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/* xstrerror.c -- jacket routine for more robust strerror() usage.

   Fri Jun 16 18:30:00 1995  Pat Rankin  <rankin@eql.caltech.edu>

   This code is in the public domain.  */

/*

@deftypefn Replacement char* xstrerror (int @var{errnum})

Behaves exactly like the standard @code{strerror} function, but

will never return a @code{NULL} pointer.

@end deftypefn

*/

#include <stdio.h>

#include "libiberty.h"

#include "config.h"

#ifdef VMS

#include <errno.h>

#if !defined (__STRICT_ANSI__) && !defined (__HIDE_FORBIDDEN_NAMES)

extern char *strerror PARAMS ((int,...));

#define DONT_DECLARE_STRERROR

#endif

#endif  /* VMS */

#ifndef DONT_DECLARE_STRERROR

extern char *strerror PARAMS ((int));

#endif

/* If strerror returns NULL, we'll format the number into a static buffer.  */

#define ERRSTR_FMT "undocumented error #%d"

static char xstrerror_buf[sizeof ERRSTR_FMT + 20];

/* Like strerror, but result is never a null pointer.  */

char *

xstrerror (errnum)

     int errnum;

{

  char *errstr;

#ifdef VMS

  char *(*vmslib_strerror) PARAMS ((int,...));

  /* Override any possibly-conflicting declaration from system header.  */

  vmslib_strerror = (char *(*) PARAMS ((int,...))) strerror;

  /* Second argument matters iff first is EVMSERR, but it's simpler to

     pass it unconditionally.  `vaxc$errno' is declared in <errno.h>

     and maintained by the run-time library in parallel to `errno'.

     We assume that `errnum' corresponds to the last value assigned to

     errno by the run-time library, hence vaxc$errno will be relevant.  */

  errstr = (*vmslib_strerror) (errnum, vaxc$errno);

#else

  errstr = strerror (errnum);

#endif

  /* If `errnum' is out of range, result might be NULL.  We'll fix that.  */

  if (!errstr)

    {

      sprintf (xstrerror_buf, ERRSTR_FMT, errnum);

      errstr = xstrerror_buf;

    }

  return errstr;

}