Workaround for incomplete junctions created by PowerShell

Scoop uses PowerShell's New-Item to create junctions.  However,
these junctions lack a PrintName.  This is a known issue which
has caused problems even for Windows' File Explorer:

   https://github.com/PowerShell/PowerShell/issues/12923

Revert commit 32de287bb (win32: code shrink readlink(2)) to that
readlink(2) uses SubstituteName instead.

(GitHub issue #261)

1 files changed, 32 insertions, 12 deletions

diff --git a/win32/mingw.c b/win32/mingw.c
index 72165cdd7..d26f9f2ff 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1533,6 +1533,30 @@ char *realpath(const char *path, char *resolved_path)
         return NULL;
 }
 
+static wchar_t *normalize_ntpath(wchar_t *wbuf)
+{
+        int i;
+        /* fix absolute path prefixes */
+        if (wbuf[0] == '\\') {
+                /* strip NT namespace prefixes */
+                if (!wcsncmp(wbuf, L"\\??\\", 4) ||
+                    !wcsncmp(wbuf, L"\\\\?\\", 4))
+                        wbuf += 4;
+                else if (!wcsnicmp(wbuf, L"\\DosDevices\\", 12))
+                        wbuf += 12;
+                /* replace remaining '...UNC\' with '\\' */
+                if (!wcsnicmp(wbuf, L"UNC\\", 4)) {
+                        wbuf += 2;
+                        *wbuf = '\\';
+                }
+        }
+        /* convert backslashes to slashes */
+        for (i = 0; wbuf[i]; i++)
+                if (wbuf[i] == '\\')
+                        wbuf[i] = '/';
+        return wbuf;
+}
+
 #define SRPB rptr->SymbolicLinkReparseBuffer
 ssize_t readlink(const char *pathname, char *buf, size_t bufsiz)
 {
@@ -1553,25 +1577,21 @@ ssize_t readlink(const char *pathname, char *buf, size_t bufsiz)
                 CloseHandle(h);
 
                 if (status && rptr->ReparseTag == IO_REPARSE_TAG_SYMLINK) {
-                        len = SRPB.PrintNameLength/sizeof(WCHAR);
-                        name = SRPB.PathBuffer + SRPB.PrintNameOffset/sizeof(WCHAR);
+                        len = SRPB.SubstituteNameLength/sizeof(WCHAR);
+                        name = SRPB.PathBuffer + SRPB.SubstituteNameOffset/sizeof(WCHAR);
                 } else if (status && rptr->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT) {
-                        len = MRPB.PrintNameLength/sizeof(WCHAR);
-                        name = MRPB.PathBuffer + MRPB.PrintNameOffset/sizeof(WCHAR);
+                        len = MRPB.SubstituteNameLength/sizeof(WCHAR);
+                        name = MRPB.PathBuffer + MRPB.SubstituteNameOffset/sizeof(WCHAR);
                 }
 
                 if (name) {
+                        name[len] = 0;
+                        name = normalize_ntpath(name);
+                        len = wcslen(name);
                         if (len > bufsiz)
                                 len = bufsiz;
-                        len = WideCharToMultiByte(CP_ACP, 0, name, len, buf, bufsiz, 0, 0);
-                        if (len) {
-                                int i;
-
-                                for (i = 0; i < len; i++)
-                                        if (buf[i] == '\\')
-                                                buf[i] = '/';
+                        if (WideCharToMultiByte(CP_ACP, 0, name, len, buf, bufsiz, 0, 0))
                                 return len;
-                        }
                 }
         }
         errno = err_win_to_posix();