Mac/Tools/pythonw.c

   1 /*
   2  * This wrapper program executes a python executable hidden inside an
   3  * application bundle inside the Python framework. This is needed to run
   4  * GUI code: some GUI API's don't work unless the program is inside an
   5  * application bundle.
   6  *
   7  * This program uses posix_spawn rather than plain execv because we need
   8  * slightly more control over how the "real" interpreter is executed.
   9  */
  10 #include <unistd.h>
  11 #include <spawn.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <errno.h>
  15 #include <err.h>
  16 #include <dlfcn.h>
  17 #include <stdlib.h>
  18 #include <Python.h>
  19
  20
  21 extern char** environ;
  22
  23 /*
  24  * Locate the python framework by looking for the
  25  * library that contains Py_Initialize.
  26  *
  27  * In a regular framework the structure is:
  28  *
  29  *    Python.framework/Versions/2.7
  30  *              /Python
  31  *              /Resources/Python.app/Contents/MacOS/Python
  32  *
  33  * In a virtualenv style structure the expected
  34  * structure is:
  35  *
  36  *    ROOT
  37  *       /bin/pythonw
  38  *       /.Python   <- the dylib
  39  *       /.Resources/Python.app/Contents/MacOS/Python
  40  *
  41  * NOTE: virtualenv's are not an officially supported
  42  * feature, support for that structure is provided as
  43  * a convenience.
  44  */
  45 static char* get_python_path(void)
  46 {
  47         size_t len;
  48         Dl_info info;
  49         char* end;
  50         char* g_path;
  51
  52         if (dladdr(Py_Initialize, &info) == 0) {
  53                 return NULL;
  54         }
  55
  56         len = strlen(info.dli_fname);
  57
  58         g_path = malloc(len+60);
  59         if (g_path == NULL) {
  60                 return NULL;
  61         }
  62
  63         strcpy(g_path, info.dli_fname);
  64         end = g_path + len - 1;
  65         while (end != g_path && *end != '/') {
  66                 end --;
  67         }
  68         end++;
  69         if (end[1] == '.') {
  70                 end++;
  71         }
  72         strcpy(end, "Resources/Python.app/Contents/MacOS/Python");
  73
  74         return g_path;
  75 }
  76
  77 static void
  78 setup_spawnattr(posix_spawnattr_t* spawnattr)
  79 {
  80         size_t ocount;
  81         size_t count;
  82         cpu_type_t cpu_types[1];
  83         short flags = 0;
  84 #ifdef __LP64__
  85         int   ch;
  86 #endif
  87
  88         if ((errno = posix_spawnattr_init(spawnattr)) != 0) {
  89                 err(2, "posix_spawnattr_int");
  90                 /* NOTREACHTED */
  91         }
  92
  93         count = 1;
  94
  95         /* Run the real python executable using the same architure as this
  96          * executable, this allows users to controle the architecture using
  97          * "arch -ppc python"
  98          */
  99
 100 #if defined(__ppc64__)
 101         cpu_types[0] = CPU_TYPE_POWERPC64;
 102
 103 #elif defined(__x86_64__)
 104         cpu_types[0] = CPU_TYPE_X86_64;
 105
 106 #elif defined(__ppc__)
 107         cpu_types[0] = CPU_TYPE_POWERPC;
 108 #elif defined(__i386__)
 109         cpu_types[0] = CPU_TYPE_X86;
 110 #else
 111 #       error "Unknown CPU"
 112 #endif
 113
 114         if (posix_spawnattr_setbinpref_np(spawnattr, count,
 115                                 cpu_types, &ocount) == -1) {
 116                 err(1, "posix_spawnattr_setbinpref");
 117                 /* NOTREACHTED */
 118         }
 119         if (count != ocount) {
 120                 fprintf(stderr, "posix_spawnattr_setbinpref failed to copy\n");
 121                 exit(1);
 122                 /* NOTREACHTED */
 123         }
 124
 125
 126         /*
 127          * Set flag that causes posix_spawn to behave like execv
 128          */
 129         flags |= POSIX_SPAWN_SETEXEC;
 130         if ((errno = posix_spawnattr_setflags(spawnattr, flags)) != 0) {
 131                 err(1, "posix_spawnattr_setflags");
 132                 /* NOTREACHTED */
 133         }
 134 }
 135
 136 int
 137 main(int argc, char **argv) {
 138         posix_spawnattr_t spawnattr = NULL;
 139         char* exec_path = get_python_path();
 140
 141
 142         setup_spawnattr(&spawnattr);
 143         posix_spawn(NULL, exec_path, NULL,
 144                 &spawnattr, argv, environ);
 145         err(1, "posix_spawn: %s", argv[0]);
 146         /* NOTREACHED */
 147 }