patch 8.1.0894: MS-Windows: resolve() does not return a reparse point

Problem:    MS-Windows: resolve() does not return a reparse point.
Solution:   Improve resolve(). (Yasuhiro Matsumoto, closes #3896)

runtime/doc/eval.txt

@@ -7385,6 +7385,9 @@ repeat({expr}, {count})					*repeat()*
 resolve({filename})					*resolve()* *E655*
 		On MS-Windows, when {filename} is a shortcut (a .lnk file),
 		returns the path the shortcut points to in a simplified form.
+		When {filename} is a symbolic link or junction point, return
+		the full path to the target. If the target of junction is
+		removed, return {filename}.
 		On Unix, repeat resolving symbolic links in all path
 		components of {filename} and return the simplified result.
 		To cope with link cycles, resolving of symbolic links is

src/buffer.c

@@ -4847,7 +4847,7 @@ fname_expand(
 	char_u  *rfname;
 
 	// If the file name is a shortcut file, use the file it links to.
-	rfname = mch_resolve_shortcut(*ffname);
+	rfname = mch_resolve_path(*ffname, FALSE);
 	if (rfname != NULL)
 	{
 	    vim_free(*ffname);

src/evalfunc.c

@@ -9912,7 +9912,7 @@ f_resolve(typval_T *argvars, typval_T *rettv)
     {
 	char_u	*v = NULL;
 
-	v = mch_resolve_shortcut(p);
+	v = mch_resolve_path(p, TRUE);
 	if (v != NULL)
 	    rettv->vval.v_string = v;
 	else

src/os_mswin.c

@@ -1823,13 +1823,181 @@ mch_print_set_fg(long_u fgcol)
 #  include <shlobj.h>
 # endif
 
