poll-h: new module

[Bruno Haible]

Eric Blake wrote:
> modern style favors splitting 
> replacement headers into separate modules from like-named functions 
> (that is, we need a new module poll-h if you want a working poll.h 
> [pollfd, nfds_t, and the various POLL macros] that can be used for 
> GNULIB_POSIXCHECK conformance and when you don't tickle the portability 
> limitations of native poll(); and poll [which depends on poll-h] if you 
> also need the gnulib fixes for the function).

Good point. We did not do the distinction in the past between 'poll'
and 'poll-h' because it was deemed unnecessary. But for using GNULIB_POSIXCHECK
it is necessary, as you say.

This patch splits the module.


2010-09-28  Bruno Haible  <address@hidden>

        New module 'poll-h'.
        * lib/poll.in.h: Include c++defs.h and warn-on-use.h.
        (poll): Use modern idiom.
        * modules/poll-h: New file.
        * modules/poll (Files): Remove lib/poll.in.h.
        (Depends-on): Add poll-h.
        (configure.ac): Invoke gl_POLL_MODULE_INDICATOR.
        (Makefile.am): Move code for generation of poll.h to modules/poll-h.
        * m4/poll_h.m4: New file.
        * m4/poll.m4 (gl_FUNC_POLL): Require gl_POLL_H. Don't check for poll.h
        here. Don't set POLL_H here. Instead, set HAVE_POLL and REPLACE_POLL
        and invoke gl_REPLACE_POLL_H.
        * lib/poll.c: Use common idiom.
        * tests/test-poll.c: Likewise.
        * doc/posix-headers/poll.texi: Mention the poll-h module.
        Suggested by Eric Blake.

=============================== modules/poll-h ===============================
Description:
A POSIX-like <poll.h>.

Files:
lib/poll.in.h
m4/poll_h.m4

Depends-on:
c++defs
warn-on-use

configure.ac:
gl_POLL_H

Makefile.am:
BUILT_SOURCES += $(POLL_H)

# We need the following in order to create <poll.h> when the system
# doesn't have one.
poll.h: poll.in.h $(CXXDEFS_H) $(WARN_ON_USE_H)
        $(AM_V_GEN)rm -f address@hidden $@ && \
        { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
          sed -e 's|@''GNULIB_POLL''@|$(GNULIB_POLL)|g' \
              -e 's|@''HAVE_POLL''@|$(HAVE_POLL)|g' \
              -e 's|@''REPLACE_POLL''@|$(REPLACE_POLL)|g' \
              -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
              -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
              < $(srcdir)/poll.in.h; \
        } > address@hidden && \
        mv -f address@hidden $@
MOSTLYCLEANFILES += poll.h poll.h-t

Include:
<poll.h>

License:
LGPLv2+

Maintainer:
Paolo Bonzini, Bruno Haible
================================ m4/poll_h.m4 ================================
# poll_h.m4 serial 1
dnl Copyright (C) 2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl Written by Bruno Haible.

AC_DEFUN([gl_POLL_H],
[
  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
  dnl once only, before all statements that occur in other macros.
  AC_REQUIRE([gl_POLL_H_DEFAULTS])

  AC_CHECK_HEADERS_ONCE([poll.h])
  if test $ac_cv_header_poll_h != yes; then
    gl_REPLACE_POLL_H
  fi

  dnl Check for declarations of anything we want to poison if the
  dnl corresponding gnulib module is not in use.
  gl_WARN_ON_USE_PREPARE([[#include <poll.h>]],
    [poll])
])

dnl Unconditionally enables the replacement of <poll.h>.
AC_DEFUN([gl_REPLACE_POLL_H],
[
  AC_REQUIRE([gl_POLL_H_DEFAULTS])
  POLL_H='poll.h'
])

AC_DEFUN([gl_POLL_MODULE_INDICATOR],
[
  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
  AC_REQUIRE([gl_POLL_H_DEFAULTS])
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
  dnl Define it also as a C macro, for the benefit of the unit tests.
  gl_MODULE_INDICATOR_FOR_TESTS([$1])
])

AC_DEFUN([gl_POLL_H_DEFAULTS],
[
  GNULIB_POLL=0;        AC_SUBST([GNULIB_POLL])
  dnl Assume proper GNU behavior unless another module says otherwise.
  POLL_H='';            AC_SUBST([POLL_H])
  HAVE_POLL=1;          AC_SUBST([HAVE_POLL])
  REPLACE_POLL=0;       AC_SUBST([REPLACE_POLL])
])
==============================================================================
--- doc/posix-headers/poll.texi.orig    Wed Sep 29 00:59:46 2010
+++ doc/posix-headers/poll.texi Tue Sep 28 23:30:01 2010
@@ -3,7 +3,7 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/susv3xbd/poll.h.html}
 
-Gnulib module: poll
+Gnulib module: poll-h
 
 Portability problems fixed by Gnulib:
 @itemize
--- lib/poll.c.orig     Wed Sep 29 00:59:46 2010
+++ lib/poll.c  Tue Sep 28 23:18:20 2010
@@ -28,7 +28,10 @@
 #include <alloca.h>
 
