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

[Andrey Borzenkov <arvidjaar@gmail.com>]

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;
-- 
tg: (ebd40b6..) u/strip-pv-trailing-blanks (depends on: master)