Subject: [PATCH 14/18] mingw: implement basic `symlink()` functionality (file symlinks only)

From: "Karsten Blees via GitGitGadget" <[email-masked]>
Date: Wed, 17 Dec 2025 14:08:51 +0000

From: Karsten Blees <[email-masked]>

Implement `symlink()`. This implementation always creates _file_
symlinks (remember: Windows discerns between symlinks pointing to
directories and those pointing to files). Support for directory symlinks
will be added in a subseqeuent commit.

This implementation fails with `ENOSYS` if symlinks are disabled or
unsupported.

Signed-off-by: Karsten Blees <[email-masked]>
Signed-off-by: Johannes Schindelin <[email-masked]>
---
 compat/mingw-posix.h |  3 +--
 compat/mingw.c       | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/compat/mingw-posix.h b/compat/mingw-posix.h
index 896aa976b1..2d989fd762 100644
--- a/compat/mingw-posix.h
+++ b/compat/mingw-posix.h
@@ -121,8 +121,6 @@ struct utsname {
  * trivial stubs
  */
 
-static inline int symlink(const char *oldpath UNUSED, const char *newpath UNUSED)
-{ errno = ENOSYS; return -1; }
 static inline int fchmod(int fildes UNUSED, mode_t mode UNUSED)
 { errno = ENOSYS; return -1; }
 #ifndef __MINGW64_VERSION_MAJOR
@@ -195,6 +193,7 @@ int setitimer(int type, struct itimerval *in, struct itimerval *out);
 int sigaction(int sig, struct sigaction *in, struct sigaction *out);
 int link(const char *oldpath, const char *newpath);
 int uname(struct utsname *buf);
+int symlink(const char *target, const char *link);
 int readlink(const char *path, char *buf, size_t bufsiz);
 
 /*
diff --git a/compat/mingw.c b/compat/mingw.c
index b407a2ac07..8d366794c4 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2698,6 +2698,34 @@ int link(const char *oldpath, const char *newpath)
 	return 0;
 }
 
+int symlink(const char *target, const char *link)
+{
+	wchar_t wtarget[MAX_PATH], wlink[MAX_PATH];
+	int len;
+
+	/* fail if symlinks are disabled or API is not supported (WinXP) */
+	if (!has_symlinks) {
+		errno = ENOSYS;
+		return -1;
+	}
+
+	if ((len = xutftowcs_path(wtarget, target)) < 0
+			|| xutftowcs_path(wlink, link) < 0)
+		return -1;
+
+	/* convert target dir separators to backslashes */
+	while (len--)
+		if (wtarget[len] == '/')
+			wtarget[len] = '\\';
+
+	/* create file symlink */
+	if (!CreateSymbolicLinkW(wlink, wtarget, 0)) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+	return 0;
+}
+
 int readlink(const char *path, char *buf, size_t bufsiz)
 {
 	WCHAR wpath[MAX_PATH];
-- 
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