From ec80c9198782b6b0c0f77c5b7ab3f0b9348aff65 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Mon, 11 May 2015 19:54:23 +0200
Subject: [PATCH 01/19] strbuf_readlink: don't call readlink twice if hint is
 the exact link size

strbuf_readlink() calls readlink() twice if the hint argument specifies the
exact size of the link target (e.g. by passing stat.st_size as returned by
lstat()). This is necessary because 'readlink(..., hint) == hint' could
mean that the buffer was too small.

Use hint + 1 as buffer size to prevent this.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 strbuf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/strbuf.c b/strbuf.c
index f6a6cf78b9..82fcc6fd35 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -480,12 +480,12 @@ int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
 	while (hint < STRBUF_MAXLINK) {
 		ssize_t len;
 
-		strbuf_grow(sb, hint);
-		len = readlink(path, sb->buf, hint);
+		strbuf_grow(sb, hint + 1);
+		len = readlink(path, sb->buf, hint + 1);
 		if (len < 0) {
 			if (errno != ERANGE)
 				break;
-		} else if (len < hint) {
+		} else if (len <= hint) {
 			strbuf_setlen(sb, len);
 			return 0;
 		}

From 15e73c4cd2ab57ec4a6cd06ebfaf2e0282d0f102 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Mon, 11 May 2015 22:15:40 +0200
Subject: [PATCH 02/19] strbuf_readlink: support link targets that exceed
 PATH_MAX

strbuf_readlink() refuses to read link targets that exceed PATH_MAX (even
if a sufficient size was specified by the caller).

As some platforms support longer paths, remove this restriction (similar
to strbuf_getcwd()).

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 strbuf.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/strbuf.c b/strbuf.c
index 82fcc6fd35..9be7fe0ca1 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -468,8 +468,6 @@ ssize_t strbuf_write(struct strbuf *sb, FILE *f)
 }
 
 
-#define STRBUF_MAXLINK (2*PATH_MAX)
-
 int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
 {
 	size_t oldalloc = sb->alloc;
@@ -477,7 +475,7 @@ int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
 	if (hint < 32)
 		hint = 32;
 
-	while (hint < STRBUF_MAXLINK) {
+	for (;;) {
 		ssize_t len;
 
 		strbuf_grow(sb, hint + 1);

From 600a48b7b390a9474e7af0285a6e41dea6d5badd Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Mon, 11 May 2015 19:58:14 +0200
Subject: [PATCH 03/19] lockfile.c: use is_dir_sep() instead of hardcoded '/'
 checks

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 lockfile.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lockfile.c b/lockfile.c
index 8e8ab4f29f..3704a603f6 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -17,14 +17,14 @@ static void trim_last_path_component(struct strbuf *path)
 	int i = path->len;
 
 	/* back up past trailing slashes, if any */
-	while (i && path->buf[i - 1] == '/')
+	while (i && is_dir_sep(path->buf[i - 1]))
 		i--;
 
 	/*
 	 * then go backwards until a slash, or the beginning of the
 	 * string
 	 */
-	while (i && path->buf[i - 1] != '/')
+	while (i && !is_dir_sep(path->buf[i - 1]))
 		i--;
 
 	strbuf_setlen(path, i);

From c1da19f19155225f1f1f39cc2a921a9aaadab20d Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Tue, 12 May 2015 11:09:01 +0200
Subject: [PATCH 04/19] Win32: don't call GetFileAttributes twice in
 mingw_lstat()

GetFileAttributes cannot handle paths with trailing dir separator. The
current [l]stat implementation calls GetFileAttributes twice if the path
has trailing slashes (first with the original path passed to [l]stat, and
and a second time with a path copy with trailing '/' removed).

With Unicode conversion, we get the length of the path for free and also
have a (wide char) buffer that can be modified.

Remove trailing directory separators before calling the Win32 API.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 48 ++++++++++++------------------------------------
 1 file changed, 12 insertions(+), 36 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 2b7514ad8e..e93637fefe 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -702,9 +702,18 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
 {
 	WIN32_FILE_ATTRIBUTE_DATA fdata;
 	wchar_t wfilename[MAX_LONG_PATH];
-	if (xutftowcs_long_path(wfilename, file_name) < 0)
+	int wlen = xutftowcs_long_path(wfilename, file_name);
+	if (wlen < 0)
 		return -1;
 
+	/* strip trailing '/', or GetFileAttributes will fail */
+	while (wlen && is_dir_sep(wfilename[wlen - 1]))
+		wfilename[--wlen] = 0;
+	if (!wlen) {
+		errno = ENOENT;
+		return -1;
+	}
+
 	if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
 		buf->st_ino = 0;
 		buf->st_gid = 0;
@@ -764,39 +773,6 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
 	return -1;
 }
 
-/* We provide our own lstat/fstat functions, since the provided
- * lstat/fstat functions are so slow. These stat functions are
- * tailored for Git's usage (read: fast), and are not meant to be
- * complete. Note that Git stat()s are redirected to mingw_lstat()
- * too, since Windows doesn't really handle symlinks that well.
- */
-static int do_stat_internal(int follow, const char *file_name, struct stat *buf)
-{
-	int namelen;
-	char alt_name[MAX_LONG_PATH];
-
-	if (!do_lstat(follow, file_name, buf))
-		return 0;
-
-	/* if file_name ended in a '/', Windows returned ENOENT;
-	 * try again without trailing slashes
-	 */
-	if (errno != ENOENT)
-		return -1;
-
-	namelen = strlen(file_name);
-	if (namelen && file_name[namelen-1] != '/')
-		return -1;
-	while (namelen && file_name[namelen-1] == '/')
-		--namelen;
-	if (!namelen || namelen >= MAX_LONG_PATH)
-		return -1;
-
-	memcpy(alt_name, file_name, namelen);
-	alt_name[namelen] = 0;
-	return do_lstat(follow, alt_name, buf);
-}
-
 int (*lstat)(const char *file_name, struct stat *buf) = mingw_lstat;
 
 static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
@@ -824,11 +800,11 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
 
 int mingw_lstat(const char *file_name, struct stat *buf)
 {
-	return do_stat_internal(0, file_name, buf);
+	return do_lstat(0, file_name, buf);
 }
 int mingw_stat(const char *file_name, struct stat *buf)
 {
-	return do_stat_internal(1, file_name, buf);
+	return do_lstat(1, file_name, buf);
 }
 
 int mingw_fstat(int fd, struct stat *buf)

From 0ba7366d1cc200046c9753cdf544a395343571c9 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sat, 16 May 2015 01:18:14 +0200
Subject: [PATCH 05/19] Win32: implement stat() with symlink support

With respect to symlinks, the current stat() implementation is almost the
same as lstat(): except for the file type (st_mode & S_IFMT), it returns
information about the link rather than the target.

Implement stat by opening the file with as little permissions as possible
and calling GetFileInformationByHandle on it. This way, all link resoltion
is handled by the Windows file system layer.

