libtds error message number will not be in the db-lib msgno list. For these reasons, libtds calls _dblib_handle_err_message which translates between libtds and db-lib semantics.
RETCODE dbrows | ( | DBPROCESS * | dbproc | ) |
Indicate whether a query returned rows.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
STATUS dbrowtype | ( | DBPROCESS * | dbproc | ) |
Get returned row's type.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
void dbsetavail | ( | DBPROCESS * | dbproc | ) |
Mark a DBPROCESS
as "available".
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
FreeTDS
behaves the way Sybase's implementation does, but so what? Many db-lib
functions set the DBPROCESS
to "not available", but only dbsetavail() resets it to "available". int dbtds | ( | DBPROCESS * | dbproc | ) |
Get the TDS version in use for dbproc.
For internal use only.
dbproc | contains all information needed by db-lib to manage communications with the server. |
DBTDS*
token. DBPROCESS* tdsdbopen | ( | LOGINREC * | login, | |
char * | server, | |||
int | msdblib | |||
) |
Form a connection with the server.
For internal use only.
Called by the dbopen()
macro, normally. If FreeTDS was configured with --enable-msdblib
, this function is called by (exported) dbopen()
function. tdsdbopen
is so-named to avoid namespace conflicts with other database libraries that use the same function name.
login | LOGINREC* carrying the account information. | |
server | name of the dataserver to connect to. |
NULL | insufficient memory, unable to connect for any reason. |
asprintf()
to avoid buffer overflow. separate error messages for no-such-server and no-such-user.