X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fpopen.c;h=64a4f619e4f1be2f4209eb9b079cf4d4b247f930;hb=21c3d05ca705daa62ec4c7444e67af48ba757c18;hp=a1f1d45bfd2b06cf3acd48e97cc02a9ea77447e4;hpb=a8f637e3c49275e6789c05d67c1fbd1751e5610a;p=gnulib.git

diff --git a/lib/popen.c b/lib/popen.c
index a1f1d45bf..64a4f619e 100644
--- a/lib/popen.c
+++ b/lib/popen.c
@@ -1,5 +1,5 @@
 /* Open a stream to a sub-process.
-   Copyright (C) 2009 Free Software Foundation, Inc.
+   Copyright (C) 2009-2011 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
@@ -18,17 +18,6 @@
 
 #include <config.h>
 
-/* Get the original definition of popen.  It might be defined as a macro.  */
-#define __need_FILE
-# include <stdio.h>
-#undef __need_FILE
-
-static inline FILE *
-orig_popen (const char *filename, const char *mode)
-{
-  return popen (filename, mode);
-}
-
 /* Specification.  */
 #include <stdio.h>
 
@@ -37,6 +26,8 @@ orig_popen (const char *filename, const char *mode)
 #include <stdlib.h>
 #include <unistd.h>
 
+#undef popen
+
 FILE *
 rpl_popen (const char *filename, const char *mode)
 {
@@ -56,21 +47,31 @@ rpl_popen (const char *filename, const char *mode)
   int cloexec1 = fcntl (STDOUT_FILENO, F_GETFD);
   int saved_errno;
 
+  /* If either stdin or stdout was closed (that is, fcntl failed),
+     then we open a dummy close-on-exec fd to occupy that slot.  That
+     way, popen's internal use of pipe() will not contain either fd 0
+     or 1, overcoming the fact that the child process blindly calls
+     close() on the parent's end of the pipe without first checking
+     whether it is clobbering the fd just placed there via dup2(); the
+     exec will get rid of the dummy fd's in the child.  Fortunately,
+     closed stderr in the parent does not cause problems in the
+     child.  */
   if (cloexec0 < 0)
     {
       if (open ("/dev/null", O_RDONLY) != STDIN_FILENO
-	  || fcntl (STDIN_FILENO, F_SETFD,
-		    fcntl (STDIN_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
-	abort ();
+          || fcntl (STDIN_FILENO, F_SETFD,
+                    fcntl (STDIN_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
+        abort ();
     }
   if (cloexec1 < 0)
     {
       if (open ("/dev/null", O_RDONLY) != STDOUT_FILENO
-	  || fcntl (STDOUT_FILENO, F_SETFD,
-		    fcntl (STDOUT_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
-	abort ();
+          || fcntl (STDOUT_FILENO, F_SETFD,
+                    fcntl (STDOUT_FILENO, F_GETFD) | FD_CLOEXEC) == -1)
+        abort ();
     }
-  result = orig_popen (filename, mode);
+  result = popen (filename, mode);
+  /* Now, close any dummy fd's created in the parent.  */
   saved_errno = errno;
   if (cloexec0 < 0)
     close (STDIN_FILENO);