[pacman-dev] [PATCH] libalpm: add PID to db.lck

[Dan McGee]

On Sun, Nov 2, 2008 at 8:22 PM, Allan McRae <allan at archlinux.org> wrote:
> This is the first step in being able to automatically remove phantom
> lock files.
>
> Signed-off-by: Allan McRae <allan at archlinux.org>
> ---
>  lib/libalpm/util.c |   15 +++++++++++++--
>  1 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
> index da3463b..811572a 100644
> --- a/lib/libalpm/util.c
> +++ b/lib/libalpm/util.c
> @@ -242,7 +242,9 @@ char *_alpm_strreplace(const char *str, const char *needle, const char *replace)
>  int _alpm_lckmk()
>  {
>        int fd;
> -       char *dir, *ptr;
> +       pid_t pid;
> +       size_t len;
> +       char *dir, *ptr, *spid;
>        const char *file = alpm_option_get_lockfile();
>
>        /* create the dir of the lockfile first */
> @@ -256,7 +258,16 @@ int _alpm_lckmk()
>
>        while((fd = open(file, O_WRONLY | O_CREAT | O_EXCL, 0000)) == -1
>                        && errno == EINTR);
> -       return(fd > 0 ? fd : -1);
> +       if(fd > 0) {
> +               pid = getpid();
> +               size_t len = snprintf(spid, 0, "%d", pid) + 1;
I think we need to use %ld here as a pid_t can be a signed type, up to
length long. Thus the whole thing:
snprintf(spid, 0, "%ld", (long)pid)
Obviously do this below too. And do you want to add a newline char in
here to make your life easier when reading this in?

> +               spid = malloc(len);
> +               snprintf(spid, len, "%d", pid) + 1;
Think you left a +1 here by accident.

> +               while(write(fd, (void *)spid, len) == -1 && errno == EINTR);
> +               fsync(fd);
> +               return(fd);
> +       }
> +       return(-1);
>  }

And re: your second message, I think your write() call is just fine here.