Branch data     Line data    Source code

       1                 :             : /*
       2                 :             :  * Copyright (c) 2016, Citrix Systems, Inc.
       3                 :             :  *
       4                 :             :  * All rights reserved.
       5                 :             :  *
       6                 :             :  * Redistribution and use in source and binary forms, with or without
       7                 :             :  * modification, are permitted provided that the following conditions are met:
       8                 :             :  * 
       9                 :             :  *  1. Redistributions of source code must retain the above copyright
      10                 :             :  *     notice, this list of conditions and the following disclaimer.
      11                 :             :  *  2. Redistributions in binary form must reproduce the above copyright
      12                 :             :  *     notice, this list of conditions and the following disclaimer in the
      13                 :             :  *     documentation and/or other materials provided with the distribution.
      14                 :             :  *  3. Neither the name of the copyright holder nor the names of its 
      15                 :             :  *     contributors may be used to endorse or promote products derived from 
      16                 :             :  *     this software without specific prior written permission.
      17                 :             :  *
      18                 :             :  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      19                 :             :  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      20                 :             :  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      21                 :             :  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
      22                 :             :  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
      23                 :             :  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
      24                 :             :  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
      25                 :             :  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
      26                 :             :  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
      27                 :             :  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
      28                 :             :  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      29                 :             :  */
      30                 :             : 
      31                 :             : #ifdef HAVE_CONFIG_H
      32                 :             : #include "config.h"
      33                 :             : #endif
      34                 :             : 
      35                 :             : #include <stdio.h>
      36                 :             : #include <errno.h>
      37                 :             : #include <fcntl.h>
      38                 :             : #include <stdlib.h>
      39                 :             : #include <unistd.h>
      40                 :             : #include <sys/file.h>
      41                 :             : 
      42                 :             : #include "tap-ctl.h"
      43                 :             : #include "blktap.h"
      44                 :             : 
      45                 :             : int
      46                 :           3 : tap_ctl_free(const int minor)
      47                 :             : {
      48                 :           3 :         char *path = NULL;
      49                 :           3 :         int mfd = -1, fd, err;
      50                 :             : 
      51                 :           3 :         fd = open(BLKTAP2_NP_RUN_DIR, O_RDONLY);
      52         [ +  + ]:           3 :         if (fd == -1) {
      53                 :           1 :                 err = -errno;
      54                 :           1 :                 EPRINTF("Failed to open runtime directory %d\n", errno);
      55                 :           1 :                 return err;
      56                 :             :         }
      57                 :             : 
      58                 :             :         /* The only way this can fail is with an EINTR or ENOLCK*/
      59                 :           2 :         err = flock(fd, LOCK_EX);
      60         [ -  + ]:           2 :         if (err == -1) {
      61                 :           0 :                 err = -errno;
      62                 :           0 :                 EPRINTF("Failed to lock runtime directory %d\n", errno);
      63                 :           0 :                 goto out;
      64                 :             :         }
      65                 :             : 
      66                 :           2 :         err = asprintf(&path, "%s/tapdisk-%d", BLKTAP2_NP_RUN_DIR, minor);
      67         [ -  + ]:           2 :         if (err == -1) {
      68                 :           0 :                 err = -errno;
      69                 :           0 :                 goto out;
      70                 :             :         }
      71                 :           2 :         err = 0;
      72                 :             : 
      73                 :             :         /* Non-Blocking lock to check it's not in use */
      74                 :           2 :         mfd = open(path, O_RDONLY);
      75         [ -  + ]:           2 :         if (mfd == -1) {
      76                 :           0 :                 err = -errno;
      77                 :           0 :                 EPRINTF("Failed to open marker file %s, %d, err=%d\n",
      78                 :             :                         path, minor, errno);
      79                 :           0 :                 goto out;
      80                 :             :         }
      81                 :             : 
      82                 :           2 :         err = flock(mfd, LOCK_EX | LOCK_NB);
      83         [ +  + ]:           2 :         if (err == -1) {
      84                 :           1 :                 err = -errno;
      85                 :           1 :                 EPRINTF("Unable to lock marker file %s, err = %d\n",
      86                 :             :                         path, errno);
      87                 :           1 :                 goto out;
      88                 :             :         }
      89                 :             : 
      90                 :           1 :         unlink(path);
      91                 :             : 
      92                 :           2 : out:
      93         [ +  - ]:           2 :         if (path)
      94                 :           2 :                 free(path);
      95                 :             : 
      96         [ +  - ]:           2 :         if (mfd != -1) {
      97                 :           2 :                 flock(mfd, LOCK_UN);
      98                 :           2 :                 close(mfd);
      99                 :             :         }
     100                 :             : 
     101                 :           2 :         flock(fd, LOCK_UN);
     102                 :           2 :         close(fd);
     103                 :             :         return err;
     104                 :             : }