libiberty/xstrerror.c

   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
   9 Behaves exactly like the standard @code{strerror} function, but
  10 will never return a @code{NULL} pointer.
  11
  12 @end deftypefn
  13
  14 */
  15
  16 #include <stdio.h>
  17
  18 #include "config.h"
  19 #include "libiberty.h"
  20
  21 #ifdef VMS
  22 #  include <errno.h>
  23 #  if !defined (__STRICT_ANSI__) && !defined (__HIDE_FORBIDDEN_NAMES)
  24 #    ifdef __cplusplus
  25 extern "C" {
  26 #    endif /* __cplusplus */
  27 extern char *strerror (int,...);
  28 #    define DONT_DECLARE_STRERROR
  29 #    ifdef __cplusplus
  30 }
  31 #    endif /* __cplusplus */
  32 #  endif
  33 #endif  /* VMS */
  34
  35
  36 #ifndef DONT_DECLARE_STRERROR
  37 #  ifdef __cplusplus
  38 extern "C" {
  39 #  endif /* __cplusplus */
  40 extern char *strerror (int);
  41 #  ifdef __cplusplus
  42 }
  43 #  endif /* __cplusplus */
  44 #endif
  45
  46 /* If strerror returns NULL, we'll format the number into a static buffer.  */
  47
  48 #define ERRSTR_FMT "undocumented error #%d"
  49 static char xstrerror_buf[sizeof ERRSTR_FMT + 20];
  50
  51 /* Like strerror, but result is never a null pointer.  */
  52
  53 char *
  54 xstrerror (int errnum)
  55 {
  56   char *errstr;
  57 #ifdef VMS
  58   char *(*vmslib_strerror) (int,...);
  59
  60   /* Override any possibly-conflicting declaration from system header.  */
  61   vmslib_strerror = (char *(*) (int,...)) strerror;
  62   /* Second argument matters iff first is EVMSERR, but it's simpler to
  63      pass it unconditionally.  `vaxc$errno' is declared in <errno.h>
  64      and maintained by the run-time library in parallel to `errno'.
  65      We assume that `errnum' corresponds to the last value assigned to
  66      errno by the run-time library, hence vaxc$errno will be relevant.  */
  67   errstr = (*vmslib_strerror) (errnum, vaxc$errno);
  68 #else
  69   errstr = strerror (errnum);
  70 #endif
  71
  72   /* If `errnum' is out of range, result might be NULL.  We'll fix that.  */
  73   if (!errstr)
  74     {
  75       sprintf (xstrerror_buf, ERRSTR_FMT, errnum);
  76       errstr = xstrerror_buf;
  77     }
  78   return errstr;
  79 }