If symlinks are disabled, use lstat() as before, but fail with ELOOP if a
symlink would have to be resolved.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index e93637fefe..0f613b7796 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -802,9 +802,26 @@ int mingw_lstat(const char *file_name, struct stat *buf)
 {
 	return do_lstat(0, file_name, buf);
 }
+
 int mingw_stat(const char *file_name, struct stat *buf)
 {
-	return do_lstat(1, file_name, buf);
+	wchar_t wfile_name[MAX_LONG_PATH];
+	HANDLE hnd;
+	int result;
+
+	/* open the file and let Windows resolve the links */
+	if (xutftowcs_long_path(wfile_name, file_name) < 0)
+		return -1;
+	hnd = CreateFileW(wfile_name, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+	if (hnd == INVALID_HANDLE_VALUE) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+	result = get_file_info_by_handle(hnd, buf);
+	CloseHandle(hnd);
+	return result;
 }
 
 int mingw_fstat(int fd, struct stat *buf)

From 95fd810f5d7db036e17e27ecce0e84ef71301613 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Tue, 12 May 2015 00:58:39 +0200
Subject: [PATCH 06/19] Win32: remove separate do_lstat() function

With the new mingw_stat() implementation, do_lstat() is only called from
mingw_lstat() (with follow == 0). Remove the extra function and the old
mingw_stat()-specific (follow == 1) logic.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 0f613b7796..925e85b2cc 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -691,14 +691,7 @@ static int has_valid_directory_prefix(wchar_t *wfilename)
 	return 1;
 }
 
-/* We keep the do_lstat code in a separate function to avoid recursion.
- * When a path ends with a slash, the stat will fail with ENOENT. In
- * this case, we strip the trailing slashes and stat again.
- *
- * If follow is true then act like stat() and report on the link
- * target. Otherwise report on the link itself.
- */
-static int do_lstat(int follow, const char *file_name, struct stat *buf)
+int mingw_lstat(const char *file_name, struct stat *buf)
 {
 	WIN32_FILE_ATTRIBUTE_DATA fdata;
 	wchar_t wfilename[MAX_LONG_PATH];
@@ -732,13 +725,7 @@ static int do_lstat(int follow, const char *file_name, struct stat *buf)
 			if (handle != INVALID_HANDLE_VALUE) {
 				if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
 						(findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
-					if (follow) {
-						char buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
-						buf->st_size = readlink(file_name, buffer, MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
-					} else {
-						buf->st_mode = S_IFLNK;
-					}
-					buf->st_mode |= S_IREAD;
+					buf->st_mode = S_IFLNK | S_IREAD;
 					if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
 						buf->st_mode |= S_IWRITE;
 				}
@@ -798,11 +785,6 @@ static int get_file_info_by_handle(HANDLE hnd, struct stat *buf)
 	return 0;
 }
 
-int mingw_lstat(const char *file_name, struct stat *buf)
-{
-	return do_lstat(0, file_name, buf);
-}
-
 int mingw_stat(const char *file_name, struct stat *buf)
 {
 	wchar_t wfile_name[MAX_LONG_PATH];

From 513a68b217d110489485718504f9db40535a9d50 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 00:17:56 +0200
Subject: [PATCH 07/19] Win32: let mingw_lstat() error early upon problems with
 reparse points

When obtaining lstat information for reparse points, we need to call
FindFirstFile() in addition to GetFileInformationEx() to obtain the type
of the reparse point (symlink, mount point etc.). However, currently there
is no error handling whatsoever if FindFirstFile() fails.

Call FindFirstFile() before modifying the stat *buf output parameter and
error out if the call fails.

Note: The FindFirstFile() return value includes all the data that we get
from GetFileAttributesEx(), so we could replace GetFileAttributesEx() with
FindFirstFile(). We don't do that because GetFileAttributesEx() is about
twice as fast for single files. I.e. we only pay the extra cost of calling
FindFirstFile() in the rare case that we encounter a reparse point.

Note: The indentation of the remaining reparse point code will be fixed in
the next patch.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 925e85b2cc..90d3ac1f17 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -694,6 +694,7 @@ static int has_valid_directory_prefix(wchar_t *wfilename)
 int mingw_lstat(const char *file_name, struct stat *buf)
 {
 	WIN32_FILE_ATTRIBUTE_DATA fdata;
+	WIN32_FIND_DATAW findbuf = { 0 };
 	wchar_t wfilename[MAX_LONG_PATH];
 	int wlen = xutftowcs_long_path(wfilename, file_name);
 	if (wlen < 0)
@@ -708,6 +709,13 @@ int mingw_lstat(const char *file_name, struct stat *buf)
 	}
 
 	if (GetFileAttributesExW(wfilename, GetFileExInfoStandard, &fdata)) {
+		/* for reparse points, use FindFirstFile to get the reparse tag */
+		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
+			HANDLE handle = FindFirstFileW(wfilename, &findbuf);
+			if (handle == INVALID_HANDLE_VALUE)
+				goto error;
+			FindClose(handle);
+		}
 		buf->st_ino = 0;
 		buf->st_gid = 0;
 		buf->st_uid = 0;
@@ -720,20 +728,16 @@ int mingw_lstat(const char *file_name, struct stat *buf)
 		filetime_to_timespec(&(fdata.ftLastWriteTime), &(buf->st_mtim));
 		filetime_to_timespec(&(fdata.ftCreationTime), &(buf->st_ctim));
 		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
-			WIN32_FIND_DATAW findbuf;
-			HANDLE handle = FindFirstFileW(wfilename, &findbuf);
-			if (handle != INVALID_HANDLE_VALUE) {
 				if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
 						(findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
 					buf->st_mode = S_IFLNK | S_IREAD;
 					if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
 						buf->st_mode |= S_IWRITE;
 				}
-				FindClose(handle);
-			}
 		}
 		return 0;
 	}
+error:
 	switch (GetLastError()) {
 	case ERROR_ACCESS_DENIED:
 	case ERROR_SHARING_VIOLATION:

From 3cc396b84f49cf407468b15d7ea0508490b7d968 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Tue, 10 Jan 2017 23:21:56 +0100
Subject: [PATCH 08/19] Win32: teach fscache and dirent about symlinks

Move S_IFLNK detection to file_attr_to_st_mode() and reuse it in fscache.

