void mysql_set_local_infile_handler(MYSQL *mysql, int
(*local_infile_init)(void **, const char *, void *), int
(*local_infile_read)(void *, char *, unsigned int), void
(*local_infile_end)(void *), int (*local_infile_error)(void *,
char*, unsigned int), void *userdata);
This function installs callbacks to be used during the
DATA LOCAL statements. It enables application
programs to exert control over local (client-side) data file
reading. The arguments are the connection handler, a set of
pointers to callback functions, and a pointer to a data area
that the callbacks can use to share information.
you must write the following callback functions:
int local_infile_init(void **ptr, const char *filename, void *userdata);
The initialization function. This is called once to do any
setup necessary, open the data file, allocate data structures,
and so forth. The first
void** argument is
a pointer to a pointer. You can set the pointer (that is,
*ptr) to a value that will be passed to
each of the other callbacks (as a
The callbacks can use this pointed-to value to maintain state
userdata argument is the
same value that is passed to
Make the initialization function return zero for success, nonzero for an error.
int local_infile_read(void *ptr, char *buf, unsigned int buf_len);
The data-reading function. This is called repeatedly to read
the data file.
buf points to the buffer
where the read data is stored, and
is the maximum number of bytes that the callback can read and
store in the buffer. (It can read fewer bytes, but should not
The return value is the number of bytes read, or zero when no more data could be read (this indicates EOF). Return a value less than zero if an error occurs.
void local_infile_end(void *ptr)
The termination function. This is called once after
local_infile_read() has returned zero (EOF)
or an error. Within this function, deallocate any memory
perform any other cleanup necessary. It is invoked even if the
initialization function returns an error.
int local_infile_error(void *ptr, char *error_msg, unsigned int error_msg_len);
The error-handling function. This is called to get a textual
error message to return to the user in case any of your other
functions returns an error.
points to the buffer into which the message is written, and
error_msg_len is the length of the buffer.
Write the message as a null-terminated string, at most
error_msg_len−1 bytes long.
The return value is the error number.
Typically, the other callbacks store the error message in the
data structure pointed to by
ptr, so that
local_infile_error() can copy the message
from there into
in your C code and passing pointers to your callback
functions, you can then issue a
LOCAL statement (for example, by using
mysql_query()). The client
library automatically invokes your callbacks. The file name
DATA LOCAL will be passed as the second parameter to