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swiggerdscho
authored andcommittedFeb 6, 2025
mingw: optionally enable wsl compability file mode bits
The Windows Subsystem for Linux (WSL) version 2 allows to use `chmod` on NTFS volumes provided that they are mounted with metadata enabled (see https://devblogs.microsoft.com/commandline/chmod-chown-wsl-improvements/ for details), for example: $ chmod 0755 /mnt/d/test/a.sh In order to facilitate better collaboration between the Windows version of Git and the WSL version of Git, we can make the Windows version of Git also support reading and writing NTFS file modes in a manner compatible with WSL. Since this slightly slows down operations where lots of files are created (such as an initial checkout), this feature is only enabled when `core.WSLCompat` is set to true. Note that you also have to set `core.fileMode=true` in repositories that have been initialized without enabling WSL compatibility. There are several ways to enable metadata loading for NTFS volumes in WSL, one of which is to modify `/etc/wsl.conf` by adding: ``` [automount] enabled = true options = "metadata,umask=027,fmask=117" ``` And reboot WSL. It can also be enabled temporarily by this incantation: $ sudo umount /mnt/c && sudo mount -t drvfs C: /mnt/c -o metadata,uid=1000,gid=1000,umask=22,fmask=111 It's important to note that this modification is compatible with, but does not depend on WSL. The helper functions in this commit can operate independently and functions normally on devices where WSL is not installed or properly configured. Signed-off-by: xungeng li <[email protected]> Signed-off-by: Johannes Schindelin <[email protected]>
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‎Documentation/config/core.txt

+6
Original file line numberDiff line numberDiff line change
@@ -771,3 +771,9 @@ core.maxTreeDepth::
771771
to allow Git to abort cleanly, and should not generally need to
772772
be adjusted. When Git is compiled with MSVC, the default is 512.
773773
Otherwise, the default is 2048.
774+
775+
core.WSLCompat::
776+
Tells Git whether to enable wsl compatibility mode.
777+
The default value is false. When set to true, Git will set the mode
778+
bits of the file in the way of wsl, so that the executable flag of
779+
files can be set or read correctly.

‎compat/mingw.c

+13
Original file line numberDiff line numberDiff line change
@@ -27,6 +27,7 @@
2727
#include "win32/fscache.h"
2828
#include "../attr.h"
2929
#include "../string-list.h"
30+
#include "win32/wsl.h"
3031

3132
#define HCAST(type, handle) ((type)(intptr_t)handle)
3233

@@ -891,6 +892,11 @@ int mingw_open (const char *filename, int oflags, ...)
891892

892893
fd = open_fn(wfilename, oflags, mode);
893894

895+
if ((oflags & O_CREAT) && fd >= 0 && are_wsl_compatible_mode_bits_enabled()) {
896+
_mode_t wsl_mode = S_IFREG | (mode&0777);
897+
set_wsl_mode_bits_by_handle((HANDLE)_get_osfhandle(fd), wsl_mode);
898+
}
899+
894900
if (fd < 0 && (oflags & O_ACCMODE) != O_RDONLY && errno == EACCES) {
895901
DWORD attrs = GetFileAttributesW(wfilename);
896902
if (attrs != INVALID_FILE_ATTRIBUTES && (attrs & FILE_ATTRIBUTE_DIRECTORY))
@@ -1190,6 +1196,11 @@ int mingw_lstat(const char *file_name, struct stat *buf)
11901196
filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
11911197
filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
11921198
filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
1199+
if (S_ISREG(buf->st_mode) &&
1200+
are_wsl_compatible_mode_bits_enabled()) {
1201+
copy_wsl_mode_bits_from_disk(wfilename, -1,
1202+
&buf->st_mode);
1203+
}
11931204
return 0;
11941205
}
11951206

@@ -1241,6 +1252,8 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
12411252
filetime_to_timespec(&(fdata.ftLastAccessTime), &(buf->st_atim));
12421253
filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
12431254
filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
1255+
if (are_wsl_compatible_mode_bits_enabled())
1256+
get_wsl_mode_bits_by_handle(hnd, &buf->st_mode);
12441257
return 0;
12451258
}
12461259

‎compat/win32/fscache.c

+16
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@
88
#include "config.h"
99
#include "../../mem-pool.h"
1010
#include "ntifs.h"
11+
#include "wsl.h"
1112