Implement DT_LNK detection in dirent.c and the fscache readdir version.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c         | 13 +++----------
 compat/win32.h         |  6 ++++--
 compat/win32/dirent.c  |  5 ++++-
 compat/win32/fscache.c |  6 ++++--
 4 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 90d3ac1f17..ee56c4e35b 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -720,21 +720,14 @@ 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.dwFileAttributes,
+				findbuf.dwReserved0);
 		buf->st_size = fdata.nFileSizeLow |
 			(((off_t)fdata.nFileSizeHigh)<<32);
 		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));
-		if (fdata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) {
-				if ((findbuf.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) &&
-						(findbuf.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
-					buf->st_mode = S_IFLNK | S_IREAD;
-					if (!(findbuf.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
-						buf->st_mode |= S_IWRITE;
-				}
-		}
 		return 0;
 	}
 error:
@@ -779,7 +772,7 @@ 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);
+	buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes, 0);
 	buf->st_size = fdata.nFileSizeLow |
 		(((off_t)fdata.nFileSizeHigh)<<32);
 	buf->st_dev = buf->st_rdev = 0; /* not used by Git */
diff --git a/compat/win32.h b/compat/win32.h
index a97e880757..671bcc81f9 100644
--- a/compat/win32.h
+++ b/compat/win32.h
@@ -6,10 +6,12 @@
 #include <windows.h>
 #endif
 
-static inline int file_attr_to_st_mode (DWORD attr)
+static inline int file_attr_to_st_mode (DWORD attr, DWORD tag)
 {
 	int fMode = S_IREAD;
-	if (attr & FILE_ATTRIBUTE_DIRECTORY)
+	if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) && tag == IO_REPARSE_TAG_SYMLINK)
+		fMode |= S_IFLNK;
+	else if (attr & FILE_ATTRIBUTE_DIRECTORY)
 		fMode |= S_IFDIR;
 	else
 		fMode |= S_IFREG;
diff --git a/compat/win32/dirent.c b/compat/win32/dirent.c
index b3bd8d7af7..8c654d722b 100644
--- a/compat/win32/dirent.c
+++ b/compat/win32/dirent.c
@@ -16,7 +16,10 @@ static inline void finddata2dirent(struct dirent *ent, WIN32_FIND_DATAW *fdata)
 	xwcstoutf(ent->d_name, fdata->cFileName, MAX_PATH * 3);
 
 	/* Set file type, based on WIN32_FIND_DATA */
-	if (fdata->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+	if ((fdata->dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)
+			&& fdata->dwReserved0 == IO_REPARSE_TAG_SYMLINK)
+		ent->d_type = DT_LNK;
+	else if (fdata->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
 		ent->d_type = DT_DIR;
 	else
 		ent->d_type = DT_REG;
diff --git a/compat/win32/fscache.c b/compat/win32/fscache.c
index 4ebd15e426..60aeeb1293 100644
--- a/compat/win32/fscache.c
+++ b/compat/win32/fscache.c
@@ -149,7 +149,8 @@ static struct fsentry *fseentry_create_entry(struct fsentry *list,
 
 	fse = fsentry_alloc(list, buf, len);
 
-	fse->st_mode = file_attr_to_st_mode(fdata->dwFileAttributes);
+	fse->st_mode = file_attr_to_st_mode(fdata->dwFileAttributes,
+			fdata->dwReserved0);
 	fse->st_size = (((off64_t) (fdata->nFileSizeHigh)) << 32)
 			| fdata->nFileSizeLow;
 	filetime_to_timespec(&(fdata->ftLastAccessTime), &(fse->st_atim));
@@ -442,7 +443,8 @@ static struct dirent *fscache_readdir(DIR *base_dir)
 	if (!next)
 		return NULL;
 	dir->pfsentry = next;
-	dir->dirent.d_type = S_ISDIR(next->st_mode) ? DT_DIR : DT_REG;
+	dir->dirent.d_type = S_ISREG(next->st_mode) ? DT_REG :
+			S_ISDIR(next->st_mode) ? DT_DIR : DT_LNK;
 	dir->dirent.d_name = (char*) next->name;
 	return &(dir->dirent);
 }

From 989e6679848424eb33ac09f25c7a3dffe0822cab Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sat, 16 May 2015 01:11:37 +0200
Subject: [PATCH 09/19] Win32: lstat(): return adequate stat.st_size for
 symlinks

Git typically doesn't trust the stat.st_size member of symlinks (e.g. see
strbuf_readlink()). However, some functions take shortcuts if st_size is 0
(e.g. diff_populate_filespec()).

In mingw_lstat() and fscache_lstat(), make sure to return an adequate size.

The extra overhead of opening and reading the reparse point to calculate
the exact size is not necessary, as git doesn't rely on the value anyway.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c         | 4 ++--
 compat/win32/fscache.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index ee56c4e35b..5a5c570f0e 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -722,8 +722,8 @@ int mingw_lstat(const char *file_name, struct stat *buf)
 		buf->st_nlink = 1;
 		buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes,
 				findbuf.dwReserved0);
-		buf->st_size = fdata.nFileSizeLow |
-			(((off_t)fdata.nFileSizeHigh)<<32);
+		buf->st_size = S_ISLNK(buf->st_mode) ? MAX_LONG_PATH :
+			fdata.nFileSizeLow | (((off_t) fdata.nFileSizeHigh) << 32);
 		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));
diff --git a/compat/win32/fscache.c b/compat/win32/fscache.c
index 60aeeb1293..345d7b226b 100644
--- a/compat/win32/fscache.c
+++ b/compat/win32/fscache.c
@@ -151,8 +151,8 @@ static struct fsentry *fseentry_create_entry(struct fsentry *list,
 
 	fse->st_mode = file_attr_to_st_mode(fdata->dwFileAttributes,
 			fdata->dwReserved0);
-	fse->st_size = (((off64_t) (fdata->nFileSizeHigh)) << 32)
-			| fdata->nFileSizeLow;
+	fse->st_size = S_ISLNK(fse->st_mode) ? MAX_LONG_PATH :
+			fdata->nFileSizeLow | (((off_t) fdata->nFileSizeHigh) << 32);
 	filetime_to_timespec(&(fdata->ftLastAccessTime), &(fse->st_atim));
 	filetime_to_timespec(&(fdata->ftLastWriteTime), &(fse->st_mtim));
 	filetime_to_timespec(&(fdata->ftCreationTime), &(fse->st_ctim));

From bb86f35716028f62c77c33c045f5ac20b297a057 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Tue, 19 May 2015 21:48:55 +0200
Subject: [PATCH 10/19] Win32: factor out retry logic

The retry pattern is duplicated in three places. It also seems to be too
hard to use: mingw_unlink() and mingw_rmdir() duplicate the code to retry,
and both of them do so incompletely. They also do not restore errno if the
user answers 'no'.

