[PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Peter Mamonov]

Deleted pieces of code detect MBR-containig device as a FAT-type device,
if it's first partition contains a FAT filesystem. This behaviour enabled one
to mount the FAT FS which is either directly on the device (disk0) or on
the first partition (disk0.0) using the same command:
    mount /dev/disk0 /fat
However, the desired behaviour can be reached with a:
    mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"

Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/filetype.c | 30 ------------------------------
 1 file changed, 30 deletions(-)

diff --git a/common/filetype.c b/common/filetype.c
index c59441d..f9e03f7 100644
--- a/common/filetype.c
+++ b/common/filetype.c
@@ -345,21 +345,6 @@ enum filetype file_name_detect_type(const char *filename)
 
 	type = file_detect_type(buf, ret);
 
-	if (type == filetype_mbr) {
-		/*
-		 * Get the first partition start sector
-		 * and check for FAT in it
-		 */
-		is_fat_or_mbr(buf, &bootsec);
-		ret = lseek(fd, (bootsec) * 512, SEEK_SET);
-		if (ret < 0)
-			goto err_out;
-		ret = read(fd, buf, 512);
-		if (ret < 0)
-			goto err_out;
-		type = is_fat_or_mbr((u8 *)buf, NULL);
-	}
-
 err_out:
 	close(fd);
 	free(buf);
@@ -385,21 +370,6 @@ enum filetype cdev_detect_type(const char *name)
 
 	type = file_detect_type(buf, ret);
 
-	if (type == filetype_mbr) {
-		unsigned long bootsec;
-		/*
-		 * Get the first partition start sector
-		 * and check for FAT in it
-		 */
-		is_fat_or_mbr(buf, &bootsec);
-
-		ret = cdev_read(cdev, buf, 512, bootsec * 512, 0);
-		if (ret < 0)
-			goto err_out;
-
-		type = is_fat_or_mbr((u8 *)buf, NULL);
-	}
-
 err_out:
 	free(buf);
 	cdev_close(cdev);
-- 
2.1.4


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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Antony Pavlov]

On Mon,  9 Nov 2015 13:32:51 +0300
Peter Mamonov <pmamonov@gmail.com> wrote:

> Deleted pieces of code detect MBR-containig device as a FAT-type device,
> if it's first partition contains a FAT filesystem. This behaviour enabled one
> to mount the FAT FS which is either directly on the device (disk0) or on
> the first partition (disk0.0) using the same command:
>     mount /dev/disk0 /fat
> However, the desired behaviour can be reached with a:
>     mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"
> 
> Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
> Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
  ^^^^^^^^^^

Ad memorandum. Sascha's ack can be found here: http://lists.infradead.org/pipermail/barebox/2015-October/024952.html


> ---
>  common/filetype.c | 30 ------------------------------
>  1 file changed, 30 deletions(-)
> 
> diff --git a/common/filetype.c b/common/filetype.c
> index c59441d..f9e03f7 100644
> --- a/common/filetype.c
> +++ b/common/filetype.c
> @@ -345,21 +345,6 @@ enum filetype file_name_detect_type(const char *filename)
>  
>  	type = file_detect_type(buf, ret);
>  
> -	if (type == filetype_mbr) {
> -		/*
> -		 * Get the first partition start sector
> -		 * and check for FAT in it
> -		 */
> -		is_fat_or_mbr(buf, &bootsec);
> -		ret = lseek(fd, (bootsec) * 512, SEEK_SET);
> -		if (ret < 0)
> -			goto err_out;
> -		ret = read(fd, buf, 512);
> -		if (ret < 0)
> -			goto err_out;
> -		type = is_fat_or_mbr((u8 *)buf, NULL);
> -	}
> -
>  err_out:
>  	close(fd);
>  	free(buf);
> @@ -385,21 +370,6 @@ enum filetype cdev_detect_type(const char *name)
>  
>  	type = file_detect_type(buf, ret);
>  
> -	if (type == filetype_mbr) {
> -		unsigned long bootsec;
> -		/*
> -		 * Get the first partition start sector
> -		 * and check for FAT in it
> -		 */
> -		is_fat_or_mbr(buf, &bootsec);
> -
> -		ret = cdev_read(cdev, buf, 512, bootsec * 512, 0);
> -		if (ret < 0)
> -			goto err_out;
> -
> -		type = is_fat_or_mbr((u8 *)buf, NULL);
> -	}
> -
>  err_out:
>  	free(buf);
>  	cdev_close(cdev);
> -- 
> 2.1.4
> 
> 
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox


-- 
-- 
Best regards,
  Antony Pavlov

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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Trent Piepho]

On Mon, 2015-11-09 at 13:32 +0300, Peter Mamonov wrote:
> Deleted pieces of code detect MBR-containig device as a FAT-type device,
> if it's first partition contains a FAT filesystem. This behaviour enabled one
> to mount the FAT FS which is either directly on the device (disk0) or on
> the first partition (disk0.0) using the same command:
>     mount /dev/disk0 /fat
> However, the desired behaviour can be reached with a:
>     mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"

The in flash env for omap is found by mounting a FAT filesystem and
reading an env file from it.  The code that does this uses the disk as
the device, rather than the partition.  Which I thought was odd and
wondered why/if that worked correctly....

