Host filesystem access

Host filesystem access

[Marco Gerards]

Hi,

Here is a patch to make it possible to access the host filesystem from
grub-emu.  This is especially useful for debugging purposes and will
make my life easier ;-).

This also adds a dummy disk which is used to give the host filesystem
a name.  It is not particularly clean, but adding this as a network is
even worse.  This can be used to access host filesystems on other
systems as well.

I will commit this after the weekend, if no-one objects.

--
Marco



2007-05-17  Marco Gerards  <marco@gnu.org>

	* conf/i386-pc.rmk (grub_emu_SOURCES): Add `disk/host.c' and
	`util/hostfs.c'.

	* disk/host.c: New file.

	* util/hostfs.c: Likewise.

	* fs/hfsplus.c (grub_hfsplus_mount): When reading out of disk,
	return `GRUB_ERR_BAD_FS'.
	* fs/sfs.c (grub_sfs_mount): Likewise.
	* fs/xfs.c (grub_xfs_mount): Likewise.

	* include/grub/disk.h (enum grub_disk_dev_id): Add
	`GRUB_DISK_DEVICE_HOST_ID'.

	* util/grub-emu.c (main): Initialize and de-initialize hostfs.


Index: conf/i386-pc.rmk
===================================================================
RCS file: /sources/grub/grub2/conf/i386-pc.rmk,v
retrieving revision 1.77
diff -u -p -u -p -r1.77 i386-pc.rmk
--- conf/i386-pc.rmk	16 May 2007 15:19:38 -0000	1.77
+++ conf/i386-pc.rmk	17 May 2007 21:17:02 -0000
@@ -90,7 +90,7 @@ grub_emu_SOURCES = commands/boot.c comma
 	commands/terminal.c commands/ls.c commands/test.c 		\
 	commands/search.c commands/blocklist.c				\
 	commands/i386/pc/halt.c commands/i386/pc/reboot.c		\
-	disk/loopback.c	disk/raid.c disk/lvm.c				\
+	disk/host.c disk/loopback.c disk/raid.c disk/lvm.c		\
 	fs/affs.c fs/ext2.c fs/fat.c fs/fshelp.c fs/hfs.c fs/iso9660.c	\
 	fs/jfs.c fs/minix.c fs/sfs.c fs/ufs.c fs/xfs.c fs/hfsplus.c	\
 	io/gzio.c							\
@@ -104,7 +104,7 @@ grub_emu_SOURCES = commands/boot.c comma
 	normal/menu.c normal/menu_entry.c normal/misc.c normal/script.c	\
 	partmap/amiga.c	partmap/apple.c partmap/pc.c partmap/sun.c	\
 	partmap/acorn.c partmap/gpt.c					\
-	util/console.c util/grub-emu.c util/misc.c			\
+	util/console.c util/hostfs.c util/grub-emu.c util/misc.c	\
 	util/biosdisk.c util/getroot.c			\
 	util/i386/pc/misc.c grub_emu_init.c
 
