Issue #6834: replace the implementation for the 'python' and 'pythonw' executables on OSX.

The previous implementation used execv(2) to run the real interpreter, which means that
you cannot use the arch(1) tool to select the architecture you want to use for a
universal build because that only affects the python/pythonw wrapper and not the actual
interpreter.

The new version uses posix_spawnv with a number of OSX-specific options that ensure that
the real interpreter is started using the same CPU architecture as the wrapper, and that
means that 'arch -ppc python' now actually works.

I've also changed the way that the wrapper looks for the framework: it is now linked to
the framework rather than hardcoding the framework path. This should make it easier to
provide pythonw support in tools like virtualenv.

6 files changed, 189 insertions, 62 deletions

diff --git a/Mac/IDLE/Info.plist.in b/Mac/IDLE/Info.plist.in
index 58e913c569..1da402c9c6 100644
--- a/Mac/IDLE/Info.plist.in
+++ b/Mac/IDLE/Info.plist.in
@@ -51,5 +51,14 @@
 	<string>%VERSION%</string>
 	<key>CFBundleVersion</key>
 	<string>%VERSION%</string>
+<!--
+	<key>LSMinimumSystemVersionByArchitecture</key>
+	<dict>
+	    <key>x86_64</key>
+	    <string>10.6.0</string>
+	    <key>ppc64</key>
+	    <string>10.6.0</string>
+	</dict>
+-->
 </dict>
 </plist>
diff --git a/Mac/IDLE/Makefile.in b/Mac/IDLE/Makefile.in
index 496c139e72..54468649c0 100644
--- a/Mac/IDLE/Makefile.in
+++ b/Mac/IDLE/Makefile.in
@@ -10,6 +10,8 @@ VERSION=	@VERSION@
 UNIVERSALSDK=@UNIVERSALSDK@
 builddir=	../..
 PYTHONFRAMEWORK=@PYTHONFRAMEWORK@
+LIPO_32BIT_FLAGS=@LIPO_32BIT_FLAGS@
+
 
 RUNSHARED=      @RUNSHARED@
 BUILDEXE=       @BUILDEXEEXT@
@@ -51,9 +53,12 @@ IDLE.app:  \
 		--iconfile=$(srcdir)/../Icons/IDLE.icns \
 		--resource=$(srcdir)/../Icons/PythonSource.icns \
 		--resource=$(srcdir)/../Icons/PythonCompiled.icns \
-		--python=$(prefix)/Resources/Python.app/Contents/MacOS/$(PYTHONFRAMEWORK)`test -f "$(DESTDIR)$(prefix)/Resources/Python.app/Contents/MacOS/$(PYTHONFRAMEWORK)-32" && echo "-32"`  \
+		--python=$(prefix)/Resources/Python.app/Contents/MacOS/Python \
 		build
-
+ifneq ($(LIPO_32BIT_FLAGS),)
+	rm "IDLE.app/Contents/MacOS/Python"
+	lipo $(LIPO_32BIT_FLAGS) -output "IDLE.app/Contents/MacOS/Python" "$(BUILDPYTHON)"
+endif
 
 Info.plist: $(srcdir)/Info.plist.in
 	sed 's/%VERSION%/'"`$(RUNSHARED) $(BUILDPYTHON) -c 'import platform; print platform.python_version()'`"'/g' < $(srcdir)/Info.plist.in > Info.plist
diff --git a/Mac/IDLE/idlemain.py b/Mac/IDLE/idlemain.py
index d6803ba832..8b8beb93d0 100644
--- a/Mac/IDLE/idlemain.py
+++ b/Mac/IDLE/idlemain.py
@@ -48,7 +48,7 @@ os.chdir(os.path.expanduser('~/Documents'))
 # the interpreter in the framework, by following the symlink
 # exported in PYTHONEXECUTABLE.
 pyex = os.environ['PYTHONEXECUTABLE']
-sys.executable = os.path.join(os.path.dirname(pyex), os.readlink(pyex))
+sys.executable = os.path.join(sys.prefix, 'bin', 'python%d.%d'%(sys.version_info[:2]))
 