Anyway, this change would break that code.  I suspect than instead of
coding the disk0 || disk0.0 method it could just mount disk0.0.  Because
the code does this (edited):

partname = asprintf("/dev/%s.0", diskdev);
ret = stat(partname, &s);
if (ret) {
  pr_err("Failed to load environment: no device '%s'\n", diskdev);
  return 0;
}
ret = mount(diskdev, "fat", "/boot", NULL);


If disk0.0 didn't exist then it wouldn't try to mount it in the 1st
place, so the ability of trying both disk0 and disk0.0 wouldn't be used.
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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Sascha Hauer]

On Mon, Nov 09, 2015 at 06:49:53PM +0000, Trent Piepho wrote:
> On Mon, 2015-11-09 at 13:32 +0300, Peter Mamonov wrote:
> > Deleted pieces of code detect MBR-containig device as a FAT-type device,
> > if it's first partition contains a FAT filesystem. This behaviour enabled one
> > to mount the FAT FS which is either directly on the device (disk0) or on
> > the first partition (disk0.0) using the same command:
> >     mount /dev/disk0 /fat
> > However, the desired behaviour can be reached with a:
> >     mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"
> 
> The in flash env for omap is found by mounting a FAT filesystem and
> reading an env file from it.  The code that does this uses the disk as
> the device, rather than the partition.  Which I thought was odd and
> wondered why/if that worked correctly....
> 
> Anyway, this change would break that code.  I suspect than instead of
> coding the disk0 || disk0.0 method it could just mount disk0.0.  Because
> the code does this (edited):
> 
> partname = asprintf("/dev/%s.0", diskdev);
> ret = stat(partname, &s);
> if (ret) {
>   pr_err("Failed to load environment: no device '%s'\n", diskdev);
>   return 0;
> }
> ret = mount(diskdev, "fat", "/boot", NULL);

This is really odd. The code first tests if the partition exists and
tries to mount the whole disk afterwards. git blame points to:

commit be322768f04603df371c9c1f08b9621690dd74c6
Author: Sascha Hauer <s.hauer@pengutronix.de>
Date:   Sat Aug 24 12:48:50 2013 +0200

    ARM: omap: Allow to set mmc devname used for booting

I think what we should do here is in the following patch. With this
Trents patch can be applied as-is. Thanks for noting, Peter.

Sascha

---------------------------8<---------------------------

From 98fb34f2aa271138eab28a36aec733fe6572339c Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Tue, 10 Nov 2015 08:58:16 +0100
Subject: [PATCH] ARM: omap: Use correct device to mount on /boot

The current code tests if a partition (i.e. disk0.0) exists and instead
of mounting boot from this partition it uses the whole device (disk0).
This only works because the the FAT code accepts a MBR as input and
automatically skips it.

Let the code use the partition to mount /boot instead as it was
intended. We don't have to stat() the partition device, since this
error will be caught by mount() anyway, so remove the unnecessary
stat().

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/mach-omap/omap_generic.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/arch/arm/mach-omap/omap_generic.c b/arch/arm/mach-omap/omap_generic.c
index 071a1bf..4e26c6b 100644
--- a/arch/arm/mach-omap/omap_generic.c
+++ b/arch/arm/mach-omap/omap_generic.c
@@ -111,7 +111,6 @@ const char *omap_get_bootmmc_devname(void)
 #define ENV_PATH "/boot/barebox.env"
 static int omap_env_init(void)
 {
-	struct stat s;
 	char *partname;
 	const char *diskdev;
 	int ret;
@@ -128,25 +127,19 @@ static int omap_env_init(void)
 
 	partname = asprintf("/dev/%s.0", diskdev);
 
-	ret = stat(partname, &s);
-
-	free(partname);
-
-	if (ret) {
-		pr_err("Failed to load environment: no device '%s'\n", diskdev);
-		return 0;
-	}
-
 	mkdir("/boot", 0666);
-	ret = mount(diskdev, "fat", "/boot", NULL);
+	ret = mount(partname, "fat", "/boot", NULL);
 	if (ret) {
-		pr_err("Failed to load environment: mount %s failed (%d)\n", diskdev, ret);
-		return 0;
+		pr_err("Failed to load environment: mount %s failed (%d)\n", partname, ret);
+		goto out;
 	}
 
