mariadb/mysys/my_error.c

/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

#include "mysys_priv.h"
#include "mysys_err.h"
#include <m_string.h>
#include <stdarg.h>
#include <m_ctype.h>
#include <my_sys.h>

/* Max length of a error message. Should be kept in sync with MYSQL_ERRMSG_SIZE. */
#define ERRMSGSIZE      (512)

/* Define some external variables for error handling */

/*
  WARNING!
  my_error family functions have to be used according following rules:
  - if message have not parameters use my_message(ER_CODE, ER(ER_CODE), MYF(N))
  - if message registered use my_error(ER_CODE, MYF(N), ...).
  - With some special text of errror message use:
  my_printf_error(ER_CODE, format, MYF(N), ...)
*/

/*
  Message texts are registered into a linked list of 'my_err_head' structs.
  Each struct contains (1.) an array of pointers to C character strings with
  '\0' termination, (2.) the error number for the first message in the array
  (array index 0) and (3.) the error number for the last message in the array
  (array index (last - first)).
  The array may contain gaps with NULL pointers and pointers to empty strings.
  Both kinds of gaps will be translated to "Unknown error %d.", if my_error()
  is called with a respective error number.
  The list of header structs is sorted in increasing order of error numbers.
  Negative error numbers are allowed. Overlap of error numbers is not allowed.
  Not registered error numbers will be translated to "Unknown error %d.".
*/
static struct my_err_head
{
  struct my_err_head *meh_next;         /* chain link */
  const char**       (*get_errmsgs)(int nr); /* returns error message format */
  uint               meh_first;       /* error number matching array slot 0 */
  uint               meh_last;          /* error number matching last slot */
} my_errmsgs_globerrs=
{NULL, get_global_errmsgs, EE_ERROR_FIRST, EE_ERROR_LAST};

static struct my_err_head *my_errmsgs_list= &my_errmsgs_globerrs;


/**
  @brief Get an error format string from one of the my_error_register()ed sets

  @note
    NULL values are possible even within a registered range.

  @param nr Errno

  @retval NULL  if no message is registered for this error number
  @retval str   C-string
*/

const char *my_get_err_msg(uint nr)
{
  const char *format;
  struct my_err_head *meh_p;

  /* Search for the range this error is in. */
  for (meh_p= my_errmsgs_list; meh_p; meh_p= meh_p->meh_next)
    if (nr <= meh_p->meh_last)
      break;

  /*
    If we found the range this error number is in, get the format string.
    If the string is empty, or a NULL pointer, or if we're out of return,
    we return NULL.
  */
  if (!(format= (meh_p && (nr >= meh_p->meh_first)) ?
                meh_p->get_errmsgs(nr)[nr - meh_p->meh_first] : NULL) ||
      !*format)
    return NULL;

  return format;
}

/**
   Internal method used to format and prepare the error structure.
   Called by my_error_prepare() and my_error().
 */
static struct Prepared_error my_error_format(uint nr, myf MyFlags, va_list args)
{
  const char *format;
  struct Prepared_error error;
  error.code= nr;
  error.flags= MyFlags;

  if (!(format = my_get_err_msg(nr)))
    (void) my_snprintf(error.message, sizeof(error.message),
                       "Unknown error %d", nr);
  else
  {
    (void) my_vsnprintf_ex(&my_charset_utf8mb3_general_ci,
                           error.message, sizeof(error.message), format, args);
  }
  return error;
}

/**
  Prepare the error message for deferred printing with my_error_issue()

  @param nr        error number
  @param MyFlags   Flags
  @param ...       variable list matching that error format string

  @retval error    prepared structure containg error code, formatted message
                   and flags
*/

struct Prepared_error my_error_prepare(uint nr, myf MyFlags, ...)
{
  struct Prepared_error error;
  va_list args;

  va_start(args,MyFlags);
  error= my_error_format(nr, MyFlags, args);
  va_end(args);

  return error;
}


/**
   Print a previously prepared error (see my_error_prepare())

 * @param error        error structure prepared for deferred printing@retval
 */
void my_error_issue(struct Prepared_error* error)
{
  (*error_handler_hook)(error->code, error->message, error->flags);
}


/**
  Fill in and print a previously registered error message.

  @note
    Goes through the (sole) function registered in error_handler_hook

  @param nr        error number
  @param MyFlags   Flags
  @param ...       variable list matching that error format string
*/

void my_error(uint nr, myf MyFlags, ...)
{
  struct Prepared_error error;
  va_list args;
  DBUG_ENTER("my_error");
  DBUG_PRINT("my", ("nr: %d  MyFlags: %lu  errno: %d", nr, MyFlags, errno));
  va_start(args,MyFlags);
  error= my_error_format(nr, MyFlags, args);
  my_error_issue(&error);
  va_end(args);
  DBUG_VOID_RETURN;
}


/**
  Print an error message.

