cosmopolitan/libc/calls/gethostname.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/utsname.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/macros.h"
#include "libc/nt/enum/computernameformat.h"
#include "libc/nt/errors.h"
#include "libc/nt/runtime.h"
#include "libc/nt/systeminfo.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"

#define CTL_KERN      1
#define KERN_HOSTNAME 10

/**
 * Returns name of host system, e.g.
 *
 *     pheidippides.domain.example
 *     ^^^^^^^^^^^^
 */
int gethostname(char *name, size_t len) {
  if (len < 1) return einval();
  if (!name) return efault();
  if (!IsWindows()) {
    if (IsBsd()) {
      char *p;
      int cmd[2];
      char buf[254];
      size_t buflen;
      cmd[0] = CTL_KERN;
      cmd[1] = KERN_HOSTNAME;
      buflen = sizeof(buf);
      if (sysctl(cmd, 2, buf, &buflen, NULL, 0) == -1) {
        if (errno == ENOMEM) errno = ENAMETOOLONG;
        return -1;
      }
      strncpy(name, buf, len);
      name[len - 1] = '\0';
      if ((p = strchr(name, '.'))) *p = '\0';
      return 0;
    } else {
      struct utsname u;
      if (uname(&u) == -1) return -1;
      memccpy(name, u.nodename, '\0', len);
      name[len - 1] = '\0';
      return 0;
    }
  } else {
    uint32_t nSize;
    char16_t name16[256];
    nSize = ARRAYLEN(name16);
    if (GetComputerNameEx(kNtComputerNameDnsHostname, name16, &nSize)) {
      tprecode16to8(name, len, name16);
      return 0;
    } else {
      return __winerr();
    }
  }
}