Port fsys_fat.c from grub legacy. This enables pygrub to load from EFI

FAT partitions on ia64.

Signed-off-by: Aron Griffis <aron@hp.com>

4 files changed, 599 insertions, 1 deletions

diff --git a/tools/libfsimage/Makefile b/tools/libfsimage/Makefile
index 2631230cae..5dc1e65f99 100644
--- a/tools/libfsimage/Makefile
+++ b/tools/libfsimage/Makefile
@@ -1,7 +1,7 @@
 XEN_ROOT = ../..
 include $(XEN_ROOT)/tools/Rules.mk
 
-SUBDIRS-y = common ufs reiserfs iso9660
+SUBDIRS-y = common ufs reiserfs iso9660 fat
 SUBDIRS-y += $(shell ./check-libext2fs)
 
 .PHONY: all
diff --git a/tools/libfsimage/fat/Makefile b/tools/libfsimage/fat/Makefile
new file mode 100644
index 0000000000..bfc55e4f8c
--- /dev/null
+++ b/tools/libfsimage/fat/Makefile
@@ -0,0 +1,13 @@
+XEN_ROOT = ../../..
+
+LIB_SRCS-y = fsys_fat.c
+
+FS = fat
+
+.PHONY: all
+all: fs-all
+
+.PHONY: install
+install: fs-install
+
+include $(XEN_ROOT)/tools/libfsimage/Rules.mk
diff --git a/tools/libfsimage/fat/fat.h b/tools/libfsimage/fat/fat.h
new file mode 100644
index 0000000000..7fed6bacb3
--- /dev/null
+++ b/tools/libfsimage/fat/fat.h
@@ -0,0 +1,100 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2001  Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ *  Defines for the FAT BIOS Parameter Block (embedded in the first block
+ *  of the partition.
+ */
+
+typedef __signed__ char __s8;
+typedef unsigned char __u8;
+typedef __signed__ short __s16;
+typedef unsigned short __u16;
+typedef __signed__ int __s32;
+typedef unsigned int __u32;
+
+/* Note that some shorts are not aligned, and must therefore
+ * be declared as array of two bytes.
+ */
+struct fat_bpb {
+	__s8	ignored[3];	/* Boot strap short or near jump */
+	__s8	system_id[8];	/* Name - can be used to special case
+				   partition manager volumes */
+	__u8	bytes_per_sect[2];	/* bytes per logical sector */
+	__u8	sects_per_clust;/* sectors/cluster */
+	__u8	reserved_sects[2];	/* reserved sectors */
+	__u8	num_fats;	/* number of FATs */
+	__u8	dir_entries[2];	/* root directory entries */
+	__u8	short_sectors[2];	/* number of sectors */
+	__u8	media;		/* media code (unused) */
+	__u16	fat_length;	/* sectors/FAT */
+	__u16	secs_track;	/* sectors per track */
+	__u16	heads;		/* number of heads */
+	__u32	hidden;		/* hidden sectors (unused) */
+	__u32	long_sectors;	/* number of sectors (if short_sectors == 0) */
+
+	/* The following fields are only used by FAT32 */
+	__u32	fat32_length;	/* sectors/FAT */
+	__u16	flags;		/* bit 8: fat mirroring, low 4: active fat */
+	__u8	version[2];	/* major, minor filesystem version */
+	__u32	root_cluster;	/* first cluster in root directory */
+	__u16	info_sector;	/* filesystem info sector */
+	__u16	backup_boot;	/* backup boot sector */
+	__u16	reserved2[6];	/* Unused */
+};
+
+#define FAT_CVT_U16(bytarr) (* (__u16*)(bytarr))
+
+/*
+ *  Defines how to differentiate a 12-bit and 16-bit FAT.
