From 75b6c0e045abb7e07773b924237c562ab9920c60 Mon Sep 17 00:00:00 2001

From: Karel Zak <kzak@redhat.com>

Date: Thu, 26 May 2016 12:02:12 +0200

Subject: [PATCH 85/86] libblkid: store only canonical devnames to the cache

Let's try to use symlink:

 # ls -la /dev/block/8\:1

 # lrwxrwxrwx 1 root root 7 May 25 16:42 /dev/block/8:1 -> ../sda1

 # blkid /dev/block/8:1

 /dev/block/8:3: LABEL="HOME" UUID="196972ad-3b13-4bba-ac54-4cb3f7b409a4" TYPE="ext4" PARTUUID="6073277f-87bc-43ff-bcfd-724c4484a63a"

unfortunately the symlink is stored to the cache:

 <device DEVNO="0x0803" TIME="1464253300.715279" LABEL="HOME" UUID="196972ad-3b13-4bba-ac54-4cb3f7b409a4" TYPE="ext4" PARTUUID="6073277f-87bc-43ff-bcfd-724c4484a63a">/dev/block/8:3</device>

next time if you ask for LABEL=HOME the answer will be /dev/block/8:3

rather than /dev/sda3.

It seems better to canonicalize the paths we store to the cache.

Unfortunately if you ask for /dev/block/8:3 then you probably expect

that blkid_dev_devname() returns the same path. This patch introduces

dev->bid_xname, this is the path used by application (and never stored

in the cache).

Upstream: http://github.com/karelzak/util-linux/commit/924c93d9df118338fd54cd73b4a45ccddc4ac103

Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1007734

Signed-off-by: Karel Zak <kzak@redhat.com>

---

 libblkid/src/blkidP.h  |  4 +++-

 libblkid/src/dev.c     | 11 +++++++++--

 libblkid/src/devname.c | 43 +++++++++++++++++++++++++++++++++++++------

 3 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/libblkid/src/blkidP.h b/libblkid/src/blkidP.h

index 7de84b4..8183c12 100644

--- a/libblkid/src/blkidP.h

+++ b/libblkid/src/blkidP.h

@@ -44,7 +44,7 @@ struct blkid_struct_dev

 	struct list_head	bid_devs;	/* All devices in the cache */

 	struct list_head	bid_tags;	/* All tags for this device */

 	blkid_cache		bid_cache;	/* Dev belongs to this cache */

-	char			*bid_name;	/* Device inode pathname */

+	char			*bid_name;	/* Device real pathn (as used in cache) */

 	char			*bid_type;	/* Preferred device TYPE */

 	int			bid_pri;	/* Device priority */

 	dev_t			bid_devno;	/* Device major/minor number */

@@ -53,6 +53,8 @@ struct blkid_struct_dev

 	unsigned int		bid_flags;	/* Device status bitflags */

 	char			*bid_label;	/* Shortcut to device LABEL */

 	char			*bid_uuid;	/* Shortcut to binary UUID */

+

+	char			*bid_xname;	/* Device path as used by application (maybe symlink..) */

 };

 #define BLKID_BID_FL_VERIFIED	0x0001	/* Device data validated from disk */

diff --git a/libblkid/src/dev.c b/libblkid/src/dev.c

index a4b2aea..d2fd3f4 100644

--- a/libblkid/src/dev.c

+++ b/libblkid/src/dev.c

@@ -60,16 +60,23 @@ void blkid_free_dev(blkid_dev dev)

 					   bit_tags);

 		blkid_free_tag(tag);

 	}

+	free(dev->bid_xname);

 	free(dev->bid_name);

 	free(dev);

 }

 /*

- * Given a blkid device, return its name

+ * Given a blkid device, return its name. The function returns the name

+ * previously used for blkid_get_dev(). This name does not have to be canonical

+ * (real path) name, but for example symlink.

  */

 const char *blkid_dev_devname(blkid_dev dev)

 {

-	return dev ? dev->bid_name : NULL;

+	if (!dev)

+		return NULL;

+	if (dev->bid_xname)

+		return dev->bid_xname;

+	return dev->bid_name;

 }

 #ifdef CONFIG_BLKID_DEBUG

diff --git a/libblkid/src/devname.c b/libblkid/src/devname.c

index 497deaf..55b9594 100644

--- a/libblkid/src/devname.c

+++ b/libblkid/src/devname.c

@@ -51,28 +51,55 @@ blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)

 {

 	blkid_dev dev = NULL, tmp;

 	struct list_head *p, *pnext;

+	char *cn = NULL;

 	if (!cache || !devname)

 		return NULL;

+	/* search by name */

 	list_for_each(p, &cache->bic_devs) {

 		tmp = list_entry(p, struct blkid_struct_dev, bid_devs);

 		if (strcmp(tmp->bid_name, devname))

 			continue;

-

-		DBG(DEVNAME, blkid_debug("found devname %s in cache", tmp->bid_name));

 		dev = tmp;

 		break;

 	}

+	/* try canonicalize the name */

+	if (!dev && (cn = canonicalize_path(devname))) {

+		if (strcmp(cn, devname) != 0) {

+			DBG(DEVNAME, blkid_debug("search cannonical %s", cn));

+			list_for_each(p, &cache->bic_devs) {

+				tmp = list_entry(p, struct blkid_struct_dev, bid_devs);

+				if (strcmp(tmp->bid_name, cn))

+					continue;

+				dev = tmp;

+

+				/* update name returned by blkid_dev_devname() */

+				free(dev->bid_xname);

+				dev->bid_xname = strdup(devname);

+				break;

+			}

+		} else {

+			free(cn);

+			cn = NULL;

+		}

+	}

+

 	if (!dev && (flags & BLKID_DEV_CREATE)) {

 		if (access(devname, F_OK) < 0)

-			return NULL;

+			goto done;

 		dev = blkid_new_dev();

 		if (!dev)

-			return NULL;

+			goto done;

 		dev->bid_time = INT_MIN;

-		dev->bid_name = strdup(devname);

+		if (cn) {

+			dev->bid_name = cn;

+			dev->bid_xname = strdup(devname);

+			cn = NULL;	/* see free() below */

+		} else

+			dev->bid_name = strdup(devname);

+

 		dev->bid_cache = cache;

 		list_add_tail(&dev->bid_devs, &cache->bic_devs);

 		cache->bic_flags |= BLKID_BIC_FL_CHANGED;

@@ -81,7 +108,7 @@ blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)

 	if (flags & BLKID_DEV_VERIFY) {

 		dev = blkid_verify(cache, dev);

 		if (!dev || !(dev->bid_flags & BLKID_BID_FL_VERIFIED))

-			return dev;

+			goto done;

 		/*

 		 * If the device is verified, then search the blkid

 		 * cache for any entries that match on the type, uuid,

@@ -112,6 +139,10 @@ blkid_dev blkid_get_dev(blkid_cache cache, const char *devname, int flags)

 				blkid_free_dev(dev2);

 		}

 	}

+done:

+	if (dev)

+		DBG(DEVNAME, blkid_debug("%s requested, found %s in cache", devname, dev->bid_name));

+	free(cn);

 	return dev;

 }

-- 

2.7.4