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mingw: Windows Docker volumes are *not* symbolic links
... even if they may look like them. As looking up the target of the "symbolic link" (just to see whether it starts with `/ContainerMappedDirectories/`) is pretty expensive, we do it when we can be *really* sure that there is a possibility that this might be the case. Signed-off-by: Johannes Schindelin <[email protected]> Signed-off-by: JiSeop Moon <[email protected]>
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3 files changed

+43
-8
lines changed

3 files changed

+43
-8
lines changed

compat/mingw.c

Lines changed: 19 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1123,7 +1123,7 @@ int mingw_lstat(const char *file_name, struct stat *buf)
11231123
buf->st_uid = 0;
11241124
buf->st_nlink = 1;
11251125
buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes,
1126-
reparse_tag);
1126+
reparse_tag, file_name);
11271127
buf->st_size = S_ISLNK(buf->st_mode) ? link_len :
11281128
fdata.nFileSizeLow | (((off_t) fdata.nFileSizeHigh) << 32);
11291129
buf->st_dev = buf->st_rdev = 0; /* not used by Git */
@@ -1174,7 +1174,7 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
11741174
buf->st_gid = 0;
11751175
buf->st_uid = 0;
11761176
buf->st_nlink = 1;
1177-
buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes, 0);
1177+
buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes, 0, NULL);
11781178
buf->st_size = fdata.nFileSizeLow |
11791179
(((off_t)fdata.nFileSizeHigh)<<32);
11801180
buf->st_dev = buf->st_rdev = 0; /* not used by Git */
@@ -4226,12 +4226,25 @@ int is_inside_windows_container(void)
42264226
return inside_container;
42274227
}
42284228

4229-
int file_attr_to_st_mode (DWORD attr, DWORD tag)
4229+
int file_attr_to_st_mode (DWORD attr, DWORD tag, const char *path)
42304230
{
42314231
int fMode = S_IREAD;
4232-
if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) && tag == IO_REPARSE_TAG_SYMLINK)
4233-
fMode |= S_IFLNK;
4234-
else if (attr & FILE_ATTRIBUTE_DIRECTORY)
4232+
if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) &&
4233+
tag == IO_REPARSE_TAG_SYMLINK) {
4234+
int flag = S_IFLNK;
4235+
char buf[MAX_LONG_PATH];
4236+
4237+
/*
4238+
* Windows containers' mapped volumes are marked as reparse
4239+
* points and look like symbolic links, but they are not.
4240+
*/
4241+
if (path && is_inside_windows_container() &&
4242+
readlink(path, buf, sizeof(buf)) > 27 &&
4243+
starts_with(buf, "/ContainerMappedDirectories/"))
4244+
flag = S_IFDIR;
4245+
4246+
fMode |= flag;
4247+
} else if (attr & FILE_ATTRIBUTE_DIRECTORY)
42354248
fMode |= S_IFDIR;
42364249
else
42374250
fMode |= S_IFREG;

compat/win32.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
#include <windows.h>
77
#endif
88

9-
extern int file_attr_to_st_mode (DWORD attr, DWORD tag);
9+
extern int file_attr_to_st_mode (DWORD attr, DWORD tag, const char *path);
1010

1111
static inline int get_file_attr(const char *fname, WIN32_FILE_ATTRIBUTE_DATA *fdata)
1212
{

compat/win32/fscache.c

Lines changed: 23 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -207,8 +207,30 @@ static struct fsentry *fseentry_create_entry(struct fscache *cache,
207207
fdata->FileAttributes & FILE_ATTRIBUTE_REPARSE_POINT ?
208208
fdata->EaSize : 0;
209209

210+
/*
211+
* On certain Windows versions, host directories mapped into
212+
* Windows Containers ("Volumes", see https://docs.docker.com/storage/volumes/)
213+
* look like symbolic links, but their targets are paths that
214+
* are valid only in kernel mode.
215+
*
216+
* Let's work around this by detecting that situation and
217+
* telling Git that these are *not* symbolic links.
218+
*/
219+
if (fse->reparse_tag == IO_REPARSE_TAG_SYMLINK &&
220+
sizeof(buf) > (size_t)(list ? list->len + 1 : 0) + fse->len + 1 &&
221+
is_inside_windows_container()) {
222+
size_t off = 0;
223+
if (list) {
224+
memcpy(buf, list->dirent.d_name, list->len);
225+
buf[list->len] = '/';
226+
off = list->len + 1;
227+
}
228+
memcpy(buf + off, fse->dirent.d_name, fse->len);
229+
buf[off + fse->len] = '\0';
230+
}
231+
210232
fse->st_mode = file_attr_to_st_mode(fdata->FileAttributes,
211-
fdata->EaSize);
233+
fdata->EaSize, buf);
212234
fse->dirent.d_type = S_ISREG(fse->st_mode) ? DT_REG :
213235
S_ISDIR(fse->st_mode) ? DT_DIR : DT_LNK;
214236
fse->u.s.st_size = S_ISLNK(fse->st_mode) ? MAX_LONG_PATH :

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