[PATCH 1/2] libblkid: add PARTTYPE tag

[PATCH 1/2] libblkid: add PARTTYPE tag

[Michael Marineau]

Add PARTTYPE to make searching for devices partition possible without
dropping to the low-level probe API and searching all devices by
PART_ENTRY_TYPE. For example to find any 'EFI System Partition' devices:

$ blkid -t PARTTYPE=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
---
 libblkid/src/verify.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libblkid/src/verify.c b/libblkid/src/verify.c
index 1c0ca0f..eac613e 100644
--- a/libblkid/src/verify.c
+++ b/libblkid/src/verify.c
@@ -38,6 +38,8 @@ static void blkid_probe_to_tags(blkid_probe pr, blkid_dev dev)
 				blkid_set_tag(dev, "PARTUUID", data, len);
 			else if (strcmp(name, "PART_ENTRY_NAME") == 0)
 				blkid_set_tag(dev, "PARTLABEL", data, len);
+			else if (strcmp(name, "PART_ENTRY_TYPE") == 0)
+				blkid_set_tag(dev, "PARTTYPE", data, len);
 
 		} else if (!strstr(name, "_ID")) {
 			/* superblock UUID, LABEL, ...
-- 
1.8.3.2

[PATCH 2/2] lsblk: add PARTTYPE tag

[Michael Marineau]

To stay in sync with blkid add PARTTYPE as an available output column.
---
 misc-utils/lsblk.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/misc-utils/lsblk.c b/misc-utils/lsblk.c
index 9b53be3..7061531 100644
--- a/misc-utils/lsblk.c
+++ b/misc-utils/lsblk.c
@@ -71,6 +71,7 @@ enum {
 	COL_TARGET,
 	COL_LABEL,
 	COL_UUID,
+	COL_PARTTYPE,
 	COL_PARTLABEL,
 	COL_PARTUUID,
 	COL_RA,
@@ -125,6 +126,7 @@ static struct colinfo infos[] = {
 	[COL_LABEL]  = { "LABEL",   0.1, 0, N_("filesystem LABEL") },
 	[COL_UUID]   = { "UUID",    36,  0, N_("filesystem UUID") },
 
+	[COL_PARTTYPE]  = { "PARTTYPE",  36,  0, N_("partition type UUID") },
 	[COL_PARTLABEL] = { "PARTLABEL", 0.1, 0, N_("partition LABEL") },
 	[COL_PARTUUID]  = { "PARTUUID",  36,  0, N_("partition UUID") },
 
@@ -208,6 +210,7 @@ struct blkdev_cxt {
 	char *fstype;		/* detected fs, NULL or "?" if cannot detect */
 	char *uuid;		/* filesystem UUID (or stack uuid) */
 	char *label;		/* filesystem label */
+	char *parttype;		/* partiton type UUID */
 	char *partuuid;		/* partition UUID */
 	char *partlabel;	/* partiton label */
 	char *wwn;		/* storage WWN */
@@ -291,6 +294,7 @@ static void reset_blkdev_cxt(struct blkdev_cxt *cxt)
 	free(cxt->fstype);
 	free(cxt->uuid);
 	free(cxt->label);
+	free(cxt->parttype);
 	free(cxt->partuuid);
 	free(cxt->partlabel);
 	free(cxt->wwn);
@@ -441,6 +445,8 @@ static int get_udev_properties(struct blkdev_cxt *cxt)
 		}
 		if ((data = udev_device_get_property_value(dev, "ID_FS_TYPE")))
 			cxt->fstype = xstrdup(data);
+		if ((data = udev_device_get_property_value(dev, "ID_PART_ENTRY_TYPE")))
+			cxt->parttype = xstrdup(data);
 		if ((data = udev_device_get_property_value(dev, "ID_PART_ENTRY_UUID")))
 			cxt->partuuid = xstrdup(data);
 		if ((data = udev_device_get_property_value(dev, "ID_WWN")))
@@ -496,6 +502,8 @@ static void probe_device(struct blkdev_cxt *cxt)
 			cxt->uuid = xstrdup(data);
 		if (!blkid_probe_lookup_value(pr, "LABEL", &data, NULL))
 			cxt->label = xstrdup(data);
+		if (!blkid_probe_lookup_value(pr, "PART_ENTRY_TYPE", &data, NULL))
+			cxt->parttype = xstrdup(data);
 		if (!blkid_probe_lookup_value(pr, "PART_ENTRY_UUID", &data, NULL))
 			cxt->partuuid = xstrdup(data);
 		if (!blkid_probe_lookup_value(pr, "PART_ENTRY_NAME", &data, NULL))
@@ -752,6 +760,11 @@ static void set_tt_data(struct blkdev_cxt *cxt, int col, int id, struct tt_line
 		if (cxt->uuid)
 			tt_line_set_data(ln, col, xstrdup(cxt->uuid));
 		break;
+	case COL_PARTTYPE:
+		probe_device(cxt);
+		if (cxt->parttype)
+			tt_line_set_data(ln, col, xstrdup(cxt->parttype));
+		break;
 	case COL_PARTLABEL:
 		probe_device(cxt);
 		if (!cxt->partlabel)
-- 
1.8.3.2