Index: disk/host.c
===================================================================
RCS file: disk/host.c
diff -N disk/host.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ disk/host.c	17 May 2007 21:17:02 -0000
@@ -0,0 +1,94 @@
+/* host.c - Dummy disk driver to provide access to the hosts filesystem  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2007  Free Software Foundation, Inc.
+ *
+ *  GRUB 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 GRUB; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* When using the disk, make a reference to this module.  Otherwise
+   the user will end up with a useless module :-).  */
+
+#include <grub/dl.h>
+#include <grub/disk.h>
+
+int grub_disk_host_i_want_a_reference;
+
+static int
+grub_host_iterate (int (*hook) (const char *name))
+{
+  if (hook ("host"))
+    return 1;
+  return 0;
+}
+
+static grub_err_t
+grub_host_open (const char *name __attribute((unused)), grub_disk_t disk)
+{
+  disk->total_sectors = 0;
+  disk->id = (int) "host";
+  
+  disk->has_partitions = 0;
+  disk->data = 0;
+
+  return GRUB_ERR_NONE;
+}
+
+static void
+grub_host_close (grub_disk_t disk __attribute((unused)))
+{
+}
+
+static grub_err_t
+grub_host_read (grub_disk_t disk __attribute((unused)),
+		grub_disk_addr_t sector __attribute((unused)),
+		grub_size_t size __attribute((unused)),
+		char *buf __attribute((unused)))
+{
+  return GRUB_ERR_OUT_OF_RANGE;
+}
+
+static grub_err_t
+grub_host_write (grub_disk_t disk __attribute ((unused)),
+		     grub_disk_addr_t sector __attribute ((unused)),
+		     grub_size_t size __attribute ((unused)),
+		     const char *buf __attribute ((unused)))
+{
+  return GRUB_ERR_OUT_OF_RANGE;
+}
+
+static struct grub_disk_dev grub_host_dev =
+  {
+    /* The only important line in this file :-) */
+    .name = "host",
+    .id = GRUB_DISK_DEVICE_HOST_ID,
+    .iterate = grub_host_iterate,
+    .open = grub_host_open,
+    .close = grub_host_close,
+    .read = grub_host_read,
+    .write = grub_host_write,
+    .next = 0
+  };
+
+GRUB_MOD_INIT(host)
+{
+  (void) mod;			/* To stop warning. */
+  grub_disk_dev_register (&grub_host_dev);
+}
+
+GRUB_MOD_FINI(host)
+{
+  grub_disk_dev_unregister (&grub_host_dev);
+}
Index: fs/affs.c
===================================================================
RCS file: /sources/grub/grub2/fs/affs.c,v
retrieving revision 1.4
diff -u -p -u -p -r1.4 affs.c
--- fs/affs.c	4 Jun 2006 15:56:54 -0000	1.4
+++ fs/affs.c	17 May 2007 21:17:02 -0000
@@ -249,6 +249,9 @@ grub_affs_mount (grub_disk_t disk)
   return data;
 
  fail:
+  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
+    grub_error (GRUB_ERR_BAD_FS, "not a affs filesystem");
+
   grub_free (data);
   grub_free (rootblock);
   return 0;
Index: fs/hfsplus.c
===================================================================
RCS file: /sources/grub/grub2/fs/hfsplus.c,v
retrieving revision 1.8
diff -u -p -u -p -r1.8 hfsplus.c
--- fs/hfsplus.c	4 Jun 2006 15:56:54 -0000	1.8
+++ fs/hfsplus.c	17 May 2007 21:17:02 -0000
@@ -482,6 +482,10 @@ grub_hfsplus_mount (grub_disk_t disk)
   return data;
 
  fail:
+
+  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
+    grub_error (GRUB_ERR_BAD_FS, "not a hfsplus filesystem");
+
   grub_free (data);
   return 0;
 }
Index: fs/sfs.c
===================================================================
RCS file: /sources/grub/grub2/fs/sfs.c,v
retrieving revision 1.5
diff -u -p -u -p -r1.5 sfs.c
--- fs/sfs.c	4 Jun 2006 15:56:54 -0000	1.5
+++ fs/sfs.c	17 May 2007 21:17:02 -0000
@@ -317,6 +317,9 @@ grub_sfs_mount (grub_disk_t disk)
   return data;
 
  fail:
+  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
+    grub_error (GRUB_ERR_BAD_FS, "not a sfs filesystem");
+
   grub_free (data);
   grub_free (rootobjc_data);
   return 0;
Index: fs/xfs.c
===================================================================
RCS file: /sources/grub/grub2/fs/xfs.c,v
retrieving revision 1.8
diff -u -p -u -p -r1.8 xfs.c
--- fs/xfs.c	4 Jun 2006 15:56:54 -0000	1.8
+++ fs/xfs.c	17 May 2007 21:17:02 -0000
@@ -515,6 +515,9 @@ grub_xfs_mount (grub_disk_t disk)
   return data;
  fail:
   
