Error handling(3)

NAME
Error handling -

How to handle errors.

  Data Structures
struct brlapi_error_t

  Defines
#define BRLAPI_ERROR_SUCCESS 0
#define BRLAPI_ERROR_NOMEM 1
#define BRLAPI_ERROR_TTYBUSY 2
#define BRLAPI_ERROR_DEVICEBUSY 3
#define BRLAPI_ERROR_UNKNOWN_INSTRUCTION 4
#define BRLAPI_ERROR_ILLEGAL_INSTRUCTION 5
#define BRLAPI_ERROR_INVALID_PARAMETER 6
#define BRLAPI_ERROR_INVALID_PACKET 7
#define BRLAPI_ERROR_CONNREFUSED 8
#define BRLAPI_ERROR_OPNOTSUPP 9
#define BRLAPI_ERROR_GAIERR 10
#define BRLAPI_ERROR_LIBCERR 11
#define BRLAPI_ERROR_UNKNOWNTTY 12
#define BRLAPI_ERROR_PROTOCOL_VERSION 13
#define BRLAPI_ERROR_EOF 14
#define BRLAPI_ERROR_EMPTYKEY 15
#define BRLAPI_ERROR_DRIVERERROR 16
#define BRLAPI_ERROR_AUTHENTICATION 17
#define brlapi_error (*brlapi_error_location())
#define brlapi_errno (brlapi_error.brlerrno)
#define brlapi_libcerrno (brlapi_error.libcerrno)
#define brlapi_gaierrno (brlapi_error.gaierrno)
#define brlapi_errfun (brlapi_error.errfun)

  Typedefs
typedef uint32_t brlapi_packetType_t
typedef void(BRLAPI_STDCALL * brlapi_exceptionHandler_t )(int error, brlapi_packetType_t type, const void *packet, size_t size)
typedef void(BRLAPI_STDCALL * brlapi__exceptionHandler_t )(brlapi_handle_t *handle, int error, brlapi_packetType_t type, const void *packet, size_t size)

  Functions
void BRLAPI_STDCALL brlapi_perror (const char *s)
brlapi_error_t *BRLAPI_STDCALL brlapi_error_location (void)
const char *BRLAPI_STDCALL brlapi_strerror (const brlapi_error_t *error)
const char *BRLAPI_STDCALL brlapi_getPacketTypeName (brlapi_packetType_t type)
int BRLAPI_STDCALL brlapi_strexception (char *buffer, size_t bufferSize, int error, brlapi_packetType_t type, const void *packet, size_t packetSize)
int BRLAPI_STDCALL brlapi__strexception (brlapi_handle_t *handle, char *buffer, size_t bufferSize, int error, brlapi_packetType_t type, const void *packet, size_t packetSize)
brlapi_exceptionHandler_t
BRLAPI_STDCALL brlapi_setExceptionHandler (brlapi_exceptionHandler_t handler)"
brlapi__exceptionHandler_t
BRLAPI_STDCALL brlapi__setExceptionHandler (brlapi_handle_t *handle, brlapi__exceptionHandler_t handler)"
void BRLAPI_STDCALL brlapi_defaultExceptionHandler (int error, brlapi_packetType_t type, const void *packet, size_t size)
void BRLAPI_STDCALL brlapi__defaultExceptionHandler (brlapi_handle_t *handle, int error, brlapi_packetType_t type, const void *packet, size_t size)

  Variables
const char * brlapi_errlist []
const int brlapi_nerr
brlapi_error_t brlapi_error
int brlapi_errno
int brlapi_libcerrno
int brlapi_gaierrno
const char * brlapi_errfun

Detailed Description

When a function fails, brlapi_errno will hold an error code to explain why it failed. It should always be reported somehow.

Although most errors are reported that way, some (called exceptions) are reported asynchronously for efficiency reasons, because they always just report a programming error. The affected functions are: brlapi_setFocus, brlapi_write* and brlapi_sendRaw. When they happen, the next call to brlapi_something will close the connection and call the exception handler. If the exception handler returns, the brlapi_something function will return an end-of-file error.

The default exception handler (brlapi_defaultExceptionHandler()) dumps the guilty packet before abort()ing. It can be replaced by calling brlapi_setExceptionHandler(). For instance, the Java and Python bindings use this for raising a Java or Python exception that may be caught.

Define Documentation

  #define brlapi_errfun (brlapi_error.errfun)
Cheat about the brlapi_errfun C token

  #define brlapi_errno (brlapi_error.brlerrno)
Cheat about the brlapi_errno C token

  #define brlapi_error (*brlapi_error_location())
Cheat about the brlapi_error C token

  #define BRLAPI_ERROR_AUTHENTICATION 17
Authentication failed

  #define BRLAPI_ERROR_CONNREFUSED 8
Connection refused

  #define BRLAPI_ERROR_DEVICEBUSY 3
A connection is already using RAW or suspend mode

