mingw: special-case `open(symlink, O_CREAT | O_EXCL)`
The `_wopen()` function would gladly follow a symbolic link to a non-existent file and create it when given above-mentioned flags. Git expects the `open()` call to fail, though. So let's add yet another work-around to pretend that Windows behaves according to POSIX, see: https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html#:~:text=If%20O_CREAT%20and%20O_EXCL%20are,set%2C%20the%20result%20is%20undefined. This is required to let t4115.8(--reject removes .rej symlink if it exists) pass on Windows when enabling the MSYS2 runtime's symbolic link support. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Dec 17, 2025 at 14:18 UTC
6fa50cc4a1979fb8a2f77a026e307d6336a09172
1 file changed
+14
compat/mingw.c
+14
@@ -629,6 +629,7 @@ int mingw_open (const char *filename, int oflags, ...)
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int fd, create = (oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL);
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wchar_t wfilename[MAX_PATH];
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open_fn_t open_fn;
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+ WIN32_FILE_ATTRIBUTE_DATA fdata;
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DECLARE_PROC_ADDR(ntdll.dll, NTSTATUS, NTAPI, RtlGetLastNtStatus, void);
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@@ -653,6 +654,19 @@ int mingw_open (const char *filename, int oflags, ...)
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else if (xutftowcs_path(wfilename, filename) < 0)
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return -1;
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+ /*
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+ * When `symlink` exists and is a symbolic link pointing to a
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+ * non-existing file, `_wopen(symlink, O_CREAT | O_EXCL)` would
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+ * create that file. Not what we want: Linux would say `EEXIST`
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+ * in that instance, which is therefore what Git expects.
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+ */
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+ if (create &&
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+ GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata) &&
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+ (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)) {
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+ errno = EEXIST;
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+ return -1;
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+ }
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+
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fd = open_fn(wfilename, oflags, mode);
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/*