1*2175Sjp161948=pod 2*2175Sjp161948 3*2175Sjp161948=head1 NAME 4*2175Sjp161948 5*2175Sjp161948BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset, 6*2175Sjp161948BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close, 7*2175Sjp161948BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending, 8*2175Sjp161948BIO_get_info_callback, BIO_set_info_callback - BIO control operations 9*2175Sjp161948 10*2175Sjp161948=head1 SYNOPSIS 11*2175Sjp161948 12*2175Sjp161948 #include <openssl/bio.h> 13*2175Sjp161948 14*2175Sjp161948 long BIO_ctrl(BIO *bp,int cmd,long larg,void *parg); 15*2175Sjp161948 long BIO_callback_ctrl(BIO *b, int cmd, void (*fp)(struct bio_st *, int, const char *, int, long, long)); 16*2175Sjp161948 char * BIO_ptr_ctrl(BIO *bp,int cmd,long larg); 17*2175Sjp161948 long BIO_int_ctrl(BIO *bp,int cmd,long larg,int iarg); 18*2175Sjp161948 19*2175Sjp161948 int BIO_reset(BIO *b); 20*2175Sjp161948 int BIO_seek(BIO *b, int ofs); 21*2175Sjp161948 int BIO_tell(BIO *b); 22*2175Sjp161948 int BIO_flush(BIO *b); 23*2175Sjp161948 int BIO_eof(BIO *b); 24*2175Sjp161948 int BIO_set_close(BIO *b,long flag); 25*2175Sjp161948 int BIO_get_close(BIO *b); 26*2175Sjp161948 int BIO_pending(BIO *b); 27*2175Sjp161948 int BIO_wpending(BIO *b); 28*2175Sjp161948 size_t BIO_ctrl_pending(BIO *b); 29*2175Sjp161948 size_t BIO_ctrl_wpending(BIO *b); 30*2175Sjp161948 31*2175Sjp161948 int BIO_get_info_callback(BIO *b,bio_info_cb **cbp); 32*2175Sjp161948 int BIO_set_info_callback(BIO *b,bio_info_cb *cb); 33*2175Sjp161948 34*2175Sjp161948 typedef void bio_info_cb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3); 35*2175Sjp161948 36*2175Sjp161948=head1 DESCRIPTION 37*2175Sjp161948 38*2175Sjp161948BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl() 39*2175Sjp161948are BIO "control" operations taking arguments of various types. 40*2175Sjp161948These functions are not normally called directly, various macros 41*2175Sjp161948are used instead. The standard macros are described below, macros 42*2175Sjp161948specific to a particular type of BIO are described in the specific 43*2175Sjp161948BIOs manual page as well as any special features of the standard 44*2175Sjp161948calls. 45*2175Sjp161948 46*2175Sjp161948BIO_reset() typically resets a BIO to some initial state, in the case 47*2175Sjp161948of file related BIOs for example it rewinds the file pointer to the 48*2175Sjp161948start of the file. 49*2175Sjp161948 50*2175Sjp161948BIO_seek() resets a file related BIO's (that is file descriptor and 51*2175Sjp161948FILE BIOs) file position pointer to B<ofs> bytes from start of file. 52*2175Sjp161948 53*2175Sjp161948BIO_tell() returns the current file position of a file related BIO. 54*2175Sjp161948 55*2175Sjp161948BIO_flush() normally writes out any internally buffered data, in some 56*2175Sjp161948cases it is used to signal EOF and that no more data will be written. 57*2175Sjp161948 58*2175Sjp161948BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of 59*2175Sjp161948"EOF" varies according to the BIO type. 60*2175Sjp161948 61*2175Sjp161948BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can 62*2175Sjp161948take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used 63*2175Sjp161948in a source/sink BIO to indicate that the underlying I/O stream should 64*2175Sjp161948be closed when the BIO is freed. 65*2175Sjp161948 66*2175Sjp161948BIO_get_close() returns the BIOs close flag. 67*2175Sjp161948 68*2175Sjp161948BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() 69*2175Sjp161948return the number of pending characters in the BIOs read and write buffers. 70*2175Sjp161948Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending() 71*2175Sjp161948return a size_t type and are functions, BIO_pending() and BIO_wpending() are 72*2175Sjp161948macros which call BIO_ctrl(). 73*2175Sjp161948 74*2175Sjp161948=head1 RETURN VALUES 75*2175Sjp161948 76*2175Sjp161948BIO_reset() normally returns 1 for success and 0 or -1 for failure. File 77*2175Sjp161948BIOs are an exception, they return 0 for success and -1 for failure. 78*2175Sjp161948 79*2175Sjp161948BIO_seek() and BIO_tell() both return the current file position on success 80*2175Sjp161948and -1 for failure, except file BIOs which for BIO_seek() always return 0 81*2175Sjp161948for success and -1 for failure. 82*2175Sjp161948 83*2175Sjp161948BIO_flush() returns 1 for success and 0 or -1 for failure. 84*2175Sjp161948 85*2175Sjp161948BIO_eof() returns 1 if EOF has been reached 0 otherwise. 86*2175Sjp161948 87*2175Sjp161948BIO_set_close() always returns 1. 88*2175Sjp161948 89*2175Sjp161948BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. 90*2175Sjp161948 91*2175Sjp161948BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending() 92*2175Sjp161948return the amount of pending data. 93*2175Sjp161948 94*2175Sjp161948=head1 NOTES 95*2175Sjp161948 96*2175Sjp161948BIO_flush(), because it can write data may return 0 or -1 indicating 97*2175Sjp161948that the call should be retried later in a similar manner to BIO_write(). 98*2175Sjp161948The BIO_should_retry() call should be used and appropriate action taken 99*2175Sjp161948is the call fails. 100*2175Sjp161948 101*2175Sjp161948The return values of BIO_pending() and BIO_wpending() may not reliably 102*2175Sjp161948determine the amount of pending data in all cases. For example in the 103*2175Sjp161948case of a file BIO some data may be available in the FILE structures 104*2175Sjp161948internal buffers but it is not possible to determine this in a 105*2175Sjp161948portably way. For other types of BIO they may not be supported. 106*2175Sjp161948 107*2175Sjp161948Filter BIOs if they do not internally handle a particular BIO_ctrl() 108*2175Sjp161948operation usually pass the operation to the next BIO in the chain. 109*2175Sjp161948This often means there is no need to locate the required BIO for 110*2175Sjp161948a particular operation, it can be called on a chain and it will 111*2175Sjp161948be automatically passed to the relevant BIO. However this can cause 112*2175Sjp161948unexpected results: for example no current filter BIOs implement 113*2175Sjp161948BIO_seek(), but this may still succeed if the chain ends in a FILE 114*2175Sjp161948or file descriptor BIO. 115*2175Sjp161948 116*2175Sjp161948Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() 117*2175Sjp161948operation. 118*2175Sjp161948 119*2175Sjp161948=head1 BUGS 120*2175Sjp161948 121*2175Sjp161948Some of the return values are ambiguous and care should be taken. In 122*2175Sjp161948particular a return value of 0 can be returned if an operation is not 123*2175Sjp161948supported, if an error occurred, if EOF has not been reached and in 124*2175Sjp161948the case of BIO_seek() on a file BIO for a successful operation. 125*2175Sjp161948 126*2175Sjp161948=head1 SEE ALSO 127*2175Sjp161948 128*2175Sjp161948TBA 129