src/wrapper/random.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * wrapper/random.c
   4  *
   5  * wrapper around bootid read. Read the boot id through the /proc filesystem.
   6  *
   7  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/errno.h>
  11
  12 /* boot_id depends on sysctl */
  13 #if defined(CONFIG_SYSCTL)
  14
  15 #include <wrapper/fs.h>
  16 #include <linux/file.h>
  17 #include <linux/sched.h>
  18 #include <linux/uaccess.h>
  19 #include <wrapper/random.h>
  20
  21 /*
  22  * Returns string boot id.
  23  */
  24 int wrapper_get_bootid(char *bootid)
  25 {
  26         struct file *file;
  27         int ret;
  28         ssize_t len;
  29
  30         file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
  31         if (IS_ERR(file))
  32                 return PTR_ERR(file);
  33
  34         len = lttng_kernel_read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
  35         if (len != BOOT_ID_LEN - 1) {
  36                 ret = -EINVAL;
  37                 goto end;
  38         }
  39
  40         bootid[BOOT_ID_LEN - 1] = '\0';
  41         ret = 0;
  42 end:
  43         filp_close(file, current->files);
  44         return ret;
  45 }
  46 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  47
  48 #else
  49
  50 int wrapper_get_bootid(char *bootid)
  51 {
  52         return -ENOSYS;
  53 }
  54 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  55
  56 #endif