Introduce a retry_ask_yes_no() helper function that handles retry with
small delay, asking the user, and restoring errno.

mingw_unlink: include _wchmod in the retry loop (which may fail if the
file is locked exclusively).

mingw_rmdir: include special error handling in the retry loop.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 98 ++++++++++++++++++++++----------------------------
 1 file changed, 43 insertions(+), 55 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 5a5c570f0e..0aceb5f72d 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -10,8 +10,6 @@
 
 #define HCAST(type, handle) ((type)(intptr_t)handle)
 
-static const int delay[] = { 0, 1, 10, 20, 40 };
-
 int err_win_to_posix(DWORD winerr)
 {
 	int error = ENOSYS;
@@ -174,15 +172,12 @@ static int read_yes_no_answer(void)
 	return -1;
 }
 
-static int ask_yes_no_if_possible(const char *format, ...)
+static int ask_yes_no_if_possible(const char *format, va_list args)
 {
 	char question[4096];
 	const char *retry_hook[] = { NULL, NULL, NULL };
-	va_list args;
 
-	va_start(args, format);
 	vsnprintf(question, sizeof(question), format, args);
-	va_end(args);
 
 	if ((retry_hook[0] = mingw_getenv("GIT_ASK_YESNO"))) {
 		retry_hook[1] = question;
@@ -204,6 +199,31 @@ static int ask_yes_no_if_possible(const char *format, ...)
 	}
 }
 
+static int retry_ask_yes_no(int *tries, const char *format, ...)
+{
+	static const int delay[] = { 0, 1, 10, 20, 40 };
+	va_list args;
+	int result, saved_errno = errno;
+
+	if ((*tries) < ARRAY_SIZE(delay)) {
+		/*
+		 * We assume that some other process had the file open at the wrong
+		 * moment and retry. In order to give the other process a higher
+		 * chance to complete its operation, we give up our time slice now.
+		 * If we have to retry again, we do sleep a bit.
+		 */
+		Sleep(delay[*tries]);
+		(*tries)++;
+		return 1;
+	}
+
+	va_start(args, format);
+	result = ask_yes_no_if_possible(format, args);
+	va_end(args);
+	errno = saved_errno;
+	return result;
+}
+
 /* Windows only */
 enum hide_dotfiles_type {
 	HIDE_DOTFILES_FALSE = 0,
@@ -272,31 +292,21 @@ static wchar_t *normalize_ntpath(wchar_t *wbuf)
 
 int mingw_unlink(const char *pathname)
 {
-	int ret, tries = 0;
+	int tries = 0;
 	wchar_t wpathname[MAX_LONG_PATH];
 	if (xutftowcs_long_path(wpathname, pathname) < 0)
 		return -1;
 
-	/* read-only files cannot be removed */
-	_wchmod(wpathname, 0666);
-	while ((ret = _wunlink(wpathname)) == -1 && tries < ARRAY_SIZE(delay)) {
+	do {
+		/* read-only files cannot be removed */
+		_wchmod(wpathname, 0666);
+		if (!_wunlink(wpathname))
+			return 0;
 		if (!is_file_in_use_error(GetLastError()))
 			break;
-		/*
-		 * We assume that some other process had the source or
-		 * destination file open at the wrong moment and retry.
-		 * In order to give the other process a higher chance to
-		 * complete its operation, we give up our time slice now.
-		 * If we have to retry again, we do sleep a bit.
-		 */
-		Sleep(delay[tries]);
-		tries++;
-	}
-	while (ret == -1 && is_file_in_use_error(GetLastError()) &&
-	       ask_yes_no_if_possible("Unlink of file '%s' failed. "
-			"Should I try again?", pathname))
-	       ret = _wunlink(wpathname);
-	return ret;
+	} while (retry_ask_yes_no(&tries, "Unlink of file '%s' failed. "
+			"Should I try again?", pathname));
+	return -1;
 }
 
 static int is_dir_empty(const wchar_t *wpath)
@@ -323,12 +333,14 @@ static int is_dir_empty(const wchar_t *wpath)
 
 int mingw_rmdir(const char *pathname)
 {
-	int ret, tries = 0;
+	int tries = 0;
 	wchar_t wpathname[MAX_LONG_PATH];
 	if (xutftowcs_long_path(wpathname, pathname) < 0)
 		return -1;
 
-	while ((ret = _wrmdir(wpathname)) == -1 && tries < ARRAY_SIZE(delay)) {
+	do {
+		if (!_wrmdir(wpathname))
+			return 0;
 		if (!is_file_in_use_error(GetLastError()))
 			errno = err_win_to_posix(GetLastError());
 		if (errno != EACCES)
@@ -337,21 +349,9 @@ int mingw_rmdir(const char *pathname)
 			errno = ENOTEMPTY;
 			break;
 		}
-		/*
-		 * We assume that some other process had the source or
-		 * destination file open at the wrong moment and retry.
-		 * In order to give the other process a higher chance to
-		 * complete its operation, we give up our time slice now.
-		 * If we have to retry again, we do sleep a bit.
-		 */
-		Sleep(delay[tries]);
-		tries++;
-	}
-	while (ret == -1 && errno == EACCES && is_file_in_use_error(GetLastError()) &&
-	       ask_yes_no_if_possible("Deletion of directory '%s' failed. "
-			"Should I try again?", pathname))
-	       ret = _wrmdir(wpathname);
-	return ret;
+	} while (retry_ask_yes_no(&tries, "Deletion of directory '%s' failed. "
+			"Should I try again?", pathname));
+	return -1;
 }
 
 static inline int needs_hiding(const char *path)
@@ -2049,20 +2049,8 @@ repeat:
 			SetFileAttributesW(wpnew, attrs);
 		}
 	}
-	if (tries < ARRAY_SIZE(delay) && gle == ERROR_ACCESS_DENIED) {
-		/*
-		 * We assume that some other process had the source or
-		 * destination file open at the wrong moment and retry.
-		 * In order to give the other process a higher chance to
-		 * complete its operation, we give up our time slice now.
-		 * If we have to retry again, we do sleep a bit.
-		 */
-		Sleep(delay[tries]);
-		tries++;
-		goto repeat;
-	}
 	if (gle == ERROR_ACCESS_DENIED &&
-	       ask_yes_no_if_possible("Rename from '%s' to '%s' failed. "
+	       retry_ask_yes_no(&tries, "Rename from '%s' to '%s' failed. "
 		       "Should I try again?", pold, pnew))
 		goto repeat;
 

From 238ec9e1cb6624e9b04b85f10cd12422640865c5 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:55:05 +0200
Subject: [PATCH 11/19] Win32: change default of 'core.symlinks' to false

Symlinks on Windows don't work the same way as on Unix systems. E.g. there
are different types of symlinks for directories and files, creating
symlinks requires administrative privileges etc.

By default, disable symlink support on Windows. I.e. users explicitly have
to enable it with 'git config [--system|--global] core.symlinks true'.

The test suite ignores system / global config files. Allow testing *with*
symlink support by checking if native symlinks are enabled in MSys2 (via
'MSYS=winsymlinks:nativestrict').

Reminder: This would need to be changed if / when we find a way to run the
test suite in a non-MSys-based shell (e.g. dash).

