Corinna Vinschen wrote:
Hi Christian,
On Nov 5 16:45, Christian Franke wrote:
...
Old IOCTL dropped and code simplified.
Great. I pushed your patch.
Thanks.
...
Last, but not least, do you see a chance to add any other /dev/disk
subdir? by-partuuid, perhaps?
Possibly, but not very soon. I'm not yet sure which API functions could be
used.
Some early draft ideas:
/dev/disk/by-partuid (Partition UUID -> device)
GPT_PART_UUID -> ../../sdXN (GPT partition UUID)
MBR_SERIAL-partN -> ../../sdYM (Fake UUID for MBR)
That should only require IOCTL_DISK_GET_PARTITION_INFO_EX, I think.
Easier than expected: DRIVE_LAYOUT_INFORMATION_EX already contains
PARTITION_INFORMATION_EX so existing scanning function could be
enhanced. Patch attached.
/dev/disk/by-uuid (Windows Volume UUID -> device)
Vol_UUID1 -> ../../sdXN (disk volume)
Vol_UUID2 -> ../../scd0 (CD/DVD drive volume)
Vol_UUID3 -> /proc/sys/GLOBAL??/Volume{UUID} (others, e.g. VeraCrypt
volume)
Yeah, tricky. These are not the partition GUIDs but the filesystem
GUIDs or serial numbers. AFAICS, Windows filesystems (FAT*, NTFS)
don't maintain a filesystem GUID, as, e. g., ext4 or xfs, but only
serial numbers you can fetch via NtQueryVolumeInformationFile.
A Linux example of that is the serial number from a FAT32 filesytem
as the EFI boot partition in by-uuid:
lrwxrwxrwx 1 root root 10 Oct 30 10:20 DC38-0407 -> ../../sda1
On second thought, maybe that's sufficient for our by-uuid emulation.
/dev/disk/by-drive (Cygwin specific: drive letter -> volume)
c -> ../by-uuid/UUID (if UUID available)
x -> /proc/sys/DosDevices/X: (others, e.g. Network, "mounted" Volume
Shadow Copy)
Ah, good idea. That's what my extension in /proc/partition already
provides, but a /dev/disk/by-drive sounds like a great idea.
Left for later :-)
Christian
From e9c9d2a1a1df9ddecd815300c62321a480f0de9b Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.fra...@t-online.de>
Date: Tue, 7 Nov 2023 10:57:15 +0100
Subject: [PATCH] Cygwin: Add /dev/disk/by-partuuid symlinks
The new directory '/dev/disk/by-partuuid' provides symlinks for each
MBR or GPT disk partition:
'MBR_SERIAL-OFFSET' -> '../../sdXN'
'GPT_GUID' -> '../../sdXN'
Signed-off-by: Christian Franke <christian.fra...@t-online.de>
---
winsup/cygwin/fhandler/dev_disk.cc | 173 ++++++++++++++++--------
winsup/cygwin/local_includes/fhandler.h | 7 +-
2 files changed, 125 insertions(+), 55 deletions(-)
diff --git a/winsup/cygwin/fhandler/dev_disk.cc
b/winsup/cygwin/fhandler/dev_disk.cc
index 9a1cae5eb..fcd0de651 100644
--- a/winsup/cygwin/fhandler/dev_disk.cc
+++ b/winsup/cygwin/fhandler/dev_disk.cc
@@ -176,9 +176,38 @@ by_id_realloc (by_id_entry *p, size_t n)
return reinterpret_cast<by_id_entry *>(p2);
}
+static bool
+format_partuuid (char *name, const PARTITION_INFORMATION_EX *pix)
+{
+ const GUID *guid;
+ switch (pix->PartitionStyle)
+ {
+ case PARTITION_STYLE_MBR: guid = &pix->Mbr.PartitionId; break;
+ case PARTITION_STYLE_GPT: guid = &pix->Gpt.PartitionId; break;
+ default: return false;
+ }
+
+ if (pix->PartitionStyle == PARTITION_STYLE_MBR && !guid->Data2
