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 <machine/stdint.h>
  45 #include <sys/stat.h>
  46 #include <sys/ioctl.h>
  47 #include "reentrant.h"
  48 #include "un-namespace.h"
  49
  50 #include "libc_private.h"
  51
  52 static char fdevname_buf[sizeof(_PATH_DEV) + NAME_MAX];
  53
  54 static once_t           fdevname_init_once = ONCE_INITIALIZER;
  55 static thread_key_t     fdevname_key;
  56 static int              fdevname_keycreated = 0;
  57
  58 int
  59 fdevname_r(int fd, char *buf, size_t len)
  60 {
  61         struct stat     sb;
  62         struct fiodname_args fa;
  63
  64         *buf = '\0';
  65
  66         /* Must be a valid file descriptor */
  67         if (_fstat(fd, &sb))
  68                 return (EBADF);
  69
  70         /* Must be a character device */
  71         if (!S_ISCHR(sb.st_mode))
  72                 return (EINVAL);
  73
  74         fa.len = len;
  75         fa.name = buf;
  76         if (_ioctl(fd, FIODNAME, &fa) == -1) {
  77                 return ERANGE;
  78         }
  79         return (0);
  80 }
  81
  82 static void
  83 fdevname_keycreate(void)
  84 {
  85         fdevname_keycreated = (thr_keycreate(&fdevname_key, free) == 0);
  86 }
  87
  88 char *
  89 fdevname(int fd)
  90 {
  91         char    *buf;
  92         int     error;
  93
  94         if (thr_main() != 0)
  95                 buf = fdevname_buf;
  96         else {
  97                 if (thr_once(&fdevname_init_once, fdevname_keycreate) != 0 ||
  98                     !fdevname_keycreated)
  99                         return (NULL);
 100                 if ((buf = thr_getspecific(fdevname_key)) == NULL) {
 101                         if ((buf = malloc(sizeof fdevname_buf)) == NULL)
 102                                 return (NULL);
 103                         if (thr_setspecific(fdevname_key, buf) != 0) {
 104                                 free(buf);
 105                                 return (NULL);
 106                         }
 107                 }
 108         }
 109
 110         if (((error = fdevname_r(fd, buf, sizeof fdevname_buf))) != 0) {
 111                 errno = error;
 112                 return (NULL);
 113         }
 114         return (buf);
 115 }