Mitigate a race condition in Windows when deleting files and directories.

original commit: 1a13def8d6570babe378f4c63b5a488fac58ed3f

LOG

@@ -883,3 +883,5 @@
   so the reduced version checks that p is a procedure.
   Also make the same change for #2%for-each.
     cp0.ss, 4.ms
+- Mitigate a race condition in Windows when deleting files and directories.
+    windows.c

c/windows.c

@@ -408,10 +408,14 @@ int S_windows_rename(const char *oldpathname, const char *newpathname) {
 
 int S_windows_rmdir(const char *pathname) {
   wchar_t wpathname[PATH_MAX];
+  int rc;
   if (MultiByteToWideChar(CP_UTF8,0,pathname,-1,wpathname,PATH_MAX) == 0)
-    return _rmdir(pathname);
+    rc =_rmdir(pathname);
   else
-    return _wrmdir(wpathname);
+    rc = _wrmdir(wpathname);
+  if (0 == rc)
+    Sleep(0); // Give Windows time to delete the directory.
+  return rc;
 }
 
 int S_windows_stat64(const char *pathname, struct STATBUF *buffer) {
@@ -432,10 +436,14 @@ int S_windows_system(const char *command) {
 
 int S_windows_unlink(const char *pathname) {
   wchar_t wpathname[PATH_MAX];
+  int rc;
   if (MultiByteToWideChar(CP_UTF8,0,pathname,-1,wpathname,PATH_MAX) == 0)
-    return _unlink(pathname);
+    rc = _unlink(pathname);
   else
-    return _wunlink(wpathname);
+    rc = _wunlink(wpathname);
+  if (0 == rc)
+    Sleep(0); // Give Windows time to delete the file.
+  return rc;
 }
 
 char *S_windows_getcwd(char *buffer, int maxlen) {

release_notes/release_notes.stex

@@ -1542,6 +1542,14 @@ in fasl files does not generally make sense.
 %-----------------------------------------------------------------------------
 \section{Bug Fixes}\label{section:bugfixes}
 
+\subsection{Permission denied after deleting files or directories in Windows}
+
+In Windows, deleting a file or directory briefly leaves the file or
+directory in a state where a subsequent create operation fails with
+permission denied. This race condition is now mitigated by a call to
+Sleep.
+[This bug applies to all versions up to 9.5 on Windows 7 and later.]
+
 \subsection{Incorrect handling of offset in
 \protect\scheme{date->time-utc} on Windows (9.5)}