tcldoc Tcl/Tk 9.0.4
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Tcl_SetErrno C API

Manipulate errno to store and retrieve error codes

Also documents Tcl_GetErrno, Tcl_ErrnoId, Tcl_ErrnoMsg, Tcl_WinConvertError

literal type exactly as shown argument replace with your value ?optional? may be omitted

Synopsis#

#include <tcl.h>

void Tcl_SetErrno(errorCode)#

int Tcl_GetErrno()#

const char * Tcl_ErrnoId()#

const char * Tcl_ErrnoMsg(errorCode)#

void Tcl_WinConvertError(winErrorCode)#

Arguments#

int errorCode (in)

A POSIX error code such as ENOENT.

DWORD winErrorCode (in)

A Windows or Winsock error code such as ERROR_FILE_NOT_FOUND.

Description#

Tcl_SetErrno and Tcl_GetErrno provide portable access to the errno variable, which is used to record a POSIX error code after system calls and other operations such as Tcl_Gets. These procedures are necessary because global variable accesses cannot be made across module boundaries on some platforms.

Tcl_SetErrno sets the errno variable to the value of the errorCode argument C procedures that wish to return error information to their callers via errno should call Tcl_SetErrno rather than setting errno directly.

Tcl_GetErrno returns the current value of errno. Procedures wishing to access errno should call this procedure instead of accessing errno directly.

Tcl_ErrnoId and Tcl_ErrnoMsg return string representations of errno values. Tcl_ErrnoId returns a machine-readable textual identifier such as “EACCES” that corresponds to the current value of errno. Tcl_ErrnoMsg returns a human-readable string such as “permission denied” that corresponds to the value of its errorCode argument. The errorCode argument is typically the value returned by Tcl_GetErrno. The strings returned by these functions are statically allocated and the caller must not free or modify them.

Tcl_WinConvertError (Windows only) maps the passed Windows or Winsock error code to a POSIX error and stores it in errno.

Keywords#

errno · error code · global variables

Copyright#