  #define BRLAPI_ERROR_DRIVERERROR 16
Packet returned by driver too large

  #define BRLAPI_ERROR_EMPTYKEY 15
Key file empty

  #define BRLAPI_ERROR_EOF 14
Unexpected end of file

  #define BRLAPI_ERROR_GAIERR 10
Getaddrinfo error

  #define BRLAPI_ERROR_ILLEGAL_INSTRUCTION 5
Forbiden in current mode

  #define BRLAPI_ERROR_INVALID_PACKET 7
Invalid size

  #define BRLAPI_ERROR_INVALID_PARAMETER 6
Out of range or have no sense

  #define BRLAPI_ERROR_LIBCERR 11
Libc error

  #define BRLAPI_ERROR_NOMEM 1
Not enough memory

  #define BRLAPI_ERROR_OPNOTSUPP 9
Operation not supported

  #define BRLAPI_ERROR_PROTOCOL_VERSION 13
Bad protocol version

  #define BRLAPI_ERROR_SUCCESS 0
Success

  #define BRLAPI_ERROR_TTYBUSY 2
A connection is already running in this tty

  #define BRLAPI_ERROR_UNKNOWN_INSTRUCTION 4
Not implemented in protocol

  #define BRLAPI_ERROR_UNKNOWNTTY 12
Couldn't find out the tty number

  #define brlapi_gaierrno (brlapi_error.gaierrno)
Cheat about the brlapi_gaierrno C token

  #define brlapi_libcerrno (brlapi_error.libcerrno)
Cheat about the brlapi_libcerrno C token

Typedef Documentation

  typedef void(BRLAPI_STDCALL * brlapi__exceptionHandler_t)(brlapi_handle_t *handle, int error, brlapi_packetType_t type, const void *packet, size_t size)

  typedef void(BRLAPI_STDCALL * brlapi_exceptionHandler_t)(int error, brlapi_packetType_t type, const void *packet, size_t size)
Types for exception handlers

Types of exception handlers which are to be given to brlapi_setExceptionHandler() and brlapi__setExceptionHandler().

Parameters:
    handle is the handle corresponding to the guilty connection;
    error is a BRLAPI_ERROR_ error code;
    type is the type of the guilty packet;
    packet points to the content of the guilty packet (might be a little bit truncated);
    size gives the guilty packet's size.

  typedef uint32_t brlapi_packetType_t
Type for packet type. Only unsigned can cross networks, 32bits

Function Documentation

  void BRLAPI_STDCALL brlapi__defaultExceptionHandler (brlapi_handle_t *handle, interror, brlapi_packetType_ttype, const void *packet, size_tsize)

  brlapi__exceptionHandler_t BRLAPI_STDCALL brlapi__setExceptionHandler (brlapi_handle_t *handle, brlapi__exceptionHandler_thandler)

  int BRLAPI_STDCALL brlapi__strexception (brlapi_handle_t *handle, char *buffer, size_tbufferSize, interror, brlapi_packetType_ttype, const void *packet, size_tpacketSize)

  void BRLAPI_STDCALL brlapi_defaultExceptionHandler (interror, brlapi_packetType_ttype, const void *packet, size_tsize)

  brlapi_error_t* BRLAPI_STDCALL brlapi_error_location (void)
Get per-thread error location

In multithreaded software, brlapi_error is thread-specific, so api.h cheats about the brlapi_error token and actually calls brlapi_error_location().

This gets the thread specific location of global variable brlapi_error

  const char* BRLAPI_STDCALL brlapi_getPacketTypeName (brlapi_packetType_ttype)
Get plain packet type

brlapi_getPacketTypeName() returns the plain packet type name corresponding to its argument.

  void BRLAPI_STDCALL brlapi_perror (const char *s)
Print a BrlAPI error message

brlapi_perror() reads brlapi_error, and acts just like perror().

  brlapi_exceptionHandler_t BRLAPI_STDCALL brlapi_setExceptionHandler (brlapi_exceptionHandler_thandler)
Set a new exception handler

brlapi_setExceptionHandler() replaces the previous exception handler with the handler parameter. The previous exception handler is returned to make chaining error handlers possible.

The default handler just prints the exception and abort()s.

  const char* BRLAPI_STDCALL brlapi_strerror (const brlapi_error_t *error)
Get plain error message

brlapi_strerror() returns the plain error message corresponding to its argument.

  int BRLAPI_STDCALL brlapi_strexception (char *buffer, size_tbufferSize, interror, brlapi_packetType_ttype, const void *packet, size_tpacketSize)
Describes an exception

brlapi_strexception() puts a text describing the given exception in buffer.

The beginning of the guilty packet is dumped as a sequence of hex bytes.

Returns:
    the size of the text describing the exception, following snprintf()'s semantics.

Variable Documentation

  const char* brlapi_errfun
Shorthand for brlapi_error.errfun

  const char* brlapi_errlist[]
Error message list

These are the string constants used by brlapi_perror().

  int brlapi_errno
Shorthand for brlapi_error.errno

  brlapi_error_t brlapi_error
Global variable brlapi_error

brlapi_error is a global left-value containing the last error information. Its errno field is not reset to BRLAPI_ERROR_SUCCESS on success.

This information may be copied in brlapi_error_t variables for later use with the brlapi_strerror function.

  int brlapi_gaierrno
Shorthand for brlapi_error.gaierrno

  int brlapi_libcerrno
Shorthand for brlapi_error.libcerrno

  const int brlapi_nerr
Number of error messages

Author

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