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/compat/mingw.c b/compat/mingw.c
index 0aceb5f72d..b2a873cd07 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2538,6 +2538,15 @@ static void setup_windows_environment(void)
 			setenv("HOME", tmp, 1);
 	}
 
+	/*
+	 * Change 'core.symlinks' default to false, unless native symlinks are
+	 * enabled in MSys2 (via 'MSYS=winsymlinks:nativestrict'). Thus we can
+	 * run the test suite (which doesn't obey config files) with or without
+	 * symlink support.
+	 */
+	if (!(tmp = getenv("MSYS")) || !strstr(tmp, "winsymlinks:nativestrict"))
+		has_symlinks = 0;
+
 	if (!getenv("LC_ALL") && !getenv("LC_CTYPE") && !getenv("LANG"))
 		setenv("LC_CTYPE", "C", 1);
 }

From a41564013a9fe4efb886e78754c450fb236aabe2 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sat, 16 May 2015 00:32:03 +0200
Subject: [PATCH 12/19] Win32: add symlink-specific error codes

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compat/mingw.c b/compat/mingw.c
index b2a873cd07..d0e3e6d0ff 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -72,6 +72,7 @@ int err_win_to_posix(DWORD winerr)
 	case ERROR_INVALID_PARAMETER: error = EINVAL; break;
 	case ERROR_INVALID_PASSWORD: error = EPERM; break;
 	case ERROR_INVALID_PRIMARY_GROUP: error = EINVAL; break;
+	case ERROR_INVALID_REPARSE_DATA: error = EINVAL; break;
 	case ERROR_INVALID_SIGNAL_NUMBER: error = EINVAL; break;
 	case ERROR_INVALID_TARGET_HANDLE: error = EIO; break;
 	case ERROR_INVALID_WORKSTATION: error = EACCES; break;
@@ -86,6 +87,7 @@ int err_win_to_posix(DWORD winerr)
 	case ERROR_NEGATIVE_SEEK: error = ESPIPE; break;
 	case ERROR_NOACCESS: error = EFAULT; break;
 	case ERROR_NONE_MAPPED: error = EINVAL; break;
+	case ERROR_NOT_A_REPARSE_POINT: error = EINVAL; break;
 	case ERROR_NOT_ENOUGH_MEMORY: error = ENOMEM; break;
 	case ERROR_NOT_READY: error = EAGAIN; break;
 	case ERROR_NOT_SAME_DEVICE: error = EXDEV; break;
@@ -106,6 +108,9 @@ int err_win_to_posix(DWORD winerr)
 	case ERROR_PIPE_NOT_CONNECTED: error = EPIPE; break;
 	case ERROR_PRIVILEGE_NOT_HELD: error = EACCES; break;
 	case ERROR_READ_FAULT: error = EIO; break;
+	case ERROR_REPARSE_ATTRIBUTE_CONFLICT: error = EINVAL; break;
+	case ERROR_REPARSE_TAG_INVALID: error = EINVAL; break;
+	case ERROR_REPARSE_TAG_MISMATCH: error = EINVAL; break;
 	case ERROR_SEEK: error = EIO; break;
 	case ERROR_SEEK_ON_DEVICE: error = ESPIPE; break;
 	case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;

From 70ab53ef125182d3eec27e43a8eaec75f3bb500a Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:06:10 +0200
Subject: [PATCH 13/19] Win32: mingw_unlink: support symlinks to directories

_wunlink() / DeleteFileW() refuses to delete symlinks to directories. If
_wunlink() fails with ERROR_ACCESS_DENIED, try _wrmdir() as well.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/compat/mingw.c b/compat/mingw.c
index d0e3e6d0ff..e407d87719 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -309,6 +309,13 @@ int mingw_unlink(const char *pathname)
 			return 0;
 		if (!is_file_in_use_error(GetLastError()))
 			break;
+		/*
+		 * _wunlink() / DeleteFileW() for directory symlinks fails with
+		 * ERROR_ACCESS_DENIED (EACCES), so try _wrmdir() as well. This is the
+		 * same error we get if a file is in use (already checked above).
+		 */
+		if (!_wrmdir(wpathname))
+			return 0;
 	} while (retry_ask_yes_no(&tries, "Unlink of file '%s' failed. "
 			"Should I try again?", pathname));
 	return -1;

From 0e44e17bb611d5c0af2f54ed62b34088dc49eee4 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Tue, 19 May 2015 22:42:48 +0200
Subject: [PATCH 14/19] Win32: mingw_rename: support renaming symlinks

MSVCRT's _wrename() cannot rename symlinks over existing files: it returns
success without doing anything. Newer MSVCR*.dll versions probably do not
have this problem: according to CRT sources, they just call MoveFileEx()
with the MOVEFILE_COPY_ALLOWED flag.

Get rid of _wrename() and call MoveFileEx() with proper error handling.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 38 +++++++++++++++++---------------------
 1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index e407d87719..c3f25c20a6 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2021,27 +2021,29 @@ int mingw_accept(int sockfd1, struct sockaddr *sa, socklen_t *sz)
 #undef rename
 int mingw_rename(const char *pold, const char *pnew)
 {
-	DWORD attrs, gle;
+	DWORD attrs = INVALID_FILE_ATTRIBUTES, gle;
 	int tries = 0;
 	wchar_t wpold[MAX_LONG_PATH], wpnew[MAX_LONG_PATH];
 	if (xutftowcs_long_path(wpold, pold) < 0 ||
 	    xutftowcs_long_path(wpnew, pnew) < 0)
 		return -1;
 
-	/*
-	 * Try native rename() first to get errno right.
-	 * It is based on MoveFile(), which cannot overwrite existing files.
-	 */
-	if (!_wrename(wpold, wpnew))
-		return 0;
-	if (errno != EEXIST)
-		return -1;
 repeat:
-	if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
+	if (MoveFileExW(wpold, wpnew,
+			MOVEFILE_REPLACE_EXISTING | MOVEFILE_COPY_ALLOWED))
 		return 0;
-	/* TODO: translate more errors */
 	gle = GetLastError();
-	if (gle == ERROR_ACCESS_DENIED &&
+
+	/* revert file attributes on failure */
+	if (attrs != INVALID_FILE_ATTRIBUTES)
+		SetFileAttributesW(wpnew, attrs);
+
+	if (!is_file_in_use_error(gle)) {
+		errno = err_win_to_posix(gle);
+		return -1;
+	}
+
+	if (attrs == INVALID_FILE_ATTRIBUTES &&
 	    (attrs = GetFileAttributesW(wpnew)) != INVALID_FILE_ATTRIBUTES) {
 		if (attrs & FILE_ATTRIBUTE_DIRECTORY) {
 			DWORD attrsold = GetFileAttributesW(wpold);
@@ -2053,16 +2055,10 @@ repeat:
 			return -1;
 		}
 		if ((attrs & FILE_ATTRIBUTE_READONLY) &&
-		    SetFileAttributesW(wpnew, attrs & ~FILE_ATTRIBUTE_READONLY)) {
-			if (MoveFileExW(wpold, wpnew, MOVEFILE_REPLACE_EXISTING))
-				return 0;
-			gle = GetLastError();
-			/* revert file attributes on failure */
-			SetFileAttributesW(wpnew, attrs);
-		}
+		    SetFileAttributesW(wpnew, attrs & ~FILE_ATTRIBUTE_READONLY))
+			goto repeat;
 	}
-	if (gle == ERROR_ACCESS_DENIED &&
-	       retry_ask_yes_no(&tries, "Rename from '%s' to '%s' failed. "
+	if (retry_ask_yes_no(&tries, "Rename from '%s' to '%s' failed. "
 		       "Should I try again?", pold, pnew))
 		goto repeat;
 

From 99d96279cb796281a9e878ac7823dadec5120141 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:17:31 +0200
Subject: [PATCH 15/19] Win32: mingw_chdir: change to symlink-resolved
 directory

If symlinks are enabled, resolve all symlinks when changing directories,
as required by POSIX.