1213
static volatile long initialized;
1314
static DWORD dwTlsIndex;
@@ -215,6 +216,21 @@ static struct fsentry *fseentry_create_entry(struct fscache *cache,
215216
&(fse->u.s.st_mtim));
216217
filetime_to_timespec((FILETIME *)&(fdata->CreationTime),
217218
&(fse->u.s.st_ctim));
219+
if (fdata->EaSize > 0 &&
220+
sizeof(buf) >= (size_t)(list ? list->len+1 : 0) + fse->len+1 &&
221+
are_wsl_compatible_mode_bits_enabled()) {
222+
size_t off = 0;
223+
wchar_t wpath[MAX_LONG_PATH];
224+
if (list && list->len) {
225+
memcpy(buf, list->dirent.d_name, list->len);
226+
buf[list->len] = '/';
227+
off = list->len + 1;
228+
}
229+
memcpy(buf + off, fse->dirent.d_name, fse->len);
230+
buf[off + fse->len] = '\0';
231+
if (xutftowcs_long_path(wpath, buf) >= 0)
232+
copy_wsl_mode_bits_from_disk(wpath, -1, &fse->st_mode);
233+
}
218234

219235
return fse;
220236
}

‎compat/win32/wsl.c

+142
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,142 @@
1+
#define USE_THE_REPOSITORY_VARIABLE
2+
#include "../../git-compat-util.h"
3+
#include "../win32.h"
4+
#include "../../repository.h"
5+
#include "config.h"
6+
#include "ntifs.h"
7+
#include "wsl.h"
8+
9+
int are_wsl_compatible_mode_bits_enabled(void)
10+
{
11+
/* default to `false` during initialization */
12+
static const int fallback = 0;
13+
static int enabled = -1;
14+
15+
if (enabled < 0) {
16+
/* avoid infinite recursion */
17+
if (!the_repository)
18+
return fallback;
19+
20+
if (the_repository->config &&
21+
the_repository->config->hash_initialized &&
22+
git_config_get_bool("core.wslcompat", &enabled) < 0)
23+
enabled = 0;
24+
}
25+
26+
return enabled < 0 ? fallback : enabled;
27+
}
28+
29+
int copy_wsl_mode_bits_from_disk(const wchar_t *wpath, ssize_t wpathlen,
30+
_mode_t *mode)
31+
{
32+
int ret = -1;
33+
HANDLE h;
34+
if (wpathlen >= 0) {
35+
/*
36+
* It's caller's duty to make sure wpathlen is reasonable so
37+
* it does not overflow.
38+
*/
39+
wchar_t *fn2 = (wchar_t*)alloca((wpathlen + 1) * sizeof(wchar_t));
40+
memcpy(fn2, wpath, wpathlen * sizeof(wchar_t));
41+
fn2[wpathlen] = 0;
42+
wpath = fn2;
43+
}
44+
h = CreateFileW(wpath, FILE_READ_EA | SYNCHRONIZE,
45+
FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
46+
NULL, OPEN_EXISTING,
47+
FILE_FLAG_BACKUP_SEMANTICS |
48+
FILE_FLAG_OPEN_REPARSE_POINT,
49+
NULL);
50+
if (h != INVALID_HANDLE_VALUE) {
51+
ret = get_wsl_mode_bits_by_handle(h, mode);
52+
CloseHandle(h);
53+
}
54+
return ret;
55+
}
56+
57+
#ifndef LX_FILE_METADATA_HAS_UID
58+
#define LX_FILE_METADATA_HAS_UID 0x1
59+
#define LX_FILE_METADATA_HAS_GID 0x2
60+
#define LX_FILE_METADATA_HAS_MODE 0x4
61+
#define LX_FILE_METADATA_HAS_DEVICE_ID 0x8
62+
#define LX_FILE_CASE_SENSITIVE_DIR 0x10
63+
typedef struct _FILE_STAT_LX_INFORMATION {
64+
LARGE_INTEGER FileId;
65+
LARGE_INTEGER CreationTime;
66+
LARGE_INTEGER LastAccessTime;
67+
LARGE_INTEGER LastWriteTime;
68+
LARGE_INTEGER ChangeTime;
69+
LARGE_INTEGER AllocationSize;
70+
LARGE_INTEGER EndOfFile;
71+
uint32_t FileAttributes;
72+
uint32_t ReparseTag;
73+
uint32_t NumberOfLinks;
74+
ACCESS_MASK EffectiveAccess;
75+
uint32_t LxFlags;
76+
uint32_t LxUid;
77+
uint32_t LxGid;
78+
uint32_t LxMode;
79+
uint32_t LxDeviceIdMajor;
80+
uint32_t LxDeviceIdMinor;
81+
} FILE_STAT_LX_INFORMATION, *PFILE_STAT_LX_INFORMATION;
82+
#endif
83+
84+
/*
85+
* This struct is extended from the original FILE_FULL_EA_INFORMATION of
86+
* Microsoft Windows.
87+
*/
88+
struct wsl_full_ea_info_t {
89+
uint32_t NextEntryOffset;
90+
uint8_t Flags;
91+
uint8_t EaNameLength;
92+
uint16_t EaValueLength;
93+
char EaName[7];
94+
char EaValue[4];
95+
char Padding[1];
96+
};
97+
98+
enum {
99+
FileStatLxInformation = 70,
100+
};
101+
__declspec(dllimport) NTSTATUS WINAPI
102+
NtQueryInformationFile(HANDLE FileHandle,
103+
PIO_STATUS_BLOCK IoStatusBlock,
104+
PVOID FileInformation, ULONG Length,
105+
uint32_t FileInformationClass);
106+
__declspec(dllimport) NTSTATUS WINAPI
107+
NtSetInformationFile(HANDLE FileHandle, PIO_STATUS_BLOCK IoStatusBlock,
108+
PVOID FileInformation, ULONG Length,
109+
uint32_t FileInformationClass);
110+
__declspec(dllimport) NTSTATUS WINAPI
111+
NtSetEaFile(HANDLE FileHandle, PIO_STATUS_BLOCK IoStatusBlock,
112+
PVOID EaBuffer, ULONG EaBufferSize);
113+
114+
int set_wsl_mode_bits_by_handle(HANDLE h, _mode_t mode)
115+
{
116+
uint32_t value = mode;
117+
struct wsl_full_ea_info_t ea_info;
118+
IO_STATUS_BLOCK iob;
119+
/* mode should be valid to make WSL happy */
120+
assert(S_ISREG(mode) || S_ISDIR(mode));
121+
ea_info.NextEntryOffset = 0;
122+
ea_info.Flags = 0;
123+
ea_info.EaNameLength = 6;
124+
ea_info.EaValueLength = sizeof(value); /* 4 */
125+
strlcpy(ea_info.EaName, "$LXMOD", sizeof(ea_info.EaName));
126+
memcpy(ea_info.EaValue, &value, sizeof(value));
127+
ea_info.Padding[0] = 0;
128+
return NtSetEaFile(h, &iob, &ea_info, sizeof(ea_info));
129+
}
130+
131+
int get_wsl_mode_bits_by_handle(HANDLE h, _mode_t *mode)
132+
{
133+
FILE_STAT_LX_INFORMATION fxi;
134+
IO_STATUS_BLOCK iob;
135+
if (NtQueryInformationFile(h, &iob, &fxi, sizeof(fxi),
136+
FileStatLxInformation) == 0) {
137+
if (fxi.LxFlags & LX_FILE_METADATA_HAS_MODE)
138+
*mode = (_mode_t)fxi.LxMode;
139+
return 0;
140+
}
141+
return -1;
142+
}

