Corinna Vinschen wrote:
On Nov 17 17:45, Christian Franke wrote:
Corinna Vinschen wrote:
On Nov 17 15:39, Christian Franke wrote:
The last two /dev/disk subdirectories :-)
Note a minor difference: On Linux, empty /dev/disk subdirectories apparently
never appear. A subdirectory is not listed in /dev/disk if it would be
empty. Not worth the effort to emulate.
Agreed. This is really great. I just pushed your patch.
However, there's something strange in terms of by-label:
I have two partitions with labels:
$ ls -l /dev/disk/by-label
total 0
lrwxrwxrwx 1 corinna vinschen 0 Nov 17 17:18 blub -> ../../sda3
lrwxrwxrwx 1 corinna vinschen 0 Nov 17 17:18 blub2 -> ../../sdb2
$
Now I change the label of sdb2 to the same "blub" string as on sda3:
$ ls -l /dev/disk/by-label
total 0
$
I'd expected to see only one, due to the name collision, but en empty
dir is a bit surprising... And it may occur more often than not, given
that the default label "New_Volume" probably won't get changed very
often.
This is intentional and inherited from the very first patch, see the loop
behind qsort(). If a range of identical names appear, all these entries are
removed. If some "random" entry would be kept, it might no longer be the
persistent link the user expects. We could possibly add some hash like done
for by-id or append a number in such cases later. Need some more time to
thing about it....
I see. Admittedly, I don't know how Linux handles this either.
A quick test on Debian 12 with by-label suggests that the last duplicate
wins. Also not very sophisticated :-)
IIRC in the past I've seen in another of these directories (by-id?) that
'#N' was appended if duplicates occur.
I will sent a patch for the new-features doc soon.
Attached.
Christian
From 5d1c82f08e4b37d65acc8bf0c76f75641d762667 Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.fra...@t-online.de>
Date: Fri, 17 Nov 2023 18:41:08 +0100
Subject: [PATCH] Cygwin: Document /dev/disk/by-* subdirectories
Signed-off-by: Christian Franke <christian.fra...@t-online.de>
---
winsup/cygwin/release/3.5.0 | 16 +++++++++++-----
winsup/doc/new-features.xml | 20 +++++++++++---------
2 files changed, 22 insertions(+), 14 deletions(-)
diff --git a/winsup/cygwin/release/3.5.0 b/winsup/cygwin/release/3.5.0
index 2d59818b5..aee21c972 100644
--- a/winsup/cygwin/release/3.5.0
+++ b/winsup/cygwin/release/3.5.0
@@ -17,11 +17,17 @@ What's new:
class expressions, and collating symbols in the search pattern, i.e.,
[:alnum:], [=a=], [.aa.].
-- Introduce /dev/disk directory with subdirectories by-id and by-partuuid.
- The by-id directory provides symlinks for each disk and its partitions:
- BUSTYPE-[VENDOR_]PRODUCT_[SERIAL|HASH][-partN] -> ../../sdX[N].
- The by-partuuid directory provides symlinks for each MBR and GPT disk
- partition: MBR_SERIAL-OFFSET -> ../../sdXN, GPT_GUID -> ../../sdXN.
+- Introduce /dev/disk directory with various by-* subdirectories which
+ provide symlinks to disk and partition raw devices:
+ by-drive/DRIVE_LETTER -> ../../sdXN
+ by-label/VOLUME_LABEL -> ../../sdXN
+ by-id/BUSTYPE-[VENDOR_]PRODUCT_[SERIAL|0xHASH][-partN] -> ../../sdX[N]
+ by-partuuid/MBR_SERIAL-OFFSET -> ../../sdXN
+ by-partuuid/GPT_GUID -> ../../sdXN
+ by-uuid/VOLUME_SERIAL -> ../../sdXN
+ by-voluuid/MBR_SERIAL-OFFSET -> ../../sdXN
+ by-voluuid/VOLUME_GUID -> ../../sdXN
+ The subdirectories by-drive and by-voluuid are Cygwin specific.
- Introduce /proc/codesets and /proc/locales with information on
supported codesets and locales for all interested parties. Locale(1)
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index a8e8a7991..2c31a4acc 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -35,17 +35,19 @@ class expressions, and collating symbols in the search
pattern, i.e.,
</para></listitem>
<listitem><para>
-Introduce /dev/disk directory with subdirectories by-id and by-partuuid.
-The by-id directory provides symlinks for each disk and its partitions:
+Introduce /dev/disk directory with various by-* subdirectories which
+provide symlinks to disk and partition raw devices:
<screen>
- BUSTYPE-[VENDOR_]PRODUCT_[SERIAL|0xHASH][-partN] -> ../../sdX[N]
- </screen>
-The by-partuuid directory provides symlinks for each MBR and GPT disk
-partition:
- <screen>
- MBR_SERIAL-OFFSET -> ../../sdXN
- GPT_GUID -> ../../sdXN
+ by-drive/DRIVE_LETTER -> ../../sdXN
+ by-label/VOLUME_LABEL -> ../../sdXN
+ by-id/BUSTYPE-[VENDOR_]PRODUCT_[SERIAL|0xHASH][-partN] -> ../../sdX[N]
+ by-partuuid/MBR_SERIAL-OFFSET -> ../../sdXN
+ by-partuuid/GPT_GUID -> ../../sdXN
+ by-uuid/VOLUME_SERIAL -> ../../sdXN
+ by-voluuid/MBR_SERIAL-OFFSET -> ../../sdXN
+ by-voluuid/VOLUME_GUID -> ../../sdXN
</screen>
+The subdirectories by-drive and by-voluuid are Cygwin specific.
</para></listitem>
<listitem><para>
--
2.42.1