Note: Git's real_path() function bases its link resolution algorithm on
this property of chdir(). Unfortunately, the current directory on Windows
is limited to only MAX_PATH (260) characters. Therefore using symlinks and
long paths in combination may be problematic.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index c3f25c20a6..b18be669a1 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -657,7 +657,24 @@ int mingw_chdir(const char *dirname)
 	wchar_t wdirname[MAX_LONG_PATH];
 	if (xutftowcs_long_path(wdirname, dirname) < 0)
 		return -1;
-	result = _wchdir(wdirname);
+
+	if (has_symlinks) {
+		HANDLE hnd = CreateFileW(wdirname, 0,
+				FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+				OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+		if (hnd == INVALID_HANDLE_VALUE) {
+			errno = err_win_to_posix(GetLastError());
+			return -1;
+		}
+		if (!GetFinalPathNameByHandleW(hnd, wdirname, ARRAY_SIZE(wdirname), 0)) {
+			errno = err_win_to_posix(GetLastError());
+			CloseHandle(hnd);
+			return -1;
+		}
+		CloseHandle(hnd);
+	}
+
+	result = _wchdir(normalize_ntpath(wdirname));
 	current_directory_len = GetCurrentDirectoryW(0, NULL);
 	return result;
 }

From d6fd6d2466b58675de0fdd4b96745eb3d703d5da Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:24:41 +0200
Subject: [PATCH 16/19] Win32: implement readlink()

Implement readlink() by reading NTFS reparse points. Works for symlinks
and directory junctions. If symlinks are disabled, fail with ENOSYS.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++
 compat/mingw.h |  3 +-
 2 files changed, 99 insertions(+), 2 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index b18be669a1..687cee3d0e 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2,6 +2,7 @@
 #include "win32.h"
 #include <conio.h>
 #include <wchar.h>
+#include <winioctl.h>
 #include "../strbuf.h"
 #include "../run-command.h"
 #include "../cache.h"
@@ -2347,6 +2348,103 @@ int link(const char *oldpath, const char *newpath)
 	return 0;
 }
 
+#ifndef _WINNT_H
+/*
+ * The REPARSE_DATA_BUFFER structure is defined in the Windows DDK (in
+ * ntifs.h) and in MSYS1's winnt.h (which defines _WINNT_H). So define
+ * it ourselves if we are on MSYS2 (whose winnt.h defines _WINNT_).
+ */
+typedef struct _REPARSE_DATA_BUFFER {
+	DWORD  ReparseTag;
+	WORD   ReparseDataLength;
+	WORD   Reserved;
+#ifndef _MSC_VER
+	_ANONYMOUS_UNION
+#endif
+	union {
+		struct {
+			WORD   SubstituteNameOffset;
+			WORD   SubstituteNameLength;
+			WORD   PrintNameOffset;
+			WORD   PrintNameLength;
+			ULONG  Flags;
+			WCHAR PathBuffer[1];
+		} SymbolicLinkReparseBuffer;
+		struct {
+			WORD   SubstituteNameOffset;
+			WORD   SubstituteNameLength;
+			WORD   PrintNameOffset;
+			WORD   PrintNameLength;
+			WCHAR PathBuffer[1];
+		} MountPointReparseBuffer;
+		struct {
+			BYTE   DataBuffer[1];
+		} GenericReparseBuffer;
+	} DUMMYUNIONNAME;
+} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
+#endif
+
+int readlink(const char *path, char *buf, size_t bufsiz)
+{
+	HANDLE handle;
+	WCHAR wpath[MAX_LONG_PATH], *wbuf;
+	REPARSE_DATA_BUFFER *b = alloca(MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
+	DWORD dummy;
+	char tmpbuf[MAX_LONG_PATH];
+	int len;
+
+	if (xutftowcs_long_path(wpath, path) < 0)
+		return -1;
+
+	/* read reparse point data */
+	handle = CreateFileW(wpath, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING,
+			FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, NULL);
+	if (handle == INVALID_HANDLE_VALUE) {
+		errno = err_win_to_posix(GetLastError());
+		return -1;
+	}
+	if (!DeviceIoControl(handle, FSCTL_GET_REPARSE_POINT, NULL, 0, b,
+			MAXIMUM_REPARSE_DATA_BUFFER_SIZE, &dummy, NULL)) {
+		errno = err_win_to_posix(GetLastError());
+		CloseHandle(handle);
+		return -1;
+	}
+	CloseHandle(handle);
+
+	/* get target path for symlinks or mount points (aka 'junctions') */
+	switch (b->ReparseTag) {
+	case IO_REPARSE_TAG_SYMLINK:
+		wbuf = (WCHAR*) (((char*) b->SymbolicLinkReparseBuffer.PathBuffer)
+				+ b->SymbolicLinkReparseBuffer.SubstituteNameOffset);
+		*(WCHAR*) (((char*) wbuf)
+				+ b->SymbolicLinkReparseBuffer.SubstituteNameLength) = 0;
+		break;
+	case IO_REPARSE_TAG_MOUNT_POINT:
+		wbuf = (WCHAR*) (((char*) b->MountPointReparseBuffer.PathBuffer)
+				+ b->MountPointReparseBuffer.SubstituteNameOffset);
+		*(WCHAR*) (((char*) wbuf)
+				+ b->MountPointReparseBuffer.SubstituteNameLength) = 0;
+		break;
+	default:
+		errno = EINVAL;
+		return -1;
+	}
+
+	/*
+	 * Adapt to strange readlink() API: Copy up to bufsiz *bytes*, potentially
+	 * cutting off a UTF-8 sequence. Insufficient bufsize is *not* a failure
+	 * condition. There is no conversion function that produces invalid UTF-8,
+	 * so convert to a (hopefully large enough) temporary buffer, then memcpy
+	 * the requested number of bytes (including '\0' for robustness).
+	 */
+	if ((len = xwcstoutf(tmpbuf, normalize_ntpath(wbuf), MAX_LONG_PATH)) < 0)
+		return -1;
+	memcpy(buf, tmpbuf, min(bufsiz, len + 1));
+	return min(bufsiz, len);
+}
+
 pid_t waitpid(pid_t pid, int *status, int options)
 {
 	HANDLE h = OpenProcess(SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
diff --git a/compat/mingw.h b/compat/mingw.h
index 4aa84ab783..7c7ce83565 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -123,8 +123,6 @@ struct utsname {
  * trivial stubs
  */
 
-static inline int readlink(const char *path, char *buf, size_t bufsiz)
-{ errno = ENOSYS; return -1; }
 static inline int symlink(const char *oldpath, const char *newpath)
 { errno = ENOSYS; return -1; }
 static inline int fchmod(int fildes, mode_t mode)
@@ -218,6 +216,7 @@ 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 readlink(const char *path, char *buf, size_t bufsiz);
 
 /*
  * replacements of existing functions

From 01ddb91674d42784ff8d8b9ec43dc689365309f6 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:32:03 +0200
Subject: [PATCH 17/19] Win32: implement basic symlink() functionality (file
 symlinks only)

Implement symlink() that always creates file symlinks. Fails with ENOSYS
if symlinks are disabled or unsupported.

