Comment that in Docker etc., get_boot_time returns the
boot time of the container, not of its host.
Also, give an example file instead of saying just “FILE”.
---
lib/boot-time.h | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/lib/boot-time.h b/lib/boot-time.h
index 195839a2c5..7abfa12e44 100644
--- a/lib/boot-time.h
+++ b/lib/boot-time.h
@@ -29,11 +29,16 @@ extern "C" {
/* Store the approximate time when the machine last booted in *P_BOOT_TIME,
and return 0. If it cannot be determined, return -1.
+ If the machine is a container inside another host machine,
+ return the boot time of the container, not the host.
+ The difference can matter in GNU/Linux, where times in /proc/stat
+ might be relative to boot time of the host, not the container.
+
This function is not multithread-safe, since on many platforms it
- invokes the functions setutxent, getutxent, endutxent. These
- functions are needed because they may lock FILE (so that we don't
- read garbage when a concurrent process writes to FILE), but their
- drawback is that they have a common global state. */
+ invokes the functions setutxent, getutxent, endutxent.
+ These functions may lock a file like /var/log/wtmp (so that we
+ don't read garbage when a concurrent process writes to that file),
+ but their drawback is that they have a common global state. */
extern int get_boot_time (struct timespec *p_boot_time);
--
2.48.1