 # Remove any sys.path entries for the Resources dir in the IDLE.app bundle.
 p = pyex.partition('.app')
@@ -68,6 +68,8 @@ for idx, value in enumerate(sys.argv):
         break
 
 # Now it is safe to import idlelib.
+from idlelib import macosxSupport
+macosxSupport._appbundle = True
 from idlelib.PyShell import main
 if __name__ == '__main__':
     main()
diff --git a/Mac/Makefile.in b/Mac/Makefile.in
index b9fd377c79..8c389eddcd 100644
--- a/Mac/Makefile.in
+++ b/Mac/Makefile.in
@@ -15,6 +15,7 @@ LDFLAGS=@LDFLAGS@
 FRAMEWORKUNIXTOOLSPREFIX=@FRAMEWORKUNIXTOOLSPREFIX@
 PYTHONFRAMEWORK=@PYTHONFRAMEWORK@
 PYTHONFRAMEWORKIDENTIFIER=@PYTHONFRAMEWORKIDENTIFIER@
+LIPO_32BIT_FLAGS=@LIPO_32BIT_FLAGS@
 
 
 # These are normally glimpsed from the previous set
@@ -42,10 +43,8 @@ APPSUBDIRS=MacOS Resources
 CACHERSRC=$(srcdir)/scripts/cachersrc.py
 compileall=$(srcdir)/../Lib/compileall.py
 
-installapps: install_Python install_BuildApplet install_PythonLauncher \
-	install_IDLE checkapplepython install_pythonw install_versionedtools
-
-installapps4way: install_Python4way install_BuildApplet install_PythonLauncher install_IDLE install_pythonw4way install_versionedtools
+installapps: install_Python install_pythonw install_BuildApplet install_PythonLauncher \
+	install_IDLE checkapplepython install_versionedtools
 
 
 install_pythonw: pythonw
@@ -53,33 +52,13 @@ install_pythonw: pythonw
 	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw "$(DESTDIR)$(prefix)/bin/python$(VERSION)"
 	ln -sf python$(VERSION) "$(DESTDIR)$(prefix)/bin/python"
 	ln -sf pythonw$(VERSION) "$(DESTDIR)$(prefix)/bin/pythonw"
-
-
-# Install 3 variants of python/pythonw: 
-# 	- 32-bit (i386 and ppc)
-# 	- 64-bit (x86_64 and ppc64)
-# 	- all    (all four architectures)
-# 	- Make 'python' and 'pythonw' aliases for the 32-bit variant
-install_pythonw4way: pythonw-32 pythonw-64 pythonw
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw-64 "$(DESTDIR)$(prefix)/bin/pythonw$(VERSION)-64"
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw-64 "$(DESTDIR)$(prefix)/bin/python$(VERSION)-64"
-	ln -sf python$(VERSION)-64 "$(DESTDIR)$(prefix)/bin/python-64"
-	ln -sf pythonw$(VERSION)-64 "$(DESTDIR)$(prefix)/bin/pythonw-64"
-
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw-32 "$(DESTDIR)$(prefix)/bin/pythonw$(VERSION)-32"
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw-32 "$(DESTDIR)$(prefix)/bin/python$(VERSION)-32"
+ifneq ($(LIPO_32BIT_FLAGS),)
+	lipo $(LIPO_32BIT_FLAGS) -output $(DESTDIR)$(prefix)/bin/python$(VERSION)-32 pythonw
+	lipo $(LIPO_32BIT_FLAGS) -output $(DESTDIR)$(prefix)/bin/pythonw$(VERSION)-32 pythonw
 	ln -sf python$(VERSION)-32 "$(DESTDIR)$(prefix)/bin/python-32"
 	ln -sf pythonw$(VERSION)-32 "$(DESTDIR)$(prefix)/bin/pythonw-32"
+endif
 
