clock: read bootid as clock monotonic ID

[lttng-modules.git] / wrapper / random.c

diff --git a/wrapper/random.c b/wrapper/random.c
new file mode 100644 (file)
index 0000000..da8cb17
--- /dev/null
+++ b/wrapper/random.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
+ *
+ * wrapper around bootid read. Using KALLSYMS to get its address when
+ * available, else we need to have a kernel that exports this function to GPL
+ * modules.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+/* boot_id depends on sysctl */
+#if defined(CONFIG_SYSCTL)
+
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include "random.h"
+
+/*
+ * Returns string boot id.
+ */
+int wrapper_get_bootid(char *bootid)
+{
+       struct file *file;
+       int ret;
+       ssize_t len;
+       mm_segment_t old_fs;
+
+       file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
+       if (IS_ERR(file))
+               return PTR_ERR(file);
+
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+
+       if (!file->f_op || !file->f_op->read) {
+               ret = -EINVAL;
+               goto end;
+       }
+
+       len = file->f_op->read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
+       if (len != BOOT_ID_LEN - 1) {
+               ret = -EINVAL;
+               goto end;
+       }
+       
+       bootid[BOOT_ID_LEN - 1] = '\0';
+       ret = 0;
+end:
+       set_fs(old_fs);
+       filp_close(file, current->files);
+       return ret;
+}
+
+#else
+
+int wrapper_get_bootid(char *bootid)
+{
+       return -ENOSYS;
+}
+
+#endif