Add support for dup2'ing files. Infrastructure and ROMFS done. Still need FAT, BINFS, NXFFS, and NFS

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5516 42af7a65-404d-4744-a932-0658087f49c3

apps/examples/posix_spawn/spawn_main.c

@@ -89,15 +89,6 @@
 #  error "You must not disable loadable modules via CONFIG_BINFMT_DISABLE in your configuration file"
 #endif
 
-/* The redirection test does not work.  This is because it tries to redirect
- * file as stdin.  That won't work now because (1) the file descriptors must
- * be dup'ed when the new task is created, and (2) there is no support in
- * place for dup'ing file descriptors for anything other than sockets and
- * character drivers.  This is a bug!
- */
-
-#define FILE_DUP_BUG 1
-
 /* Describe the ROMFS file system */
 
 #define SECTORSIZE   512
@@ -147,9 +138,7 @@ static unsigned int g_mmstep;     /* Memory Usage at beginning of test step */
 
 static const char delimiter[] =
   "****************************************************************************";
-#ifndef FILE_DUP_BUG
 static const char g_redirect[] = "redirect";
-#endif
 static const char g_hello[]    = "hello";
 static const char g_data[]     = "testdata.txt";
 
@@ -375,8 +364,6 @@ int spawn_main(int argc, char *argv[])
    * Case 2: Simple program with redirection of stdin to a file input
    *************************************************************************/
 
-#ifndef FILE_DUP_BUG
-
   /* Output a seperated so that we can clearly discriminate the output of
    * this program from the others.
    */
@@ -463,7 +450,6 @@ int spawn_main(int argc, char *argv[])
   posix_spawnattr_dump(&attr);
 
   mm_update(&g_mmstep, "after file_action/attr destruction");
-#endif
 
   /* Clean-up */