+typedef enum _FILE_INFO_BY_HANDLE_CLASS_ {
+  FileBasicInfo_,
+  FileStandardInfo_,
+  FileNameInfo_,
+  FileRenameInfo_,
+  FileDispositionInfo_,
+  FileAllocationInfo_,
+  FileEndOfFileInfo_,
+  FileStreamInfo_,
+  FileCompressionInfo_,
+  FileAttributeTagInfo_,
+  FileIdBothDirectoryInfo_,
+  FileIdBothDirectoryRestartInfo_,
+  FileIoPriorityHintInfo_,
+  FileRemoteProtocolInfo_,
+  FileFullDirectoryInfo_,
+  FileFullDirectoryRestartInfo_,
+  FileStorageInfo_,
+  FileAlignmentInfo_,
+  FileIdInfo_,
+  FileIdExtdDirectoryInfo_,
+  FileIdExtdDirectoryRestartInfo_,
+  FileDispositionInfoEx_,
+  FileRenameInfoEx_,
+  MaximumFileInfoByHandleClass_
+} FILE_INFO_BY_HANDLE_CLASS_;
+
+typedef struct _FILE_NAME_INFO_ {
+  DWORD FileNameLength;
+  WCHAR FileName[1];
+} FILE_NAME_INFO_;
+
+typedef BOOL (WINAPI *pfnGetFileInformationByHandleEx)(
+	HANDLE				hFile,
+	FILE_INFO_BY_HANDLE_CLASS_	FileInformationClass,
+	LPVOID				lpFileInformation,
+	DWORD				dwBufferSize);
+static pfnGetFileInformationByHandleEx pGetFileInformationByHandleEx = NULL;
+
+typedef BOOL (WINAPI *pfnGetVolumeInformationByHandleW)(
+	HANDLE	hFile,
+	LPWSTR	lpVolumeNameBuffer,
+	DWORD	nVolumeNameSize,
+	LPDWORD	lpVolumeSerialNumber,
+	LPDWORD	lpMaximumComponentLength,
+	LPDWORD	lpFileSystemFlags,
+	LPWSTR	lpFileSystemNameBuffer,
+	DWORD	nFileSystemNameSize);
+static pfnGetVolumeInformationByHandleW pGetVolumeInformationByHandleW = NULL;
+
+    char_u *
+resolve_reparse_point(char_u *fname)
+{
+    HANDLE	    h = INVALID_HANDLE_VALUE;
+    DWORD	    size;
+    char_u	    *rfname = NULL;
+    FILE_NAME_INFO_ *nameinfo = NULL;
+    WCHAR	    buff[MAX_PATH], *volnames = NULL;
+    HANDLE	    hv;
+    DWORD	    snfile, snfind;
+    static BOOL	    loaded = FALSE;
+
+    if (pGetFileInformationByHandleEx == NULL ||
+	    pGetVolumeInformationByHandleW == NULL)
+    {
+	HMODULE hmod = GetModuleHandle("kernel32.dll");
+
+	if (loaded == TRUE)
+	    return NULL;
+	pGetFileInformationByHandleEx = (pfnGetFileInformationByHandleEx)
+		GetProcAddress(hmod, "GetFileInformationByHandleEx");
+	pGetVolumeInformationByHandleW = (pfnGetVolumeInformationByHandleW)
+		GetProcAddress(hmod, "GetVolumeInformationByHandleW");
+	loaded = TRUE;
+	if (pGetFileInformationByHandleEx == NULL ||
+		pGetVolumeInformationByHandleW == NULL)
+	    return NULL;
+    }
+
+    if (enc_codepage >= 0 && (int)GetACP() != enc_codepage)
+    {
+	WCHAR	*p;
+
+	p = enc_to_utf16(fname, NULL);
+	if (p == NULL)
+	    goto fail;
+
+	if ((GetFileAttributesW(p) & FILE_ATTRIBUTE_REPARSE_POINT) == 0)
+	{
+	    vim_free(p);
+	    goto fail;
+	}
+
+	h = CreateFileW(p, 0, 0, NULL, OPEN_EXISTING,
+		FILE_FLAG_BACKUP_SEMANTICS, NULL);
+	vim_free(p);
+    }
+    else
+    {
+	if ((GetFileAttributes((char*) fname) &
+		    FILE_ATTRIBUTE_REPARSE_POINT) == 0)
+	    goto fail;
+
+	h = CreateFile((char*) fname, 0, 0, NULL, OPEN_EXISTING,
+		FILE_FLAG_BACKUP_SEMANTICS, NULL);
+    }
+
+    if (h == INVALID_HANDLE_VALUE)
+	goto fail;
+
+    size = sizeof(FILE_NAME_INFO_) + sizeof(WCHAR) * (MAX_PATH - 1);
+    nameinfo = (FILE_NAME_INFO_*)alloc(size + sizeof(WCHAR));
+    if (nameinfo == NULL)
+	goto fail;
+
+    if (!pGetFileInformationByHandleEx(h, FileNameInfo_, nameinfo, size))
+	goto fail;
+
+    nameinfo->FileName[nameinfo->FileNameLength / sizeof(WCHAR)] = 0;
+
+    if (!pGetVolumeInformationByHandleW(
+	    h, NULL, 0, &snfile, NULL, NULL, NULL, 0))
+	goto fail;
+
+    hv = FindFirstVolumeW(buff, MAX_PATH);
+    if (hv == INVALID_HANDLE_VALUE)
+	goto fail;
+
+    do {
+	GetVolumeInformationW(
+		buff, NULL, 0, &snfind, NULL, NULL, NULL, 0);
+	if (snfind == snfile)
+	    break;
+    } while (FindNextVolumeW(hv, buff, MAX_PATH));
+
+    FindVolumeClose(hv);
+
+    if (snfind != snfile)
+	goto fail;
+
+    size = 0;
+    if (!GetVolumePathNamesForVolumeNameW(buff, NULL, 0, &size) &&
+	    GetLastError() != ERROR_MORE_DATA)
+	goto fail;
+
+    volnames = (WCHAR*)alloc(size * sizeof(WCHAR));
+    if (!GetVolumePathNamesForVolumeNameW(buff, volnames, size,
+		&size))
+	goto fail;
+
+    wcscpy(buff, volnames);
+    if (nameinfo->FileName[0] == '\\')
+	wcscat(buff, nameinfo->FileName + 1);
+    else
+	wcscat(buff, nameinfo->FileName);
+    rfname = utf16_to_enc(buff, NULL);
+
+fail:
+    if (h != INVALID_HANDLE_VALUE)
+	CloseHandle(h);
+    if (nameinfo != NULL)
+	vim_free(nameinfo);
+    if (volnames != NULL)
+	vim_free(volnames);
+
+    return rfname;
+}
+
 /*
  * When "fname" is the name of a shortcut (*.lnk) resolve the file it points
  * to and return that name in allocated memory.
  * Otherwise NULL is returned.
  */
-    char_u *
+    static char_u *
-mch_resolve_shortcut(char_u *fname)
+resolve_shortcut(char_u *fname)
 {
     HRESULT		hr;
     IShellLink		*psl = NULL;
@@ -1937,6 +2105,16 @@ shortcut_end:
     CoUninitialize();
     return rfname;
 }
+
+    char_u *
+mch_resolve_path(char_u *fname, int reparse_point)
+{
+    char_u  *path = resolve_shortcut(fname);
+
+    if (path == NULL && reparse_point)
+	path = resolve_reparse_point(fname);
+    return path;
+}
 #endif
 
