1/* xstrerror.c -- jacket routine for more robust strerror() usage.
2   Fri Jun 16 18:30:00 1995  Pat Rankin  <rankin@eql.caltech.edu>
3   This code is in the public domain.  */
4
5/*
6
7@deftypefn Replacement char* xstrerror (int @var{errnum})
8
9Behaves exactly like the standard @code{strerror} function, but
10will never return a @code{NULL} pointer.
11
12@end deftypefn
13
14*/
15
16#include <stdio.h>
17
18#include "libiberty.h"
19#include "config.h"
20
21#ifdef VMS
22#include <errno.h>
23#if !defined (__STRICT_ANSI__) && !defined (__HIDE_FORBIDDEN_NAMES)
24extern char *strerror PARAMS ((int,...));
25#define DONT_DECLARE_STRERROR
26#endif
27#endif	/* VMS */
28
29#ifndef DONT_DECLARE_STRERROR
30extern char *strerror PARAMS ((int));
31#endif
32
33/* If strerror returns NULL, we'll format the number into a static buffer.  */
34
35#define ERRSTR_FMT "undocumented error #%d"
36static char xstrerror_buf[sizeof ERRSTR_FMT + 20];
37
38/* Like strerror, but result is never a null pointer.  */
39
40char *
41xstrerror (errnum)
42     int errnum;
43{
44  char *errstr;
45#ifdef VMS
46  char *(*vmslib_strerror) PARAMS ((int,...));
47
48  /* Override any possibly-conflicting declaration from system header.  */
49  vmslib_strerror = (char *(*) PARAMS ((int,...))) strerror;
50  /* Second argument matters iff first is EVMSERR, but it's simpler to
51     pass it unconditionally.  `vaxc$errno' is declared in <errno.h>
52     and maintained by the run-time library in parallel to `errno'.
53     We assume that `errnum' corresponds to the last value assigned to
54     errno by the run-time library, hence vaxc$errno will be relevant.  */
55  errstr = (*vmslib_strerror) (errnum, vaxc$errno);
56#else
57  errstr = strerror (errnum);
58#endif
59
60  /* If `errnum' is out of range, result might be NULL.  We'll fix that.  */
61  if (!errstr)
62    {
63      sprintf (xstrerror_buf, ERRSTR_FMT, errnum);
64      errstr = xstrerror_buf;
65    }
66  return errstr;
67}
68