Re: [PATCH] fix parsing of LVM PV names for short names

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

Go ahead
On 27.07.2013 12:09, Andrey Borzenkov wrote:
> Default format of vgs output is
>
> - two spaces as standard prefix
> - PV name left aligned to field width which is 10 characters
>
> This means that if PV name has less than 10 chacaters it has some spaces at
> the end.
>
> Example:
>
> linux-chxo:~ # vgs -o pv_name --noheadings | cat -E
>    /dev/md1  $
>    /dev/md101$
> linux-chxo:~ #
>
> There is no explicit option to turn off alignment; it is implicitly
> disabled if one of --separator or --nameprefixes option is used.
>
> --separator was added in 2007, --nameprefixes - in 2009. So let's use
> --separator to extend range of versions we are compatible with. Note that
> one or another must be used, current parsing is broken otherwise.
>
> Signed-off-by: Andrey Borzenkov <arvidjaar@gmail.com>
>
> ---
>   util/getroot.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/util/getroot.c b/util/getroot.c
> index 2ad8a55..3afcf96 100644
> --- a/util/getroot.c
> +++ b/util/getroot.c
> @@ -1322,7 +1322,7 @@ grub_util_get_dev_abstraction (const char *os_dev)
>   static void
>   pull_lvm_by_command (const char *os_dev)
>   {
> -  char *argv[6];
> +  char *argv[8];
>     int fd;
>     pid_t pid;
>     FILE *mdadm;
> @@ -1351,12 +1351,17 @@ pull_lvm_by_command (const char *os_dev)
>
>     /* execvp has inconvenient types, hence the casts.  None of these
>        strings will actually be modified.  */
> +  /* by default PV name is left aligned in 10 character field, meaning that
> +     we do not know where name ends. Using dummy --separator disables
> +     alignment. We have a single field, so separator itself is not output */
>     argv[0] = (char *) "vgs";
>     argv[1] = (char *) "--options";
>     argv[2] = (char *) "pv_name";
>     argv[3] = (char *) "--noheadings";
> -  argv[4] = vgname;
> -  argv[5] = NULL;
> +  argv[4] = (char *) "--separator";
> +  argv[5] = (char *) ":";
> +  argv[6] = vgname;
> +  argv[7] = NULL;
>
>     pid = exec_pipe (argv, &fd);
>     free (vgname);
> @@ -1376,6 +1381,7 @@ pull_lvm_by_command (const char *os_dev)
>     while (getline (&buf, &len, mdadm) > 0)
>       {
>         char *ptr;
> +      /* LVM adds two spaces as standard prefix */
>         for (ptr = buf; ptr < buf + 2 && *ptr == ' '; ptr++);
>         if (*ptr == '\0')
>   	continue;
>