 #if (defined(FEAT_EVAL) && !defined(FEAT_GUI)) || defined(PROTO)

src/proto/os_mswin.pro

@@ -37,7 +37,7 @@ int mch_print_text_out(char_u *p, int len);
 void mch_print_set_font(int iBold, int iItalic, int iUnderline);
 void mch_print_set_bg(long_u bgcol);
 void mch_print_set_fg(long_u fgcol);
-char_u *mch_resolve_shortcut(char_u *fname);
+char_u *mch_resolve_path(char_u *fname, int reparse_point);
 void win32_set_foreground(void);
 void serverInitMessaging(void);
 void serverSetName(char_u *name);

src/testdir/test_functions.vim

@@ -188,7 +188,7 @@ func Test_strftime()
   call assert_fails('call strftime("%Y", [])', 'E745:')
 endfunc
 
-func Test_resolve()
+func Test_resolve_unix()
   if !has('unix')
     return
   endif
@@ -234,6 +234,103 @@ func Test_resolve()
   call delete('Xlink1')
 endfunc
 
+func s:normalize_fname(fname)
+  let ret = substitute(a:fname, '\', '/', 'g')
+  let ret = substitute(ret, '//', '/', 'g')
+  let ret = tolower(ret)
+endfunc
+
+func Test_resolve_win32()
+  if !has('win32')
+    return
+  endif
+
+  " test for shortcut file
+  if executable('cscript')
+    new Xfile
+    wq
+    call writefile([
+    \ 'Set fs = CreateObject("Scripting.FileSystemObject")',
+    \ 'Set ws = WScript.CreateObject("WScript.Shell")',
+    \ 'Set shortcut = ws.CreateShortcut("Xlink.lnk")',
+    \ 'shortcut.TargetPath = fs.BuildPath(ws.CurrentDirectory, "Xfile")', 
+    \ 'shortcut.Save'
+    \], 'link.vbs')
+    silent !cscript link.vbs
+    call delete('link.vbs')
+    call assert_equal(s:normalize_fname(getcwd() . '\Xfile'), s:normalize_fname(resolve('./Xlink.lnk')))
+    call delete('Xfile')
+
+    call assert_equal(s:normalize_fname(getcwd() . '\Xfile'), s:normalize_fname(resolve('./Xlink.lnk')))
+    call delete('Xlink.lnk')
+  else
+    echomsg 'skipped test for shortcut file'
+  endif
+
+  " remove files
+  call delete('Xlink')
+  call delete('Xdir', 'd')
+  call delete('Xfile')
+
+  " test for symbolic link to a file
+  new Xfile
+  wq
+  silent !mklink Xlink Xfile
+  if !v:shell_error
+    call assert_equal(s:normalize_fname(getcwd() . '\Xfile'), s:normalize_fname(resolve('./Xlink')))
+    call delete('Xlink')
+  else
+    echomsg 'skipped test for symbolic link to a file'
+  endif
+  call delete('Xfile')
+
+  " test for junction to a directory
+  call mkdir('Xdir')
+  silent !mklink /J Xlink Xdir
+  if !v:shell_error
+    call assert_equal(s:normalize_fname(getcwd() . '\Xdir'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
+
+    call delete('Xdir', 'd')
+
+    " test for junction already removed
+    call assert_equal(s:normalize_fname(getcwd() . '\Xlink'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
+    call delete('Xlink')
+  else
+    echomsg 'skipped test for junction to a directory'
+    call delete('Xdir', 'd')
+  endif
+
+  " test for symbolic link to a directory
+  call mkdir('Xdir')
+  silent !mklink /D Xlink Xdir
+  if !v:shell_error
+    call assert_equal(s:normalize_fname(getcwd() . '\Xdir'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
+
+    call delete('Xdir', 'd')
+
+    " test for symbolic link already removed
+    call assert_equal(s:normalize_fname(getcwd() . '\Xlink'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
+    call delete('Xlink')
+  else
+    echomsg 'skipped test for symbolic link to a directory'
+    call delete('Xdir', 'd')
+  endif
+
+  " test for buffer name
+  new Xfile
+  wq
+  silent !mklink Xlink Xfile
+  if !v:shell_error
+    edit Xlink
+    call assert_equal('Xlink', bufname('%'))
+    call delete('Xlink')
+    bw!
+  else
+    echomsg 'skipped test for buffer name'
+  endif
+  call delete('Xfile')
+endfunc
+
 func Test_simplify()
   call assert_equal('',            simplify(''))
   call assert_equal('/',           simplify('/'))

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    894,
 /**/
     893,
 /**/