trusty (3) erl_error.3erl.gz

NAME

       erl_error - Error Print Routines

DESCRIPTION

       This module contains some error printing routines taken from Advanced Programming in the UNIX Environment
       by W. Richard Stevens.

       These functions are all called in the same manner as printf(),  i.e.  with  a  string  containing  format
       specifiers followed by a list of corresponding arguments. All output from these functions is to stderr.

EXPORTS

       void erl_err_msg(FormatStr, ... )

              Types:

                 const char *FormatStr;

              The message provided by the caller is printed. This function is simply a wrapper for fprintf().

       void erl_err_quit(FormatStr, ... )

              Types:

                 const char *FormatStr;

              Use  this  function  when a fatal error has occurred that is not due to a system call. The message
              provided by the caller is printed and the process terminates with an exit value of 1. The function
              does not return.

       void erl_err_ret(FormatStr, ... )

              Types:

                 const char *FormatStr;

              Use  this  function  after  a  failed  system  call. The message provided by the caller is printed
              followed by a string describing the reason for failure.

       void erl_err_sys(FormatStr, ... )

              Types:

                 const char *FormatStr;

              Use this function after a failed system call. The  message  provided  by  the  caller  is  printed
              followed  by  a  string describing the reason for failure, and the process terminates with an exit
              value of 1. The function does not return.

ERROR REPORTING

       Most functions in erl_interface report failures to the caller by  returning  some  otherwise  meaningless
       value (typically NULL or a negative number). As this only tells you that things did not go well, you will
       have to examine the error code in erl_errno if you want to find out more about the failure.

EXPORTS

       volatile int erl_errno

              erl_errno is initially (at program startup) zero and is then set by many  erl_interface  functions
              on  failure  to  a non-zero error code to indicate what kind of error it encountered. A successful
              function call might change erl_errno (by calling some other function that fails), but no  function
              will  ever  set  it  to  zero.  This means that you cannot use erl_errno to see if a function call
              failed. Instead, each function reports failure in its own way (usually  by  returning  a  negative
              number or NULL), in which case you can examine erl_errno for details.

              erl_errno uses the error codes defined in your system's <errno.h>.

          Note:
              Actually,  erl_errno  is a "modifiable lvalue" (just like ISO C defines errno to be) rather than a
              variable. This means it might be implemented as a macro (expanding to, e.g.,  *_erl_errno()).  For
              reasons of thread- (or task-)safety, this is exactly what we do on most platforms.