| =pod |
| |
| =head1 NAME |
| |
| BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset, |
| BIO_seek, BIO_tell, 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_seek(BIO *b, int ofs); |
| int BIO_tell(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 resets a BIO to some initial state, in the case |
| of file related BIOs for example it rewinds the file pointer to the |
| start of the file. |
| |
| BIO_seek() resets a file related BIO's (that is file descriptor and |
| FILE BIOs) file position pointer to B<ofs> bytes from start of file. |
| |
| BIO_tell() returns the current file position of a file related BIO. |
| |
| 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 characters 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() normally returns 1 for success and 0 or -1 for failure. File |
| BIOs are an exception, they return 0 for success and -1 for failure. |
| |
| BIO_seek() and BIO_tell() both return the current file position on success |
| and -1 for failure, except file BIOs which for BIO_seek() always return 0 |
| for success and -1 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. |
| |
| Filter BIOs if they do not internally handle a particular BIO_ctrl() |
| operation usually pass the operation to the next BIO in the chain. |
| This often means there is no need to locate the required BIO for |
| a particular operation, it can be called on a chain and it will |
| be automatically passed to the relevant BIO. However this can cause |
| unexpected results: for example no current filter BIOs implement |
| BIO_seek(), but this may still succeed if the chain ends in a FILE |
| or file descriptor BIO. |
| |
| Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() |
| operation. |
| |
| =head1 BUGS |
| |
| Some of the return values are ambiguous and care should be taken. In |
| particular a return value of 0 can be returned if an operation is not |
| supported, if an error occurred, if EOF has not been reached and in |
| the case of BIO_seek() on a file BIO for a successful operation. |
| |
| =head1 SEE ALSO |
| |
| TBA |
