Tcl/Tk Applications | Tcl Commands | Tk Commands | Tcl Library | Tk Library
- NAME
- Tcl_SetErrno, Tcl_GetErrno, Tcl_ErrnoId, Tcl_ErrnoMsg - manipulate errno to store and retrieve error codes
- SYNOPSIS
- #include <tcl.h>
- void
- Tcl_SetErrno(errorCode)
- int
- Tcl_GetErrno()
- const char *
- Tcl_ErrnoId()
- const char *
- Tcl_ErrnoMsg(errorCode)
- ARGUMENTS
- DESCRIPTION
- KEYWORDS
NAME
Tcl_SetErrno, Tcl_GetErrno, Tcl_ErrnoId, Tcl_ErrnoMsg - manipulate errno to store and retrieve error codesSYNOPSIS
#include <tcl.h>void
Tcl_SetErrno(errorCode)
int
Tcl_GetErrno()
const char *
Tcl_ErrnoId()
const char *
Tcl_ErrnoMsg(errorCode)
ARGUMENTS
- int errorCode (in)
- A POSIX error code such as ENOENT.
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.