[ovs-dev] [worker 05/12] daemon: Factor out code into new function fork_and_wait_for_startup().

[Ethan Jackson]

Looks good, thanks.

Ethan

On Tue, May 22, 2012 at 5:19 PM, Ben Pfaff <blp at nicira.com> wrote:
> This function will be useful in an upcoming commit.
>
> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
>  lib/daemon.c |   33 +++++++++++++++++++++++++++------
>  lib/daemon.h |    2 ++
>  2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/lib/daemon.c b/lib/daemon.c
> index ecca606..a2eff07 100644
> --- a/lib/daemon.c
> +++ b/lib/daemon.c
> @@ -245,6 +245,32 @@ daemonize(void)
>     daemonize_complete();
>  }
>
> +/* Calls fork() and on success returns its return value.  On failure, logs an
> + * error and exits unsuccessfully.
> + *
> + * Post-fork, but before returning, this function calls a few other functions
> + * that are generally useful if the child isn't planning to exec a new
> + * process. */
> +pid_t
> +fork_and_clean_up(void)
> +{
> +    pid_t pid;
> +
> +    pid = fork();
> +    if (pid > 0) {
> +        /* Running in parent process. */
> +        fatal_signal_fork();
> +    } else if (!pid) {
> +        /* Running in child process. */
> +        time_postfork();
> +        lockfile_postfork();
> +    } else {
> +        VLOG_FATAL("fork failed (%s)", strerror(errno));
> +    }
> +
> +    return pid;
> +}
> +
>  /* Forks, then:
>  *
>  *   - In the parent, waits for the child to signal that it has completed its
> @@ -264,14 +290,13 @@ fork_and_wait_for_startup(int *fdp)
>
>     xpipe(fds);
>
> -    pid = fork();
> +    pid = fork_and_clean_up();
>     if (pid > 0) {
>         /* Running in parent process. */
>         size_t bytes_read;
>         char c;
>
>         close(fds[1]);
> -        fatal_signal_fork();
>         if (read_fully(fds[0], &c, 1, &bytes_read) != 0) {
>             int retval;
>             int status;
> @@ -301,11 +326,7 @@ fork_and_wait_for_startup(int *fdp)
>     } else if (!pid) {
>         /* Running in child process. */
>         close(fds[0]);
> -        time_postfork();
> -        lockfile_postfork();
>         *fdp = fds[1];
> -    } else {
> -        VLOG_FATAL("fork failed (%s)", strerror(errno));
>     }
>
>     return pid;
> diff --git a/lib/daemon.h b/lib/daemon.h
> index 8d52594..63b64b9 100644
> --- a/lib/daemon.h
> +++ b/lib/daemon.h
> @@ -73,4 +73,6 @@ void daemon_usage(void);
>  pid_t read_pidfile(const char *name);
>  pid_t read_pidfile_if_exists(const char *name);
>
> +pid_t fork_and_clean_up(void);
> +
>  #endif /* daemon.h */
> --
> 1.7.2.5
>
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