+ */
+
+#define FAT_MAX_12BIT_CLUST       4087	/* 4085 + 2 */
+
+/*
+ *  Defines for the file "attribute" byte
+ */
+
+#define FAT_ATTRIB_OK_MASK        0x37
+#define FAT_ATTRIB_NOT_OK_MASK    0xC8
+#define FAT_ATTRIB_DIR            0x10
+#define FAT_ATTRIB_LONGNAME       0x0F
+
+/*
+ *  Defines for FAT directory entries
+ */
+
+#define FAT_DIRENTRY_LENGTH       32
+
+#define FAT_DIRENTRY_ATTRIB(entry) \
+  (*((unsigned char *) (entry+11)))
+#define FAT_DIRENTRY_VALID(entry) \
+  ( ((*((unsigned char *) entry)) != 0) \
+    && ((*((unsigned char *) entry)) != 0xE5) \
+    && !(FAT_DIRENTRY_ATTRIB(entry) & FAT_ATTRIB_NOT_OK_MASK) )
+#define FAT_DIRENTRY_FIRST_CLUSTER(entry) \
+  ((*((unsigned short *) (entry+26)))+(*((unsigned short *) (entry+20)) << 16))
+#define FAT_DIRENTRY_FILELENGTH(entry) \
+  (*((unsigned long *) (entry+28)))
+
+#define FAT_LONGDIR_ID(entry) \
+  (*((unsigned char *) (entry)))
+#define FAT_LONGDIR_ALIASCHECKSUM(entry) \
+  (*((unsigned char *) (entry+13)))
diff --git a/tools/libfsimage/fat/fsys_fat.c b/tools/libfsimage/fat/fsys_fat.c
new file mode 100644
index 0000000000..9d74bdf1a9
--- /dev/null
+++ b/tools/libfsimage/fat/fsys_fat.c
@@ -0,0 +1,485 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2000,2001,2005   Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <limits.h>
+#include <fsimage_grub.h>
+#include "fat.h"
+
+struct fat_superblock 
+{
+  int fat_offset;
+  int fat_length;
+  int fat_size;
+  int root_offset;
+  int root_max;
+  int data_offset;
+  
+  int num_sectors;
+  int num_clust;
+  int clust_eof_marker;
+  int sects_per_clust;
+  int sectsize_bits;
+  int clustsize_bits;
+  int root_cluster;
+  
+  int cached_fat;
+  int file_cluster;
+  int current_cluster_num;
+  int current_cluster;
+};
+
+/* pointer(s) into filesystem info buffer for DOS stuff */
+#define FAT_SUPER ( (struct fat_superblock *) \
+ 		    ( FSYS_BUF + 32256) )/* 512 bytes long */
+#define FAT_BUF   ( FSYS_BUF + 30208 )	/* 4 sector FAT buffer */
+#define NAME_BUF  ( FSYS_BUF + 29184 )	/* Filename buffer (833 bytes) */
+
+#define FAT_CACHE_SIZE 2048
+
+#define log2 grub_log2
+
+int
+fat_mount (fsi_file_t *ffi, const char *options)
+{
+  struct fat_bpb bpb;
+  __u32 magic, first_fat;
+  
+  /* Read bpb */
+  if (! devread (ffi, 0, 0, sizeof (bpb), (char *) &bpb))
+    return 0;
+
+  /* Check if the number of sectors per cluster is zero here, to avoid
+     zero division.  */
+  if (bpb.sects_per_clust == 0)
+    return 0;
+  
+  FAT_SUPER->sectsize_bits = log2 (FAT_CVT_U16 (bpb.bytes_per_sect));
+  FAT_SUPER->clustsize_bits
+    = FAT_SUPER->sectsize_bits + log2 (bpb.sects_per_clust);
+  
+  /* Fill in info about super block */
+  FAT_SUPER->num_sectors = FAT_CVT_U16 (bpb.short_sectors) 
+    ? FAT_CVT_U16 (bpb.short_sectors) : bpb.long_sectors;
+  
+  /* FAT offset and length */
+  FAT_SUPER->fat_offset = FAT_CVT_U16 (bpb.reserved_sects);
+  FAT_SUPER->fat_length = 
+    bpb.fat_length ? bpb.fat_length : bpb.fat32_length;
+  
+  /* Rootdir offset and length for FAT12/16 */
+  FAT_SUPER->root_offset = 
+    FAT_SUPER->fat_offset + bpb.num_fats * FAT_SUPER->fat_length;
+  FAT_SUPER->root_max = FAT_DIRENTRY_LENGTH * FAT_CVT_U16(bpb.dir_entries);
+  
+  /* Data offset and number of clusters */
+  FAT_SUPER->data_offset = 
+    FAT_SUPER->root_offset
+    + ((FAT_SUPER->root_max - 1) >> FAT_SUPER->sectsize_bits) + 1;
+  FAT_SUPER->num_clust = 
+    2 + ((FAT_SUPER->num_sectors - FAT_SUPER->data_offset) 
+	 / bpb.sects_per_clust);
