On Sat, 17 Jun 2023 13:36:20 +0800
Bin Meng wrote:
> From: Zhangjin Wu
>
> Based on the old close_all_open_fd() of util/async-teardown.c, a new
> generic qemu_close_range() has been added in osdep.c.
>
> Now, let's switch over to use the generic qemu_close_range().
>
> Signed-off-by: Zhangjin Wu
> Signed-off-by: Bin Meng
>
> ---
>
> Changes in v3:
> - limit the last_fd of qemu_close_range() to sysconf(_SC_OPEN_MAX)
>
> Changes in v2:
> - new patch: "util/async-teardown: Use qemu_close_range() to close fds"
>
> util/async-teardown.c | 42 ++
> 1 file changed, 2 insertions(+), 40 deletions(-)
>
> diff --git a/util/async-teardown.c b/util/async-teardown.c
> index 7e0177a8da..e102912f3f 100644
> --- a/util/async-teardown.c
> +++ b/util/async-teardown.c
> @@ -29,44 +29,6 @@
>
> static pid_t the_ppid;
>
> -/*
> - * Close all open file descriptors.
> - */
> -static void close_all_open_fd(void)
> -{
> -struct dirent *de;
> -int fd, dfd;
> -DIR *dir;
> -
> -#ifdef CONFIG_CLOSE_RANGE
> -int r = close_range(0, ~0U, 0);
> -if (!r) {
> -/* Success, no need to try other ways. */
> -return;
> -}
> -#endif
> -
> -dir = opendir("/proc/self/fd");
> -if (!dir) {
> -/* If /proc is not mounted, close fds one by one. */
> -int open_max = sysconf(_SC_OPEN_MAX), i;
> -for (i = 0; i < open_max; i++) {
> -close(i);
> -}
> -return;
> -}
> -/* Avoid closing the directory. */
> -dfd = dirfd(dir);
> -
> -for (de = readdir(dir); de; de = readdir(dir)) {
> -fd = atoi(de->d_name);
> -if (fd != dfd) {
> -close(fd);
> -}
> -}
> -closedir(dir);
> -}
> -
> static void hup_handler(int signal)
> {
> /* Check every second if this process has been reparented. */
> @@ -84,6 +46,7 @@ static int async_teardown_fn(void *arg)
> struct sigaction sa = { .sa_handler = hup_handler };
> sigset_t hup_signal;
> char name[16];
> +int open_max = sysconf(_SC_OPEN_MAX);
>
> /* Set a meaningful name for this process. */
> snprintf(name, 16, "cleanup/%d", the_ppid);
> @@ -92,9 +55,8 @@ static int async_teardown_fn(void *arg)
> /*
> * Close all file descriptors that might have been inherited from the
> * main qemu process when doing clone, needed to make libvirt happy.
> - * Not using close_range for increased compatibility with older kernels.
> */
> -close_all_open_fd();
> +qemu_close_range(0, open_max - 1);
I think it would look easier to read if you just put the sysconf() call
here and avoid an extra variable
>
> /* Set up a handler for SIGHUP and unblock SIGHUP. */
> sigaction(SIGHUP, &sa, NULL);