  @note
    Just like my_error, but for cases when the error message is not ER(error)

  @param error     error number
  @param format    format string
  @param MyFlags   Flags
  @param ...       variable list matching that error format string
*/

void my_printf_error(uint error, const char *format, myf MyFlags, ...)
{
  va_list args;
  char ebuff[ERRMSGSIZE];
  DBUG_ENTER("my_printf_error");
  DBUG_PRINT("my", ("nr: %d  MyFlags: %lu  errno: %d  format: %s",
		    error, MyFlags, errno, format));

  va_start(args,MyFlags);
  (void) my_vsnprintf_ex(&my_charset_utf8mb3_general_ci, ebuff,
                         sizeof(ebuff), format, args);
  va_end(args);
  (*error_handler_hook)(error, ebuff, MyFlags);
  DBUG_VOID_RETURN;
}

/**
  Print an error message.

  @note
    Goes through the (sole) function registered in error_handler_hook

  @param error     error number
  @param format    format string
  @param MyFlags   Flags
  @param ap        variable list matching that error format string
*/

void my_printv_error(uint error, const char *format, myf MyFlags, va_list ap)
{
  char ebuff[ERRMSGSIZE];
  DBUG_ENTER("my_printv_error");
  DBUG_PRINT("my", ("nr: %d  MyFlags: %lu  errno: %d  format: %s",
		    error, MyFlags, errno, format));

  (void) my_vsnprintf(ebuff, sizeof(ebuff), format, ap);
  (*error_handler_hook)(error, ebuff, MyFlags);
  DBUG_VOID_RETURN;
}


/**
  Print an error message.

  @note
    Goes through the (sole) function registered in error_handler_hook

  @param error     error number
  @param str       error message
  @param MyFlags   Flags
*/

void my_message(uint error, const char *str, register myf MyFlags)
{
  (*error_handler_hook)(error, str, MyFlags);
}


/**
  Register error messages for use with my_error().

  @description

    The pointer array is expected to contain addresses to NUL-terminated
    C character strings. The array contains (last - first + 1) pointers.
    NULL pointers and empty strings ("") are allowed. These will be mapped to
    "Unknown error" when my_error() is called with a matching error number.
    This function registers the error numbers 'first' to 'last'.
    No overlapping with previously registered error numbers is allowed.

  @param   errmsgs  array of pointers to error messages
  @param   first    error number of first message in the array
  @param   last     error number of last message in the array

  @retval  0        OK
  @retval  != 0     Error
*/

int my_error_register(const char** (*get_errmsgs)(int error), uint first,
                      uint last)
{
  struct my_err_head *meh_p;
  struct my_err_head **search_meh_pp;

  /* Allocate a new header structure. */
  if (! (meh_p= (struct my_err_head*) my_malloc(key_memory_my_err_head,
                                                sizeof(struct my_err_head),
                                                MYF(MY_WME))))
    return 1;
  meh_p->get_errmsgs= get_errmsgs;
  meh_p->meh_first= first;
  meh_p->meh_last= last;

  /* Search for the right position in the list. */
  for (search_meh_pp= &my_errmsgs_list;
       *search_meh_pp;
       search_meh_pp= &(*search_meh_pp)->meh_next)
  {
    if ((*search_meh_pp)->meh_last > first)
      break;
  }

  /* Error numbers must be unique. No overlapping is allowed. */
  if (*search_meh_pp && ((*search_meh_pp)->meh_first <= last))
  {
    my_free(meh_p);
    return 1;
  }

  /* Insert header into the chain. */
  meh_p->meh_next= *search_meh_pp;
  *search_meh_pp= meh_p;
  return 0;
}


/**
  Unregister formerly registered error messages.

  @description

    This function unregisters the error numbers 'first' to 'last'.
    These must have been previously registered by my_error_register().
    'first' and 'last' must exactly match the registration.
    If a matching registration is present, the header is removed from the
    list and the pointer to the error messages pointers array is returned.
    (The messages themselves are not released here as they may be static.)
    Otherwise, NULL is returned.

  @param   first     error number of first message
  @param   last      error number of last message

  @retval  NULL      Error, no such number range registered.
  @retval  non-NULL  OK, returns address of error messages pointers array.
*/

my_bool my_error_unregister(uint first, uint last)
{
  struct my_err_head    *meh_p;
  struct my_err_head    **search_meh_pp;

  /* Search for the registration in the list. */
  for (search_meh_pp= &my_errmsgs_list;
       *search_meh_pp;
       search_meh_pp= &(*search_meh_pp)->meh_next)
  {
    if (((*search_meh_pp)->meh_first == first) &&
        ((*search_meh_pp)->meh_last == last))
      break;
  }
  if (! *search_meh_pp)
    return TRUE;
  
  /* Remove header from the chain. */
  meh_p= *search_meh_pp;
  *search_meh_pp= meh_p->meh_next;

  my_free(meh_p);
  
  return FALSE;
}


/**
  Unregister all formerly registered error messages.

  @description

    This function unregisters all error numbers that previously have
    been previously registered by my_error_register().
    All headers are removed from the list; the messages themselves are
    not released here as they may be static.
*/

void my_error_unregister_all(void)
{
  struct my_err_head *cursor, *saved_next;

  for (cursor= my_errmsgs_globerrs.meh_next; cursor != NULL; cursor= saved_next)
  {
    /* We need this ptr, but we're about to free its container, so save it. */
    saved_next= cursor->meh_next;

    my_free(cursor);
  }
  my_errmsgs_globerrs.meh_next= NULL;  /* Freed in first iteration above. */

  my_errmsgs_list= &my_errmsgs_globerrs;
}