stdalign: relax _Alignof and tighten _Alignas test

[gnulib.git] / lib / popen.c

diff --git a/lib/popen.c b/lib/popen.c
index a1f1d45..7b82bce 100644 (file)
--- 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) 2009-2012 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
@@ -18,24 +18,17 @@
 
 #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>
 
-#include <errno.h>
-#include <fcntl.h>
-#include <stdlib.h>
-#include <unistd.h>
+#if HAVE_POPEN
+
+# include <errno.h>
+# include <fcntl.h>
+# include <stdlib.h>
+# include <unistd.h>
+
+# undef popen
 
 FILE *
 rpl_popen (const char *filename, const char *mode)
@@ -56,21 +49,31 @@ 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);
@@ -79,3 +82,22 @@ rpl_popen (const char *filename, const char *mode)
   errno = saved_errno;
   return result;
 }
+
+#else
+/* Native Windows API.  */
+
+# include <string.h>
+
+FILE *
+popen (const char *filename, const char *mode)
+{
+  /* Use binary mode by default.  */
+  if (strcmp (mode, "r") == 0)
+    mode = "rb";
+  else if (strcmp (mode, "w") == 0)
+    mode = "wb";
+
+  return _popen (filename, mode);
+}
+
+#endif