+  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
+    grub_error (GRUB_ERR_BAD_FS, "not an xfs filesystem");
+
   grub_free (data);
   
   return 0;
Index: include/grub/disk.h
===================================================================
RCS file: /sources/grub/grub2/include/grub/disk.h,v
retrieving revision 1.12
diff -u -p -u -p -r1.12 disk.h
--- include/grub/disk.h	10 Nov 2006 23:31:54 -0000	1.12
+++ include/grub/disk.h	17 May 2007 21:17:02 -0000
@@ -34,7 +34,8 @@ enum grub_disk_dev_id
     GRUB_DISK_DEVICE_LOOPBACK_ID,
     GRUB_DISK_DEVICE_EFIDISK_ID,
     GRUB_DISK_DEVICE_RAID_ID,
-    GRUB_DISK_DEVICE_LVM_ID
+    GRUB_DISK_DEVICE_LVM_ID,
+    GRUB_DISK_DEVICE_HOST_ID
   };
 
 struct grub_disk;
Index: util/grub-emu.c
===================================================================
RCS file: /sources/grub/grub2/util/grub-emu.c,v
retrieving revision 1.34
diff -u -p -u -p -r1.34 grub-emu.c
--- util/grub-emu.c	16 May 2007 21:38:44 -0000	1.34
+++ util/grub-emu.c	17 May 2007 21:17:02 -0000
@@ -185,6 +185,8 @@ main (int argc, char *argv[])
   /* XXX: This is a bit unportable.  */
   grub_util_biosdisk_init (args.dev_map);
 
+  grub_hostfs_init ();
+
   grub_init_all ();
 
   /* Make sure that there is a root device.  */
@@ -210,6 +212,8 @@ main (int argc, char *argv[])
 
   grub_fini_all ();
 
+  grub_hostfs_fini ();
+
   grub_machine_fini ();
   
   return 0;
Index: util/hostfs.c
===================================================================
RCS file: util/hostfs.c
diff -N util/hostfs.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ util/hostfs.c	17 May 2007 21:17:02 -0000
@@ -0,0 +1,131 @@
+/* hostfs.c - Dummy filesystem to provide access to the hosts filesystem  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2007  Free Software Foundation, Inc.
+ *
+ *  GRUB 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 GRUB; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <grub/fs.h>
+#include <grub/file.h>
+#include <grub/disk.h>
+#include <grub/misc.h>
+
+#include <dirent.h>
+#include <stdio.h>
+
+static grub_err_t
+grub_hostfs_dir (grub_device_t device, const char *path, 
+		 int (*hook) (const char *filename, int dir))
+{
+  DIR *dir;
+
+  /* Check if the disk is our dummy disk.  */
+  if (grub_strcmp (device->disk->name, "host"))
+    return grub_error (GRUB_ERR_BAD_FS, "not a hostfs");
+
+  dir = opendir (path);
+  if (! dir)
+    return grub_error (GRUB_ERR_BAD_FILENAME,
+		       "can't open the hostfs directory `%s'", path);
+
+  while (1)
+    {
+      struct dirent *de;
+
+      de = readdir (dir);
+      if (! de)
+	break;
+
+      hook (de->d_name, de->d_type == DT_DIR);
+    }
+
+  closedir (dir);
+
+  return GRUB_ERR_NONE;
+}
+
+/* Open a file named NAME and initialize FILE.  */
+static grub_err_t
+grub_hostfs_open (struct grub_file *file, const char *name)
+{
+  FILE *f;
+
+  f = fopen (name, "r");
+  if (! f)
+    return grub_error (GRUB_ERR_BAD_FILENAME,
+		       "can't open `%s'", name);
+  file->data = f;
+
+  fseek (f, 0, SEEK_END);
+  file->size = ftell (f);
+  fseek (f, 0, SEEK_SET);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_ssize_t
+grub_hostfs_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  FILE *f;
+
+  f = (FILE *) file->data;
+  int s= fread (buf, 1, len, f);
+
+  return s;
+}
+
+static grub_err_t
+grub_hostfs_close (grub_file_t file)
+{
+  FILE *f;
+
+  f = (FILE *) file->data;
+  fclose (f);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_hostfs_label (grub_device_t device __attribute ((unused)),
+		   char **label __attribute ((unused)))
+{
+  return GRUB_ERR_NONE;
+}
+
+static struct grub_fs grub_hostfs_fs =
+  {
+    .name = "hostfs",
+    .dir = grub_hostfs_dir,
+    .open = grub_hostfs_open,
+    .read = grub_hostfs_read,
+    .close = grub_hostfs_close,
+    .label = grub_hostfs_label,
+    .next = 0
+  };
+
+\f
+
+void
+grub_hostfs_init (void)
+{
+  grub_fs_register (&grub_hostfs_fs);
+}
+
+void
+grub_hostfs_fini (void)
+{
+  grub_fs_unregister (&grub_hostfs_fs);
+}

