lib/gethostname.c

   1 /* gethostname emulation for SysV and POSIX.1.
   2
   3    Copyright (C) 1992, 2003, 2006, 2008-2020 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* David MacKenzie <djm@gnu.ai.mit.edu>
  19    Windows port by Simon Josefsson <simon@josefsson.org> */
  20
  21 #include <config.h>
  22
  23 #if !(defined _WIN32 && !defined __CYGWIN__)
  24 /* Unix API.  */
  25
  26 /* Specification.  */
  27 #include <unistd.h>
  28
  29 #ifdef HAVE_UNAME
  30 # include <sys/utsname.h>
  31 #endif
  32
  33 #include <string.h>
  34
  35 /* Put up to LEN chars of the host name into NAME.
  36    Null terminate it if the name is shorter than LEN.
  37    Return 0 if ok, -1 if error.  */
  38
  39 #include <stddef.h>
  40
  41 int
  42 gethostname (char *name, size_t len)
  43 {
  44 #ifdef HAVE_UNAME
  45   struct utsname uts;
  46
  47   if (uname (&uts) == -1)
  48     return -1;
  49   if (len > sizeof (uts.nodename))
  50     {
  51       /* More space than we need is available.  */
  52       name[sizeof (uts.nodename)] = '\0';
  53       len = sizeof (uts.nodename);
  54     }
  55   strncpy (name, uts.nodename, len);
  56 #else
  57   strcpy (name, "");            /* Hardcode your system name if you want.  */
  58 #endif
  59   return 0;
  60 }
  61
  62 #else
  63 /* Native Windows API.  Which primitive to choose?
  64    - gethostname() requires linking with -lws2_32.
  65    - GetComputerName() does not return the right kind of hostname.
  66    - GetComputerNameEx(ComputerNameDnsHostname,...) returns the right hostname,
  67      but it is hard to use portably:
  68        - It requires defining _WIN32_WINNT to at least 0x0500.
  69        - With mingw, it also requires
  70          "#define GetComputerNameEx GetComputerNameExA".
  71        - With older versions of mingw, none of the declarations are present at
  72          all, not even of the enum value ComputerNameDnsHostname.
  73    So we use gethostname().  Linking with -lws2_32 is the least evil.  */
  74
  75 #define WIN32_LEAN_AND_MEAN
  76 /* Get winsock2.h. */
  77 #include <unistd.h>
  78
  79 /* Get INT_MAX.  */
  80 #include <limits.h>
  81
  82 /* Get set_winsock_errno. */
  83 #include "w32sock.h"
  84
  85 #include "sockets.h"
  86
  87 #undef gethostname
  88
  89 int
  90 rpl_gethostname (char *name, size_t len)
  91 {
  92   int r;
  93
  94   if (len > INT_MAX)
  95     len = INT_MAX;
  96   gl_sockets_startup (SOCKETS_1_1);
  97   r = gethostname (name, (int) len);
  98   if (r < 0)
  99     set_winsock_errno ();
 100
 101   return r;
 102 }
 103
 104 #endif