+  FAT_SUPER->sects_per_clust = bpb.sects_per_clust;
+  
+  if (!bpb.fat_length)
+    {
+      /* This is a FAT32 */
+      if (FAT_CVT_U16(bpb.dir_entries))
+ 	return 0;
+      
+      if (bpb.flags & 0x0080)
+	{
+	  /* FAT mirroring is disabled, get active FAT */
+	  int active_fat = bpb.flags & 0x000f;
+	  if (active_fat >= bpb.num_fats)
+	    return 0;
+	  FAT_SUPER->fat_offset += active_fat * FAT_SUPER->fat_length;
+	}
+      
+      FAT_SUPER->fat_size = 8;
+      FAT_SUPER->root_cluster = bpb.root_cluster;
+
+      /* Yes the following is correct.  FAT32 should be called FAT28 :) */
+      FAT_SUPER->clust_eof_marker = 0xffffff8;
+    } 
+  else 
+    {
+      if (!FAT_SUPER->root_max)
+ 	return 0;
+      
+      FAT_SUPER->root_cluster = -1;
+      if (FAT_SUPER->num_clust > FAT_MAX_12BIT_CLUST) 
+	{
+	  FAT_SUPER->fat_size = 4;
+	  FAT_SUPER->clust_eof_marker = 0xfff8;
+	} 
+      else
+	{
+	  FAT_SUPER->fat_size = 3;
+	  FAT_SUPER->clust_eof_marker = 0xff8;
+	}
+    }
+
+  /* Now do some sanity checks */
+  
+  if (FAT_CVT_U16(bpb.bytes_per_sect) != (1 << FAT_SUPER->sectsize_bits)
+      || FAT_CVT_U16(bpb.bytes_per_sect) != SECTOR_SIZE
+      || bpb.sects_per_clust != (1 << (FAT_SUPER->clustsize_bits
+ 				       - FAT_SUPER->sectsize_bits))
+      || FAT_SUPER->num_clust <= 2
+      || (FAT_SUPER->fat_size * FAT_SUPER->num_clust / (2 * SECTOR_SIZE)
+ 	  > FAT_SUPER->fat_length))
+    return 0;
+  
+  /* kbs: Media check on first FAT entry [ported from PUPA] */
+
+  if (!devread(ffi, FAT_SUPER->fat_offset, 0,
+               sizeof(first_fat), (char *)&first_fat))
+    return 0;
+
+  if (FAT_SUPER->fat_size == 8)
+    {
+      first_fat &= 0x0fffffff;
+      magic = 0x0fffff00;
+    }
+  else if (FAT_SUPER->fat_size == 4)
+    {
+      first_fat &= 0x0000ffff;
+      magic = 0xff00;
+    }
+  else
+    {
+      first_fat &= 0x00000fff;
+      magic = 0x0f00;
+    }
+
+  /* Ignore the 3rd bit, because some BIOSes assigns 0xF0 to the media
+     descriptor, even if it is a so-called superfloppy (e.g. an USB key).
+     The check may be too strict for this kind of stupid BIOSes, as
+     they overwrite the media descriptor.  */
+  if ((first_fat | 0x8) != (magic | bpb.media | 0x8))
+    return 0;
+
+  FAT_SUPER->cached_fat = - 2 * FAT_CACHE_SIZE;
+  return 1;
+}
+
+int
+fat_read (fsi_file_t *ffi, char *buf, int len)
+{
+  int logical_clust;
+  int offset;
+  int ret = 0;
+  int size;
+  
+  if (FAT_SUPER->file_cluster < 0)
+    {
+      /* root directory for fat16 */
+      size = FAT_SUPER->root_max - filepos;
+      if (size > len)
+ 	size = len;
+      if (!devread(ffi, FAT_SUPER->root_offset, filepos, size, buf))
+ 	return 0;
+      filepos += size;
+      return size;
+    }
+  
+  logical_clust = filepos >> FAT_SUPER->clustsize_bits;
+  offset = (filepos & ((1 << FAT_SUPER->clustsize_bits) - 1));
+  if (logical_clust < FAT_SUPER->current_cluster_num)
+    {
+      FAT_SUPER->current_cluster_num = 0;
+      FAT_SUPER->current_cluster = FAT_SUPER->file_cluster;
+    }
+  
+  while (len > 0)
+    {
+      int sector;
+      while (logical_clust > FAT_SUPER->current_cluster_num)
+	{
+	  /* calculate next cluster */
+	  int fat_entry = 
+	    FAT_SUPER->current_cluster * FAT_SUPER->fat_size;
+	  int next_cluster;
+	  int cached_pos = (fat_entry - FAT_SUPER->cached_fat);
+	  
+	  if (cached_pos < 0 || 
+	      (cached_pos + FAT_SUPER->fat_size) > 2*FAT_CACHE_SIZE)
+	    {
+	      FAT_SUPER->cached_fat = (fat_entry & ~(2*SECTOR_SIZE - 1));
