[PATCH] Cygwin: Add /dev/disk/by-drive and /dev/disk/by-uuid symlinks
Christian Franke
Christian.Franke@t-online.de
Thu Nov 16 17:02:44 GMT 2023
Corinna Vinschen wrote:
> On Nov 16 12:50, Christian Franke wrote:
> ...
>>> I also tried an NTFS partition and the output looks like this:
>>>
>>> 0FD4F62866CFBF09 -> ../../sdc1
>>>
>>> This is the 64 bit volume serial number as returned by
>>> DeviceIoControl(FSCTL_GET_NTFS_VOLUME_DATA)(*).
>>>
>>> Wouldn't that be what we want to see, too?
>> Hmm...... yes. Should both information be provided in by-uuid or only the
>> serial numbers? In the latter case, should we add e.g. by-voluuid for the
>> volume GUIDs ?
> Good question... by-voluuid sounds like a nice idea. It's a Windows-only
> concept anyway, so it might make sense to present it in its own directory.
Then by-voluuid is easy, changed patch is attached. I try to provide a
patch for a new by-uuid with filesystem serial numbers soon.
-------------- next part --------------
From 39cdbadeacfb226ad082f4f635285298aa5ad1bb Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.franke@t-online.de>
Date: Thu, 16 Nov 2023 17:51:08 +0100
Subject: [PATCH] Cygwin: Add /dev/disk/by-drive and /dev/disk/by-voluuid
symlinks
The new directory '/dev/disk/by-drive' provides symlinks for each
disk related drive letter:
'x' -> '../../sdXN'
The new directory '/dev/disk/by-voluuid' provides symlinks for each
disk related storage volume:
'MBR_SERIAL-OFFSET' -> '../../sdXN'
'VOLUME_GUID' -> '../../sdXN'
Both directories provide Windows specific information and do not
exist on Linux.
Signed-off-by: Christian Franke <christian.franke@t-online.de>
---
winsup/cygwin/fhandler/dev_disk.cc | 143 ++++++++++++++++++++----
winsup/cygwin/local_includes/fhandler.h | 3 +-
2 files changed, 126 insertions(+), 20 deletions(-)
diff --git a/winsup/cygwin/fhandler/dev_disk.cc b/winsup/cygwin/fhandler/dev_disk.cc
index 11b24042f..5f79ab5e9 100644
--- a/winsup/cygwin/fhandler/dev_disk.cc
+++ b/winsup/cygwin/fhandler/dev_disk.cc
@@ -158,6 +158,92 @@ storprop_to_id_name (HANDLE devhdl, const UNICODE_STRING *upath,
return 1;
}
+/* ("HarddiskN", PART_NUM) -> "\\\\?\\Volume{GUID}\\" */
+static bool
+partition_to_volpath (const UNICODE_STRING *drive_uname, DWORD part_num,
+ WCHAR (& volpath)[MAX_PATH])
+{
+ WCHAR gpath[MAX_PATH];
+ __small_swprintf (gpath, L"\\\\?\\GLOBALROOT\\Device\\%S\\Partition%u\\",
+ drive_uname, part_num);
+ if (!GetVolumeNameForVolumeMountPointW (gpath, volpath, sizeof(volpath)))
+ {
+ debug_printf ("GetVolumeNameForVolumeMountPointW(%W): %E", gpath);
+ return false;
+ }
+ debug_printf ("%W -> %W", gpath, volpath);
+ return true;
+}
+
+/* ("HarddiskN", PART_NUM) -> "x" */
+static bool
+partition_to_drive(const UNICODE_STRING *drive_uname, DWORD part_num,
+ WCHAR *w_buf, char *name)
+{
+ WCHAR volpath[MAX_PATH];
+ if (!partition_to_volpath (drive_uname, part_num, volpath))
+ return false;
+
+ DWORD len;
+ if (!GetVolumePathNamesForVolumeNameW (volpath, w_buf, NT_MAX_PATH, &len))
+ {
+ debug_printf ("GetVolumePathNamesForVolumeNameW(%W): %E", volpath);
+ return false;
+ }
+ debug_printf ("%W -> '%W'%s", volpath, w_buf,
+ (w_buf[0] && wcschr (w_buf, L'\0')[1] ? ", ..." : ""));
+
+ /* Find first "X:\\", skip if not found.
+ FIXME: Support multiple drive letters. */
+ WCHAR *p;
+ for (p = w_buf; ; p = wcschr (p, L'\0') + 1)
+ {
+ if (!*p)
+ return false;
+ if (L'A' <= p[0] && p[0] <= L'Z' && p[1] == L':' && p[2] == L'\\' && !p[3])
+ break;
+ }
+ name[0] = (p[0] - L'A') + 'a';
+ name[1] = '\0';
+ return true;
+}
+
+/* ("HarddiskN", PART_NUM) -> "VOLUME_GUID" */
+static bool
+partition_to_voluuid(const UNICODE_STRING *drive_uname, DWORD part_num,
+ char *name)
+{
+ WCHAR volpath[MAX_PATH];
+ if (!partition_to_volpath (drive_uname, part_num, volpath))
+ return false;
+
+ /* Skip if not "\\\\?\\Volume{GUID}...". */
+ static const WCHAR prefix[] = L"\\\\?\\Volume{";
+ const size_t prefix_len = sizeof (prefix) / sizeof(WCHAR) - 1, uuid_len = 36;
+ if (!(!wcsncmp (volpath, prefix, prefix_len)
+ && volpath[prefix_len + uuid_len] == L'}'))
+ return false;
+
+ /* Extract GUID. */
+ volpath[prefix_len + uuid_len] = 0;
+ __small_sprintf (name, "%W", volpath + prefix_len);
+
+ if (!strncmp (name + 9, "0000-0000-00", 12) && !strcmp (name + 32, "0000"))
+ {
+ /* MBR "GUID": Use same SERIAL-OFFSET format as in by-partuuid directory.
