Re: [PATCH] iso9660 UUID support by using the creation date/time

[Felix Zielcke <fzielcke@z-51.de>]

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Hello list,

Am Sonntag, den 31.08.2008, 15:47 +0200 schrieb Robert Millan:

> Nice work :-)

By the way the TAB key on emacs is really nice you even don't need to
care about moving the cursor to the beginning of the line :)

> > The specs say that it's allowed to contain only zeros but I think this
> > shouldn't be a big problem.
> 
> I think this could indeed be a problem if it leads to collisions.  If "all
> zeroes" is detected, one could rise an error in uuid() function to prevent the
> caller from taking the value into consideration.

I have now used grub_error (GRUB_ERR_BAD_NUMBER)

But maybe it would be better to make a new type for this, though I don't
have yet an idea how to call it.
Suggestions please :)


> Since the string contains human-readable information, may I suggest separating
> it with dashes to make it easier to comprehend?

Good idea, I should have done that first that would make it even for me a bit easier.
I did it now even more human-readable for the `sizeof ()' 

-- 
Felix Zielcke

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2008-08-31  Felix Zielcke  <fzielcke@z-51.de>

	* fs/iso9660.c (grub_iso9660_date): New structure.
	(grub_iso9660_primary_voldesc): Add `grub_iso9660_date' member.
	(grub_iso9660_uuid): New function.


Index: fs/iso9660.c
===================================================================
--- fs/iso9660.c	(Revision 1839)
+++ fs/iso9660.c	(Arbeitskopie)
@@ -67,6 +67,18 @@ struct grub_iso9660_dir
   grub_uint8_t namelen;
 } __attribute__ ((packed));
 
+struct grub_iso9660_date
+{
+  grub_uint8_t year[4];
+  grub_uint8_t month[2];
+  grub_uint8_t day[2];
+  grub_uint8_t hour[2];
+  grub_uint8_t minute[2];
+  grub_uint8_t second[2];
+  grub_uint8_t hundredth[2];
+  grub_uint8_t offset;
+}__attribute__ ((packed));
+
 /* The primary volume descriptor.  Only little endian is used.  */
 struct grub_iso9660_primary_voldesc
 {
@@ -81,6 +93,8 @@ struct grub_iso9660_primary_voldesc
   grub_uint32_t path_table;
   grub_uint8_t unused5[12];
   struct grub_iso9660_dir rootdir;
+  grub_uint8_t unused6[641];
+  struct grub_iso9660_date created;
 } __attribute__ ((packed));
 
 /* A single entry in the path table.  */
@@ -812,8 +826,59 @@ grub_iso9660_label (grub_device_t device
   return grub_errno;
 }
 
-\f
 
+static grub_err_t
+grub_iso9660_uuid (grub_device_t device, char **uuid)
+{
+  struct grub_iso9660_data *data;
+  grub_disk_t disk = device->disk;
+
+#ifndef GRUB_UTIL
+  grub_dl_ref (my_mod);
+#endif
+
+  data = grub_iso9660_mount (disk);
+  if (data)
+    {
+      if (! data->voldesc.created.year[0] && ! data->voldesc.created.year[1]
+	  && ! data->voldesc.created.year[2] && ! data->voldesc.created.year[3]
+	  && ! data->voldesc.created.month[0] && ! data->voldesc.created.month[1]
+	  && ! data->voldesc.created.day[0] && ! data->voldesc.created.day[1]
+	  && ! data->voldesc.created.hour[0] && ! data->voldesc.created.hour[1]
+	  && ! data->voldesc.created.minute[0] && ! data->voldesc.created.minute[1]
+	  && ! data->voldesc.created.second[0] && ! data->voldesc.created.second[1]
+	  && ! data->voldesc.created.hundredth[0] && ! data->voldesc.created.hundredth[1])
+	{
+	  grub_error (GRUB_ERR_BAD_NUMBER, "No creation date in filesystem to generate UUID.");
+	  *uuid = NULL;
+	}
+      else 
+	{
+	  *uuid = grub_malloc (sizeof ("YYYY-MM-DD-HH-mm-ss-hh") + sizeof ('\0'));
+	  grub_sprintf (*uuid, "%c%c%c%c-%c%c-%c%c-%c%c-%c%c-%c%c-%c%c",
+			data->voldesc.created.year[0], data->voldesc.created.year[1], 
+			data->voldesc.created.year[2], data->voldesc.created.year[3],
+			data->voldesc.created.month[0], data->voldesc.created.month[1],
+			data->voldesc.created.day[0], data->voldesc.created.day[1],
+			data->voldesc.created.hour[0], data->voldesc.created.hour[1],
+			data->voldesc.created.minute[0], data->voldesc.created.minute[1],
+			data->voldesc.created.second[0], data->voldesc.created.second[1],
+			data->voldesc.created.hundredth[0], data->voldesc.created.hundredth[1]);
+	}
+    }
+  else
+    *uuid = NULL;
+
+#ifndef GRUB_UTIL
+	grub_dl_unref (my_mod);
+#endif
+
+  grub_free (data);
+
+  return grub_errno;
+}
+
+\f
 static struct grub_fs grub_iso9660_fs =
   {
     .name = "iso9660",
@@ -822,6 +887,7 @@ static struct grub_fs grub_iso9660_fs =
     .read = grub_iso9660_read,
     .close = grub_iso9660_close,
     .label = grub_iso9660_label,
+    .uuid = grub_iso9660_uuid,
     .next = 0
   };