+ && !guid->Data3 && !guid->Data4[6] && !guid->Data4[7])
+ /* MBR "GUID": SERIAL-0000-0000-00NN-NNNNNNN00000
+ Byte offset in LE order -----^^^^-^^^^^^^
+ Print as: SERIAL-OFFSET */
+ __small_sprintf(name,
+ "%08_x-%02_x%02_x%02_x%02_x%02_x%02_x",
+ guid->Data1, guid->Data4[5], guid->Data4[4], guid->Data4[3],
+ guid->Data4[2], guid->Data4[1], guid->Data4[0]);
+ else
+ __small_sprintf(name,
+
"%08_x-%04_x-%04_x-%02_x%02_x-%02_x%02_x%02_x%02_x%02_x%02_x",
+ guid->Data1, guid->Data2, guid->Data3,
+ guid->Data4[0], guid->Data4[1], guid->Data4[2],
guid->Data4[3],
+ guid->Data4[4], guid->Data4[5], guid->Data4[6],
guid->Data4[7]);
+ return true;
+}
+
/* Create sorted name -> drive mapping table. Must be freed by caller. */
static int
-get_by_id_table (by_id_entry * &table)
+get_by_id_table (by_id_entry * &table, fhandler_dev_disk::dev_disk_location
loc)
{
table = nullptr;
@@ -282,25 +311,31 @@ get_by_id_table (by_id_entry * &table)
}
}
- /* Fetch storage properties and create the ID string. */
- int rc = storprop_to_id_name (devhdl, &upath, ioctl_buf,
- table[table_size].name);
- if (rc <= 0)
+ const char *drive_name = "";
+ if (loc == fhandler_dev_disk::disk_by_id)
{
- if (rc < 0)
- errno_set = true;
- continue;
+ /* Fetch storage properties and create the ID string. */
+ int rc = storprop_to_id_name (devhdl, &upath, ioctl_buf,
+ table[table_size].name);
+ if (rc <= 0)
+ {
+ if (rc < 0)
+ errno_set = true;
+ continue;
+ }
+ drive_name = table[table_size].name;
+ table[table_size].drive = drive_num;
+ table[table_size].part = 0;
+ table_size++;
}
- int drive_index = table_size++;
- size_t drive_len = strlen(table[drive_index].name);
- table[drive_index].drive = drive_num;
- table[drive_index].part = 0;
- /* Fetch drive layout info to get size of all partitions on disk. */
+ /* Fetch drive layout info to information of all partitions on disk.
*/
DWORD bytes_read;
if (!DeviceIoControl (devhdl, IOCTL_DISK_GET_DRIVE_LAYOUT_EX,
nullptr, 0,
ioctl_buf, NT_MAX_PATH, &bytes_read, nullptr))
{
+ __seterrno_from_win_error (GetLastError ());
+ errno_set = true;
debug_printf ("DeviceIoControl(%S, "
"IOCTL_DISK_GET_DRIVE_LAYOUT_EX): %E", &upath);
continue;
@@ -311,7 +346,8 @@ get_by_id_table (by_id_entry * &table)
reinterpret_cast<const DRIVE_LAYOUT_INFORMATION_EX *>(ioctl_buf);
for (DWORD i = 0; i < dlix->PartitionCount; i++)
{
- DWORD part_num = dlix->PartitionEntry[i].PartitionNumber;
+ const PARTITION_INFORMATION_EX *pix = &dlix->PartitionEntry[i];
+ DWORD part_num = pix->PartitionNumber;
/* A partition number of 0 denotes an extended partition or a
filler entry as described in
fhandler_dev_floppy::lock_partition. Just skip. */
@@ -319,9 +355,22 @@ get_by_id_table (by_id_entry * &table)
continue;
if (part_num > max_part_num)
break;
- table[table_size] = table[drive_index];
- __small_sprintf(table[table_size].name + drive_len, "-part%u",
- part_num);
+
+ char *name = table[table_size].name;
+ switch (loc)
+ {
+ case fhandler_dev_disk::disk_by_id:
+ __small_sprintf (name, "%s-part%u", drive_name, part_num);
+ break;
+