+ SERIAL-0000-0000-009a-785634120000 -> SERIAL-123456789a00 */
+ for (int i = 9, j = 30; i < 19; i += 2, j -= 2)
+ {
+ if (j == 22) // name[j + 1] == '-'
+ j--;
+ name[i] = name[j];
+ name[i + 1] = name[j + 1];
+ }
+ name[21] = '\0';
+ }
+ return true;
+}
+
struct by_id_entry
{
char name[NAME_MAX + 1];
@@ -208,6 +294,7 @@ format_partuuid (char *name, const PARTITION_INFORMATION_EX *pix)
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;
}
@@ -237,6 +324,7 @@ get_by_id_table (by_id_entry * &table, fhandler_dev_disk::dev_disk_location loc)
unsigned alloc_size = 0, table_size = 0;
tmp_pathbuf tp;
char *ioctl_buf = tp.c_get ();
+ WCHAR *w_buf = tp.w_get ();
DIRECTORY_BASIC_INFORMATION *dbi_buf =
reinterpret_cast<DIRECTORY_BASIC_INFORMATION *>(tp.w_get ());
@@ -365,6 +453,11 @@ get_by_id_table (by_id_entry * &table, fhandler_dev_disk::dev_disk_location loc)
char *name = table[table_size].name;
switch (loc)
{
+ case fhandler_dev_disk::disk_by_drive:
+ if (!partition_to_drive (&dbi->ObjectName, part_num, w_buf, name))
+ continue;
+ break;
+
case fhandler_dev_disk::disk_by_id:
__small_sprintf (name, "%s-part%u", drive_name, part_num);
break;
@@ -374,6 +467,11 @@ get_by_id_table (by_id_entry * &table, fhandler_dev_disk::dev_disk_location loc)
continue;
break;
+ case fhandler_dev_disk::disk_by_voluuid:
+ if (!partition_to_voluuid (&dbi->ObjectName, part_num, name))
+ continue;
+ break;
+
default: continue; /* Should not happen. */
}
table[table_size].drive = drive_num;
@@ -417,10 +515,17 @@ get_by_id_table (by_id_entry * &table, fhandler_dev_disk::dev_disk_location loc)
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;
+static const char by_drive[] = "/by-drive";
+const size_t by_drive_len = sizeof(by_drive) - 1;
+
+/* Keep this in sync with enum fhandler_dev_disk::dev_disk_location starting
+ at disk_by_drive. */
+static const char * const by_dir_names[] {
+ "/by-drive", "/by-id", "/by-partuuid", "/by-voluuid"
+};
+const size_t by_dir_names_size = sizeof(by_dir_names) / sizeof(by_dir_names[0]);
+static_assert((size_t) fhandler_dev_disk::disk_by_drive + by_dir_names_size - 1
+ == (size_t) fhandler_dev_disk::disk_by_voluuid);
fhandler_dev_disk::fhandler_dev_disk ():
fhandler_virtual (),
@@ -440,22 +545,23 @@ fhandler_dev_disk::init_dev_disk ()
/* Determine location. */
const char *path = get_name ();
size_t dirlen = 0;
+ loc = invalid_loc; // "/dev/disk/invalid"
if (!path_prefix_p (dev_disk, path, dev_disk_len, false))
- loc = invalid_loc; // should not happen
+ ; // 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 = 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 = invalid_loc; // "/dev/disk/invalid"
+ for (size_t i = 0; i < by_dir_names_size; i++)
+ {
+ const char *dir = by_dir_names[i];
+ size_t len = strlen(dir);
+ if (path_prefix_p (dir, path + dev_disk_len, len, false))
+ {
+ loc = (dev_disk_location) (disk_by_drive + i); // "/dev/disk/by-..."
+ dirlen = dev_disk_len + len;
+ break;
+ }
+ }
loc_is_link = false;
if (dirlen)
@@ -594,10 +700,9 @@ fhandler_dev_disk::readdir (DIR *dir, dirent *de)
dir->__d_position++;
res = 0;
}
- else if (loc == disk_dir && dir->__d_position < 2 + 2)
+ else if (loc == disk_dir && dir->__d_position < 2 + (int) by_dir_names_size)
{
- static const char * const names[2] {by_id, by_partuuid};
- strcpy (de->d_name, names[dir->__d_position - 2] + 1);
+ strcpy (de->d_name, by_dir_names[dir->__d_position - 2] + 1);
de->d_type = DT_DIR;
dir->__d_position++;
res = 0;
diff --git a/winsup/cygwin/local_includes/fhandler.h b/winsup/cygwin/local_includes/fhandler.h
index 6013496d5..86c7b20a2 100644
--- a/winsup/cygwin/local_includes/fhandler.h
+++ b/winsup/cygwin/local_includes/fhandler.h
@@ -3197,7 +3197,8 @@ class fhandler_dev_disk: public fhandler_virtual
public:
enum dev_disk_location {
unknown_loc, invalid_loc, disk_dir,
- disk_by_id, disk_by_partuuid
+ /* Keep these in sync with dev_disk.cc:by_dir_names array: */
+ disk_by_drive, disk_by_id, disk_by_partuuid, disk_by_voluuid
};
private:
--
2.42.1
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