Hello everyone,
I write this list because the discussion is quite technical.
I was trying to create a test for a program that uses libparted. This program
creates random partitions in the available spaces, trying to align them
according to the type of table. There is something I do not understand in the
libparted behavior and I would like to understand with you if it is correct.
To show you better I created a minimal program that creates a new table and
shows the default status.
>>> WARNING: THIS PROGRAM MODIFIES THE DEVICE! <<<
To compile the code:
gcc -c -o ped-disk-new-fresh sourcefile.c -lparted
To run the program:
/path/to/ped-disk-new-fresh DEVICE-PATH DISK-TYPE
DISK-TYPE is one of PedDiskType name (msdos|sun|dvh|gpt...).
The first thing is that the sun disklabel type does not support the
PED_DISK_TYPE_CYLINDER_ALIGNMENT flag.
In the file `INCLUDEPATH/parted/disk.h' I read this:
enum _PedDiskFlag {
/* This flag (which defaults to true) controls if disk types for
which cylinder alignment is optional do cylinder alignment when a
new partition gets added.
This flag is available for msdos and sun disklabels (for sun labels
it only controls the aligning of the end of the partition) */
PED_DISK_CYLINDER_ALIGNMENT=1,
...
But running the program I get this output:
user@host:~/$ sudo ./ped-disk-new-fresh /dev/sdb sun
type: sun
Features:
PED_DISK_TYPE_EXTENDED: no
PED_DISK_TYPE_PARTITION_NAME: no
Flags:
PED_DISK_CYLINDER_ALIGNMENT: unavailable
PED_DISK_GPT_PMBR_BOOT: unavailable
Partitions:
---
Num: -1:
Type: 4 (free)
Start: 0s (0.00MiB)
End: 16097129s (7860MiB)
---
Num: -1:
Type: 8 (metadata)
Start: 16097130s (7860MiB)
End: 16099327s (7861MiB)
The second thing concerns dvh disks. When we create a new disk, the parted
library automatically creates the header volume. But is it correct to be
indicated as (logical|freespace)? This is the output I see:
user@host:~/$ sudo ./ped-disk-new-fresh /dev/sdb dvh
type: dvh
Features:
PED_DISK_TYPE_EXTENDED: yes
PED_DISK_TYPE_PARTITION_NAME: yes
Flags:
PED_DISK_CYLINDER_ALIGNMENT: unavailable
PED_DISK_GPT_PMBR_BOOT: unavailable
Partitions:
---
Num: 9:
Type: 2 (extended)
Start: 0s (0.00MiB)
End: 4095s (2.00MiB)
---
Num: -1:
Type: 9 (metadata)
Start: 0s (0.00MiB)
End: 0s (0.00MiB)
---
Num: -1:
Type: 5 (free)
Start: 1s (0.00MiB)
End: 4095s (2.00MiB)
---
Num: -1:
Type: 4 (free)
Start: 4096s (2.00MiB)
End: 16099327s (7861MiB)
Output of util-linux fdisk on the device shows:
Disklabel type: sgi
Device Start End Sectors Size Id Type Attrs
/dev/sdb9 0 4095 4096 2M 0 SGI volhdr
/dev/sdb11 0 16099327 16099328 7.7G 6 SGI volume
Is this behavior correct?
One last thing: what does libparted do when a new partition is added? How
should alignment be handled? Libparted allows you to add misaligned partitions?
Greetings,
Christian.#include <parted/parted.h>
int main(int argc, char *argv[])
{
PedDevice *dev;
PedDiskType *type;
PedDisk *disk;
PedPartition *part;
if(argc < 3)
{
printf("usage: %s <dev-path> <disk-type>\n", argv[0]);
exit(EXIT_FAILURE);
}
if((dev = ped_device_get(argv[1])) == NULL
|| (type = ped_disk_type_get(argv[2])) == NULL
|| (disk = ped_disk_new_fresh(dev, type)) == NULL)
exit(EXIT_FAILURE);
printf("type: %s\n"
"Features:\n"
" PED_DISK_TYPE_EXTENDED: %s\n"
" PED_DISK_TYPE_PARTITION_NAME: %s\n"
"Flags:\n"
" PED_DISK_CYLINDER_ALIGNMENT: %s\n"
" PED_DISK_GPT_PMBR_BOOT: %s\n",
type->name,
ped_disk_type_check_feature(type, PED_DISK_TYPE_EXTENDED) ? "yes" : "no",
ped_disk_type_check_feature(type, PED_DISK_TYPE_PARTITION_NAME) ? "yes" : "no",
ped_disk_is_flag_available(disk, PED_DISK_CYLINDER_ALIGNMENT) ?
ped_disk_get_flag(disk, PED_DISK_CYLINDER_ALIGNMENT) ? "true" : "false" : "unavailable",
ped_disk_is_flag_available(disk, PED_DISK_GPT_PMBR_BOOT) ?
ped_disk_get_flag(disk, PED_DISK_GPT_PMBR_BOOT) ? "true" : "false" : "unavailable");
printf("Partitions:\n");
for(part = ped_disk_next_partition(disk, NULL);
part != NULL;
part = ped_disk_next_partition(disk, part))
{
char *s, *e;
char *sm, *em;
s = ped_unit_format_custom(dev, part->geom.start, PED_UNIT_SECTOR);
sm = ped_unit_format_custom(dev, part->geom.start, PED_UNIT_MEBIBYTE);
e = ped_unit_format_custom(dev, part->geom.end, PED_UNIT_SECTOR);
em = ped_unit_format_custom(dev, part->geom.end, PED_UNIT_MEBIBYTE);
printf("---\n"
" Num: %d:\n"
" Type: %d (%s)\n"
" Start: %s (%s)\n"
" End: %s (%s)\n",
part->num,
part->type,
ped_partition_type_get_name(part->type),
s, sm, e, em);
free(s);
free(e);
}
ped_disk_commit(disk);
return EXIT_SUCCESS;
}