‎compat/win32/wsl.h

+12
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
1+
#ifndef COMPAT_WIN32_WSL_H
2+
#define COMPAT_WIN32_WSL_H
3+
4+
int are_wsl_compatible_mode_bits_enabled(void);
5+
6+
int copy_wsl_mode_bits_from_disk(const wchar_t *wpath, ssize_t wpathlen,
7+
_mode_t *mode);
8+
9+
int get_wsl_mode_bits_by_handle(HANDLE h, _mode_t *mode);
10+
int set_wsl_mode_bits_by_handle(HANDLE h, _mode_t mode);
11+
12+
#endif

‎config.mak.uname

+2-2
Original file line numberDiff line numberDiff line change
@@ -501,7 +501,7 @@ endif
501501
compat/win32/path-utils.o \
502502
compat/win32/pthread.o compat/win32/syslog.o \
503503
compat/win32/trace2_win32_process_info.o \
504-
compat/win32/dirent.o compat/win32/fscache.o
504+
compat/win32/dirent.o compat/win32/fscache.o compat/win32/wsl.o
505505
COMPAT_CFLAGS = -D__USE_MINGW_ACCESS -DDETECT_MSYS_TTY -DENSURE_MSYSTEM_IS_SET -DNOGDI -DHAVE_STRING_H -Icompat -Icompat/regex -Icompat/win32 -DSTRIP_EXTENSION=\".exe\"
506506
BASIC_LDFLAGS = -IGNORE:4217 -IGNORE:4049 -NOLOGO
507507
# invalidcontinue.obj allows Git's source code to close the same file
@@ -704,7 +704,7 @@ ifeq ($(uname_S),MINGW)
704704
compat/win32/flush.o \
705705
compat/win32/path-utils.o \
706706
compat/win32/pthread.o compat/win32/syslog.o \
707-
compat/win32/dirent.o compat/win32/fscache.o
707+
compat/win32/dirent.o compat/win32/fscache.o compat/win32/wsl.o
708708
BASIC_CFLAGS += -DWIN32
709709
EXTLIBS += -lws2_32
710710
GITLIBS += git.res

‎contrib/buildsystems/CMakeLists.txt

+1
Original file line numberDiff line numberDiff line change
@@ -293,6 +293,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
293293
compat/win32/syslog.c
294294
compat/win32/trace2_win32_process_info.c
295295
compat/win32/dirent.c
296+
compat/win32/wsl.c
296297
compat/nedmalloc/nedmalloc.c
297298
compat/strdup.c
298299
compat/win32/fscache.c)

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