--- /dev/null
+=pod
+
+=head1 NAME
+
+ BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl - 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
All these functions return either the amount of data successfully read or
written (if the return value is positive) or that no data was successfully
-read or written (if the result is zero or negative).
+read or written if the result is 0 or -1. If the return value is -2 then
+the operation is not implemented in the specific BIO type.
=head1 NOTES
-A negative or zero return is not necessarily an indication of an error. In
+A 0 or -1 return is not necessarily an indication of an error. In
particular when the source/sink is non-blocking or of a certain type (for
example an SSL BIO can retry even if the underlying connection is blocking)
it may merely be an indication that no data is currently available and that
--- /dev/null
+=pod
+
+=head1 NAME
+
+ BIO_set_callback, BIO_get_callback - BIO callback
+
+=head1 SYNOPSIS
+
+ #include <openssl/bio.h>
+
+ #define BIO_set_callback(b,cb) ((b)->callback=(cb))
+ #define BIO_get_callback(b) ((b)->callback)
+ #define BIO_set_callback_arg(b,arg) ((b)->cb_arg=(char *)(arg))
+ #define BIO_get_callback_arg(b) ((b)->cb_arg)
+
+ long BIO_debug_callback(BIO *bio,int cmd,const char *argp,int argi,
+ long argl,long ret);
+
+ typedef long callback(BIO *b, int oper, const char *argp,
+ int argi, long argl, long retvalue);
+
+=head1 DESCRIPTION
+
+BIO_set_callback() and BIO_get_callback() set and retrieve the BIO callback,
+they are both macros. The callback is called during most high level BIO
+operations. It can be used for debugging purposes to trace operations on
+a BIO or to modify its operation.
+
+BIO_set_callback_arg() and BIO_get_callback_arg() are macros which can be
+used to set and retrieve an argument for use in the callback.
+
+BIO_debug_callback() is a standard debugging callback which prints
+out information relating to each BIO operation. If the callback
+argument is set if is interpreted as a BIO to send the information
+to, otherwise stderr is used.
+
+callback() is the callback function itself. The meaning of each
+argument is described below.
+
+The BIO the callback is attached to is passed in B<b>.
+
+B<oper> is set to the operation being performed. For some operations
+the callback is called twice, once before and once after the actual
+operation, the latter case has B<oper> or'ed with BIO_CB_RETURN.
+
+The meaning of the arguments B<argp>, B<argi> and B<argl> depends on
+the value of B<oper>, that is the operation being performed.
+
+B<retvalue> is the return value that would be returned to the
+application if no callback were present. The actual value returned
+is the return value of the callback itself. In the case of callbacks
+called before the actual BIO operation 1 is placed in retvalue, if
+the return value is not positive it will be immediately returned to
+the application and the BIO operation will not be performed.
+
+The callback should normally simply return B<retvalue> when it has
+finished processing, unless if specifically wishes to modify the
+value returned to the application.
+
+=head1 CALLBACK OPERATIONS
+
+=over 4
+
+=item B<BIO_free(b)>
+
+callback(b, BIO_CB_FREE, NULL, 0L, 0L, 1L) is called before the
+free operation.
+
+=item B<BIO_read(b, out, outl)>
+
+callback(b, BIO_CB_READ, out, outl, 0L, 1L) is called before
+the read and callback(b, BIO_CB_READ|BIO_CB_RETURN, out, outl, 0L, retvalue)
+after.
+
+=item B<BIO_write(b, in, inl)>
+
+callback(b, BIO_CB_WRITE, in, inl, 0L, 1L) is called before
+the write and callback(b, BIO_CB_WRITE|BIO_CB_RETURN, in, inl, 0L, retvalue)
+after.
+
+=item B<BIO_gets(b, out, outl)>
+
+callback(b, BIO_CB_GETS, out, outl, 0L, 1L) is called before
+the operation and callback(b, BIO_CB_GETS|BIO_CB_RETURN, out, outl, 0L, retvalue)
+after.
+
+=item B<BIO_puts(b, in)>
+
+callback(b, BIO_CB_WRITE, in, 0, 0L, 1L) is called before
+the operation and callback(b, BIO_CB_WRITE|BIO_CB_RETURN, in, 0, 0L, retvalue)
+after.
+
+=item B<BIO_ctrl(BIO *b, int cmd, long larg, void *parg)>
+
+callback(b,BIO_CB_CTRL,parg,cmd,larg,1L) is called before the call and
+callback(b,BIO_CB_CTRL|BIO_CB_RETURN,parg,cmd, larg,ret) after.
+
+=back
+
+=head1 EXAMPLE
+
+The BIO_debug_callback() function is a good example, its source is
+in crypto/bio/bio_cb.c
+
+=head1 SEE ALSO
+
+TBA
} while((len <= 0) && BIO_should_retry(bio));
While an application may retry a failed non blocking call immediately
-this is likely to be very inefficient because the call is likely to
-fail repeatedly until data can be processed. An application will normally
-wait until the necessary condition is satisfied. How this is done depends
-on the underlying I/O structure.
+this is likely to be very inefficient because the call will fail
+repeatedly until data can be processed or is available. An application
+will normally wait until the necessary condition is satisfied. How
+this is done depends on the underlying I/O structure.
For example if the cause is ultimately a socket and BIO_should_read()
is true then a call to select() may be made to wait until data is
been read.
It is possible for a BIO to block indefinitely if the underlying I/O
-structure cannot process the data. This depends on the behaviour of
+structure cannot process or return any data. This depends on the behaviour of
the platforms I/O functions. This is often not desirable: one solution
is to use non blocking I/O and use a timeout on the select() (or
equivalent) call.
projects / oweals / openssl.git / commitdiff