Re: [PATCH] use vgs --nameprefixes to protect against whitespace changes

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

On 19.07.2013 09:11, Andrey Borzenkov wrote:
> Do not assume single blank at the end of PV name. At least
> lvm2-2.02.98-24.3 (openSUSE 13.1 M3) puts exra blank at the end.
>
> linux-chxo:~ # grub2-probe -t abstraction /lib
> mdadm: cannot open /dev/md1  : No such file or directory
> grub2-probe: error: cannot open `/dev/md1  ': No such file or directory.
> linux-chxo:~ # : Update grub with patch
> linux-chxo:~ # grub2-probe -t abstraction /lib
> diskfilter mdraid1x lvm
> linux-chxo:~ # vgs --options pv_name --noheadings | xxd
> 0000000: 2020 2f64 6576 2f6d 6431 2020 0a           /dev/md1  .
> linux-chxo:~ # rpm -q lvm2
> lvm2-2.02.98-24.3.i586
>
> This patch changes it to use --nameprefixes which returns each PV name as
>    LVM2_PV_NAME='xxx'
>
This code wouldn't handle name containing \n correctly but it's a 
subject for another patch as issue is already present.
Go ahead.
> Signed-off-by: Andrey Borzenkov <arvidjaar@gmail.com>
>
> ---
>   util/getroot.c | 20 +++++++++++++++-----
>   1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/util/getroot.c b/util/getroot.c
> index 2ad8a55..479ab78 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[7];
>     int fd;
>     pid_t pid;
>     FILE *mdadm;
> @@ -1355,8 +1355,9 @@ pull_lvm_by_command (const char *os_dev)
>     argv[1] = (char *) "--options";
>     argv[2] = (char *) "pv_name";
>     argv[3] = (char *) "--noheadings";
> -  argv[4] = vgname;
> -  argv[5] = NULL;
> +  argv[4] = (char *) "--nameprefixes";
> +  argv[5] = vgname;
> +  argv[6] = NULL;
>
>     pid = exec_pipe (argv, &fd);
>     free (vgname);
> @@ -1376,10 +1377,19 @@ pull_lvm_by_command (const char *os_dev)
>     while (getline (&buf, &len, mdadm) > 0)
>       {
>         char *ptr;
> -      for (ptr = buf; ptr < buf + 2 && *ptr == ' '; ptr++);
> +
> +      grub_util_info ("vgs returned PV: %s", buf);
> +
> +      for (ptr = buf; *ptr == ' '; ptr++);
>         if (*ptr == '\0')
>   	continue;
> -      *(ptr + strlen (ptr) - 1) = '\0';
> +      if (strncmp (buf, "LVM2_PV_NAME='", sizeof ("LVM2_PV_NAME='") - 1))
> +	continue;
> +      ptr = buf + sizeof ("LVM2_PV_NAME='") - 1;
> +      if (*(buf + len - 1) != '\'')
> +	continue;
> +      *(buf + len - 1) = '\0';
> +      /* FIXME can PV name contain "'"? */
>         grub_util_pull_device (ptr);
>       }
>
>