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mingw: use ChangeTime for st_ctim when it is the latest time #6539

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mingw: use ChangeTime for st_ctim when it is the latest time #6539

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7d2bf16
mingw: use stat APIs that also return ChangeTime
jzbakh Oct 30, 2026
a01c480
mingw: let Git see cloud file placeholders as reparse points
jzbakh Nov 1, 2026
e94002a
mingw: use ChangeTime for st_ctim when it is the latest time
jzbakh Nov 1, 2026
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20 changes: 20 additions & 0 deletions compat/mingw-posix.h
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Original file line number Diff line number Diff line change
Expand Up @@ -374,6 +374,26 @@ static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
ts->tv_nsec = (hnsec % 10000000) * 100;
}

/*
* st_ctim: ChangeTime if it is later than both CreationTime and
* LastWriteTime, CreationTime otherwise. Always CreationTime for reparse
* points, such as cloud file placeholders, whose ChangeTime moves when
* they are pinned, unpinned, hydrated or dehydrated.
*/
static inline void filetimes_to_ctim(const LARGE_INTEGER *change,
const LARGE_INTEGER *creation,
const LARGE_INTEGER *last_write,
DWORD attributes, struct timespec *ts)
{
const LARGE_INTEGER *t = creation;

if (!(attributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
change->QuadPart > creation->QuadPart &&
change->QuadPart > last_write->QuadPart)
t = change;
filetime_to_timespec((const FILETIME *)t, ts);
}

struct mingw_stat {
_dev_t st_dev;
_ino_t st_ino;
Expand Down
102 changes: 86 additions & 16 deletions compat/mingw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1346,9 +1346,52 @@ static int read_reparse_point(const WCHAR *wpath, BOOL fail_on_unknown_tag,
return 0;
}

#ifdef _MSC_VER
/* missing from the Windows SDK's winternl.h */
typedef struct _FILE_NETWORK_OPEN_INFORMATION {
LARGE_INTEGER CreationTime;
LARGE_INTEGER LastAccessTime;
LARGE_INTEGER LastWriteTime;
LARGE_INTEGER ChangeTime;
LARGE_INTEGER AllocationSize;
LARGE_INTEGER EndOfFile;
ULONG FileAttributes;
} FILE_NETWORK_OPEN_INFORMATION;
#endif

NTSYSAPI NTSTATUS NTAPI NtQueryFullAttributesFile(
POBJECT_ATTRIBUTES attributes, FILE_NETWORK_OPEN_INFORMATION *info);
NTSYSAPI NTSTATUS NTAPI RtlDosPathNameToNtPathName_U_WithStatus(
PCWSTR dos_path, PUNICODE_STRING nt_path, PWSTR *file_part,
PVOID reserved);

/* Like GetFileAttributesExW(), but also returns ChangeTime */
static BOOL get_file_attributes(const wchar_t *wpath,
FILE_NETWORK_OPEN_INFORMATION *info)
{
UNICODE_STRING name;
OBJECT_ATTRIBUTES attributes;
NTSTATUS status;

if (!NT_SUCCESS(RtlDosPathNameToNtPathName_U_WithStatus(wpath, &name,
NULL, NULL))) {
/* as GetFileAttributesExW() does */
SetLastError(ERROR_PATH_NOT_FOUND);
return FALSE;
}
InitializeObjectAttributes(&attributes, &name, OBJ_CASE_INSENSITIVE,
NULL, NULL);
status = NtQueryFullAttributesFile(&attributes, info);
RtlFreeUnicodeString(&name);
if (NT_SUCCESS(status))
return TRUE;
SetLastError(RtlNtStatusToDosError(status));
return FALSE;
}

int mingw_lstat(const char *file_name, struct stat *buf)
{
WIN32_FILE_ATTRIBUTE_DATA fdata;
FILE_NETWORK_OPEN_INFORMATION fdata;
DWORD reparse_tag = 0;
int link_len = 0;
wchar_t wfilename[MAX_LONG_PATH];
Expand All @@ -1364,9 +1407,9 @@ int mingw_lstat(const char *file_name, struct stat *buf)
return -1;
}

if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
if (get_file_attributes(wfilename, &fdata)) {
/* for reparse points, get the link tag and length */
if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
if (fdata.FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
char tmpbuf[MAX_LONG_PATH];

if (read_reparse_point(wfilename, FALSE, tmpbuf,
Expand All @@ -1377,14 +1420,18 @@ int mingw_lstat(const char *file_name, struct stat *buf)
buf->st_gid = 0;
buf->st_uid = 0;
buf->st_nlink = 1;
buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes,
buf->st_mode = file_attr_to_st_mode(fdata.FileAttributes,
reparse_tag, file_name);
buf->st_size = S_ISLNK(buf->st_mode) ? link_len :
fdata.nFileSizeLow | (((off_t) fdata.nFileSizeHigh) << 32);
fdata.EndOfFile.QuadPart;
buf->st_dev = buf->st_rdev = 0; /* not used by Git */
filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
filetime_to_timespec((FILETIME *)&(fdata.LastAccessTime),
&(buf->st_atim));
filetime_to_timespec((FILETIME *)&(fdata.LastWriteTime),
&(buf->st_mtim));
filetimes_to_ctim(&(fdata.ChangeTime), &(fdata.CreationTime),
&(fdata.LastWriteTime), fdata.FileAttributes,
&(buf->st_ctim));
if (S_ISREG(buf->st_mode) &&
are_wsl_compatible_mode_bits_enabled()) {
copy_wsl_mode_bits_from_disk(wfilename, -1,
Expand Down Expand Up @@ -1423,9 +1470,13 @@ int (*lstat)(const char *file_name, struct stat *buf) = mingw_lstat;