+	      cached_pos = (fat_entry - FAT_SUPER->cached_fat);
+	      sector = FAT_SUPER->fat_offset
+		+ FAT_SUPER->cached_fat / (2*SECTOR_SIZE);
+	      if (!devread (ffi, sector, 0, FAT_CACHE_SIZE, (char*) FAT_BUF))
+		return 0;
+	    }
+	  next_cluster = * (unsigned long *) (FAT_BUF + (cached_pos >> 1));
+	  if (FAT_SUPER->fat_size == 3)
+	    {
+	      if (cached_pos & 1)
+		next_cluster >>= 4;
+	      next_cluster &= 0xFFF;
+	    }
+	  else if (FAT_SUPER->fat_size == 4)
+	    next_cluster &= 0xFFFF;
+	  
+	  if (next_cluster >= FAT_SUPER->clust_eof_marker)
+	    return ret;
+	  if (next_cluster < 2 || next_cluster >= FAT_SUPER->num_clust)
+	    {
+	      errnum = ERR_FSYS_CORRUPT;
+	      return 0;
+	    }
+	  
+	  FAT_SUPER->current_cluster = next_cluster;
+	  FAT_SUPER->current_cluster_num++;
+	}
+      
+      sector = FAT_SUPER->data_offset +
+	((FAT_SUPER->current_cluster - 2) << (FAT_SUPER->clustsize_bits
+ 					      - FAT_SUPER->sectsize_bits));
+      size = (1 << FAT_SUPER->clustsize_bits) - offset;
+      if (size > len)
+	size = len;
+      
+      disk_read_func = disk_read_hook;
+      
+      devread(ffi, sector, offset, size, buf);
+      
+      disk_read_func = NULL;
+      
+      len -= size;
+      buf += size;
+      ret += size;
+      filepos += size;
+      logical_clust++;
+      offset = 0;
+    }
+  return errnum ? 0 : ret;
+}
+
+int
+fat_dir (fsi_file_t *ffi, char *dirname)
+{
+  char *rest, ch, dir_buf[FAT_DIRENTRY_LENGTH];
+  char *filename = (char *) NAME_BUF;
+  int attrib = FAT_ATTRIB_DIR;
+#ifndef STAGE1_5
+  int do_possibilities = 0;
+#endif
+  
+  /* XXX I18N:
+   * the positions 2,4,6 etc are high bytes of a 16 bit unicode char 
+   */
+  static unsigned char longdir_pos[] = 
+  { 1, 3, 5, 7, 9, 14, 16, 18, 20, 22, 24, 28, 30 };
+  int slot = -2;
+  int alias_checksum = -1;
+  
+  FAT_SUPER->file_cluster = FAT_SUPER->root_cluster;
+  filepos = 0;
+  FAT_SUPER->current_cluster_num = INT_MAX;
+  
+  /* main loop to find desired directory entry */
+ loop:
+  
+  /* if we have a real file (and we're not just printing possibilities),
+     then this is where we want to exit */
+  
+  if (!*dirname || isspace (*dirname))
+    {
+      if (attrib & FAT_ATTRIB_DIR)
+	{
+	  errnum = ERR_BAD_FILETYPE;
+	  return 0;
+	}
+      
+      return 1;
+    }
+  
+  /* continue with the file/directory name interpretation */
+  
+  while (*dirname == '/')
+    dirname++;
+  
+  if (!(attrib & FAT_ATTRIB_DIR))
+    {
+      errnum = ERR_BAD_FILETYPE;
+      return 0;
+    }
+  /* Directories don't have a file size */
+  filemax = INT_MAX;
+  
+  for (rest = dirname; (ch = *rest) && !isspace (ch) && ch != '/'; rest++);
+  
+  *rest = 0;
+  
+# ifndef STAGE1_5
+  if (print_possibilities && ch != '/')
+    do_possibilities = 1;
+# endif
+  
+  while (1)
+    {
+      if (fat_read (ffi, dir_buf, FAT_DIRENTRY_LENGTH) != FAT_DIRENTRY_LENGTH
+	  || dir_buf[0] == 0)
+	{
+	  if (!errnum)
+	    {
+# ifndef STAGE1_5
+	      if (print_possibilities < 0)
+		{
+#if 0
+		  putchar ('\n');
+#endif
+		  return 1;
+		}
+# endif /* STAGE1_5 */
+	      
+	      errnum = ERR_FILE_NOT_FOUND;
+	      *rest = ch;
+	    }
+	  
+	  return 0;
+	}
+      
+      if (FAT_DIRENTRY_ATTRIB (dir_buf) == FAT_ATTRIB_LONGNAME)
+	{
+	  /* This is a long filename.  The filename is build from back
+	   * to front and may span multiple entries.  To bind these
+	   * entries together they all contain the same checksum over
+	   * the short alias.
