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 #include <linux/module.h>
  12
  13 /* boot_id depends on sysctl */
  14 #if defined(CONFIG_SYSCTL)
  15
  16 #include <wrapper/fs.h>
  17 #include <linux/file.h>
  18 #include <linux/sched.h>
  19 #include <linux/uaccess.h>
  20 #include <wrapper/random.h>
  21
  22 /*
  23  * Returns string boot id.
  24  */
  25 int wrapper_get_bootid(char *bootid)
  26 {
  27         struct file *file;
  28         int ret;
  29         ssize_t len;
  30
  31         file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
  32         if (IS_ERR(file))
  33                 return PTR_ERR(file);
  34
  35         len = lttng_kernel_read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
  36         if (len != BOOT_ID_LEN - 1) {
  37                 ret = -EINVAL;
  38                 goto end;
  39         }
  40
  41         bootid[BOOT_ID_LEN - 1] = '\0';
  42         ret = 0;
  43 end:
  44         filp_close(file, current->files);
  45         return ret;
  46 }
  47 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  48
  49 #else
  50
  51 int wrapper_get_bootid(char *bootid)
  52 {
  53         return -ENOSYS;
  54 }
  55 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  56
  57 #endif