-	pr_debug("Loading default env from %s on device %s\n", ENV_PATH, diskdev);
+	pr_debug("Loading default env from %s on device %s\n", ENV_PATH, partname);
 	default_environment_path_set(ENV_PATH);
 
+out:
+	free(partname);
+
 	return 0;
 }
 late_initcall(omap_env_init);
-- 
2.6.1

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Sascha Hauer]

On Tue, Nov 10, 2015 at 09:04:23AM +0100, Sascha Hauer wrote:
> On Mon, Nov 09, 2015 at 06:49:53PM +0000, Trent Piepho wrote:
> > On Mon, 2015-11-09 at 13:32 +0300, Peter Mamonov wrote:
> > > Deleted pieces of code detect MBR-containig device as a FAT-type device,
> > > if it's first partition contains a FAT filesystem. This behaviour enabled one
> > > to mount the FAT FS which is either directly on the device (disk0) or on
> > > the first partition (disk0.0) using the same command:
> > >     mount /dev/disk0 /fat
> > > However, the desired behaviour can be reached with a:
> > >     mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"
> > 
> > The in flash env for omap is found by mounting a FAT filesystem and
> > reading an env file from it.  The code that does this uses the disk as
> > the device, rather than the partition.  Which I thought was odd and
> > wondered why/if that worked correctly....
> > 
> > Anyway, this change would break that code.  I suspect than instead of
> > coding the disk0 || disk0.0 method it could just mount disk0.0.  Because
> > the code does this (edited):
> > 
> > partname = asprintf("/dev/%s.0", diskdev);
> > ret = stat(partname, &s);
> > if (ret) {
> >   pr_err("Failed to load environment: no device '%s'\n", diskdev);
> >   return 0;
> > }
> > ret = mount(diskdev, "fat", "/boot", NULL);
> 
> This is really odd. The code first tests if the partition exists and
> tries to mount the whole disk afterwards. git blame points to:
> 
> commit be322768f04603df371c9c1f08b9621690dd74c6
> Author: Sascha Hauer <s.hauer@pengutronix.de>
> Date:   Sat Aug 24 12:48:50 2013 +0200
> 
>     ARM: omap: Allow to set mmc devname used for booting
> 
> I think what we should do here is in the following patch. With this
> Trents patch can be applied as-is. Thanks for noting, Peter.

Sorry, I mixed you two up. I mean: With this Peters patch can be
applied as-is. Thanks for noting, Trent.

Sascha

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Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Trent Piepho]

On Tue, 2015-11-10 at 09:04 +0100, Sascha Hauer wrote:

> From 98fb34f2aa271138eab28a36aec733fe6572339c Mon Sep 17 00:00:00 2001
> From: Sascha Hauer <s.hauer@pengutronix.de>
> Date: Tue, 10 Nov 2015 08:58:16 +0100
> Subject: [PATCH] ARM: omap: Use correct device to mount on /boot
> 
> The current code tests if a partition (i.e. disk0.0) exists and instead
> of mounting boot from this partition it uses the whole device (disk0).
> This only works because the the FAT code accepts a MBR as input and
> automatically skips it.

I agree, this should fix it.

> 
> Let the code use the partition to mount /boot instead as it was
> intended. We don't have to stat() the partition device, since this
> error will be caught by mount() anyway, so remove the unnecessary
> stat().

There are copies of this code in rpi.c and socfpga/generic.c.  They
don't suffer from the whole disk flaw, but they do stat() first as well.

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Re: [PATCH] common: filetype: do not redetect MBR-type devices as a FAT-type

[Sascha Hauer]

On Mon, Nov 09, 2015 at 01:32:51PM +0300, Peter Mamonov wrote:
> Deleted pieces of code detect MBR-containig device as a FAT-type device,
> if it's first partition contains a FAT filesystem. This behaviour enabled one
> to mount the FAT FS which is either directly on the device (disk0) or on
> the first partition (disk0.0) using the same command:
>     mount /dev/disk0 /fat
> However, the desired behaviour can be reached with a:
>     mount /dev/disk0 /fat || mount /dev/disk0.0 /fat || echo "Mounting failed"
> 
> Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
> Acked-by: Sascha Hauer <s.hauer@pengutronix.de>

Please don't add Acked-by for patches the person has never seen. I
agreed to the approach of removing the check here, but I can only ever
ack a patch that I have seen.

Applied this with my ack removed.

Sascha


-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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