fix for rename function on Mingw

[Ben Pfaff]

On the Windows platform, Microsoft documents the rename function
as refusing to replace existing destination files.  This is
allowed by C89 (and C99) but it is not POSIX-compliant, and it
can be quite surprising to programs that want to atomically
replace files.

Here is a gnulib commit that I am proposing.  It (cross)compiles
on Mingw, but I am waiting to hear back from my Windows tester to
find out whether it actually solves the problem for him.

Comments?

commit 7243a5ecda0db712da438b1cfcad89c18264fdb3
Author: Ben Pfaff <address@hidden>
Date:   Fri Mar 20 22:02:50 2009 -0700

    Make rename replace existing destinations on Windows.

diff --git a/ChangeLog b/ChangeLog
index 4a23101..642a615 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-03-20  Ben Pfaff  <address@hidden>
+
+       Make rename replace existing destinations on Windows.
+       * m4/rename.m4: Add test for Mingw.
+       * lib/rename.c: Add rename replacement that uses MoveFileEx with
+       MOVEFILE_REPLACE_EXISTING to replace existing destination files.
+       * doc/posix-functions/rename.texi: Document.
+
 2009-03-20  Bruno Haible  <address@hidden>
 
        Make sockets.h self-contained.
diff --git a/doc/posix-functions/rename.texi b/doc/posix-functions/rename.texi
index 62b1fc8..aa7287a 100644
--- a/doc/posix-functions/rename.texi
+++ b/doc/posix-functions/rename.texi
@@ -12,8 +12,15 @@ Portability problems fixed by Gnulib:
 This function does not work when the source file name ends in a slash on
 some platforms:
 SunOS 4.1.
address@hidden
+This function will not replace an existing destination on some
+platforms:
+mingw.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
+This function will not replace a destination that is currently opened
+by any process:
+mingw.
 @end itemize
diff --git a/lib/rename.c b/lib/rename.c
index 9667c39..f0486d9 100644
--- a/lib/rename.c
+++ b/lib/rename.c
@@ -1,8 +1,9 @@
-/* Work around the bug in some systems whereby rename fails when the source
-   file has a trailing slash.  The rename functions of SunOS 4.1.1_U1 and
-   mips-dec-ultrix4.4 have this bug.
+/* Work around rename bugs in some systems.  On SunOS 4.1.1_U1
+   and mips-dec-ultrix4.4, rename fails when the source file has
+   a trailing slash.  On mingw, rename fails when the destination
+   exists.
 
-   Copyright (C) 2001, 2002, 2003, 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002, 2003, 2005, 2006, 2009 Free Software Foundation, 
Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -22,6 +23,99 @@
 #include <config.h>
 #undef rename
 
