openssl/doc/crypto/BIO_ctrl.pod
Richard Levitte 8eec1389fb BIO_seed() and BIO_tell() were documented in two other documents,
which is redundant.  They are now in their own document.

Also, in the name section, all the functions described shoud be
enumerated.  This will also make it much simpler to generate softlinks
name like each function to man-pages containing the info.
2000-09-14 20:24:56 +00:00

96 lines
3.4 KiB
Text

=pod
=head1 NAME
BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset,
BIO_flush, BIO_eof, BIO_set_close, BIO_get_close, BIO_pending,
BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending, BIO_get_info_callback,
BIO_set_info_callback - BIO control operations
=head1 SYNOPSIS
#include <openssl/bio.h>
long BIO_ctrl(BIO *bp,int cmd,long larg,void *parg);
long BIO_callback_ctrl(BIO *b, int cmd, void (*fp)(struct bio_st *, int, const char *, int, long, long));
char * BIO_ptr_ctrl(BIO *bp,int cmd,long larg);
long BIO_int_ctrl(BIO *bp,int cmd,long larg,int iarg);
int BIO_reset(BIO *b);
int BIO_flush(BIO *b);
int BIO_eof(BIO *b);
int BIO_set_close(BIO *b,long flag);
int BIO_get_close(BIO *b);
int BIO_pending(BIO *b);
int BIO_wpending(BIO *b);
size_t BIO_ctrl_pending(BIO *b);
size_t BIO_ctrl_wpending(BIO *b);
int BIO_get_info_callback(BIO *b,bio_info_cb **cbp);
int BIO_set_info_callback(BIO *b,bio_info_cb *cb);
typedef void bio_info_cb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3);
=head1 DESCRIPTION
BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl()
are BIO "control" operations taking arguments of various types.
These functions are not normally called directly, various macros
are used instead. The standard macros are described below, macros
specific to a particular type of BIO are described in the specific
BIOs manual page as well as any special features of the standard
calls.
BIO_reset() typically reset a BIO to some initial state, in the case
of file related BIOs for example it rewinds the file pointer.
BIO_flush() normally writes out any internally buffered data, in some
cases it is used to signal EOF and that no more data will be written.
BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of
"EOF" varies according to the BIO type.
BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can
take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used
in a source/sink BIO to indicate that the underlying I/O stream should
be closed when the BIO is freed.
BIO_get_close() returns the BIOs close flag.
BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
return the number of pending characterers in the BIOs read and write buffers.
Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending()
return a size_t type and are functions, BIO_pending() and BIO_wpending() are
macros which call BIO_ctrl().
=head1 RETURN VALUES
BIO_reset() returns 1 fo success and 0 for failure.
BIO_flush() returns 1 for success and 0 or -1 for failure.
BIO_eof() returns 1 if EOF has been reached 0 otherwise.
BIO_set_close() always returns 1.
BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE.
BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
return the amount of pending data.
=head1 NOTES
BIO_flush(), because it can write data may return 0 or -1 indicating
that the call should be retried later in a similar manner to BIO_write().
The BIO_should_retry() call should be used and appropriate action taken
is the call fails.
The return values of BIO_pending() and BIO_wpending() may not reliably
determine the amount of pending data in all cases. For example in the
case of a file BIO some data may be available in the FILE structures
internal buffers but it is not possible to determine this in a
portably way. For other types of BIO they may not be supported.
=head1 SEE ALSO
TBA