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err(3)
NAME
  err - Error codes

SYNOPSIS
  #include <openssl/err.h>

  unsigned long ERR_get_error(
	  void );

  unsigned long ERR_peek_error(
	  void );

  unsigned long ERR_get_error_line(
	  const char **file,
	  int *line );

  unsigned long ERR_peek_error_line(
	  const char **file,
	  int *line );

  unsigned long ERR_get_error_line_data(
	  const char **file,
	  int *line,
	  const char **data,
	  int *flags );

  unsigned long ERR_peek_error_line_data(
	  const char **file,
	  int *line,
	  const char **data,
	  int *flags );

  int ERR_GET_LIB(
	  unsigned long e );

  int ERR_GET_FUNC(
	  unsigned long e );

  int ERR_GET_REASON(
	  unsigned long e );

  void ERR_clear_error(
	  void );

  char *ERR_error_string(
	  unsigned long e,
	  char *buf );

  const char*ERR_lib_error_string(
	  unsigned long e );

  const char*ERR_func_error_string(
	  unsigned long e );

  const char*ERR_reason_error_string(
	  unsigned long e );

  void ERR_print_errors(
	  BIO *bp );

  void ERR_print_errors_fp(
	  FILE *fp );

  void ERR_load_crypto_strings(
	  void );

  void ERR_free_strings(
	  void );

  void ERR_remove_state(
	  unsigned long pid );

  void ERR_put_error(
	  int lib,
	  int func,
	  int reason,
	  const char *file,
	  int line );

  void ERR_add_error_data(
	  int num, ... );

  void ERR_load_strings(
	  int lib,
	  ERR_STRING_DATA str[] );

  unsigned long ERR_PACK(
	  int lib,
	  int func,
	  int reason );

  int ERR_get_next_error_library(
	  void );

DESCRIPTION
  When a call to the OpenSSL library fails, this is usually signalled by the
  return value, and an error code is stored in an error queue associated with
  the current thread. The err library provides functions to obtain these
  error codes and textual error messages.

  The ERR_get_error(3) reference page describes how to access error codes.

  Error codes contain information about where the error occurred, and what
  went wrong. The ERR_GET_LIB(3) reference page describes how to extract this
  information. A method to obtain human-readable error messages is described
  in ERR_error_string(3).

  The ERR_clear_error() function can be used to clear the error queue.

  The ERR_remove_state() function should be used to avoid memory leaks when
  threads are terminated.

ERRORS
  See ERR_put_error(3) if you want to record error codes in the OpenSSL error
  system from within your application.

  The remainder of this section explains how to add new error codes to
  OpenSSL or add error codes from external libraries.

  Reporting errors

  Each sublibrary has a specific macro, XXXerr(), that is used to report
  errors. Its first argument is a function code, XXX_F_..., and the second
  argument is a reason code, XXX_R_.... Function codes are derived from the
  function names; reason codes consist of textual error descriptions. For
  example, the ssl23_read() function reports a handshake failure as follows:

       SSLerr(SSL_F_SSL23_READ, SSL_R_SSL_HANDSHAKE_FAILURE);

  Function and reason codes should consist of upper case characters, numbers
  and underscores only. The error file generation script translates function
  codes into function names by looking in the header files for an appropriate
  function name. If none is found it just uses the capitalized form, such as
  SSL23_READ in the previous example.

  The trailing section of a reason code (after the _R_) is translated into
  lower case, and underscores are changed to spaces.

  When you are using new function or reason codes, run the make errors
  command. The necessary #defines will automatically be added to the
  sublibrary's header file.

  Although a library will normally report errors using its own specific
  XXXerr() macro, another library's macro can be used. This is usually done
  when a library wants to include ASN1 code which must use the ASN1err()
  macro.

  Adding new libraries

  When adding a new sublibrary to OpenSSL, take the following steps:

   1.  Assign it a library number, ERR_LIB_XXX.

   2.  Define a macro, XXXerr(), (both in <err.h>).

   3.  Add its name to ERR_str_libraries[] (in crypto/err/err.c).

   4.  Add ERR_load_XXX_strings to the ERR_load _crypto_strings() function
       (in crypto/err/err_all.c).

   5.  Add an entry, L	     XXX     xxx.h   xxx_err.c, to
       crypto/err/openssl.ec, and add xxx_err.c to the Makefile.

       Running make errors will generate a file, xxx_err.c, and add all error
       codes used in the library to <xxx.h>.

  In addition, the library include file must have a certain form. Typically
  it will initially look like the following example:

	#ifndef HEADER_XXX_H
	#define HEADER_XXX_H

	#ifdef __cplusplus
	extern "C" {
	#endif

	/* Include files */

	#include <openssl/bio.h>
	#include <openssl/x509.h>

	/* Macros, structures and function prototypes */

	/* BEGIN ERROR CODES */

  The BEGIN ERROR CODES sequence is used by the error code generation script
  as the point to place new error codes. Any text after this point will be
  overwritten when make errors is run.	The closing #endif will be added
  automatically by the script.

  The generated C error code file xxx_err.c will load the header files
  <stdio.h>, <openssl/err.h> and <openssl/xxx.h> so the header file must load
  any additional header files containing any definitions it uses.

  Using Error Codes in External Libraries

  It also is possible to use OpenSSL's error code scheme in external
  libraries.  The library needs to load its own codes and call the OpenSSL
  error code insertion script mkerr.pl explicitly to add codes to the header
  file and generate the C error code file. This will normally be done if the
  external library needs to generate new ASN1 structures but it can also be
  used to add more general purpose error code handling.

  Internals

  The error queues are stored in a hash table with one ERR_STATE entry for
  each pid. The ERR_get_state() function returns the current thread's
  ERR_STATE. An ERR_STATE can hold up to ERR_NUM_ERRORS error codes. When
  more error codes are added, the old ones are overwritten, on the assumption
  that the most recent errors are most important.

  Error strings are also stored in hash tables. The hash tables can be
  obtained by calling ERR_get_err_state_table(void) and
  ERR_get_string_table(void), respectively.

SEE ALSO
  Functions: CRYPTO_set_id_callback(3), CRYPTO_set_locking_callback(3),
  ERR_get_error(3), ERR_GET_LIB(3), ERR_clear_error(3), ERR_error_string(3),
  ERR_print_errors(3), ERR_load_crypto_strings(3), ERR_remove_state(3),
  ERR_put_error(3), ERR_load_strings(3), SSL_get_error(3)

Index for Section 3

Alphabetical listing for E

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