NAME

XSetErrorHandler, XGetErrorText, XDisplayName, XSetIOErrorHandler, XGetErrorDatabaseText - default error handlers

SYNTAX

int (*XSetErrorHandler(int (*_h_a_n_d_l_e_r)(Display *, XErrorEvent *)))(); int XGetErrorText(Display *_d_i_s_p_l_a_y, int _c_o_d_e, char *_b_u_f_f_e_r___r_e_t_u_r_n, int _l_e_n_g_t_h); char *XDisplayName(char *_s_t_r_i_n_g); int (*XSetIOErrorHandler(int (*_h_a_n_d_l_e_r)(Display *)))(); int XGetErrorDatabaseText(Display *_d_i_s_p_l_a_y, char *_n_a_m_e, char *_m_e_s_s_a_g_e, char *_d_e_f_a_u_l_t___s_t_r_i_n_g, char *_b_u_f_f_e_r___r_e_t_u_r_n, int _l_e_n_g_t_h);

ARGUMENTS

_b_u_f_f_e_r___r_e_t_u_r_n Returns the error description.
_c_o_d_e Specifies the error code for which you want to obtain a description.
_d_e_f_a_u_l_t___s_t_r_i_n_g Specifies the default error message if none is found in the database.
_d_i_s_p_l_a_y Specifies the connection to the X server.
_h_a_n_d_l_e_r Specifies the program's supplied error handler.
_l_e_n_g_t_h Specifies the size of the buffer.
_m_e_s_s_a_g_e Specifies the type of the error message.
_n_a_m_e Specifies the name of the application.
_s_t_r_i_n_g Specifies the character string.

DESCRIPTION

Xlib generally calls the program's supplied error handler whenever an error is received. It is not called on _B_a_d_N_a_m_e errors from _O_p_e_n_F_o_n_t, _L_o_o_k_u_p_C_o_l_o_r, or _A_l_l_o_c_N_a_m_e_d_C_o_l_o_r protocol requests or on _B_a_d_F_o_n_t errors from a _Q_u_e_r_y_F_o_n_t protocol request. These errors generally are reflected back to the program through the procedural interface. Because this condition is not assumed to be fatal, it is acceptable for your error handler to return; the returned value is ignored. However, the error handler should not call any functions (directly or indirectly) on the display that will generate protocol requests or that will look for input events. The previous error handler is returned.

The _X_G_e_t_E_r_r_o_r_T_e_x_t function copies a null-terminated string describing the specified error code into the specified buffer. The returned text is in the encoding of the current locale. It is recommended that you use this function to obtain an error description because extensions to Xlib may define their own error codes and error strings.

The _X_D_i_s_p_l_a_y_N_a_m_e function returns the name of the display that _X_O_p_e_n_D_i_s_p_l_a_y would attempt to use. If a NULL string is specified, _X_D_i_s_p_l_a_y_N_a_m_e looks in the environment for the display and returns the display name that _X_O_p_e_n_D_i_s_p_l_a_y would attempt to use. This makes it easier to report to the user precisely which display the program attempted to open when the initial connection attempt failed.

The _X_S_e_t_I_O_E_r_r_o_r_H_a_n_d_l_e_r sets the fatal I/O error handler. Xlib calls the program's supplied error handler if any sort of system call error occurs (for example, the connection to the server was lost). This is assumed to be a fatal condition, and the called routine should not return. If the I/O error handler does return, the client process exits.

Note that the previous error handler is returned.

The _X_G_e_t_E_r_r_o_r_D_a_t_a_b_a_s_e_T_e_x_t function returns a null-terminated message (or the default message) from the error message database. Xlib uses this function internally to look up its error messages. The text in the default_string argument is assumed to be in the encoding of the current locale, and the text stored in the buffer_return argument is in the encoding of the current locale.

The name argument should generally be the name of your application. The message argument should indicate which type of error message you want. If the name and message are not in the Host Portable Character Encoding, the result is implementation-dependent. Xlib uses three predefined ``application names'' to report errors. In these names, uppercase and lowercase matter.

XProtoError The protocol error number is used as a string for the message argument.
XlibMessage These are the message strings that are used internally by the library.
XRequest For a core protocol request,
the major request protocol number is used for the message argument. For an extension request, the extension name (as given by _I_n_i_t_E_x_t_e_n_s_i_o_n) followed by a period (.) and the minor request protocol number is used for the message argument. If no string is found in the error database, the default_string is returned to the buffer argument.

SEE ALSO

XOpenDisplay(3X11), XSynchronize(3X11)
_X_l_i_b _- _C _L_a_n_g_u_a_g_e _X _I_n_t_e_r_f_a_c_e