Re: Host filesystem access

[Robert Millan]

On Thu, May 17, 2007 at 11:28:12PM +0200, Marco Gerards wrote:
> +    grub_error (GRUB_ERR_BAD_FS, "not a affs filesystem");
> +    grub_error (GRUB_ERR_BAD_FS, "not a hfsplus filesystem");
> +    grub_error (GRUB_ERR_BAD_FS, "not a sfs filesystem");

I think these should be "an" (but not sure about all them, any native English
speaker around?).

> diff -u -p -u -p -r1.34 grub-emu.c
> --- util/grub-emu.c	16 May 2007 21:38:44 -0000	1.34
> +++ util/grub-emu.c	17 May 2007 21:17:02 -0000
> @@ -185,6 +185,8 @@ main (int argc, char *argv[])
>    /* XXX: This is a bit unportable.  */
>    grub_util_biosdisk_init (args.dev_map);
>  
> +  grub_hostfs_init ();
> +
>    grub_init_all ();

I find it counter-intuitive that grub_init_all doesn't imply grub_hostfs_init;
if there's a design reason for this, maybe the function should be renamed ?
(how about grub_filesystems_init + grub_partmaps_init ?)

-- 
Robert Millan

My spam trap is honeypot@aybabtu.com.  Note: this address is only intended
for spam harvesters.  Writing to it will get you added to my black list.

Re: Host filesystem access

[Marco Gerards]

Robert Millan <rmh@aybabtu.com> writes:

> On Thu, May 17, 2007 at 11:28:12PM +0200, Marco Gerards wrote:
>> +    grub_error (GRUB_ERR_BAD_FS, "not a affs filesystem");
>> +    grub_error (GRUB_ERR_BAD_FS, "not a hfsplus filesystem");
>> +    grub_error (GRUB_ERR_BAD_FS, "not a sfs filesystem");
>
> I think these should be "an" (but not sure about all them, any native English
> speaker around?).

Ehm, yes, I think so :-)

>> diff -u -p -u -p -r1.34 grub-emu.c
>> --- util/grub-emu.c	16 May 2007 21:38:44 -0000	1.34
>> +++ util/grub-emu.c	17 May 2007 21:17:02 -0000
>> @@ -185,6 +185,8 @@ main (int argc, char *argv[])
>>    /* XXX: This is a bit unportable.  */
>>    grub_util_biosdisk_init (args.dev_map);
>>  
>> +  grub_hostfs_init ();
>> +
>>    grub_init_all ();
>
> I find it counter-intuitive that grub_init_all doesn't imply grub_hostfs_init;
> if there's a design reason for this, maybe the function should be renamed ?
> (how about grub_filesystems_init + grub_partmaps_init ?)

