BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO
#include <openssl/bio.h> const BIO_METHOD *BIO_s_fd(void); int BIO_set_fd(BIO *b, int fd, int c); int BIO_get_fd(BIO *b, int *c); BIO *BIO_new_fd(int fd, int close_flag);
BIO_s_fd() returns the file descriptor BIO method. This is a wrapper round the platforms file descriptor routines such as read() and write().
BIO_read_ex() and BIO_write_ex() read or write the underlying descriptor. BIO_puts() is supported but BIO_gets() is not.
If the close flag is set then close() is called on the underlying file descriptor when the BIO is freed.
BIO_reset() attempts to change the file pointer to the start of file such as by using lseek(fd, 0, 0).
BIO_seek() sets the file pointer to position ofs from start of file such as by using lseek(fd, ofs, 0).
BIO_tell() returns the current file position such as by calling lseek(fd, 0, 1).
BIO_set_fd() sets the file descriptor of BIO b to fd and the close flag to c.
BIO_get_fd() places the file descriptor of BIO b in c if it is not NULL. It also returns the file descriptor.
BIO_new_fd() returns a file descriptor BIO using fd and close_flag.
The behaviour of BIO_read_ex() and BIO_write_ex() depends on the behavior of the platforms read() and write() calls on the descriptor. If the underlying file descriptor is in a non blocking mode then the BIO will behave in the manner described in the BIO_read_ex(3) and BIO_should_retry(3) manual pages.
File descriptor BIOs should not be used for socket I/O. Use socket BIOs instead.
BIO_set_fd() and BIO_get_fd() are implemented as macros.
BIO_s_fd() returns the file descriptor BIO method.
BIO_set_fd() returns 1 on success or <=0 for failure.
BIO_get_fd() returns the file descriptor or -1 if the BIO has not been initialized. It also returns zero and negative values if other error occurs.
BIO_new_fd() returns the newly allocated BIO or NULL is an error occurred.
This is a file descriptor BIO version of "Hello World":
BIO *out; out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE); BIO_printf(out, "Hello World\n"); BIO_free(out);
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