+ case fhandler_dev_disk::disk_by_partuuid:
+ if (!format_partuuid (name, pix))
+ continue;
+ break;
+
+ default: continue; /* Should not happen. */
+ }
+ table[table_size].drive = drive_num;
table[table_size].part = part_num;
table_size++;
}
@@ -362,10 +411,15 @@ get_by_id_table (by_id_entry * &table)
const char dev_disk[] = "/dev/disk";
const size_t dev_disk_len = sizeof (dev_disk) - 1;
+static const char by_id[] = "/by-id";
+const size_t by_id_len = sizeof(by_id) - 1;
+static const char by_partuuid[] = "/by-partuuid";
+const size_t by_partuuid_len = sizeof(by_partuuid) - 1;
fhandler_dev_disk::fhandler_dev_disk ():
fhandler_virtual (),
loc (unknown_loc),
+ loc_is_link (false),
drive_from_id (-1),
part_from_id (0)
{
@@ -377,32 +431,46 @@ fhandler_dev_disk::init_dev_disk ()
if (loc != unknown_loc)
return;
- static const char by_id[] = "/by-id";
- const size_t by_id_len = sizeof(by_id) - 1;
-
/* Determine location. */
const char *path = get_name ();
+ size_t dirlen = 0;
if (!path_prefix_p (dev_disk, path, dev_disk_len, false))
loc = invalid_loc; // should not happen
else if (!path[dev_disk_len])
loc = disk_dir; // "/dev/disk"
- else if (!path_prefix_p (by_id, path + dev_disk_len, by_id_len, false))
- loc = invalid_loc; // "/dev/disk/invalid"
- else if (!path[dev_disk_len + by_id_len])
- loc = by_id_dir; // "/dev/disk/by-id"
- else if (strchr (path + dev_disk_len + by_id_len + 1, '/'))
- loc = invalid_loc; // "/dev/disk/by-id/dir/invalid"
+ else if (path_prefix_p (by_id, path + dev_disk_len, by_id_len, false))
+ {
+ loc = disk_by_id; // "/dev/disk/by-id.."
+ dirlen = dev_disk_len + by_id_len;
+ }
+ else if (path_prefix_p (by_partuuid, path + dev_disk_len, by_partuuid_len,
false))
+ {
+ loc = disk_by_partuuid; // "/dev/disk/by-partuuid..."
+ dirlen = dev_disk_len + by_partuuid_len;
+ }
else
- loc = by_id_link; // possible "/dev/disk/by-id/LINK"
- debug_printf ("'%s': loc %d", path, (int)loc);
+ loc = invalid_loc; // "/dev/disk/invalid"
+
+ loc_is_link = false;
+ if (dirlen)
+ {
+ if (!path[dirlen])
+ ; // "/dev/disk/by-..."
+ else if (!strchr (path + dirlen + 1, '/'))
+ loc_is_link = true; // "/dev/disk/by-.../LINK"
+ else
+ loc = invalid_loc; // "/dev/disk/by-.../dir/invalid"
+ }
- /* Done if "/dev/disk", "/dev/disk/by_id" or invalid. */
- if (loc != by_id_link)
+ debug_printf ("%s: loc %d, loc_is_link %d", path, (int) loc, (int)
loc_is_link);
+
+ /* Done if directory or invalid. */
+ if (!loc_is_link)
return;
- /* Check whether "/dev/disk/by_id/LINK" exists. */
+ /* Check whether "/dev/disk/by-.../LINK" exists. */
by_id_entry *table;
- int table_size = get_by_id_table (table);
+ int table_size = get_by_id_table (table, loc);
if (!table)
{
loc = invalid_loc;
@@ -410,7 +478,7 @@ fhandler_dev_disk::init_dev_disk ()
}
by_id_entry key;
- strcpy (key.name, path + dev_disk_len + by_id_len + 1);
+ strcpy (key.name, path + dirlen + 1);
const void *found = bsearch (&key, table, table_size, sizeof (*table),
by_id_compare_name);
if (found)
@@ -430,16 +498,12 @@ fhandler_dev_disk::exists ()
{
debug_printf ("exists (%s)", get_name ());
