Doug MacEachern commented to me that perl, and some other apps, are

  calling GetModuleName or other Win32 APIs to retrieve the relative or
  working path.  Since some of these app authors have never observed an
  '\\?\D\Somepath" style unlimited-length filename, and retrieve as much
  when we spawn a process with that format, it's probably much safer to
  drop the extra decoration when we don't need it (because our filename
  is smaller than the Win32 MAX_PATH length.)

  So this patch does just that, and only uses "\\?\" notation when the
  filename is quite huge.


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@62689 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 28 insertions, 14 deletions

diff --git a/file_io/win32/open.c b/file_io/win32/open.c
index 09ef76c9a..aad54853e 100644
--- a/file_io/win32/open.c
+++ b/file_io/win32/open.c
@@ -84,20 +84,34 @@ apr_status_t utf8_to_unicode_path(apr_wchar_t* retstr, apr_size_t retlen,
     int srcremains = strlen(srcstr) + 1;
     apr_wchar_t *t = retstr;
     apr_status_t rv;
-    if (srcstr[1] == ':' && (srcstr[2] == '/' || srcstr[2] == '\\')) {
-        wcscpy (retstr, L"\\\\?\\");
-        retlen -= 4;
-        t += 4;
-    }
-    else if ((srcstr[0] == '/' || srcstr[0] == '\\')
-          && (srcstr[1] == '/' || srcstr[1] == '\\')
-          && (srcstr[2] != '?')) {
-        /* Skip the slashes */
-        srcstr += 2;
-        srcremains -= 2;
-        wcscpy (retstr, L"\\\\?\\UNC\\");
-        retlen -= 8;
-        t += 8;
+
+    /* This is correct, we don't twist the filename if it is will
+     * definately be shorter than MAX_PATH.  It merits some 
+     * performance testing to see if this has any effect, but there
+     * seem to be applications that get confused by the resulting
+     * Unicode \\?\ style file names, especially if they use argv[0]
+     * or call the Win32 API functions such as GetModuleName, etc.
+     * Not every application is prepared to handle such names.
+     *
+     * Note that a utf-8 name can never result in more wide chars
+     * than the original number of utf-8 narrow chars.
+     */
+    if (srcremains > MAX_PATH) {
+        if (srcstr[1] == ':' && (srcstr[2] == '/' || srcstr[2] == '\\')) {
+            wcscpy (retstr, L"\\\\?\\");
+            retlen -= 4;
+            t += 4;
+        }
+        else if ((srcstr[0] == '/' || srcstr[0] == '\\')
+              && (srcstr[1] == '/' || srcstr[1] == '\\')
+              && (srcstr[2] != '?')) {
+            /* Skip the slashes */
+            srcstr += 2;
+            srcremains -= 2;
+            wcscpy (retstr, L"\\\\?\\UNC\\");
+            retlen -= 8;
+            t += 8;
+        }
     }
 
     if (rv = conv_utf8_to_ucs2(srcstr, &srcremains, t, &retlen)) {