coreutils hostname / gethostname fixes

[Paul Eggert]

I installed these fixes for coreutils hostname, including its use of
gethostname.  The code didn't work for host names longer than INT_MAX
(possible on GNU/Hurd, perhaps?), and while I was fixing this I
noticed that it didn't properly work around the SunOS 5.5 bug in some
cases.  There are a couple of other very minor cleanups (e.g., with
the patch it no longer assumesthat errno can't ever validly equal
9999).

2004-08-02  Paul Eggert  <address@hidden>

        * lib/xgethostname.c: Don't include <sys/types.h> or "exit.h";
        no longer needed.
        (errno): Remove decl; we now assume C89 or better.
        Include unistd.h if available, for gethostname.
        (ENAMETOOLONG): Define to 0, not 9999, to avoid colliding with
        existing errno values if any.
        (gethostname): Remove decl, since unistd.h declares it (or doesn't,
        in which case it's an older system and it should just work).
        (xgethostname): Don't assume host name length is less than INT_MAX.
        Exit if malloc fails, just as the comment says.
        * src/hostname.c: Include "xgethostname.h".
        (xgethostname): Remove decl; xgethostname.h has it.
        (sethostname) [!defined(HAVE_SETHOSTNAME) && defined(HAVE_SYSINFO)
        && defined (HAVE_SYS_SYSTEMINFO_H) && defined(HAVE_LIMITS_H)]: Use
        prototypes rather than K&R form.  Assume any negative value from
        sysinfo denotes failure, not just -1.
        (main): Simplify use of sethostname.

Index: lib/xgethostname.c
===================================================================
RCS file: /home/eggert/coreutils/cu/lib/xgethostname.c,v
retrieving revision 1.19
diff -p -u -r1.19 xgethostname.c
--- lib/xgethostname.c  16 Oct 2003 06:26:56 -0000      1.19
+++ lib/xgethostname.c  2 Aug 2004 21:47:55 -0000
@@ -1,5 +1,7 @@
 /* xgethostname.c -- return current hostname with unlimited length
-   Copyright (C) 1992, 1996, 2000, 2001, 2003 Free Software Foundation, Inc.
+
+   Copyright (C) 1992, 1996, 2000, 2001, 2003, 2004 Free Software
+   Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -25,60 +27,56 @@
 #include "xgethostname.h"
 
 #include <stdlib.h>
-#include <sys/types.h>
-
 #include <errno.h>
-#ifndef errno
-extern int errno;
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
 #endif
 
 #include "error.h"
-#include "exit.h"
 #include "xalloc.h"
 
 #ifndef ENAMETOOLONG
-# define ENAMETOOLONG 9999
+# define ENAMETOOLONG 0
 #endif
 
-int gethostname ();
-
 #ifndef INITIAL_HOSTNAME_LENGTH
 # define INITIAL_HOSTNAME_LENGTH 34
 #endif
 
 /* Return the current hostname in malloc'd storage.
    If malloc fails, exit.
-   Upon any other failure, return NULL.  */
+   Upon any other failure, return NULL and set errno.  */
 char *
 xgethostname (void)
 {
-  char *hostname;
-  size_t size;
+  char *hostname = NULL;
+  size_t size = INITIAL_HOSTNAME_LENGTH;
 
-  size = INITIAL_HOSTNAME_LENGTH;
-  /* Use size + 1 here rather than size to work around the bug
-     in SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME
-     even when the name is longer than the supplied buffer.  */
-  hostname = xmalloc (size + 1);
   while (1)
     {
-      int k = size - 1;
-      int err;
-
+      /* Use SIZE_1 here rather than SIZE to work around the bug in
+        SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME
+        even when the name is as long as the supplied buffer.  */
+      size_t size_1;
+
+      hostname = x2realloc (hostname, &size);
+      size_1 = size - 1;
+      hostname[size_1 - 1] = '\0';
       errno = 0;
-      hostname[k] = '\0';
-      err = gethostname (hostname, size);
-      if (err >= 0 && hostname[k] == '\0')
-       break;
-      else if (err < 0 && errno != ENAMETOOLONG && errno != 0)
+
+      if (gethostname (hostname, size_1) == 0)
+       {
+         if (! hostname[size_1 - 1])
+           break;
+       }
+      else if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL)
        {
          int saved_errno = errno;
          free (hostname);
          errno = saved_errno;
          return NULL;
        }
-      size *= 2;
-      hostname = xrealloc (hostname, size + 1);
     }
 
   return hostname;
Index: src/hostname.c
===================================================================
RCS file: /home/eggert/coreutils/cu/src/hostname.c,v
retrieving revision 1.52
diff -p -u -r1.52 hostname.c
--- src/hostname.c      21 Jun 2004 15:03:35 -0000      1.52
+++ src/hostname.c      2 Aug 2004 21:45:11 -0000
@@ -25,6 +25,7 @@
 #include "long-options.h"
 #include "error.h"
 #include "quote.h"
+#include "xgethostname.h"
 
 /* The official name of this program (e.g., no `g' prefix).  */
 #define PROGRAM_NAME "hostname"
@@ -40,23 +41,15 @@ int sethostname ();
 # include <sys/systeminfo.h>
 
 int
-sethostname (name, namelen)
-     char *name;
-     int namelen;
+sethostname (char *name, size_t namelen)
 {
   /* Using sysinfo() is the SVR4 mechanism to set a hostname. */
-  int result;
-
-  result = sysinfo (SI_SET_HOSTNAME, name, namelen);
-
-  return (result == -1 ? result : 0);
+  return (sysinfo (SI_SET_HOSTNAME, name, namelen) < 0 ? -1 : 0);
 }
 
 # define HAVE_SETHOSTNAME 1  /* Now we have it... */
 #endif
 
-char *xgethostname ();
-
 /* The name this program was run with. */
 char *program_name;
 
@@ -109,11 +102,8 @@ main (int argc, char **argv)
 #ifdef HAVE_SETHOSTNAME
   if (argc == 2)
     {
-      int err;
-
       /* Set hostname to argv[1].  */
-      err = sethostname (argv[1], strlen (argv[1]));
-      if (err != 0)
+      if (sethostname (argv[1], strlen (argv[1])) != 0)
        error (EXIT_FAILURE, errno, _("cannot set hostname to `%s'"), argv[1]);
       exit (EXIT_SUCCESS);
     }