mirror of https://github.com/openssl/openssl
99 lines
2.7 KiB
Plaintext
99 lines
2.7 KiB
Plaintext
=pod
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=head1 NAME
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BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO
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=head1 SYNOPSIS
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#include <openssl/bio.h>
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const BIO_METHOD *BIO_s_fd(void);
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int BIO_set_fd(BIO *b, int fd, int c);
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int BIO_get_fd(BIO *b, int *c);
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BIO *BIO_new_fd(int fd, int close_flag);
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=head1 DESCRIPTION
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BIO_s_fd() returns the file descriptor BIO method. This is a wrapper
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round the platforms file descriptor routines such as read() and write().
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BIO_read_ex() and BIO_write_ex() read or write the underlying descriptor.
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BIO_puts() is supported but BIO_gets() is not.
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If the close flag is set then close() is called on the underlying
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file descriptor when the BIO is freed.
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BIO_reset() attempts to change the file pointer to the start of file
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such as by using B<lseek(fd, 0, 0)>.
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BIO_seek() sets the file pointer to position B<ofs> from start of file
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such as by using B<lseek(fd, ofs, 0)>.
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BIO_tell() returns the current file position such as by calling
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B<lseek(fd, 0, 1)>.
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BIO_set_fd() sets the file descriptor of BIO B<b> to B<fd> and the close
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flag to B<c>.
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BIO_get_fd() places the file descriptor of BIO B<b> in B<c> if it is not NULL.
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It also returns the file descriptor.
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BIO_new_fd() returns a file descriptor BIO using B<fd> and B<close_flag>.
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=head1 NOTES
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The behaviour of BIO_read_ex() and BIO_write_ex() depends on the behavior of the
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platforms read() and write() calls on the descriptor. If the underlying
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file descriptor is in a non blocking mode then the BIO will behave in the
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manner described in the L<BIO_read_ex(3)> and L<BIO_should_retry(3)>
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manual pages.
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File descriptor BIOs should not be used for socket I/O. Use socket BIOs
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instead.
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BIO_set_fd() and BIO_get_fd() are implemented as macros.
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=head1 RETURN VALUES
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BIO_s_fd() returns the file descriptor BIO method.
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BIO_set_fd() returns 1 on success or <=0 for failure.
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BIO_get_fd() returns the file descriptor or -1 if the BIO has not
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been initialized. It also returns zero and negative values if other error occurs.
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BIO_new_fd() returns the newly allocated BIO or NULL is an error
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occurred.
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=head1 EXAMPLES
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This is a file descriptor BIO version of "Hello World":
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BIO *out;
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out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
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BIO_printf(out, "Hello World\n");
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BIO_free(out);
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=head1 SEE ALSO
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L<BIO_seek(3)>, L<BIO_tell(3)>,
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L<BIO_reset(3)>, L<BIO_read_ex(3)>,
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L<BIO_write_ex(3)>, L<BIO_puts(3)>,
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L<BIO_gets(3)>, L<BIO_printf(3)>,
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L<BIO_set_close(3)>, L<BIO_get_close(3)>
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=head1 COPYRIGHT
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Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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