How to recognize the file system used? (FAT32?)

Aymenov · 12-03-2007, 05:35 AM

Hello,

Is there a function that can tell us the type of file systm used?
In fact, I'm working on a program that does some treatments according to the file system partition. In particular, I need to know if a device (portable mp3 player for exemple) is a FAT32 partition?
How can do that by programming?

Thank you for your help

AnanthaP · 12-03-2007, 07:32 AM

Dont know about any function but here is a possibile pseudo code.

If a file is available in a partition that is mounted as FAT32 - say, then the file must be in FAT32 format. So I would look for the full DIRNAME portion of the file name and see if it is in a mounted path.

End

ghostdog74 · 12-03-2007, 08:01 AM

the mount command can show you the file system mounted.

marozsas · 12-03-2007, 08:05 AM

You mean a system call ? May be you can inspect the source code of the command file(1).
The command file with the flag "-s" can tell you what is the filesystem of a device.

Code:

[root@babylon5 ~]# file -s /dev/sda2
/dev/sda2: Linux rev 1.0 ext3 filesystem data (needs journal recovery)
[root@babylon5 ~]# file -s /dev/sdc1
/dev/sdc1: x86 boot sector, mkdosfs boot message display, code offset 0x3c, OEM-ID " mkdosfs", sectors/cluster 16, root entries 512, Media descriptor 0xf8, sectors/FAT 249, heads 32, sectors 1017824 (volumes > 32 MB) , serial number 0x4744ab1a, label: "disk512    ", FAT (16 bit)
[root@babylon5 ~]#

In the above example, /dev/sdc1 is a usb memory stick.
There is no need to mount the device to do that.

Aymenov · 12-03-2007, 09:25 AM

Quote:

Originally Posted by marozsas

You mean a system call ? May be you can inspect the source code of the command file(1).
The command file with the flag "-s" can tell you what is the filesystem of a device.

Code:

[root@babylon5 ~]# file -s /dev/sda2
/dev/sda2: Linux rev 1.0 ext3 filesystem data (needs journal recovery)
[root@babylon5 ~]# file -s /dev/sdc1
/dev/sdc1: x86 boot sector, mkdosfs boot message display, code offset 0x3c, OEM-ID " mkdosfs", sectors/cluster 16, root entries 512, Media descriptor 0xf8, sectors/FAT 249, heads 32, sectors 1017824 (volumes > 32 MB) , serial number 0x4744ab1a, label: "disk512    ", FAT (16 bit)
[root@babylon5 ~]#

In the above example, /dev/sdc1 is a usb memory stick.
There is no need to mount the device to do that.

Yes I think it is possible to use the cmd "file -s /dev/*".
I think that we can also use the getmntany routine:
int getmntany(FILE *fp, struct mnttab *mp, struct mnttab *mpref);
It searches the file referenced by fp until a match is found between a line in the file and mpref.
The mp (it is a structure) will contain useful information:
char *mnt_special; /* name of mounted resource */
char *mnt_mountp; /* mount point */
char *mnt_fstype; /* type of file system mounted */
char *mnt_mntopts; /* options for this mount */
char *mnt_time; /* time file system mounted */

But, I have another question. How can I get the name of the device? For example, how do you know that the line corresponding to the usb memory stick is /dev/sdc1? "sdc1" is the default name for usb memory stick?
The answer may be evident but I am beginner in Linux programmation.

Thank you for your help

marozsas · 12-03-2007, 09:49 AM

Quote:

But, I have another question. How can I get the name of the device?

I'm sorry, I am not a programmer.
From an user's point of view, I need to look at "/var/log/message" for messages like this:

Code:

Dec  3 13:35:06 babylon5 kernel: sd 9:0:0:0: [sdc] Attached SCSI removable disk
Dec  3 13:35:06 babylon5 kernel: sd 9:0:0:0: Attached scsi generic sg3 type 0
Dec  3 13:35:06 babylon5 hald: mounted /dev/sdc1 on behalf of uid 500

I believe the sub-system HAL can give you with the tools and functions to receive notifications when a device is plugged in/out or to browse the current devices(see "lshal").