From fe8c2f111758b54f07d0c6ca99aa86222e8c2645 Mon Sep 17 00:00:00 2001
From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>
Date: Fri, 11 May 2012 21:07:39 +0200
Subject: [PATCH] 	Use grub-probe and not cmp to check that disk is
 empty.

	* util/grub-install.in: Use grub-probe for zero-check.
	* util/grub-probe.c (PRINT_ZERO_CHECK): New enum value.
	(probe): Handle PRINT_ZERO_CHECK.
	(argp_parser): Handle -t zero_check.
---
 ChangeLog            | 11 ++++++++++-
 util/grub-install.in |  2 +-
 util/grub-probe.c    | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 62df29c96..e68cc9d80 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,13 @@
-2012-05-10  Vladimir Serbinenko  <phcoder@gmail.com>
+2012-05-11  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	Use grub-probe and not cmp to check that disk is empty.
+
+	* util/grub-install.in: Use grub-probe for zero-check.
+	* util/grub-probe.c (PRINT_ZERO_CHECK): New enum value.
+	(probe): Handle PRINT_ZERO_CHECK.
+	(argp_parser): Handle -t zero_check.
+
+2012-05-11  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	Flush block cache on adding disk to device map.
 
diff --git a/util/grub-install.in b/util/grub-install.in
index 03d7e1fca..b8e1d5a52 100644
--- a/util/grub-install.in
+++ b/util/grub-install.in
@@ -776,7 +776,7 @@ elif [ "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" = "i386-ieee1275" ]
 		exit 1
             fi
 
-            if [ "$(file -s "${install_device}" -b | awk '{ print $1 }')" = ELF ] || [ $(cmp /dev/zero "${install_device}" &>/dev/null) ]; then
+            if [ "$(file -s "${install_device}" -b | awk '{ print $1 }')" = ELF ] || [ x$("${grub_probe}" -m "${device_map}" -d "${install_device}" -t zero_check) = xtrue ]; then
             # Change boot device to the harddisk root
 		boot_device="$ofpath"
 		dd if="${grubdir}/${grub_modinfo_target_cpu}-$grub_modinfo_platform/core.${imgext}" of="${install_device}" status=noxfer || {
diff --git a/util/grub-probe.c b/util/grub-probe.c
index 8734366cd..8beb1bc60 100644
--- a/util/grub-probe.c
+++ b/util/grub-probe.c
@@ -67,6 +67,7 @@ enum {
   PRINT_ARC_HINT,
   PRINT_COMPATIBILITY_HINT,
   PRINT_MSDOS_PARTTYPE,
+  PRINT_ZERO_CHECK,
   PRINT_DISK
 };
 
@@ -392,6 +393,45 @@ probe (const char *path, char **device_names, char delim)
       goto end;
     }
 
+  if (print == PRINT_ZERO_CHECK)
+    {
+      for (curdev = drives_names; *curdev; curdev++)
+	{
+	  grub_device_t dev = NULL;
+	  grub_uint32_t buffer[32768];
+	  grub_disk_addr_t addr;
+	  grub_disk_addr_t dsize;
+
+	  grub_util_info ("opening %s", *curdev);
+	  dev = grub_device_open (*curdev);
+	  if (! dev || !dev->disk)
+	    grub_util_error ("%s", grub_errmsg);
+
+	  dsize = grub_disk_get_size (dev->disk);
+	  for (addr = 0; addr < dsize;
+	       addr += sizeof (buffer) / GRUB_DISK_SECTOR_SIZE)
+	    {
+	      grub_size_t sz = sizeof (buffer);
+	      grub_uint32_t *ptr;
+
+	      if (sizeof (buffer) / GRUB_DISK_SECTOR_SIZE > dsize - addr)
+		sz = (dsize - addr) * GRUB_DISK_SECTOR_SIZE;
+	      grub_disk_read (dev->disk, addr, 0, sz, buffer);
+
+	      for (ptr = buffer; ptr < buffer + sz / sizeof (*buffer); ptr++)
+		if (*ptr)
+		  {
+		    grub_printf ("false\n");
+		    grub_device_close (dev);
+		    goto end;
+		  }
+	    }
+
+	  grub_device_close (dev);
+	}
+      grub_printf ("true\n");
+    }
+
   if (print == PRINT_FS || print == PRINT_FS_UUID
       || print == PRINT_FS_LABEL)
     {
@@ -770,6 +810,8 @@ argp_parser (int key, char *arg, struct argp_state *state)
 	print = PRINT_ARC_HINT;
       else if (!strcmp (arg, "compatibility_hint"))
 	print = PRINT_COMPATIBILITY_HINT;
+      else if (strcmp (arg, "zero_check") == 0)
+	print = PRINT_ZERO_CHECK;
       else if (!strcmp (arg, "disk"))
 	print = PRINT_DISK;
       else