X-Git-Url: https://git.openssl.org/gitweb/?a=blobdiff_plain;f=doc%2Fcrypto%2FBIO_ctrl.pod;h=722e8b8f46c9c5b202bb4283338e7411d582f2d7;hb=fde2257f055f187e8e78542ea6d64ad6c206d10b;hp=421a3ac1cbd75a8a69aa3c759d9777db9cfa14ac;hpb=1e4e5492966007268485920a56613b9c6893f237;p=openssl.git diff --git a/doc/crypto/BIO_ctrl.pod b/doc/crypto/BIO_ctrl.pod index 421a3ac1cb..722e8b8f46 100644 --- a/doc/crypto/BIO_ctrl.pod +++ b/doc/crypto/BIO_ctrl.pod @@ -3,9 +3,9 @@ =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 +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 @@ -17,6 +17,8 @@ BIO_set_info_callback - BIO control operations 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); @@ -41,8 +43,14 @@ 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_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 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. @@ -65,7 +73,12 @@ macros which call BIO_ctrl(). =head1 RETURN VALUES -BIO_reset() returns 1 for success and 0 for failure. +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. @@ -91,14 +104,24 @@ 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 the do not internally handle a particular BIO_ctrl() +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. +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 -Source/sink BIOs will return an error if the do not recognize the -BIO_ctrl() operation. +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