[Libguestfs] [PATCH] daemon: drop error message check in do_part_expand_gpt

[Denis Plotnikov]

part-expand-gpt takes extreme cautions and doesn't proceed to writing
to the disk if the preliminary dry run of sgdisk has generated any
warnings on stdout.

This blocks the use of part-expand-gpt on disk shrink (with disk
resize being the main usecase for part-expand-gpt), because sgdisk dry
run produces a warning in that case.

So remove the excessive safety check, and leave it up to the caller.

Signed-off-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan at virtuozzo.com>
---
 daemon/parted.c                | 20 +-------------------
 tests/gdisk/test-expand-gpt.pl | 24 +++++++++++++++++++++---
 2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/daemon/parted.c b/daemon/parted.c
index 070ed4790..2cc714d64 100644
--- a/daemon/parted.c
+++ b/daemon/parted.c
@@ -699,26 +699,8 @@ do_part_expand_gpt(const char *device)
 {
   CLEANUP_FREE char *err = NULL;
 
-  /* If something is broken, sgdisk may try to correct it.
-   * (e.g. recreate partition table and so on).
-   * We do not want such behavior, so dry-run at first.*/
   int r = commandf (NULL, &err, COMMAND_FLAG_FOLD_STDOUT_ON_STDERR,
-                    "sgdisk", "--pretend", "-e", device, NULL);
-
-  if (r == -1) {
-    reply_with_error ("%s --pretend -e %s: %s", "sgdisk", device, err);
-    return -1;
-  }
-  if (err && strlen(err) != 0) {
-    /* Unexpected actions. */
-    reply_with_error ("%s --pretend -e %s: %s", "sgdisk", device, err);
-    return -1;
-  }
-  free(err);
-
-  /* Now we can do a real run. */
-  r = commandf (NULL, &err, COMMAND_FLAG_FOLD_STDOUT_ON_STDERR,
-                "sgdisk", "-e", device, NULL);
+                    "sgdisk", "-e", device, NULL);
 
   if (r == -1) {
     reply_with_error ("%s -e %s: %s", "sgdisk", device, err);
diff --git a/tests/gdisk/test-expand-gpt.pl b/tests/gdisk/test-expand-gpt.pl
index 4d647f1af..f17d034ee 100755
--- a/tests/gdisk/test-expand-gpt.pl
+++ b/tests/gdisk/test-expand-gpt.pl
@@ -54,11 +54,29 @@ sub tests {
 	my $end_sectors = 100 * 1024 * 2 - $output;
 	die unless $end_sectors <= 34;
 
-	# Negative tests.
+	# Negative test.
 	eval { $g->part_expand_gpt ("/dev/sdb") };
 	die unless $@;
-	eval { $g->part_expand_gpt ("/dev/sda1") };
-	die unless $@;
+
+	$g->close ();
+
+	# Disk shrink test
+	die if system ("qemu-img resize --shrink disk_gpt.img 50M &>/dev/null");
+
+	$g = Sys::Guestfs->new ();
+
+	$g->add_drive ("disk_gpt.img", format => "qcow2");
+	$g->launch ();
+
+	die if $g->part_expand_gpt ("/dev/sda");
+
+	my $output = $g->debug ("sh", ["sgdisk", "-p", "/dev/sda"]);
+	die if $output eq "";
+	$output =~ s/\n/ /g;
+	$output =~ s/.*last usable sector is (\d+).*/$1/g;
+
+	my $end_sectors = 50 * 1024 * 2 - $output;
+	die unless $end_sectors <= 34;
 }
 
 eval { tests() };
-- 
2.17.2