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw "$(DESTDIR)$(prefix)/bin/pythonw$(VERSION)-all"
-	$(INSTALL_PROGRAM) $(STRIPFLAG) pythonw "$(DESTDIR)$(prefix)/bin/python$(VERSION)-all"
-	ln -sf python$(VERSION)-all "$(DESTDIR)$(prefix)/bin/python-all"
-	ln -sf pythonw$(VERSION)-all "$(DESTDIR)$(prefix)/bin/pythonw-all"
-
-	ln -sf pythonw$(VERSION)-32	"$(DESTDIR)$(prefix)/bin/pythonw$(VERSION)"
-	ln -sf python$(VERSION)-32	"$(DESTDIR)$(prefix)/bin/python$(VERSION)"
-	ln -sf pythonw$(VERSION)-32	"$(DESTDIR)$(prefix)/bin/pythonw"
-	ln -sf python$(VERSION)-32	"$(DESTDIR)$(prefix)/bin/python"
 
 #
 # Install unix tools in /usr/local/bin. These are just aliases for the 
@@ -97,10 +76,6 @@ installunixtools:
 	done
 
 
-# TODO: install symlinks for -32, -64 and -all as well
-installunixtools4way: installunixtools
-
-
 #
 # Like installunixtools, but only install links to the versioned binaries.
 #
@@ -114,9 +89,6 @@ altinstallunixtools:
 		ln -fs "$(prefix)/bin/$${fn}" "$(DESTDIR)$(FRAMEWORKUNIXTOOLSPREFIX)/bin/$${fn}" ;\
 	done
 
-# TODO: -32, -64 and -all variants
-altinstallunixtools4way: altinstallunixtools
-
 # By default most tools are installed without a version in their basename, to
 # make it easier to install (and use) several python versions side-by-side move
 # the tools to a version-specific name and add the non-versioned name as an
@@ -141,16 +113,7 @@ install_versionedtools:
 
 
 pythonw: $(srcdir)/Tools/pythonw.c Makefile
-	$(CC) $(LDFLAGS) -o $@ $(srcdir)/Tools/pythonw.c \
-		-DPYTHONWEXECUTABLE='"$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)"'
-
-pythonw-32: $(srcdir)/Tools/pythonw.c Makefile
-	$(CC) $(LDFLAGS) -o $@ -arch i386 -arch ppc $(srcdir)/Tools/pythonw.c \
-		-DPYTHONWEXECUTABLE='"$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)-32"'
-
-pythonw-64: $(srcdir)/Tools/pythonw.c Makefile
-	$(CC) $(LDFLAGS) -o $@ -arch x86_64 -arch ppc64 $(srcdir)/Tools/pythonw.c \
-		-DPYTHONWEXECUTABLE='"$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)-64"'
+	$(CC) $(LDFLAGS) -o $@ $(srcdir)/Tools/pythonw.c -I.. -I$(srcdir)/../Include ../$(PYTHONFRAMEWORK).framework/Versions/$(VERSION)/$(PYTHONFRAMEWORK)
 
 install_PythonLauncher:
 	cd PythonLauncher && make install DESTDIR=$(DESTDIR)
@@ -206,11 +169,6 @@ install_Python:
 		> "$(DESTDIR)$(APPINSTALLDIR)/Contents/Info.plist"
 	rm "$(DESTDIR)$(APPINSTALLDIR)/Contents/Info.plist.in"
 