static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
{
BY_HANDLE_FILE_INFORMATION fdata;
FILE_BASIC_INFO basic;
FILE_STANDARD_INFO standard;

if (!GetFileInformationByHandle(hnd, &fdata)) {
if (!GetFileInformationByHandleEx(hnd, FileBasicInfo, &basic,
sizeof(basic)) ||
!GetFileInformationByHandleEx(hnd, FileStandardInfo, &standard,
sizeof(standard))) {
errno = err_win_to_posix(GetLastError());
return -1;
}
Expand All @@ -1434,13 +1485,16 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
buf->st_gid = 0;
buf->st_uid = 0;
buf->st_nlink = 1;
buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes, 0, NULL);
buf->st_size = fdata.nFileSizeLow |
(((off_t)fdata.nFileSizeHigh)<<32);
buf->st_mode = file_attr_to_st_mode(basic.FileAttributes, 0, NULL);
buf->st_size = standard.EndOfFile.QuadPart;
buf->st_dev = buf->st_rdev = 0; /* not used by Git */
filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
filetime_to_timespec((FILETIME *)&(basic.LastAccessTime),
&(buf->st_atim));
filetime_to_timespec((FILETIME *)&(basic.LastWriteTime),
&(buf->st_mtim));
filetimes_to_ctim(&(basic.ChangeTime), &(basic.CreationTime),
&(basic.LastWriteTime), basic.FileAttributes,
&(buf->st_ctim));
if (are_wsl_compatible_mode_bits_enabled())
get_wsl_mode_bits_by_handle(hnd, &buf->st_mode);
return 0;
Expand Down Expand Up @@ -4382,6 +4436,21 @@ static void adjust_symlink_flags(void)
}
}

/*
* Windows may hide that a file is a cloud file placeholder (OneDrive and
* others) from lstat() but not from the FSCache. Expose placeholders, so
* that filetimes_to_ctim() gets the same attributes from both.
*/
static void expose_placeholders(void)
{
DECLARE_PROC_ADDR(ntdll.dll, CHAR, NTAPI,
RtlSetProcessPlaceholderCompatibilityMode, CHAR);

/* 2: PHCM_EXPOSE_PLACEHOLDERS */
if (INIT_PROC_ADDR(RtlSetProcessPlaceholderCompatibilityMode))
RtlSetProcessPlaceholderCompatibilityMode(2);
}

static BOOL WINAPI handle_ctrl_c(DWORD ctrl_type)
{
if (ctrl_type != CTRL_C_EVENT)
Expand Down Expand Up @@ -4428,6 +4497,7 @@ int wmain(int argc, const wchar_t **wargv)

maybe_redirect_std_handles();
adjust_symlink_flags();
expose_placeholders();
fsync_object_files = 1;

/* determine size of argv and environ conversion buffer */
Expand Down
5 changes: 3 additions & 2 deletions compat/win32/fscache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -241,8 +241,9 @@ static struct fsentry *fseentry_create_entry(struct fscache *cache,
&(fse->u.s.st_atim));
filetime_to_timespec((FILETIME *)&(fdata->LastWriteTime),
&(fse->u.s.st_mtim));
filetime_to_timespec((FILETIME *)&(fdata->CreationTime),
&(fse->u.s.st_ctim));
filetimes_to_ctim(&(fdata->ChangeTime), &(fdata->CreationTime),
&(fdata->LastWriteTime), fdata->FileAttributes,
&(fse->u.s.st_ctim));
if (fdata->EaSize > 0 &&
sizeof(buf) >= (size_t)(list ? list->len+1 : 0) + fse->len+1 &&
are_wsl_compatible_mode_bits_enabled()) {
Expand Down
16 changes: 16 additions & 0 deletions t/t0010-racy-git.sh
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Expand Up @@ -29,4 +29,20 @@ do
'
done

test_expect_success 'notice a rewrite that keeps size and mtime' '
echo frotz >rewritten &&
test-tool chmtime =1700000000 rewritten &&
git update-index --add rewritten &&

# ctime may only be compared to the second
sleep 1 &&
echo xyzzy >rewritten &&
test-tool chmtime =1700000000 rewritten &&
echo "AM rewritten" >expect &&
git -c core.fscache=false status --porcelain rewritten >actual &&
test_cmp expect actual &&
git -c core.fscache=true status --porcelain rewritten >actual &&
test_cmp expect actual
'

test_done
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