mirror of https://github.com/openssl/openssl.git
169 lines
4.7 KiB
Plaintext
169 lines
4.7 KiB
Plaintext
=pod
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=head1 NAME
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BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
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BIO_read_filename, BIO_write_filename, BIO_append_filename,
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BIO_rw_filename - FILE bio
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=head1 SYNOPSIS
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#include <openssl/bio.h>
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const BIO_METHOD *BIO_s_file(void);
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BIO *BIO_new_file(const char *filename, const char *mode);
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BIO *BIO_new_fp(FILE *stream, int flags);
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BIO_set_fp(BIO *b, FILE *fp, int flags);
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BIO_get_fp(BIO *b, FILE **fpp);
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int BIO_read_filename(BIO *b, char *name);
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int BIO_write_filename(BIO *b, char *name);
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int BIO_append_filename(BIO *b, char *name);
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int BIO_rw_filename(BIO *b, char *name);
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=head1 DESCRIPTION
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BIO_s_file() returns the BIO file method. As its name implies it
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is a wrapper round the stdio FILE structure and it is a
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source/sink BIO.
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Calls to BIO_read_ex() and BIO_write_ex() read and write data to the
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underlying stream. BIO_gets() and BIO_puts() are supported on file BIOs.
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BIO_flush() on a file BIO calls the fflush() function on the wrapped
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stream.
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BIO_reset() attempts to change the file pointer to the start of file
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using fseek(stream, 0, 0).
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BIO_seek() sets the file pointer to position B<ofs> from start of file
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using fseek(stream, ofs, 0).
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BIO_eof() calls feof().
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Setting the BIO_CLOSE flag calls fclose() on the stream when the BIO
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is freed.
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BIO_new_file() creates a new file BIO with mode B<mode> the meaning
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of B<mode> is the same as the stdio function fopen(). The BIO_CLOSE
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flag is set on the returned BIO.
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BIO_new_fp() creates a file BIO wrapping B<stream>. Flags can be:
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BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
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stream to text mode, default is binary: this only has any effect under
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Win32).
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BIO_set_fp() sets the fp of a file BIO to B<fp>. B<flags> has the same
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meaning as in BIO_new_fp(), it is a macro.
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BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
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BIO_seek() is a macro that sets the position pointer to B<offset> bytes
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from the start of file.
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BIO_tell() returns the value of the position pointer.
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BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
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BIO_rw_filename() set the file BIO B<b> to use file B<name> for
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reading, writing, append or read write respectively.
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=head1 NOTES
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When wrapping stdout, stdin or stderr the underlying stream should not
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normally be closed so the BIO_NOCLOSE flag should be set.
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Because the file BIO calls the underlying stdio functions any quirks
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in stdio behaviour will be mirrored by the corresponding BIO.
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On Windows BIO_new_files reserves for the filename argument to be
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UTF-8 encoded. In other words if you have to make it work in multi-
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lingual environment, encode filenames in UTF-8.
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=head1 RETURN VALUES
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BIO_s_file() returns the file BIO method.
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BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error
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occurred.
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BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure
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(although the current implementation never return 0).
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BIO_seek() returns the same value as the underlying fseek() function:
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0 for success or -1 for failure.
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BIO_tell() returns the current file position.
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BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
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BIO_rw_filename() return 1 for success or 0 for failure.
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=head1 EXAMPLES
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File BIO "hello world":
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BIO *bio_out;
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bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
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BIO_printf(bio_out, "Hello World\n");
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Alternative technique:
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BIO *bio_out;
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bio_out = BIO_new(BIO_s_file());
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if (bio_out == NULL)
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/* Error */
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if (!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE))
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/* Error */
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BIO_printf(bio_out, "Hello World\n");
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Write to a file:
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BIO *out;
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out = BIO_new_file("filename.txt", "w");
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if (!out)
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/* Error */
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BIO_printf(out, "Hello World\n");
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BIO_free(out);
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Alternative technique:
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BIO *out;
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out = BIO_new(BIO_s_file());
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if (out == NULL)
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/* Error */
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if (!BIO_write_filename(out, "filename.txt"))
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/* Error */
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BIO_printf(out, "Hello World\n");
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BIO_free(out);
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=head1 BUGS
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BIO_reset() and BIO_seek() are implemented using fseek() on the underlying
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stream. The return value for fseek() is 0 for success or -1 if an error
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occurred this differs from other types of BIO which will typically return
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1 for success and a non positive value if an error occurred.
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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_flush(3)>,
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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 2000-2020 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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