5 BIO_read, BIO_write, BIO_gets, BIO_puts - BIO I/O functions
9 #include <openssl/bio.h>
11 int BIO_read(BIO *b, void *buf, int len);
12 int BIO_gets(BIO *b,char *buf, int size);
13 int BIO_write(BIO *b, const void *buf, int len);
14 int BIO_puts(BIO *b,const char *buf);
18 BIO_read() attempts to read B<len> bytes from BIO B<b> and places
21 BIO_gets() performs the BIOs "gets" operation and places the data
22 in B<buf>. Usually this operation will attempt to read a line of data
23 from the BIO of maximum length B<len>. There are exceptions to this
24 however, for example BIO_gets() on a digest BIO will calculate and
25 return the digest and other BIOs may not support BIO_gets() at all.
27 BIO_write() attempts to write B<len> bytes from B<buf> to BIO B<b>.
29 BIO_puts() attempts to write a null terminated string B<buf> to BIO B<b>
33 All these functions return either the amount of data successfully read or
34 written (if the return value is positive) or that no data was successfully
35 read or written if the result is 0 or -1. If the return value is -2 then
36 the operation is not implemented in the specific BIO type.
40 A 0 or -1 return is not necessarily an indication of an error. In
41 particular when the source/sink is non-blocking or of a certain type (for
42 example an SSL BIO can retry even if the underlying connection is blocking)
43 it may merely be an indication that no data is currently available and that
44 the application should retry the operation later. L<BIO_should_retry(3)|BIO_should_retry(3)>
45 can be called to determine the precise cause.
47 If the BIO_gets() function is not supported by a BIO then it possible to
48 work around this by adding a buffering BIO L<BIO_f_buffer(3)|BIO_f_buffer(3)>