The reason why I did this is that hostfs is not a module.
grub_init_all initializes all modules, there is no way you can split
this up in an easy way.

The main thing I had some doubts on was if the dummy disk driver is
way too ugly or not.

--
Marco

Re: Host filesystem access

[Bruno Wolff III]

On Fri, May 18, 2007 at 08:48:37 +0200,
  Robert Millan <rmh@aybabtu.com> wrote:
> On Thu, May 17, 2007 at 11:28:12PM +0200, Marco Gerards wrote:
> > +    grub_error (GRUB_ERR_BAD_FS, "not a affs filesystem");
> > +    grub_error (GRUB_ERR_BAD_FS, "not a hfsplus filesystem");
> > +    grub_error (GRUB_ERR_BAD_FS, "not a sfs filesystem");
> 
> I think these should be "an" (but not sure about all them, any native English
> speaker around?).

If the file system types are read as acronyms then they will start with a
vowel sound and it sounds more natural to use 'an'. I am not sure what the
offical grammer rule is though.

Re: Host filesystem access

[Jan C. Kleinsorge]

"affs filesystem" is filesystem doubled anyway. How about ".. filesystem
is not of type hffs"?


Jan

Bruno Wolff III wrote:
> On Fri, May 18, 2007 at 08:48:37 +0200,
>   Robert Millan <rmh@aybabtu.com> wrote:
>   
>> On Thu, May 17, 2007 at 11:28:12PM +0200, Marco Gerards wrote:
>>     
>>> +    grub_error (GRUB_ERR_BAD_FS, "not a affs filesystem");
>>> +    grub_error (GRUB_ERR_BAD_FS, "not a hfsplus filesystem");
>>> +    grub_error (GRUB_ERR_BAD_FS, "not a sfs filesystem");
>>>       
>> I think these should be "an" (but not sure about all them, any native English
>> speaker around?).
>>     
>
> If the file system types are read as acronyms then they will start with a
> vowel sound and it sounds more natural to use 'an'. I am not sure what the
> offical grammer rule is though.
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
>
>   

Re: Host filesystem access

[Robert Millan]

On Fri, May 18, 2007 at 04:08:38PM +0200, Jan C. Kleinsorge wrote:
> "affs filesystem" is filesystem doubled anyway. How about ".. filesystem
> is not of type hffs"?

Some acronyms appear to be designed on purpose to produce RAS syndrome... (GPT
comes to mind here).

Maybe we should just accept it ;-)

-- 
Robert Millan

My spam trap is honeypot@aybabtu.com.  Note: this address is only intended
for spam harvesters.  Writing to it will get you added to my black list.

Re: Host filesystem access

[Robert Millan]

On Fri, May 18, 2007 at 08:59:45AM +0200, Marco Gerards wrote:
> >
> > I find it counter-intuitive that grub_init_all doesn't imply grub_hostfs_init;
> > if there's a design reason for this, maybe the function should be renamed ?
> > (how about grub_filesystems_init + grub_partmaps_init ?)
> 
> The reason why I did this is that hostfs is not a module.
> grub_init_all initializes all modules, there is no way you can split
> this up in an easy way.

But it could be renamed to grub_init_all_modules :-)

-- 
Robert Millan

My spam trap is honeypot@aybabtu.com.  Note: this address is only intended
for spam harvesters.  Writing to it will get you added to my black list.

Re: Host filesystem access

[Marco Gerards]

Marco Gerards <mgerards@xs4all.nl> writes:

Hi,

> Here is a patch to make it possible to access the host filesystem from
> grub-emu.  This is especially useful for debugging purposes and will
> make my life easier ;-).
>
> This also adds a dummy disk which is used to give the host filesystem
> a name.  It is not particularly clean, but adding this as a network is
> even worse.  This can be used to access host filesystems on other
> systems as well.
>
> I will commit this after the weekend, if no-one objects.

Actually, I have completely forgotten about this.  It's has been
committed now.

--
Marco