Re: hfs patch (Re: State of GRUB on PowerPC)

["Michel Dänzer" <michel@daenzer.net>]

On Sat, 2009-02-07 at 23:38 -0500, Pavel Roskin wrote:
> Quoting Robert Millan <rmh@aybabtu.com>:
> 
> > On Tue, Jan 27, 2009 at 08:19:41AM +0100, Michel Dänzer wrote:
> >> +/*
> >> + * unsigned char caseorder[]
> >> + *
> >> + * Defines the lexical ordering of characters on the Macintosh
> >> + *
> >> + * Composition of the 'casefold' and 'order' tables from ARDI's code
> >> + * with the entry for 0x20 changed to match that for 0xCA to remove
> >> + * special case for those two characters.
> >> + */
> >> +static unsigned char caseorder[256] = {
> >> +	0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F,
> >
> > Could you be more specific about what the table contents mean?

BTW, let me point out again that this table including comment is a
verbatim copy from the Linux kernel fs/hfs/string.c . Sorry if I didn't
make this clear enough in my original post.

> Michel may know better, but I think it's the order of characters.   
> Those with the lower order go first in the sorted binary tree.  Those  
> with the same order are equivalent on the filesystem level.  That is,  
> "foo" can only be between "bar" and "quux" in the node tree.  "foo"  
> and "Foo" are the same tree node and thus the same file.

I think that's a nice summary, thanks.


> >> +  for (i = 0; i < k1->strlen && i < k2->strlen; i++) {
> >> +    cmp = caseorder[k1->str[i]] - caseorder[k2->str[i]];
> >
> > I think "a = (b != c)" would be more efficient (and also work).
> 
> I don't think so.

Yeah, definitely not. We have to use the same sort order as the HFS
on-disk trees, or we are unable to look up some files.


Below is a new patch with the opening { moved after newlines and the
ChangeLog entry included.


--- grub2-1.96+20081201.orig/ChangeLog	2008-11-29 22:05:59.000000000 +0100
+++ grub2-1.96+20081201/ChangeLog	2009-02-09 16:59:30.000000000 +0100
@@ -0,0 +1,7 @@
+2009-01-29  Michel Dänzer  <michel@daenzer.net>
+
+        * fs/hfs.c (grub_hfs_cmp_catkeys): Use lookup table for HFS
+        B-tree sort order. Otherwise we fail to look up some files,
+        e.g. with an underscore in the name, so e.g. the _linux module  
+        can't be loaded from an HFS filesystem.
+
--- grub2-1.96+20081201.orig/fs/hfs.c	2008-01-23 21:21:18.000000000 +0100
+++ grub2-1.96+20081201/fs/hfs.c	2009-02-09 17:06:35.000000000 +0100
@@ -391,6 +391,35 @@ grub_hfs_mount (grub_disk_t disk)
 }
 
 
+/*
+ * unsigned char caseorder[]
+ *
+ * Defines the lexical ordering of characters on the Macintosh
+ *
+ * Composition of the 'casefold' and 'order' tables from ARDI's code
+ * with the entry for 0x20 changed to match that for 0xCA to remove
+ * special case for those two characters.
+ */
+static unsigned char caseorder[256] =
+{
+	0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F,
+	0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F,
+	0x20,0x22,0x23,0x28,0x29,0x2A,0x2B,0x2C,0x2F,0x30,0x31,0x32,0x33,0x34,0x35,0x36,
+	0x37,0x38,0x39,0x3A,0x3B,0x3C,0x3D,0x3E,0x3F,0x40,0x41,0x42,0x43,0x44,0x45,0x46,
+	0x47,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xA9,0xAA,0xAB,0xAC,0xAD,
+	0x4E,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xAF,0xB0,0xB1,0xB2,0xB3,
+	0x4A,0x4C,0x5A,0x60,0x7B,0x7F,0x98,0x4F,0x49,0x51,0x4A,0x4B,0x4C,0x5A,0x60,0x63,
+	0x64,0x65,0x6E,0x6F,0x70,0x71,0x7B,0x84,0x85,0x86,0x7F,0x80,0x9A,0x9B,0x9C,0x98,
+	0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0x94,0xBB,0xBC,0xBD,0xBE,0xBF,0xC0,0x4D,0x81,
+	0xC1,0xC2,0xC3,0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xCB,0x55,0x8A,0xCC,0x4D,0x81,
+	0xCD,0xCE,0xCF,0xD0,0xD1,0xD2,0xD3,0x26,0x27,0xD4,0x20,0x49,0x4B,0x80,0x82,0x82,
+	0xD5,0xD6,0x24,0x25,0x2D,0x2E,0xD7,0xD8,0xA6,0xD9,0xDA,0xDB,0xDC,0xDD,0xDE,0xDF,
+	0xE0,0xE1,0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xEB,0xEC,0xED,0xEE,0xEF,
+	0xF0,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFC,0xFD,0xFE,0xFF
+};
+
 /* Compare the K1 and K2 catalog file keys.  */
 static int
 grub_hfs_cmp_catkeys (struct grub_hfs_catalog_key *k1,
@@ -398,17 +427,20 @@ grub_hfs_cmp_catkeys (struct grub_hfs_ca
 {
   int cmp = (grub_be_to_cpu32 (k1->parent_dir)
 	     - grub_be_to_cpu32 (k2->parent_dir));
+  int i;
   
   if (cmp != 0)
     return cmp;
-  
-  cmp = grub_strncasecmp ((char *) (k1->str), (char *) (k2->str), k1->strlen);
-  
-  /* This is required because the compared strings are not of equal
-     length.  */
-  if (cmp == 0 && k1->strlen < k2->strlen)
-    return -1;
-  return cmp;
+
+  for (i = 0; i < k1->strlen && i < k2->strlen; i++)
+  {
+    cmp = caseorder[k1->str[i]] - caseorder[k2->str[i]];
+
+    if (cmp != 0)
+      return cmp;
+  }
+
+  return k1->strlen - k2->strlen;
 }
 
 


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer