popen: Make more robust on Windows.

* lib/popen.c: On native Windows, use the _popen based code even if
HAVE_POPEN is set.
* doc/posix-functions/popen.texi: Mention necessity of COMSPEC
environment variable on native Windows.

diff --git a/ChangeLog b/ChangeLog
index 3771ec1..2a0b728 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2012-01-31  Bruno Haible  <bruno@clisp.org>
+
+       popen: Make more robust on Windows.
+       * lib/popen.c: On native Windows, use the _popen based code even if
+       HAVE_POPEN is set.
+       * doc/posix-functions/popen.texi: Mention necessity of COMSPEC
+       environment variable on native Windows.
+
 2012-01-30  Bruno Haible  <bruno@clisp.org>
 
        pclose: Fix typo.

diff --git a/doc/posix-functions/popen.texi b/doc/posix-functions/popen.texi
index e9fac3b..5182214 100644 (file)
--- a/doc/posix-functions/popen.texi
+++ b/doc/posix-functions/popen.texi
@@ -20,6 +20,9 @@ Cygwin 1.5.x.
 Portability problems not fixed by Gnulib:
 @itemize
 @item
+On native Windows platforms, this functions terminates the current process
+with exit code 127 if the environment variable @code{COMSPEC} is not set.
+@item
 Some platforms mistakenly set the close-on-exec bit, then if it is
 cleared by the application, the platform then leaks file descriptors
 from earlier @code{popen} calls into subsequent @code{popen} children:

diff --git a/lib/popen.c b/lib/popen.c
index 7b82bce..1460e9e 100644 (file)
--- a/lib/popen.c
+++ b/lib/popen.c
@@ -21,7 +21,24 @@
 /* Specification.  */
 #include <stdio.h>
 
-#if HAVE_POPEN
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+/* 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);
+}
+
+#else
 
 # include <errno.h>
 # include <fcntl.h>
@@ -33,7 +50,7 @@
 FILE *
 rpl_popen (const char *filename, const char *mode)
 {
-  /* The mingw popen works fine, and all other platforms have fcntl.
+  /* All other platforms have popen and fcntl.
      The bug of the child clobbering its own file descriptors if stdin
      or stdout was closed in the parent can be worked around by
      opening those two fds as close-on-exec to begin with.  */
@@ -83,21 +100,4 @@ rpl_popen (const char *filename, const char *mode)
   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