Occlude unsupported _S_IFBLK feature; resolve issue [#1146].

diff --git a/mingwrt/ChangeLog b/mingwrt/ChangeLog
index 3ed92d0..e2677bd 100644 (file)
--- a/mingwrt/ChangeLog
+++ b/mingwrt/ChangeLog
@@ -1,3 +1,15 @@
+2016-05-19  Keith Marshall  <keithmarshall@users.sourceforge.net>
+
+       Occlude unsupported _S_IFBLK feature; resolve issue [#1146].
+
+       * include/sys/stat.h (_MINGW_S_IFBLK_KLUDGE): New feature test macro;
+       do not define it, and strongly recommend that it remains undefined.
+       [!_MINGW_S_IFBLK_KLUDGE] (_S_IFBLK, S_IFBLK): Do not define them.
+       [!_MINGW_S_IFBLK_KLUDGE] (_S_ISBLK, S_ISBLK): Poison them.
+       [_MINGW_S_IFBLK_KLUDGE] (_S_IFBLK, S_IFBLK): Adjust definitions; use a
+       modified value, which is guaranteed to be impossible to match in...
+       [_S_ISBLK, S_ISBLK]: ...these, thus enforcing false test results.
+
 2016-05-18  Keith Marshall  <keithmarshall@users.sourceforge.net>
 
        Fix a typo in a <sys/stat.h> inline function definition.

diff --git a/mingwrt/include/sys/stat.h b/mingwrt/include/sys/stat.h
index 2a44d91..fb84d90 100644 (file)
--- a/mingwrt/include/sys/stat.h
+++ b/mingwrt/include/sys/stat.h
@@ -59,10 +59,24 @@
  */
 #define _S_IFIFO       0x1000  /* FIFO */
 #define _S_IFCHR       0x2000  /* Character */
-#define _S_IFBLK       0x3000  /* Block: Is this ever set under w32? */
 #define _S_IFDIR       0x4000  /* Directory */
 #define _S_IFREG       0x8000  /* Regular */
 
+#ifdef _MINGW_S_IFBLK_KLUDGE
+/* For preference, this kludge should NOT be enabled; for rationale,
+ * see: https://sourceforge.net/p/mingw/bugs/1146
+ *
+ * MS-Windows doesn't support testing for block special devices via the
+ * st_mode flags; ideally, client code to be ported to Windows should not
+ * blindly assume that S_IFBLK (or _S_IFBLK) is defined, but should rather
+ * check for it, and compile dependent code conditionally.  Notwithstanding,
+ * this kludge allows the user to force a definition, which we arbitrarily
+ * choose to ensure that S_ISBLK (or _S_ISBLK) always returns FALSE, (i.e.
+ * choose a value such that _S_IFBLK & _S_IFMT can NEVER equal _S_IFBLK).
+ */
+#define _S_IFBLK       0x3001  /* Block: unsupported on Win32 */
+#endif
+
 #define _S_IFMT        0xF000  /* File type mask */
 
 #define _S_IEXEC       0x0040
@@ -84,7 +98,9 @@
 
 #define S_IFIFO        _S_IFIFO
 #define S_IFCHR        _S_IFCHR
+#ifdef _S_IFBLK
 #define S_IFBLK        _S_IFBLK
+#endif
 #define S_IFDIR        _S_IFDIR
 #define S_IFREG        _S_IFREG
 #define S_IFMT         _S_IFMT
@@ -103,6 +119,15 @@
 #define S_ISREG(m)     (((m) & S_IFMT) == S_IFREG)
 
 #endif /* !_NO_OLDNAMES */
+
+#ifndef _S_IFBLK
+/* When the _S_IFBLK kludge is NOT enabled, (as it ideally should not be),
+ * ensure that any attempt to use its dependent macros is firmly denied.
+ */
+# pragma GCC poison _S_ISBLK
+# pragma GCC poison S_ISBLK
+
+#endif /* !_S_IFBLK */
 #endif /* !__WCHAR_H_SOURCED__ */
 
 #ifndef RC_INVOKED