util/opendev.c

   1 /*
   2  * Copyright (c) 2000, Todd C. Miller.  All rights reserved.
   3  * Copyright (c) 1996, Jason Downs.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
  15  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  16  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  17  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
  18  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  19  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  20  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  21  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <ctype.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #include <limits.h>
  31 #include <paths.h>
  32 #include <stdio.h>
  33 #include <string.h>
  34 #include <pthread.h>
  35
  36 #include "util.h"
  37
  38 /*
  39  * opendev(3) is an inherently non-thread-safe API, since
  40  * it returns a buffer to global storage. However we can
  41  * at least make sure the storage allocation is thread safe
  42  * and does not leak memory in case of simultaneous
  43  * initialization
  44  */
  45 static pthread_once_t opendev_namebuf_once = PTHREAD_ONCE_INIT;
  46 static char *namebuf = NULL;
  47
  48 static void opendev_namebuf_init(void);
  49
  50 int
  51 opendev(path, oflags, dflags, realpath)
  52         char *path;
  53         int oflags;
  54         int dflags;
  55         char **realpath;
  56 {
  57         int fd;
  58         char *slash, *prefix;
  59
  60         /* Initial state */
  61         if (realpath)
  62                 *realpath = path;
  63         fd = -1;
  64         errno = ENOENT;
  65
  66         if (pthread_once(&opendev_namebuf_once,
  67                                          opendev_namebuf_init)
  68                 || !namebuf) {
  69                 errno = ENOMEM;
  70                 return -1;
  71         }
  72
  73         if (dflags & OPENDEV_BLCK)
  74                 prefix = "";                    /* block device */
  75         else
  76                 prefix = "r";                   /* character device */
  77
  78         if ((slash = strchr(path, '/')))
  79                 fd = open(path, oflags);
  80         else if (dflags & OPENDEV_PART) {
  81                 if (snprintf(namebuf, PATH_MAX, "%s%s%s",
  82                     _PATH_DEV, prefix, path) < PATH_MAX) {
  83                         char *slice;
  84                         while ((slice = strrchr(namebuf, 's')) &&
  85                             isdigit(*(slice-1))) *slice = '\0';
  86                         fd = open(namebuf, oflags);
  87                         if (realpath)
  88                                 *realpath = namebuf;
  89                 } else
  90                         errno = ENAMETOOLONG;
  91         }
  92         if (!slash && fd == -1 && errno == ENOENT) {
  93                 if (snprintf(namebuf, PATH_MAX, "%s%s%s",
  94                     _PATH_DEV, prefix, path) < PATH_MAX) {
  95                         fd = open(namebuf, oflags);
  96                         if (realpath)
  97                                 *realpath = namebuf;
  98                 } else
  99                         errno = ENAMETOOLONG;
 100         }
 101         return (fd);
 102 }
 103
 104 static void opendev_namebuf_init(void)
 105 {
 106         namebuf = malloc(PATH_MAX);
 107 }