ensure_inited ();
- switch (loc)
- {
- case disk_dir:
- case by_id_dir:
- return virt_directory;
- case by_id_link:
- return virt_symlink;
- default:
- return virt_none;
- }
+ if (loc == invalid_loc)
+ return virt_none;
+ else if (loc_is_link)
+ return virt_symlink;
+ else
+ return virt_directory;
}
int
@@ -454,7 +518,7 @@ fhandler_dev_disk::fstat (struct stat *buf)
}
fhandler_base::fstat (buf);
- buf->st_mode = (loc == by_id_link ? S_IFLNK | S_IWUSR | S_IWGRP | S_IWOTH
+ buf->st_mode = (loc_is_link ? S_IFLNK | S_IWUSR | S_IWGRP | S_IWOTH
: S_IFDIR) | STD_RBITS | STD_XBITS;
buf->st_ino = get_ino ();
return 0;
@@ -470,16 +534,16 @@ DIR *
fhandler_dev_disk::opendir (int fd)
{
ensure_inited ();
- if (!(loc == disk_dir || loc == by_id_dir))
+ if (loc_is_link)
{
set_errno (ENOTDIR);
return nullptr;
}
by_id_entry *table = nullptr;
- if (loc == by_id_dir)
+ if (loc != disk_dir)
{
- int table_size = get_by_id_table (table);
+ int table_size = get_by_id_table (table, loc);
if (table_size < 0)
return nullptr; /* errno is set. */
if (table)
@@ -524,14 +588,15 @@ fhandler_dev_disk::readdir (DIR *dir, dirent *de)
dir->__d_position++;
res = 0;
}
- else if (loc == disk_dir && dir->__d_position == 2)
+ else if (loc == disk_dir && dir->__d_position < 2 + 2)
{
- strcpy (de->d_name, "by-id");
+ static const char * const names[2] {by_id, by_partuuid};
+ strcpy (de->d_name, names[dir->__d_position - 2] + 1);
de->d_type = DT_DIR;
dir->__d_position++;
res = 0;
}
- else if (loc == by_id_dir && *dir_id_table (dir))
+ else if (*dir_id_table (dir))
{
const char *name = (*dir_id_table (dir))[dir->__d_position - 2].name;
if (name[0])
@@ -559,7 +624,8 @@ fhandler_dev_disk::open (int flags, mode_t mode)
int err = 0;
if (!fhandler_virtual::open (flags, mode))
err = -1;
- else if (loc == disk_dir || loc == by_id_dir)
+ /* else if (loc_is_link) {} */ /* should not happen. */
+ else if (loc != invalid_loc)
{
if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
err = EEXIST;
@@ -568,8 +634,7 @@ fhandler_dev_disk::open (int flags, mode_t mode)
else
diropen = true;
}
- /* else if (loc == by_id_link) { } */ /* should not happen */
- else /* (loc == invalid_loc) */
+ else
{
if (flags & O_CREAT)
err = EROFS;
@@ -600,7 +665,7 @@ fhandler_dev_disk::fill_filebuf ()
{
debug_printf ("fill_filebuf (%s)", get_name ());
ensure_inited ();
- if (!(loc == by_id_link && drive_from_id >= 0))
+ if (!(loc_is_link && drive_from_id >= 0))
return false;
char buf[32];
diff --git a/winsup/cygwin/local_includes/fhandler.h
b/winsup/cygwin/local_includes/fhandler.h
index cd61aadf8..6013496d5 100644
--- a/winsup/cygwin/local_includes/fhandler.h
+++ b/winsup/cygwin/local_includes/fhandler.h
@@ -3194,10 +3194,15 @@ class fhandler_procnet: public fhandler_proc
class fhandler_dev_disk: public fhandler_virtual
{
+public:
enum dev_disk_location {
- unknown_loc, invalid_loc, disk_dir, by_id_dir, by_id_link
+ unknown_loc, invalid_loc, disk_dir,
+ disk_by_id, disk_by_partuuid
};
+
+private:
dev_disk_location loc;
+ bool loc_is_link;
void init_dev_disk ();
void ensure_inited ()
--
2.42.1
