/*
 * This wrapper program executes a python executable hidden inside an
 * 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.
 *
 * On OSX 10.4 (and earlier) this falls back to using exec because the
 * posix_spawnv functions aren't available there.
 */

#pragma weak_import posix_spawnattr_init
#pragma weak_import posix_spawnattr_setbinpref_np
#pragma weak_import posix_spawnattr_setflags
#pragma weak_import posix_spawn

#include <Python.h>
#include <unistd.h>
#ifdef HAVE_SPAWN_H
#include <spawn.h>
#endif
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <err.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <Python.h>
#include <mach-o/dyld.h>


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 == '.') {
 end++;
 }
 strcpy(end, "Resources/Python.app/Contents/MacOS/" PYTHONFRAMEWORK);

 return g_path;
}

#ifdef HAVE_SPAWN_H
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 architecture as this
 * executable, this allows users to control 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 */
 }
}
#endif

int
main(int argc, char **argv) {
 char* exec_path = get_python_path();
 static char path[PATH_MAX * 2];
 static char real_path[PATH_MAX * 2];
 int status;
 uint32_t size = PATH_MAX * 2;

 /* Set the original executable path in the environment. */
 status = _NSGetExecutablePath(path, &size);
 if (status == 0) {
 /*
 * Note: don't call 'realpath', that will
 * erase symlink information, and that
 * breaks "pyvenv --symlink"
 *
 * It is nice to have the directory name
 * as a cleaned up absolute path though,
 * therefore call realpath on dirname(path)
 */
 char* slash = strrchr(path, '/');
 if (slash) {
 char replaced;
 replaced = slash[1];
 slash[1] = 0;
 if (realpath(path, real_path) == NULL) {
 err(1, "realpath: %s", path);
 }
 slash[1] = replaced;
 if (strlcat(real_path, slash, sizeof(real_path)) > sizeof(real_path)) {
 errno = EINVAL;
 err(1, "realpath: %s", path);
 }

 } else {
 if (realpath(".", real_path) == NULL) {
 err(1, "realpath: %s", path);
 }
 if (strlcat(real_path, "/", sizeof(real_path)) > sizeof(real_path)) {
 errno = EINVAL;
 err(1, "realpath: %s", path);
 }
 if (strlcat(real_path, path, sizeof(real_path)) > sizeof(real_path)) {
 errno = EINVAL;
 err(1, "realpath: %s", path);
 }
 }

 setenv("__PYVENV_LAUNCHER__", real_path, 1);
 }

 /*
 * Let argv[0] refer to the new interpreter. This is needed to
 * get the effect we want on OSX 10.5 or earlier. That is, without
 * changing argv[0] the real interpreter won't have access to
 * the Window Server.
 */
 argv[0] = exec_path;

#ifdef HAVE_SPAWN_H
 /* We're weak-linking to posix-spawnv to ensure that
 * an executable build on 10.5 can work on 10.4.
 */
 if (posix_spawn != NULL) {
 posix_spawnattr_t spawnattr = NULL;

 setup_spawnattr(&spawnattr);
 posix_spawn(NULL, exec_path, NULL,
 &spawnattr, argv, environ);
 err(1, "posix_spawn: %s", exec_path);
 }
#endif
 execve(exec_path, argv, environ);
 err(1, "execve: %s", argv[0]);
 /* NOTREACHED */
}