# cpl_error.h File Reference

`#include "cpl_port.h"`

Go to the source code of this file.

## Functions
void | CPLError (CPLErr eErrClass, int err_no, const char *fmt,...)
void | CPLEmergencyError (const char *)
void | CPLErrorReset (void)
int | CPLGetLastErrorNo (void)
CPLErr | CPLGetLastErrorType (void)
const char * | CPLGetLastErrorMsg (void)
void * | CPLGetErrorHandlerUserData (void)
CPLErrorHandler | CPLSetErrorHandler (CPLErrorHandler)
CPLErrorHandler | CPLSetErrorHandlerEx (CPLErrorHandler, void *)
void | CPLPushErrorHandler (CPLErrorHandler)
void | CPLPushErrorHandlerEx (CPLErrorHandler, void *)
void | CPLPopErrorHandler (void)
void | CPLDebug (const char *, const char *,...)
void | _CPLAssert (const char *, const char *, int)

## Detailed Description

CPL error handling services.

## Function Documentation

void _CPLAssert | ( | const char * | pszExpression,
|  | const char * | pszFile,
|  | int | iLine |
| ) |  |  |

Report failure of a logical assertion.

Applications would normally use the CPLAssert() macro which expands into code calling _CPLAssert() only if the condition fails. _CPLAssert() will generate a CE_Fatal error call to CPLError(), indicating the file name, and line number of the failed assertion, as well as containing the assertion itself.

There is no reason for application code to call _CPLAssert() directly.

void CPLDebug | ( | const char * | pszCategory,
|  | const char * | pszFormat,
|  |  | ... |
| ) |  |  |

Display a debugging message.

The category argument is used in conjunction with the CPL_DEBUG environment variable to establish if the message should be displayed. If the CPL_DEBUG environment variable is not set, no debug messages are emitted (use CPLError(CE_Warning,...) to ensure messages are displayed). If CPL_DEBUG is set, but is an empty string or the word "ON" then all debug messages are shown. Otherwise only messages whose category appears somewhere within the CPL_DEBUG value are displayed (as determinted by strstr()).

Categories are usually an identifier for the subsystem producing the error. For instance "GDAL" might be used for the GDAL core, and "TIFF" for messages from the TIFF translator.

Parameters:

  | pszCategory | name of the debugging message category.
  | pszFormat | printf() style format string for message to display. Remaining arguments are assumed to be for format.

void CPLEmergencyError | ( | const char * | pszMessage | ) |

Fatal error when things are bad.

This function should be called in an emergency situation where it is unlikely that a regular error report would work. This would include in the case of heap exhaustion for even small allocations, or any failure in the process of reporting an error (such as TLS allocations).

This function should never return. After the error message has been reported as best possible, the application will abort() similarly to how CPLError() aborts on CE_Fatal class errors.

Parameters:

  | pszMessage | the error message to report.

void CPLError | ( | CPLErr | eErrClass,
|  | int | err_no,
|  | const char * | fmt,
|  |  | ... |
| ) |  |  |

Report an error.

This function reports an error in a manner that can be hooked and reported appropriate by different applications.

The effect of this function can be altered by applications by installing a custom error handling using CPLSetErrorHandler().

The eErrClass argument can have the value CE_Warning indicating that the message is an informational warning, CE_Failure indicating that the action failed, but that normal recover mechanisms will be used or CE_Fatal meaning that a fatal error has occured, and that CPLError() should not return.

The default behaviour of CPLError() is to report errors to stderr, and to abort() after reporting a CE_Fatal error. It is expected that some applications will want to supress error reporting, and will want to install a C++ exception, or longjmp() approach to no local fatal error recovery.

Regardless of how application error handlers or the default error handler choose to handle an error, the error number, and message will be stored for recovery with CPLGetLastErrorNo() and CPLGetLastErrorMsg().

Parameters:

  | eErrClass | one of CE_Warning, CE_Failure or CE_Fatal.
  | err_no | the error number (CPLE_*) from cpl_error.h.
  | fmt | a printf() style format string. Any additional arguments will be treated as arguments to fill in this format in a manner similar to printf().

void CPLErrorReset | ( | void |  | ) |

Erase any traces of previous errors.

This is normally used to ensure that an error which has been recovered from does not appear to be still in play with high level functions.

void* CPLGetErrorHandlerUserData | ( | void |  | ) |

Fetch the user data for the error context

Fetches the user data for the current error context. You can set the user data for the error context when you add your handler by issuing CPLSetErrorHandlerEx() and CPLPushErrorHandlerEx(). Note that user data is primarily intended for providing context within error handlers themselves, but they could potentially be abused in other useful ways with the usual caveat emptor understanding.

