getting disks in C

son_t · 02-12-2007, 05:15 AM

Hello

Could anyone tell me how I go about getting a list of disks on a system in C?

I am just reading a disk in a raw way on Debian Linux like this:

Code:

int inCc=0, start=0;
int inFd=0, readsize=16;

unsigned char *diskin = (char *)malloc(readsize);

char *inFile = "/dev/hdc";
lseek(inFd,start,SEEK_SET);
inCc = read(inFd,diskin,readsize);

Do I just generate strings "/dev/hda", "/dev/hdc", "/dev/hde", etc and see if they exist?

On Solaris I can use 'iostat' to return the disk lables 'c0t0d0', etc but on Debian (after installing sysstat) it gives me 'ide/host0/bus1/target0/lun0/disc' etc... How do I get it to give me hda, hdc, etc?

TIA

gnashley · 02-12-2007, 06:18 AM

'blkid' does what you want, I believe.

son_t · 02-12-2007, 07:19 AM

Thanks, but the attached disk might not be a block device (a non Linux formatted disk).

gnashley · 02-13-2007, 03:03 AM

blkid will show non-linux filesystems also. fdisk -l will show non-formatted partitions as well. If no recognized partitions are present it will still show the full physical device. Note that it may help to include support for other types of partition tables/maps in your kernel.

son_t · 02-14-2007, 02:50 AM

Thanks for the further reply.

I have 2 HDDs on my Debian system. One is the systems disk /dev/hda with various partitions and one 'really raw' (say pull the HDD out of a PVR or similar) HDD '/dev/hdc' to which I can read and write to with no problems.

Neither blkid or fdisk -l shows it:
/dev/hda1: LABEL="/" UUID="626f345b-0fb7-48b7-9326-9427e1d168e7" SEC_TYPE="ext2" TYPE="ext3"
/dev/hda5: TYPE="swap"

and fdisk -l returns nothing (not even the /dev/hda device).

gnashley · 02-14-2007, 04:37 AM

How about lspci?
What kind of filesystem is the /dev/hdc formatted with? And what kind of partiton table/map does it use(what's a PVR)?

son_t · 03-13-2007, 07:05 AM

A PVR is a Personal Video Recorder, a TiVo is an example of a PVR and my particular one has its own FS.

So is this the only way I can detect if the HDD is present?

Code:

void main()
{
        char *disk_arr[] = {"/dev/hda","/dev/hdb","/dev/hdc","/dev/hdd","/dev/hde","/dev/sda","/dev/sdb","/dev/sdc","/dev/sdd","/dev/sde"};
        char *disk=NULL;
        int dcnt=10;
        int i=0;
 
        while(!disk && i<dcnt)
        {
                if(checkdisk(disk_arr[i]))
                        disk=newString(disk_arr[i]);
                i++;
        }
}

Any other suggestion or improvement on this code?