Note: CreateSymbolicLinkW() was introduced with symlink support in Windows
Vista. For compatibility with Windows XP, we need to load it dynamically
and fail gracefully if it isnt's available.

Signed-off-by: Karsten Blees <blees@dcon.de>
---
 compat/mingw.c | 28 ++++++++++++++++++++++++++++
 compat/mingw.h |  3 +--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 687cee3d0e..f3e53239fb 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2348,6 +2348,34 @@ int link(const char *oldpath, const char *newpath)
 	return 0;
 }
 
+int symlink(const char *target, const char *link)
+{
+	wchar_t wtarget[MAX_LONG_PATH], wlink[MAX_LONG_PATH];
+	int len;
+
+	/* fail if symlinks are disabled or API is not supported (WinXP) */
+	if (!has_symlinks) {
+		errno = ENOSYS;
+		return -1;
+	}
+
+	if ((len = xutftowcs_long_path(wtarget, target)) < 0
+			|| xutftowcs_long_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;
+}
+
 #ifndef _WINNT_H
 /*
  * The REPARSE_DATA_BUFFER structure is defined in the Windows DDK (in
diff --git a/compat/mingw.h b/compat/mingw.h
index 7c7ce83565..938c81ea1e 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -123,8 +123,6 @@ struct utsname {
  * trivial stubs
  */
 
-static inline int symlink(const char *oldpath, const char *newpath)
-{ errno = ENOSYS; return -1; }
 static inline int fchmod(int fildes, mode_t mode)
 { errno = ENOSYS; return -1; }
 #ifndef __MINGW64_VERSION_MAJOR
@@ -216,6 +214,7 @@ 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);
 
 /*

From 91ffd5d1fbca5ad973e28657556e18294acc9377 Mon Sep 17 00:00:00 2001
From: Karsten Blees <blees@dcon.de>
Date: Sun, 24 May 2015 01:48:35 +0200
Subject: [PATCH 18/19] Win32: symlink: add support for symlinks to directories

Symlinks on Windows have a flag that indicates whether the target is a file
or a directory. Symlinks of wrong type simply don't work. This even affects
core Win32 APIs (e.g. DeleteFile() refuses to delete directory symlinks).

However, CreateFile() with FILE_FLAG_BACKUP_SEMANTICS doesn't seem to care.
Check the target type by first creating a tentative file symlink, opening
it, and checking the type of the resulting handle. If it is a directory,
recreate the symlink with the directory flag set.

It is possible to create symlinks before the target exists (or in case of
symlinks to symlinks: before the target type is known). If this happens,
create a tentative file symlink and postpone the directory decision: keep
a list of phantom symlinks to be processed whenever a new directory is
created in mingw_mkdir().

Limitations: This algorithm may fail if a link target changes from file to
directory or vice versa, or if the target directory is created in another
process.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)

diff --git a/compat/mingw.c b/compat/mingw.c
index f3e53239fb..1c364e64df 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -271,6 +271,131 @@ int mingw_core_config(const char *var, const char *value, void *cb)
 	return 0;
 }
 
+enum phantom_symlink_result {
+	PHANTOM_SYMLINK_RETRY,
+	PHANTOM_SYMLINK_DONE,
+	PHANTOM_SYMLINK_DIRECTORY
+};
+
+static inline int is_wdir_sep(wchar_t wchar)
+{
+	return wchar == L'/' || wchar == L'\\';
+}
+
+static const wchar_t *make_relative_to(const wchar_t *path,
+				       const wchar_t *relative_to, wchar_t *out,
+				       size_t size)
+{
+	size_t i = wcslen(relative_to), len;
+
+	/* Is `path` already absolute? */
+	if (is_wdir_sep(path[0]) ||
+	    (iswalpha(path[0]) && path[1] == L':' && is_wdir_sep(path[2])))
+		return path;
+
+	while (i > 0 && !is_wdir_sep(relative_to[i - 1]))
+		i--;
+
+	/* Is `relative_to` in the current directory? */
+	if (!i)
+		return path;
+
+	len = wcslen(path);
+	if (i + len + 1 > size) {
+		error("Could not make '%S' relative to '%S' (too large)",
+		      path, relative_to);
+		return NULL;
+	}
+
+	memcpy(out, relative_to, i * sizeof(wchar_t));
+	wcscpy(out + i, path);
+	return out;
+}
+
+/*
+ * Changes a file symlink to a directory symlink if the target exists and is a
+ * directory.
+ */
+static enum phantom_symlink_result
+process_phantom_symlink(const wchar_t *wtarget, const wchar_t *wlink)
+{
+	HANDLE hnd;
+	BY_HANDLE_FILE_INFORMATION fdata;
+	wchar_t relative[MAX_LONG_PATH];
+	const wchar_t *rel;
+
+	/* check that wlink is still a file symlink */
+	if ((GetFileAttributesW(wlink)
+			& (FILE_ATTRIBUTE_REPARSE_POINT | FILE_ATTRIBUTE_DIRECTORY))
+			!= FILE_ATTRIBUTE_REPARSE_POINT)
+		return PHANTOM_SYMLINK_DONE;
+
+	/* make it relative, if necessary */
+	rel = make_relative_to(wtarget, wlink, relative, ARRAY_SIZE(relative));
+	if (!rel)
+		return PHANTOM_SYMLINK_DONE;
+
+	/* let Windows resolve the link by opening it */
+	hnd = CreateFileW(rel, 0,
+			FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL,
+			OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+	if (hnd == INVALID_HANDLE_VALUE) {
+		errno = err_win_to_posix(GetLastError());
+		return PHANTOM_SYMLINK_RETRY;
+	}
+
+	if (!GetFileInformationByHandle(hnd, &fdata)) {
+		errno = err_win_to_posix(GetLastError());
+		CloseHandle(hnd);
+		return PHANTOM_SYMLINK_RETRY;
+	}
+	CloseHandle(hnd);
+
+	/* if target exists and is a file, we're done */
+	if (!(fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
+		return PHANTOM_SYMLINK_DONE;
+
+	/* otherwise recreate the symlink with directory flag */
+	if (DeleteFileW(wlink) && CreateSymbolicLinkW(wlink, wtarget, 1))
+		return PHANTOM_SYMLINK_DIRECTORY;
+
+	errno = err_win_to_posix(GetLastError());
+	return PHANTOM_SYMLINK_RETRY;
+}
+
+/* keep track of newly created symlinks to non-existing targets */
+struct phantom_symlink_info {
+	struct phantom_symlink_info *next;
+	wchar_t *wlink;
+	wchar_t *wtarget;
+};
+
+static struct phantom_symlink_info *phantom_symlinks = NULL;
+static CRITICAL_SECTION phantom_symlinks_cs;
+
+static void process_phantom_symlinks(void)
+{
+	struct phantom_symlink_info *current, **psi;
+	EnterCriticalSection(&phantom_symlinks_cs);
+	/* process phantom symlinks list */
+	psi = &phantom_symlinks;
+	while ((current = *psi)) {
+		enum phantom_symlink_result result = process_phantom_symlink(
+				current->wtarget, current->wlink);
+		if (result == PHANTOM_SYMLINK_RETRY) {
+			psi = &current->next;
+		} else {
+			/* symlink was processed, remove from list */
+			*psi = current->next;
+			free(current);
+			/* if symlink was a directory, start over */
+			if (result == PHANTOM_SYMLINK_DIRECTORY)
+				psi = &phantom_symlinks;
+		}
+	}
+	LeaveCriticalSection(&phantom_symlinks_cs);
+}
+
 /* Normalizes NT paths as returned by some low-level APIs. */
 static wchar_t *normalize_ntpath(wchar_t *wbuf)
 {
@@ -420,6 +545,8 @@ int mingw_mkdir(const char *path, int mode)
 		return -1;
 