Re: [PATCH 2/2] lsblk: add PARTTYPE tag

[Karel Zak]

On Tue, Jan 14, 2014 at 01:19:50PM -0800, Michael Marineau wrote:
>  misc-utils/lsblk.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)

 Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH 1/2] libblkid: add PARTTYPE tag

[Karel Zak]

On Tue, Jan 14, 2014 at 01:19:49PM -0800, Michael Marineau wrote:
> Add PARTTYPE to make searching for devices partition possible without
> dropping to the low-level probe API and searching all devices by
> PART_ENTRY_TYPE. For example to find any 'EFI System Partition' devices:
> 
> $ blkid -t PARTTYPE=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
> ---
>  libblkid/src/verify.c | 2 ++
>  1 file changed, 2 insertions(+)

 I think it's unnecessary (and maybe bad idea) to add a new tags to
 the high level part of the library. The high level tags have been
 introduced to support mount/fsck devices by LABEL= or UUID= tags
 (only this is reason why we have the new PARTUUID= tag there). I'd
 like to keep this layer as minimal as possible (due the problem with
 caching in blkid.tab file).
 
 If you need information about devices then use lsblk(8) rather than
 blkid(8).

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: [PATCH 1/2] libblkid: add PARTTYPE tag

[Michael Marineau]

On Mon, Feb 10, 2014 at 1:57 AM, Karel Zak <kzak@redhat.com> wrote:
> On Tue, Jan 14, 2014 at 01:19:49PM -0800, Michael Marineau wrote:
>> Add PARTTYPE to make searching for devices partition possible without
>> dropping to the low-level probe API and searching all devices by
>> PART_ENTRY_TYPE. For example to find any 'EFI System Partition' devices:
>>
>> $ blkid -t PARTTYPE=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
>> ---
>>  libblkid/src/verify.c | 2 ++
>>  1 file changed, 2 insertions(+)
>
>  I think it's unnecessary (and maybe bad idea) to add a new tags to
>  the high level part of the library. The high level tags have been
>  introduced to support mount/fsck devices by LABEL= or UUID= tags
>  (only this is reason why we have the new PARTUUID= tag there). I'd
>  like to keep this layer as minimal as possible (due the problem with
>  caching in blkid.tab file).
>
>  If you need information about devices then use lsblk(8) rather than
>  blkid(8).

My situation is actually scanning for a partitions of particular types
using the libblkid library. The high level blkid API provides a really
nice way to do this except it is completely impossible to query for
new tags even if the tool has sufficient privileges to re-scan
devices. The low level API on the other hand is good at getting lots
of detail on a single device but tedious to use for scanning an entire
system for a single device. It isn't even possible to use the high
level API to query for PTTYPE="gpt" for a list of candidates to
directly read since whole disks get dropped from the high level API
when partitions are found on them. The patch to lsblk was just an
adjunct "might as well add this there too" sort of change, it doesn't
actually do what I need since I need an API.

What's the problem with caching you refer to? Is there a different
change to the high level API that would make it more flexible while
keeping the default set of values reported/cached minimal?

One thought on how this may be useful in general, with PARTTYPE the
following following could be used mount the same partitions that
systemd-gpt-auto-generato and systemd-efi-boot-generator would:

mount PARTTYPE=c12a7328-f81f-11d2-ba4b-00a0c93ec93b /boot
mount PARTTYPE=933ac7e1-2eb4-4f13-b8440e14e2aef915 /home