On Sun, 1 Feb 2026 at 18:08, Jon Turney <[email protected]> wrote:
>
> On 31/01/2026 18:42, Dan Shelton via Cygwin wrote:
> > Hello, on Cygwin 3.6.6-1.x86_64 on CYGWIN_NT-10.0-19045/Win10 I get
> > these errors from git fsck when working on a clean clone of the
> > gcc.git repro:
> >
> > git fsck
> > error: refs/tags/.cyg000000000559e25517156b51cf219f51/libgcj-2.95.1:
> > badRefName: invalid refname format
> > error: refs/tags/.cyg000000000559e25517156b51cf219f51/libgcj-2.95.0:
> > badRefName: invalid refname format
> > error: refs/tags/.cyg000000000559e25817156b51cf219f51/libf2c-0.5.22:
> > badRefName: invalid refname format
> > error: refs/tags/.cyg000000000559e25817156b51cf219f51/libf2c-0.5.21:
> > badRefName: invalid refname format
> >
> > git fsck then exits with error code 8, breaking our scripts.
> >
> > Is this a Cygwin bug or feature running wild?
> Yes.
>
> These .cygXXX files are made by the cygwin DLL (I think it's something
> like a hardlink to the running executable so we can fork even if it's
> deleted, but I might well be misremembering the details) and are
> supposed to get automatically removed.
>
> Obviously, 'git fsck' objects to their presence, but it is safe to
> remove them.
I'm not sure whether the Cygwin code is correct. I did a peek with a
kernel debugger, and I see that FILE_RENAME_INFORMATION.RootDirectory
is always NULL if a file gets renamed to .cyg000000000xxxx. But if I
try that with NTFS or SMB, the NtSetInformationFile() to set
FileRenameInformation always fails.
I think this bug is there since a LONG time, and only bothers
filesystems which are not NTFS.
I made this testcase:
-x-x-x-x-x-x-x-x-x-x-x-x-
#include <windows.h>
#include <wchar.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#ifdef _MSC_VER
#pragma comment(lib, "ntdll.lib")
#endif
typedef LONG NTSTATUS;
#ifndef NT_SUCCESS
#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)
#endif
typedef struct _IO_STATUS_BLOCK {
union { NTSTATUS Status; PVOID Pointer; } DUMMYUNIONNAME;
ULONG_PTR Information;
} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK;
typedef enum _FILE_INFORMATION_CLASS {
FileRenameInformation = 10
} FILE_INFORMATION_CLASS;
typedef struct _FILE_RENAME_INFORMATION {
BOOLEAN ReplaceIfExists;
HANDLE RootDirectory;
ULONG FileNameLength;
WCHAR FileName[1];
} FILE_RENAME_INFORMATION, *PFILE_RENAME_INFORMATION;
#ifdef __cplusplus
extern "C" {
#endif
NTSTATUS NTAPI NtSetInformationFile(HANDLE, PIO_STATUS_BLOCK, PVOID,
ULONG, FILE_INFORMATION_CLASS);
ULONG NTAPI RtlNtStatusToDosError(NTSTATUS);
#ifdef __cplusplus
}
#endif
static HANDLE OpenForRenameW(const wchar_t* fullDosPath)
{
DWORD share = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
DWORD flags = FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT;
return CreateFileW(fullDosPath, GENERIC_READ | DELETE |
SYNCHRONIZE, share, NULL, OPEN_EXISTING, flags, NULL);
}
int wmain(int ac, wchar_t *av[])
{
wchar_t *srcfile = av[1];
wchar_t *dstfile = av[2];
if (ac != 3) {
fwprintf(stderr, L"%ls: Usage: renametest <srcfile>
<dstfile>\n", av[0]);
return 2;
}
HANDLE srch = OpenForRenameW(srcfile);
if (srch == INVALID_HANDLE_VALUE) {
fwprintf(stderr, L"%ls: Cannot open srcfile, lasterr=%d\n",
av[0], (int)GetLastError());
}
PFILE_RENAME_INFORMATION fri;
size_t fri_len = sizeof(FILE_RENAME_INFORMATION) +
(wcslen(dstfile)+1)*sizeof(wchar_t);
fri = calloc(1, fri_len);
if (fri == NULL) {
fwprintf(stderr, L"%ls: Out of memory\n", av[0]);
return 2;
}
fri->ReplaceIfExists = TRUE;
fri->RootDirectory = NULL;
fri->FileNameLength = (wcslen(dstfile)+1)*sizeof(wchar_t);
memcpy(&fri->FileName[0], dstfile, fri->FileNameLength);
IO_STATUS_BLOCK isb = { 0 };
NTSTATUS status = NtSetInformationFile(srch, &isb, fri, fri_len,
FileRenameInformation);
printf("ntstatus=0x%lx\n", (long)status);
CloseHandle(srch);
return EXIT_SUCCESS;
}
-x-x-x-x-x-x-x-x-x-x-x-x-
Dan
--
Dan Shelton - Cluster Specialist Win/Lin/Bsd
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