 	ret = _wmkdir(wpath);
+	if (!ret)
+		process_phantom_symlinks();
 	if (!ret && needs_hiding(path))
 		return set_hidden_flag(wpath, 1);
 	return ret;
@@ -2373,6 +2500,42 @@ int symlink(const char *target, const char *link)
 		errno = err_win_to_posix(GetLastError());
 		return -1;
 	}
+
+	/* convert to directory symlink if target exists */
+	switch (process_phantom_symlink(wtarget, wlink)) {
+	case PHANTOM_SYMLINK_RETRY:	{
+		/* if target doesn't exist, add to phantom symlinks list */
+		wchar_t wfullpath[MAX_LONG_PATH];
+		struct phantom_symlink_info *psi;
+
+		/* convert to absolute path to be independent of cwd */
+		len = GetFullPathNameW(wlink, MAX_LONG_PATH, wfullpath, NULL);
+		if (!len || len >= MAX_LONG_PATH) {
+			errno = err_win_to_posix(GetLastError());
+			return -1;
+		}
+
+		/* over-allocate and fill phantom_symlink_info structure */
+		psi = xmalloc(sizeof(struct phantom_symlink_info)
+			+ sizeof(wchar_t) * (len + wcslen(wtarget) + 2));
+		psi->wlink = (wchar_t *)(psi + 1);
+		wcscpy(psi->wlink, wfullpath);
+		psi->wtarget = psi->wlink + len + 1;
+		wcscpy(psi->wtarget, wtarget);
+
+		EnterCriticalSection(&phantom_symlinks_cs);
+		psi->next = phantom_symlinks;
+		phantom_symlinks = psi;
+		LeaveCriticalSection(&phantom_symlinks_cs);
+		break;
+	}
+	case PHANTOM_SYMLINK_DIRECTORY:
+		/* if we created a dir symlink, process other phantom symlinks */
+		process_phantom_symlinks();
+		break;
+	default:
+		break;
+	}
 	return 0;
 }
 
@@ -2909,6 +3072,7 @@ int wmain(int argc, const wchar_t **wargv)
 
 	/* initialize critical section for waitpid pinfo_t list */
 	InitializeCriticalSection(&pinfo_cs);
+	InitializeCriticalSection(&phantom_symlinks_cs);
 
 	/* set up default file mode and file modes for stdin/out/err */
 	_fmode = _O_BINARY;

From 7f6787a66facd746f41ec0511c09d9e0042d3eb9 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Tue, 30 May 2017 21:50:57 +0200
Subject: [PATCH 19/19] mingw: try to create symlinks without elevated
 permissions

With Windows 10 Build 14972 in Developer Mode, a new flag is supported
by CreateSymbolicLink() to create symbolic links even when running
outside of an elevated session (which was previously required).

This new flag is called SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE and
has the numeric value 0x02.

Previous Windows 10 versions will not understand that flag and return an
ERROR_INVALID_PARAMETER, therefore we have to be careful to try passing
that flag only when the build number indicates that it is supported.

For more information about the new flag, see this blog post:
https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/

This patch is loosely based on the patch submitted by Samuel D. Leslie
as https://github.com/git-for-windows/git/pull/1184.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/mingw.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 1c364e64df..e7a8f40f34 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -271,6 +271,8 @@ int mingw_core_config(const char *var, const char *value, void *cb)
 	return 0;
 }
 
+static DWORD symlink_file_flags = 0, symlink_directory_flags = 1;
+
 enum phantom_symlink_result {
 	PHANTOM_SYMLINK_RETRY,
 	PHANTOM_SYMLINK_DONE,
@@ -356,7 +358,8 @@ process_phantom_symlink(const wchar_t *wtarget, const wchar_t *wlink)
 		return PHANTOM_SYMLINK_DONE;
 
 	/* otherwise recreate the symlink with directory flag */
-	if (DeleteFileW(wlink) && CreateSymbolicLinkW(wlink, wtarget, 1))
+	if (DeleteFileW(wlink) &&
+	    CreateSymbolicLinkW(wlink, wtarget, symlink_directory_flags))
 		return PHANTOM_SYMLINK_DIRECTORY;
 
 	errno = err_win_to_posix(GetLastError());
@@ -2496,7 +2499,7 @@ int symlink(const char *target, const char *link)
 			wtarget[len] = '\\';
 
 	/* create file symlink */
-	if (!CreateSymbolicLinkW(wlink, wtarget, 0)) {
+	if (!CreateSymbolicLinkW(wlink, wtarget, symlink_file_flags)) {
 		errno = err_win_to_posix(GetLastError());
 		return -1;
 	}
@@ -3011,6 +3014,24 @@ static void maybe_redirect_std_handles(void)
 				  GENERIC_WRITE, FILE_FLAG_NO_BUFFERING);
 }
 
+static void adjust_symlink_flags(void)
+{
+	/*
+	 * Starting with Windows 10 Build 14972, symbolic links can be created
+	 * using CreateSymbolicLink() without elevation by passing the flag
+	 * SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE (0x02) as last
+	 * parameter, provided the Developer Mode has been enabled. Some
+	 * earlier Windows versions complain about this flag with an
+	 * ERROR_INVALID_PARAMETER, hence we have to test the build number
+	 * specifically.
+	 */
+	if (GetVersion() >= 14972 << 16) {
+		symlink_file_flags |= 2;
+		symlink_directory_flags |= 2;
+	}
+
+}
+
 #ifdef _MSC_VER
 #ifdef _DEBUG
 #include <crtdbg.h>
@@ -3043,6 +3064,7 @@ int wmain(int argc, const wchar_t **wargv)
 #endif
 
 	maybe_redirect_std_handles();
+	adjust_symlink_flags();
 
 	/* determine size of argv and environ conversion buffer */
 	maxlen = wcslen(wargv[0]);