The original pattern for creating the pid file was:
open_create(pid_file)
write(pid_file, pid)
close(pid_file)
But if a power outage occurs between open_create and write, the file will
be empty and httpd will refuse to start afterwards unless the corrupt pid
file is removed.
This patch uses the pattern:
open_create(temp_pid_file)
write(temp_pid_file)
close(temp_pid_file)
rename(temp_pid_file, pid_file)
which is guaranteed to be atomic, provided that temp_pid_file and pid_file
are located in the same file system, which this patch does by creating
a temporary file name with the pattern:
pid_file_name + random_suffix
Patch is upstream as of
dd10a9352e,
which will be in the next 2.5.x version.
Signed-off-by: Nicolas Carrier <nicolas.carrier@orolia.com>
[Thomas: update to use upstreamed patch.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
67fbb903b6