[PATCH] PreP zero compare

[PATCH] PreP zero compare

[Vladimir 'φ-coder/phcoder' Serbinenko]

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Please test attached patch

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko


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=== modified file 'util/grub-install.in'
--- util/grub-install.in	2012-05-08 21:11:47 +0000
+++ util/grub-install.in	2012-05-10 08:01:38 +0000
@@ -776,7 +776,7 @@ elif [ "${grub_modinfo_target_cpu}-${gru
 		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 || {

=== modified file 'util/grub-probe.c'
--- util/grub-probe.c	2012-02-26 16:28:05 +0000
+++ util/grub-probe.c	2012-05-10 08:00:23 +0000
@@ -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_n
       goto end;
     }
 
+  if (print == PRINT_ZERO_CHECK)
+    {
+      for (curdev = device_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
 	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


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