BIO_s_file.pod 4.7 KB

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  1. =pod
  2. =head1 NAME
  3. BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
  4. BIO_read_filename, BIO_write_filename, BIO_append_filename,
  5. BIO_rw_filename - FILE bio
  6. =head1 SYNOPSIS
  7. #include <openssl/bio.h>
  8. const BIO_METHOD *BIO_s_file(void);
  9. BIO *BIO_new_file(const char *filename, const char *mode);
  10. BIO *BIO_new_fp(FILE *stream, int flags);
  11. BIO_set_fp(BIO *b, FILE *fp, int flags);
  12. BIO_get_fp(BIO *b, FILE **fpp);
  13. int BIO_read_filename(BIO *b, char *name)
  14. int BIO_write_filename(BIO *b, char *name)
  15. int BIO_append_filename(BIO *b, char *name)
  16. int BIO_rw_filename(BIO *b, char *name)
  17. =head1 DESCRIPTION
  18. BIO_s_file() returns the BIO file method. As its name implies it
  19. is a wrapper round the stdio FILE structure and it is a
  20. source/sink BIO.
  21. Calls to BIO_read_ex() and BIO_write_ex() read and write data to the
  22. underlying stream. BIO_gets() and BIO_puts() are supported on file BIOs.
  23. BIO_flush() on a file BIO calls the fflush() function on the wrapped
  24. stream.
  25. BIO_reset() attempts to change the file pointer to the start of file
  26. using fseek(stream, 0, 0).
  27. BIO_seek() sets the file pointer to position B<ofs> from start of file
  28. using fseek(stream, ofs, 0).
  29. BIO_eof() calls feof().
  30. Setting the BIO_CLOSE flag calls fclose() on the stream when the BIO
  31. is freed.
  32. BIO_new_file() creates a new file BIO with mode B<mode> the meaning
  33. of B<mode> is the same as the stdio function fopen(). The BIO_CLOSE
  34. flag is set on the returned BIO.
  35. BIO_new_fp() creates a file BIO wrapping B<stream>. Flags can be:
  36. BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
  37. stream to text mode, default is binary: this only has any effect under
  38. Win32).
  39. BIO_set_fp() set the fp of a file BIO to B<fp>. B<flags> has the same
  40. meaning as in BIO_new_fp(), it is a macro.
  41. BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
  42. BIO_seek() is a macro that sets the position pointer to B<offset> bytes
  43. from the start of file.
  44. BIO_tell() returns the value of the position pointer.
  45. BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
  46. BIO_rw_filename() set the file BIO B<b> to use file B<name> for
  47. reading, writing, append or read write respectively.
  48. =head1 NOTES
  49. When wrapping stdout, stdin or stderr the underlying stream should not
  50. normally be closed so the BIO_NOCLOSE flag should be set.
  51. Because the file BIO calls the underlying stdio functions any quirks
  52. in stdio behaviour will be mirrored by the corresponding BIO.
  53. On Windows BIO_new_files reserves for the filename argument to be
  54. UTF-8 encoded. In other words if you have to make it work in multi-
  55. lingual environment, encode file names in UTF-8.
  56. =head1 EXAMPLES
  57. File BIO "hello world":
  58. BIO *bio_out;
  59. bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
  60. BIO_printf(bio_out, "Hello World\n");
  61. Alternative technique:
  62. BIO *bio_out;
  63. bio_out = BIO_new(BIO_s_file());
  64. if (bio_out == NULL)
  65. /* Error */
  66. if (!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE))
  67. /* Error */
  68. BIO_printf(bio_out, "Hello World\n");
  69. Write to a file:
  70. BIO *out;
  71. out = BIO_new_file("filename.txt", "w");
  72. if (!out)
  73. /* Error */
  74. BIO_printf(out, "Hello World\n");
  75. BIO_free(out);
  76. Alternative technique:
  77. BIO *out;
  78. out = BIO_new(BIO_s_file());
  79. if (out == NULL)
  80. /* Error */
  81. if (!BIO_write_filename(out, "filename.txt"))
  82. /* Error */
  83. BIO_printf(out, "Hello World\n");
  84. BIO_free(out);
  85. =head1 RETURN VALUES
  86. BIO_s_file() returns the file BIO method.
  87. BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error
  88. occurred.
  89. BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure
  90. (although the current implementation never return 0).
  91. BIO_seek() returns the same value as the underlying fseek() function:
  92. 0 for success or -1 for failure.
  93. BIO_tell() returns the current file position.
  94. BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
  95. BIO_rw_filename() return 1 for success or 0 for failure.
  96. =head1 BUGS
  97. BIO_reset() and BIO_seek() are implemented using fseek() on the underlying
  98. stream. The return value for fseek() is 0 for success or -1 if an error
  99. occurred this differs from other types of BIO which will typically return
  100. 1 for success and a non positive value if an error occurred.
  101. =head1 SEE ALSO
  102. L<BIO_seek(3)>, L<BIO_tell(3)>,
  103. L<BIO_reset(3)>, L<BIO_flush(3)>,
  104. L<BIO_read_ex(3)>,
  105. L<BIO_write_ex(3)>, L<BIO_puts(3)>,
  106. L<BIO_gets(3)>, L<BIO_printf(3)>,
  107. L<BIO_set_close(3)>, L<BIO_get_close(3)>
  108. =head1 COPYRIGHT
  109. Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
  110. Licensed under the OpenSSL license (the "License"). You may not use
  111. this file except in compliance with the License. You can obtain a copy
  112. in the file LICENSE in the source distribution or at
  113. L<https://www.openssl.org/source/license.html>.
  114. =cut