+#if RENAME_DEST_EXISTS_BUG
+/* This replacement must come first, otherwise when cross
+ * compiling to Windows we will guess that it has the trailing
+ * slash bug and entirely miss this one. */
+#include <errno.h>
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+/* Rename the file SRC to DST.  This replacement is necessary on
+   Windows, on which the system rename function will not replace
+   an existing DST.  */
+int
+rpl_rename (char const *src, char const *dst)
+{
+  if (MoveFileEx (src, dst, MOVEFILE_REPLACE_EXISTING))
+    return 0;
+  else
+    {
+      switch (GetLastError())
+        {
+        case ERROR_FILE_NOT_FOUND:
+        case ERROR_PATH_NOT_FOUND:
+        case ERROR_BAD_PATHNAME:
+        case ERROR_DIRECTORY:
+          errno = ENOENT;
+          break;
+
+        case ERROR_ACCESS_DENIED:
+        case ERROR_SHARING_VIOLATION:
+          errno = EACCES;
+          break;
+
+        case ERROR_OUTOFMEMORY:
+          errno = ENOMEM;
+          break;
+
+        case ERROR_CURRENT_DIRECTORY:
+          errno = EBUSY;
+          break;
+
+        case ERROR_NOT_SAME_DEVICE:
+          errno = EXDEV;
+          break;
+
+        case ERROR_WRITE_PROTECT:
+          errno = EROFS;
+          break;
+
+        case ERROR_WRITE_FAULT:
+        case ERROR_READ_FAULT:
+        case ERROR_GEN_FAILURE:
+          errno = EIO;
+          break;
+
+        case ERROR_HANDLE_DISK_FULL:
+        case ERROR_DISK_FULL:
+        case ERROR_DISK_TOO_FRAGMENTED:
+          errno = ENOSPC;
+          break;
+
+        case ERROR_FILE_EXISTS:
+        case ERROR_ALREADY_EXISTS:
+          errno = EEXIST;
+          break;
+
+        case ERROR_BUFFER_OVERFLOW:
+        case ERROR_FILENAME_EXCED_RANGE:
+          errno = ENAMETOOLONG;
+          break;
+
+        case ERROR_INVALID_NAME:
+        case ERROR_DELETE_PENDING:
+          errno = EPERM;        /* ? */
+          break;
+
+#ifndef ERROR_FILE_TOO_LARGE
+/* This value is documented but not defined in all versions of windows.h. */
+#define ERROR_FILE_TOO_LARGE 223
+#endif
+        case ERROR_FILE_TOO_LARGE:
+          errno = EFBIG;
+          break;
+
+        default:
+          errno = EINVAL;
+          break;
+        }
+
+      return -1;
+    }
+}
+#elif RENAME_TRAILING_SLASH_BUG
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -54,3 +148,4 @@ rpl_rename (char const *src, char const *dst)
 
   return ret_val;
 }
+#endif /* RENAME_TRAILING_SLASH_BUG */
diff --git a/m4/rename.m4 b/m4/rename.m4
index fa7ae8d..9829308 100644
--- a/m4/rename.m4
+++ b/m4/rename.m4
@@ -15,7 +15,8 @@ dnl
 
 AC_DEFUN([gl_FUNC_RENAME],
 [
- AC_CACHE_CHECK([whether rename is broken],
+  AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_CACHE_CHECK([whether rename is broken with a trailing slash],
   gl_cv_func_rename_trailing_slash_bug,
   [
     rm -rf conftest.d1 conftest.d2
@@ -37,13 +38,29 @@ AC_DEFUN([gl_FUNC_RENAME],
 
       rm -rf conftest.d1 conftest.d2
   ])
-  if test $gl_cv_func_rename_trailing_slash_bug = yes; then
+ AC_CACHE_CHECK([whether rename is broken when the destination exists],
+  gl_cv_func_rename_dest_exists_bug,
+  [
+    case "$host_os" in
+      mingw*) gl_cv_func_rename_dest_exists_bug=yes ;;
+      *) gl_cv_func_rename_dest_exists_bug=no ;;
+    esac
+  ])
+  if test $gl_cv_func_rename_trailing_slash_bug = yes ||
+     test $gl_cv_func_rename_dest_exists_bug = yes; then
     AC_LIBOBJ([rename])
     AC_DEFINE([rename], [rpl_rename],
       [Define to rpl_rename if the replacement function should be used.])
-    AC_DEFINE([RENAME_TRAILING_SLASH_BUG], [1],
-      [Define if rename does not work for source file names with a trailing
-       slash, like the one from SunOS 4.1.1_U1.])
+    if test $gl_cv_func_rename_trailing_slash_bug; then
+      AC_DEFINE([RENAME_TRAILING_SLASH_BUG], [1],
+       [Define if rename does not work for source file names with a trailing
+        slash, like the one from SunOS 4.1.1_U1.])
+    fi  
+    if test $gl_cv_func_rename_dest_exists_bug; then
+      AC_DEFINE([RENAME_DEST_EXISTS_BUG], [1],
+       [Define if rename does not work when the destination file exists,
+        as on Windows.])
+    fi  
     gl_PREREQ_RENAME
   fi
 ])

-- 
"If a person keeps faithfully busy each hour of the working day, he
 can count on waking up some morning to find himself one of the
 competent ones of his generation."
--William James