Re: [autoconf] AmigaOS fork()

[Rüdiger Kuhlmann]

2001-06-15 Rüdiger Kuhlmann <address@hidden>
 
        * acfunctions.m4: (AC_FUNC_VFORK) renamed to _AC_FUNC_VFORK. Remove
          AC_DEFINEs and don't guess cross-compilation values.
          (_AC_FUNC_FORK) New, check whether fork() isn't just a stub.
          (AC_FUNC_FORK) New, use _AC_FUNC_VFORK and _AC_FUNC_FORK to
          define HAVE_WORKING_FORK, HAVE_WORKING_VFORK; and vfork to fork
          if vfork doesn't work. Guess values if cross-compiling, but warn.
        * acfunctions: add AC_FUNC_FORK.
        * doc/autoconf.texi: Document AC_FUNC_FORK. Give example to
          define and vfork appropriately.

Index: acfunctions
===================================================================
RCS file: /cvs/autoconf/acfunctions,v
retrieving revision 1.14
diff -u -r1.14 acfunctions
--- acfunctions 2001/05/31 15:44:27     1.14
+++ acfunctions 2001/06/17 14:13:06
@@ -26,6 +26,7 @@
 error          AC_FUNC_ERROR_AT_LINE
 error_at_line  AC_FUNC_ERROR_AT_LINE
 fnmatch                AC_FUNC_FNMATCH
+fork           AC_FUNC_FORK     
 fseeko         AC_FUNC_FSEEKO
 ftello         AC_FUNC_FSEEKO
 getgroups      AC_FUNC_GETGROUPS
@@ -56,7 +57,7 @@
 strftime       AC_FUNC_STRFTIME
 strtod         AC_FUNC_STRTOD
 utime          AC_FUNC_UTIME_NULL
-vfork          AC_FUNC_VFORK
+vfork          AC_FUNC_FORK
 vfprintf       AC_FUNC_VPRINTF
 vprintf                AC_FUNC_VPRINTF
 vsprintf       AC_FUNC_VPRINTF
Index: acfunctions.m4
===================================================================
RCS file: /cvs/autoconf/acfunctions.m4,v
retrieving revision 1.37
diff -u -r1.37 acfunctions.m4
--- acfunctions.m4      2001/06/15 17:44:17     1.37
+++ acfunctions.m4      2001/06/17 14:13:10
@@ -1443,12 +1443,74 @@
 AU_ALIAS([AC_UTIME_NULL], [AC_FUNC_UTIME_NULL])
 
 
-# AC_FUNC_VFORK
+# AC_FUNC_FORK
 # -------------
-AC_DEFUN([AC_FUNC_VFORK],
-[AC_REQUIRE([AC_TYPE_PID_T])dnl
-AC_CHECK_HEADERS(unistd.h vfork.h)
-AC_CACHE_CHECK(for working vfork, ac_cv_func_vfork_works,
+AC_DEFUN([AC_FUNC_FORK],
+  [AC_REQUIRE([AC_TYPE_PID_T])dnl
+  AC_CHECK_HEADERS(unistd.h vfork.h)
+  AC_CHECK_FUNCS(fork vfork)
+  ac_cv_func_fork_works=$ac_cv_func_fork
+  if test "x$ac_cv_func_fork" = xyes; then
+    _AC_FUNC_FORK
+  fi
+  if test "x$ac_cv_func_fork_works" = xcross"; then
+    case "$host" in
+      *-*-amigaos* | *-*-msdosdjgpp*)
+        # Override, as these systems have only a dummy fork() stub
+        ac_cv_func_fork_works=no
+        ;;
+      *)
+        ac_cv_func_fork_works=yes
+        ;;
+    esac
+    AC_MSG_WARN(CROSS: Result $ac_cv_func_fork_works guessed due to 
cross-compiling.)
+  fi
+  ac_cv_func_vfork_works=$ac_cv_func_vfork
+  if test "x$ac_cv_func_vfork" = xyes; then
+    _AC_FUNC_VFORK
+  fi;
+  if test "x$ac_cv_func_fork_works" = xcross"; then
+    ac_cv_func_vfork_works=ac_cv_func_vfork
+    AC_MSG_WARN(CROSS: Result $ac_cv_func_vfork_works guessed due to 
cross-compiling.)
+  fi
+  
+  if test "x$ac_cv_func_vfork_works" = xyes; then
+    AC_DEFINE(HAVE_WORKING_VFORK, 1, [Define if `vfork' works.])
+  else
+    AC_DEFINE(vfork, fork, [Define as `fork' if `vfork' does not work.])
+  fi
+  if test "x$ac_cv_func_fork_works" = xyes; then
+    AC_DEFINE(HAVE_WORKING_FORK, 1, [Define if `fork' works.])
+  endif
+])# AC_FUNC_FORK
+
+
+# _AC_FUNC_FORK
+# -------------
+AC_DEFUN([_AC_FUNC_FORK],
+  [AC_CACHE_CHECK(for working fork, ac_cv_func_fork_works,
+    [AC_RUN_IFELSE([/* By Rüdiger Kuhlmann. */
+      #include <sys/types.h>
+      #if HAVE_UNISTD_H
+      # include <unistd.h>
+      #endif
+      /* Some systems only have a dummy stub for fork() */
+      int main ()
+      {
+        if (fork() < 0)
+          exit (1);
+        exit (0);
+      }],
+    [ac_cv_func_fork_works=yes],
+    [ac_cv_func_fork_works=no],
+    [ac_cv_func_fork_works=cross])])]
+)# _AC_FUNC_FORK
+
+
+# _AC_FUNC_VFORK
+# -------------
+AC_DEFUN([_AC_FUNC_VFORK],
+[AC_CACHE_CHECK(for working vfork, ac_cv_func_vfork_works,
 [AC_TRY_RUN([/* Thanks to Paul Eggert for this test.  */
 #include <stdio.h>
 #include <sys/types.h>
@@ -1544,17 +1606,17 @@
 }],
             [ac_cv_func_vfork_works=yes],
             [ac_cv_func_vfork_works=no],
-            [AC_CHECK_FUNC(vfork)
-ac_cv_func_vfork_works=$ac_cv_func_vfork])])
-if test "x$ac_cv_func_vfork_works" = xno; then
-  AC_DEFINE(vfork, fork, [Define as `fork' if `vfork' does not work.])
-fi
-])# AC_FUNC_VFORK
+            [ac_cv_func_vfork_works=cross])])
+])# _AC_FUNC_VFORK
 