Returns:
  the user data pointer for the error context

const char* CPLGetLastErrorMsg | ( | void |  | ) |

Get the last error message.

Fetches the last error message posted with CPLError(), that hasn't been cleared by CPLErrorReset(). The returned pointer is to an internal string that should not be altered or freed.

Returns:
  the last error message, or NULL if there is no posted error message.

int CPLGetLastErrorNo | ( | void |  | ) |

Fetch the last error number.

Fetches the last error number posted with CPLError(), that hasn't been cleared by CPLErrorReset(). This is the error number, not the error class.

Returns:
  the error number of the last error to occur, or CPLE_None (0) if there are no posted errors.

CPLErr CPLGetLastErrorType | ( | void |  | ) |

Fetch the last error type.

Fetches the last error type posted with CPLError(), that hasn't been cleared by CPLErrorReset(). This is the error class, not the error number.

Returns:
  the error type of the last error to occur, or CE_None (0) if there are no posted errors.

void CPLPopErrorHandler | ( | void |  | ) |

Pop error handler off stack.

Discards the current error handler on the error handler stack, and restores the one in use before the last CPLPushErrorHandler() call. This method has no effect if there are no error handlers on the current threads error handler stack.

void CPLPushErrorHandler | ( | CPLErrorHandler | pfnErrorHandlerNew | ) |

Push a new CPLError handler.

This pushes a new error handler on the thread-local error handler stack. This handler will be used until removed with CPLPopErrorHandler().

The CPLSetErrorHandler() docs have further information on how CPLError handlers work.

Parameters:

  | pfnErrorHandlerNew | new error handler function.

void CPLPushErrorHandlerEx | ( | CPLErrorHandler | pfnErrorHandlerNew,
|  | void * | pUserData |
| ) |  |  |

Push a new CPLError handler with user data on the error context.

This pushes a new error handler on the thread-local error handler stack. This handler will be used until removed with CPLPopErrorHandler(). Obtain the user data back by using CPLGetErrorContext().

The CPLSetErrorHandler() docs have further information on how CPLError handlers work.

Parameters:

  | pfnErrorHandlerNew | new error handler function.
  | pUserData | User data to put on the error context.

CPLErrorHandler CPLSetErrorHandler | ( | CPLErrorHandler | pfnErrorHandlerNew | ) |

Install custom error handler.

Allow the library's user to specify his own error handler function. A valid error handler is a C function with the following prototype:

         void MyErrorHandler(CPLErr eErrClass, int err_no, const char *msg)

Pass NULL to come back to the default behavior. The default behaviour (CPLDefaultErrorHandler()) is to write the message to stderr.

The msg will be a partially formatted error message not containing the "ERROR %d:" portion emitted by the default handler. Message formatting is handled by CPLError() before calling the handler. If the error handler function is passed a CE_Fatal class error and returns, then CPLError() will call abort(). Applications wanting to interrupt this fatal behaviour will have to use longjmp(), or a C++ exception to indirectly exit the function.

Another standard error handler is CPLQuietErrorHandler() which doesn't make any attempt to report the passed error or warning messages but will process debug messages via CPLDefaultErrorHandler.

Note that error handlers set with CPLSetErrorHandler() apply to all threads in an application, while error handlers set with CPLPushErrorHandler are thread-local. However, any error handlers pushed with CPLPushErrorHandler (and not removed with CPLPopErrorHandler) take precidence over the global error handlers set with CPLSetErrorHandler(). Generally speaking CPLSetErrorHandler() would be used to set a desired global error handler, while CPLPushErrorHandler() would be used to install a temporary local error handler, such as CPLQuietErrorHandler() to suppress error reporting in a limited segment of code.

Parameters:

  | pfnErrorHandlerNew | new error handler function.

Returns:
  returns the previously installed error handler.

CPLErrorHandler CPLSetErrorHandlerEx | ( | CPLErrorHandler | pfnErrorHandlerNew,
|  | void * | pUserData |
| ) |  |  |

Install custom error handle with user's data. This method is essentially CPLSetErrorHandler with an added pointer to pUserData. The pUserData is not returned in the CPLErrorHandler, however, and must be fetched via CPLGetLastErrorUserData

Parameters:

  | pfnErrorHandlerNew | new error handler function.
  | pUserData | User data to carry along with the error context.

Returns:
  returns the previously installed error handler.

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