-install_Python4way: install_Python
-	lipo  -extract i386 -extract ppc7400 -output "$(DESTDIR)$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)-32" "$(DESTDIR)$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)"
-	lipo  -extract x86_64 -extract ppc64 -output "$(DESTDIR)$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)-64" "$(DESTDIR)$(APPINSTALLDIR)/Contents/MacOS/$(PYTHONFRAMEWORK)"
-
-
 
 install_IDLE:
 	cd IDLE && make install
@@ -218,9 +176,13 @@ install_IDLE:
 install_BuildApplet:
 	$(RUNSHARED) @ARCH_RUN_32BIT@ $(BUILDPYTHON) $(srcdir)/scripts/BuildApplet.py \
 		--destroot "$(DESTDIR)" \
-		--python=$(prefix)/Resources/Python.app/Contents/MacOS/$(PYTHONFRAMEWORK)`test -f "$(DESTDIR)$(prefix)/Resources/Python.app/Contents/MacOS/$(PYTHONFRAMEWORK)-32" && echo "-32"`  \
+		--python=$(prefix)/Resources/Python.app/Contents/MacOS/Python \
 		--output "$(DESTDIR)$(PYTHONAPPSDIR)/Build Applet.app" \
 		$(srcdir)/scripts/BuildApplet.py
+ifneq ($(LIPO_32BIT_FLAGS),)
+	rm "$(DESTDIR)$(PYTHONAPPSDIR)/Build Applet.app/Contents/MacOS/Python"
+	lipo $(LIPO_32BIT_FLAGS) -output "$(DESTDIR)$(PYTHONAPPSDIR)/Build Applet.app/Contents/MacOS/Python" $(BUILDPYTHON)
+endif   
 
 MACLIBDEST=$(LIBDEST)/plat-mac
 MACTOOLSDEST=$(prefix)/Mac/Tools
diff --git a/Mac/README b/Mac/README
index c4f6b655fb..988e624c4b 100644
--- a/Mac/README
+++ b/Mac/README
@@ -25,7 +25,7 @@ Mac-specific arguments to configure
   Create a universal binary build of of Python. This can be used with both
   regular and framework builds.
 
-  The optional argument specifies with OSX SDK should be used to perform the
+  The optional argument specifies which OSX SDK should be used to perform the
   build. This defaults to ``/Developer/SDKs/MacOSX.10.4u.sdk``, specify 
   ``/`` when building on a 10.5 system, especially when building 64-bit code.
 
@@ -88,10 +88,29 @@ values are available:
 
   * ``intel``:	  ``i386``, ``x86_64``
 
-To build a universal binary that includes a 64-bit architecture you must build
-on a system running OSX 10.5 or later. The ``all`` flavour can only be build on
+To build a universal binary that includes a 64-bit architecture, you must build
+on a system running OSX 10.5 or later. The ``all`` flavour can only be built on
 OSX 10.5.
 
+The makefile for a framework build will install ``python32`` and ``pythonw32`` 
+binaries when the universal architecures includes at least one 32-bit architecture
+(that is, for all flavours but ``64-bit``).
+
+Running a specific archicture
+.............................
+
+You can run code using a specific architecture using the ``arch`` command::
+
+   $ arch -i386 python
+
+Or to explicitly run in 32-bit mode, regardless of the machine hardware::
+
+   $ arch -i386 -ppc python
+
+NOTE: When you're using a framework install of Python this requires at least
+Python 2.7 or 3.2, in earlier versions the python (and pythonw) commands are
+wrapper tools that execute the real interpreter without ensuring that the
+real interpreter runs with the same architecture.
 
 Building and using a framework-based Python on Mac OS X.
 ========================================================
diff --git a/Mac/Tools/pythonw.c b/Mac/Tools/pythonw.c
index e70a76f846..d7a86f2643 100644
--- a/Mac/Tools/pythonw.c
+++ b/Mac/Tools/pythonw.c
@@ -3,15 +3,145 @@
  * application bundle inside the Python framework. This is needed to run
  * GUI code: some GUI API's don't work unless the program is inside an
  * application bundle.
+ *
+ * This program uses posix_spawn rather than plain execv because we need
+ * slightly more control over how the "real" interpreter is executed.
  */
 #include <unistd.h>
+#include <spawn.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
 #include <err.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <Python.h>
 