 
+# AU::AC_FUNC_VFORK
+# ------------
+AU_ALIAS([AC_FUNC_VFORK], [AC_FUNC_FORK])
+
 # AU::AC_VFORK
 # ------------
-AU_ALIAS([AC_VFORK], [AC_FUNC_VFORK])
+AU_ALIAS([AC_VFORK], [AC_FUNC_FORK])
 
 
 # AC_FUNC_VPRINTF
Index: doc/autoconf.texi
===================================================================
RCS file: /cvs/autoconf/doc/autoconf.texi,v
retrieving revision 1.467
diff -u -r1.467 autoconf.texi
--- doc/autoconf.texi   2001/06/15 17:44:17     1.467
+++ doc/autoconf.texi   2001/06/17 14:14:52
@@ -3233,6 +3233,38 @@
 Solaris 2.4), define @code{HAVE_FNMATCH}.
 @end defmac
 
address@hidden AC_FUNC_FORK
address@hidden FUNC_FORK
address@hidden HAVE_VFORK_H
address@hidden HAVE_WORKING_FORK
address@hidden HAVE_WORKING_VFORK
address@hidden vfork
+This macro checks for the @code{fork} and @code{vfork} functions. If a
+working @code{fork} is found, define @code{HAVE_WORKING_FORK}. This macro
+checks whether @code{fork} is just a stub by trying to run it.
+
+If @file{vfork.h} is found, define @code{HAVE_VFORK_H}. If a working
address@hidden is found, define @code{HAVE_WORKING_VFORK}. Otherwise,
+define @code{vfork} to be @code{fork} for backward compatibility with
+previous versions of @command{autoconf}. This macro checks for several known
+errors in implementations of @code{vfork} and considers the system to not
+have a working @code{vfork} if it detects any of them. It is not considered
+to be an implementation error if a child's invocation of @code{signal}
+modifies the parent's signal handler, since child processes rarely change
+their signal handlers.
+
+Since this macro defines @code{vfork} only for backward compatibility with
+previous versions of @command{autoconf} you're encouraged to define it
+yourself in new code:
address@hidden
address@hidden
+#if !HAVE_WORKING_VFORK
+# define vfork fork
+#endif
address@hidden group
address@hidden example
address@hidden defmac
+
 @defmac AC_FUNC_FSEEKO
 @maindex FUNC_FSEEKO
 @cvindex _LARGEFILE_SOURCE
@@ -3461,19 +3493,6 @@
 @cvindex HAVE_UTIME_NULL
 If @samp{utime(@var{file}, NULL)} sets @var{file}'s timestamp to
 the present, define @code{HAVE_UTIME_NULL}.
address@hidden defmac
-
address@hidden AC_FUNC_VFORK
address@hidden FUNC_VFORK
address@hidden HAVE_VFORK_H
address@hidden vfork
-If @file{vfork.h} is found, define @code{HAVE_VFORK_H}.  If a working
address@hidden is not found, define @code{vfork} to be @code{fork}.  This
-macro checks for several known errors in implementations of @code{vfork}
-and considers the system to not have a working @code{vfork} if it
-detects any of them.  It is not considered to be an implementation error
-if a child's invocation of @code{signal} modifies the parent's signal
-handler, since child processes rarely change their signal handlers.
 @end defmac
 
 @defmac AC_FUNC_VPRINTF


-- 
A "No" uttered from deepest conviction is better and greater than a
"Yes" merely uttered to please, or what is worse, to avoid trouble.
                -- Mahatma Ghandi