lib/libc/gen/fdevname.c

   1 /*
   2  * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Alex Hornung <ahornung@gmail.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34 #include "namespace.h"
  35 #include <sys/types.h>
  36 #include <fcntl.h>
  37 #include <dirent.h>
  38 #include <stdlib.h>
  39 #include <termios.h>
  40 #include <unistd.h>
  41 #include <string.h>
  42 #include <paths.h>
  43 #include <errno.h>
  44 #include <limits.h>
  45 #include <machine/stdint.h>
  46 #include <sys/stat.h>
  47 #include <sys/ioctl.h>
  48 #include "reentrant.h"
  49 #include "un-namespace.h"
  50
  51 #include "libc_private.h"
  52
  53 static char fdevname_buf[sizeof(_PATH_DEV) + NAME_MAX];
  54
  55 static once_t           fdevname_init_once = ONCE_INITIALIZER;
  56 static thread_key_t     fdevname_key;
  57 static int              fdevname_keycreated = 0;
  58
  59 int
  60 fdevname_r(int fd, char *buf, size_t len)
  61 {
  62         struct stat     sb;
  63         struct fiodname_args fa;
  64
  65         *buf = '\0';
  66
  67         /* Must be a valid file descriptor */
  68         if (_fstat(fd, &sb))
  69                 return (EBADF);
  70
  71         /* Must be a character device */
  72         if (!S_ISCHR(sb.st_mode))
  73                 return (EINVAL);
  74
  75         fa.len = len;
  76         fa.name = buf;
  77         if (_ioctl(fd, FIODNAME, &fa) == -1) {
  78                 return ERANGE;
  79         }
  80         return (0);
  81 }
  82
  83 static void
  84 fdevname_keycreate(void)
  85 {
  86         fdevname_keycreated = (thr_keycreate(&fdevname_key, free) == 0);
  87 }
  88
  89 char *
  90 fdevname(int fd)
  91 {
  92         char    *buf;
  93         int     error;
  94
  95         if (thr_main() != 0)
  96                 buf = fdevname_buf;
  97         else {
  98                 if (thr_once(&fdevname_init_once, fdevname_keycreate) != 0 ||
  99                     !fdevname_keycreated)
 100                         return (NULL);
 101                 if ((buf = thr_getspecific(fdevname_key)) == NULL) {
 102                         if ((buf = malloc(sizeof fdevname_buf)) == NULL)
 103                                 return (NULL);
 104                         if (thr_setspecific(fdevname_key, buf) != 0) {
 105                                 free(buf);
 106                                 return (NULL);
 107                         }
 108                 }
 109         }
 110
 111         if (((error = fdevname_r(fd, buf, sizeof fdevname_buf))) != 0) {
 112                 errno = error;
 113                 return (NULL);
 114         }
 115         return (buf);
 116 }