 #include <sys/types.h>
-#include "poll.h"
+
+/* Specification.  */
+#include <poll.h>
+
 #include <errno.h>
 #include <limits.h>
 #include <assert.h>
--- lib/poll.in.h.orig  Wed Sep 29 00:59:46 2010
+++ lib/poll.in.h       Wed Sep 29 00:49:26 2010
@@ -22,6 +22,12 @@
 #ifndef _GL_POLL_H
 #define _GL_POLL_H
 
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+
 /* fake a poll(2) environment */
 #define POLLIN      0x0001      /* any readable data available   */
 #define POLLPRI     0x0002      /* OOB/Urgent readable data      */
@@ -43,11 +49,33 @@
 
 typedef unsigned long nfds_t;
 
-extern int poll (struct pollfd *pfd, nfds_t nfd, int timeout);
+#if @GNULIB_POLL@
+# if @REPLACE_POLL@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef poll
+#   define poll rpl_poll
+#  endif
+_GL_FUNCDECL_RPL (poll, int, (struct pollfd *pfd, nfds_t nfd, int timeout));
+_GL_CXXALIAS_RPL (poll, int, (struct pollfd *pfd, nfds_t nfd, int timeout));
+# else
+#  if address@hidden@
+_GL_FUNCDECL_SYS (poll, int, (struct pollfd *pfd, nfds_t nfd, int timeout));
+#  endif
+_GL_CXXALIAS_SYS (poll, int, (struct pollfd *pfd, nfds_t nfd, int timeout));
+# endif
+_GL_CXXALIASWARN (poll);
+#elif defined GNULIB_POSIXCHECK
+# undef poll
+# if HAVE_RAW_DECL_POLL
+_GL_WARN_ON_USE (poll, "poll is unportable - "
+                 "use gnulib module poll for portability");
+# endif
+#endif
 
 /* Define INFTIM only if doing so conforms to POSIX.  */
 #if !defined (_POSIX_C_SOURCE) && !defined (_XOPEN_SOURCE)
 #define INFTIM (-1)
 #endif
 
+
 #endif /* _GL_POLL_H */
--- m4/poll.m4.orig     Wed Sep 29 00:59:46 2010
+++ m4/poll.m4  Wed Sep 29 00:11:10 2010
@@ -1,4 +1,4 @@
-# poll.m4 serial 9
+# poll.m4 serial 10
 dnl Copyright (c) 2003, 2005, 2006, 2007, 2009, 2010 Free Software Foundation,
 dnl Inc.
 dnl This file is free software; the Free Software Foundation
@@ -7,8 +7,9 @@
 
 AC_DEFUN([gl_FUNC_POLL],
 [
-  AC_CHECK_HEADERS([poll.h])
+  AC_REQUIRE([gl_POLL_H])
   if test "$ac_cv_header_poll_h" = no; then
+    ac_cv_func_poll=no
     gl_cv_func_poll=no
   else
     AC_CHECK_FUNC([poll],
@@ -51,18 +52,22 @@
 #endif
 ], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
   fi
-  if test $gl_cv_func_poll = yes; then
-    AC_DEFINE([HAVE_POLL], [1],
-      [Define to 1 if you have the 'poll' function and it works.])
-    POLL_H=
-  else
+  if test $gl_cv_func_poll != yes; then
+    AC_CHECK_FUNC([poll], [ac_cv_func_poll=yes], [ac_cv_func_poll=no])
+    if test $ac_cv_func_poll = no; then
+      HAVE_POLL=0
+    else
+      REPLACE_POLL=1
+    fi
+  fi
+  if test $HAVE_POLL = 0 || $REPLACE_POLL = 1; then
+    gl_REPLACE_POLL_H
     AC_LIBOBJ([poll])
-    AC_DEFINE([poll], [rpl_poll],
-      [Define to poll if the replacement function should be used.])
     gl_PREREQ_POLL
-    POLL_H=poll.h
+  else
+    AC_DEFINE([HAVE_POLL], [1],
+      [Define to 1 if you have the 'poll' function and it works.])
   fi
-  AC_SUBST([POLL_H])
 ])
 
 # Prerequisites of lib/poll.c.
--- modules/poll.orig   Wed Sep 29 00:59:46 2010
+++ modules/poll        Tue Sep 28 23:51:15 2010
@@ -3,10 +3,10 @@
 
 Files:
 lib/poll.c
-lib/poll.in.h
 m4/poll.m4
 
 Depends-on:
+poll-h
 alloca
 select
 sys_select
@@ -15,19 +15,9 @@
 
 configure.ac:
 gl_FUNC_POLL
+gl_POLL_MODULE_INDICATOR([poll])
 
 Makefile.am:
-BUILT_SOURCES += $(POLL_H)
-
-# We need the following in order to create <poll.h> when the system
-# doesn't have one.
-poll.h: poll.in.h
-       $(AM_V_GEN)rm -f address@hidden $@ && \
-       { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
-         cat $(srcdir)/poll.in.h; \
-       } > address@hidden && \
-       mv -f address@hidden $@
-MOSTLYCLEANFILES += poll.h poll.h-t
 
 Include:
 <poll.h>
--- tests/test-poll.c.orig      Wed Sep 29 00:59:46 2010
+++ tests/test-poll.c   Tue Sep 28 23:40:34 2010
@@ -19,6 +19,7 @@
 
 #include <config.h>
 
+/* Specification.  */
 #include <poll.h>
 
 #include "signature.h"