+	   *
+	   * The id field tells if this is the first entry (the last
+	   * part) of the long filename, and also at which offset this
+	   * belongs.
+	   *
+	   * We just write the part of the long filename this entry
+	   * describes and continue with the next dir entry.
+	   */
+	  int i, offset;
+	  unsigned char id = FAT_LONGDIR_ID(dir_buf);
+	  
+	  if ((id & 0x40)) 
+	    {
+	      id &= 0x3f;
+	      slot = id;
+	      filename[slot * 13] = 0;
+	      alias_checksum = FAT_LONGDIR_ALIASCHECKSUM(dir_buf);
+	    } 
+	  
+	  if (id != slot || slot == 0
+	      || alias_checksum != FAT_LONGDIR_ALIASCHECKSUM(dir_buf))
+	    {
+	      alias_checksum = -1;
+	      continue;
+	    }
+	  
+	  slot--;
+	  offset = slot * 13;
+	  
+	  for (i=0; i < 13; i++)
+	    filename[offset+i] = dir_buf[longdir_pos[i]];
+	  continue;
+	}
+      
+      if (!FAT_DIRENTRY_VALID (dir_buf))
+	continue;
+      
+      if (alias_checksum != -1 && slot == 0)
+	{
+	  int i;
+	  unsigned char sum;
+	  
+	  slot = -2;
+	  for (sum = 0, i = 0; i< 11; i++)
+	    sum = ((sum >> 1) | (sum << 7)) + dir_buf[i];
+	  
+	  if (sum == alias_checksum)
+	    {
+# ifndef STAGE1_5
+	      if (do_possibilities)
+		goto print_filename;
+# endif /* STAGE1_5 */
+	      
+	      if (substring (dirname, filename) == 0)
+		break;
+	    }
+	}
+      
+      /* XXX convert to 8.3 filename format here */
+      {
+	int i, j, c;
+	
+	for (i = 0; i < 8 && (c = filename[i] = tolower (dir_buf[i]))
+	       && !isspace (c); i++);
+	
+	filename[i++] = '.';
+	
+	for (j = 0; j < 3 && (c = filename[i + j] = tolower (dir_buf[8 + j]))
+	       && !isspace (c); j++);
+	
+	if (j == 0)
+	  i--;
+	
+	filename[i + j] = 0;
+      }
+      
+# ifndef STAGE1_5
+      if (do_possibilities)
+	{
+	print_filename:
+	  if (substring (dirname, filename) <= 0)
+	    {
+	      if (print_possibilities > 0)
+		print_possibilities = -print_possibilities;
+	      print_a_completion (filename);
+	    }
+	  continue;
+	}
+# endif /* STAGE1_5 */
+      
+      if (substring (dirname, filename) == 0)
+	break;
+    }
+  
+  *(dirname = rest) = ch;
+  
+  attrib = FAT_DIRENTRY_ATTRIB (dir_buf);
+  filemax = FAT_DIRENTRY_FILELENGTH (dir_buf);
+  filepos = 0;
+  FAT_SUPER->file_cluster = FAT_DIRENTRY_FIRST_CLUSTER (dir_buf);
+  FAT_SUPER->current_cluster_num = INT_MAX;
+  
+  /* go back to main loop at top of function */
+  goto loop;
+}
+
+fsi_plugin_ops_t *
+fsi_init_plugin(int version, fsi_plugin_t *fp, const char **name)
+{
+	static fsig_plugin_ops_t ops = {
+		FSIMAGE_PLUGIN_VERSION,
+		.fpo_mount = fat_mount,
+		.fpo_dir = fat_dir,
+		.fpo_read = fat_read
+	};
+
+	*name = "fat";
+	return (fsig_init(fp, &ops));
+}