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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(),  that  is,  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 because of a system
              call. The message provided by the caller is printed and the process terminates with
              exit value 1. This 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 exit value 1. This 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, 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 can change erl_errno (by
              calling some other function that fails), but no function does never 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:
              erl_errno  is  a  "modifiable  lvalue" (just like ISO C defines errno to be) rather
              than a variable. This means it can be implemented as a  macro  (expanding  to,  for
              example,  *_erl_errno()).  For  reasons  of thread safety (or task safety), this is
              exactly what we do on most platforms.