-static char Python[] = PYTHONWEXECUTABLE;
 
-int main(int argc, char **argv) {
-	argv[0] = Python;
-	execv(Python, argv);
-	err(1, "execv: %s", Python);
+extern char** environ;
+
+/*
+ * Locate the python framework by looking for the
+ * library that contains Py_Initialize.
+ *
+ * In a regular framework the structure is:
+ *
+ *    Python.framework/Versions/2.7
+ *    		/Python
+ *		/Resources/Python.app/Contents/MacOS/Python
+ *
+ * In a virtualenv style structure the expected
+ * structure is:
+ *
+ *    ROOT
+ *       /bin/pythonw
+ *       /.Python   <- the dylib
+ *       /.Resources/Python.app/Contents/MacOS/Python
+ *
+ * NOTE: virtualenv's are not an officially supported 
+ * feature, support for that structure is provided as
+ * a convenience.
+ */
+static char* get_python_path(void)
+{
+	size_t len;
+	Dl_info info;
+	char* end;
+	char* g_path;
+
+	if (dladdr(Py_Initialize, &info) == 0) {
+		return NULL;
+	}
+
+	len = strlen(info.dli_fname);
+
+	g_path = malloc(len+60);
+	if (g_path == NULL) {
+		return NULL;
+	}
+
+	strcpy(g_path, info.dli_fname);
+	end = g_path + len - 1;
+	while (end != g_path && *end != '/') {
+		end --;
+	}
+	end++;
+	if (end[1] == '.') {
+		end++;
+	}
+	strcpy(end, "Resources/Python.app/Contents/MacOS/Python");
+
+	return g_path;
+}
+
+static void
+setup_spawnattr(posix_spawnattr_t* spawnattr)
+{
+	size_t ocount;
+	size_t count;
+	cpu_type_t cpu_types[1];
+	short flags = 0;
+#ifdef __LP64__
+	int   ch;
+#endif
+
+	if ((errno = posix_spawnattr_init(spawnattr)) != 0) {
+		err(2, "posix_spawnattr_int");
+		/* NOTREACHTED */
+	}
+
+	count = 1;
+
+	/* Run the real python executable using the same architure as this 
+	 * executable, this allows users to controle the architecture using 
+	 * "arch -ppc python"
+	 */
+
+#if defined(__ppc64__)
+	cpu_types[0] = CPU_TYPE_POWERPC64;
+
+#elif defined(__x86_64__)
+	cpu_types[0] = CPU_TYPE_X86_64;
+
+#elif defined(__ppc__)
+	cpu_types[0] = CPU_TYPE_POWERPC;
+#elif defined(__i386__)
+	cpu_types[0] = CPU_TYPE_X86;
+#else
+#	error "Unknown CPU"
+#endif
+
+	if (posix_spawnattr_setbinpref_np(spawnattr, count, 
+				cpu_types, &ocount) == -1) {
+		err(1, "posix_spawnattr_setbinpref");
+		/* NOTREACHTED */
+	}
+	if (count != ocount) {
+		fprintf(stderr, "posix_spawnattr_setbinpref failed to copy\n");
+		exit(1);
+		/* NOTREACHTED */
+	}
+
+
+	/* 
+	 * Set flag that causes posix_spawn to behave like execv
+	 */
+	flags |= POSIX_SPAWN_SETEXEC;
+	if ((errno = posix_spawnattr_setflags(spawnattr, flags)) != 0) {
+		err(1, "posix_spawnattr_setflags");
+		/* NOTREACHTED */
+	}
+}
+
+int 
+main(int argc, char **argv) {
+	posix_spawnattr_t spawnattr = NULL;
+	char* exec_path = get_python_path();
+
+
+	setup_spawnattr(&spawnattr);		
+	posix_spawn(NULL, exec_path, NULL,
+		&spawnattr, argv, environ);
+	err(1, "posix_spawn: %s", argv[0]);
 	/* NOTREACHED */
 }