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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  * On OSX 10.4 (and earlier) this falls back to using exec because the
11  * posix_spawnv functions aren't available there.
12  */
13 #pragma weak_import posix_spawnattr_init
14 #pragma weak_import posix_spawnattr_setbinpref_np
15 #pragma weak_import posix_spawnattr_setflags
16 #pragma weak_import posix_spawn
17 
18 #include <Python.h>
19 #include <unistd.h>
20 #ifdef HAVE_SPAWN_H
21 #include <spawn.h>
22 #endif
23 #include <stdio.h>
24 #include <string.h>
25 #include <errno.h>
26 #include <err.h>
27 #include <dlfcn.h>
28 #include <stdlib.h>
29 
30 
31 extern char** environ;
32 
33 /*
34  * Locate the python framework by looking for the
35  * library that contains Py_Initialize.
36  *
37  * In a regular framework the structure is:
38  *
39  *    Python.framework/Versions/2.7
40  *              /Python
41  *              /Resources/Python.app/Contents/MacOS/Python
42  *
43  * In a virtualenv style structure the expected
44  * structure is:
45  *
46  *    ROOT
47  *       /bin/pythonw
48  *       /.Python   <- the dylib
49  *       /.Resources/Python.app/Contents/MacOS/Python
50  *
51  * NOTE: virtualenv's are not an officially supported
52  * feature, support for that structure is provided as
53  * a convenience.
54  */
get_python_path(void)55 static char* get_python_path(void)
56 {
57     size_t len;
58     Dl_info info;
59     char* end;
60     char* g_path;
61 
62     if (dladdr(Py_Initialize, &info) == 0) {
63         return NULL;
64     }
65 
66     len = strlen(info.dli_fname);
67 
68     g_path = malloc(len+60);
69     if (g_path == NULL) {
70         return NULL;
71     }
72 
73     strcpy(g_path, info.dli_fname);
74     end = g_path + len - 1;
75     while (end != g_path && *end != '/') {
76         end --;
77     }
78     end++;
79     if (*end == '.') {
80         end++;
81     }
82     strcpy(end, "Resources/Python.app/Contents/MacOS/" PYTHONFRAMEWORK);
83 
84     return g_path;
85 }
86 
87 #ifdef HAVE_SPAWN_H
88 static void
setup_spawnattr(posix_spawnattr_t * spawnattr)89 setup_spawnattr(posix_spawnattr_t* spawnattr)
90 {
91     size_t ocount;
92     size_t count;
93     cpu_type_t cpu_types[1];
94     short flags = 0;
95 #ifdef __LP64__
96     int   ch;
97 #endif
98 
99     if ((errno = posix_spawnattr_init(spawnattr)) != 0) {
100         err(2, "posix_spawnattr_int");
101         /* NOTREACHTED */
102     }
103 
104     count = 1;
105 
106     /* Run the real python executable using the same architecture as this
107      * executable, this allows users to control the architecture using
108      * "arch -ppc python"
109      */
110 
111 #if defined(__ppc64__)
112     cpu_types[0] = CPU_TYPE_POWERPC64;
113 
114 #elif defined(__x86_64__)
115     cpu_types[0] = CPU_TYPE_X86_64;
116 
117 #elif defined(__ppc__)
118     cpu_types[0] = CPU_TYPE_POWERPC;
119 #elif defined(__i386__)
120     cpu_types[0] = CPU_TYPE_X86;
121 #else
122 #       error "Unknown CPU"
123 #endif
124 
125     if (posix_spawnattr_setbinpref_np(spawnattr, count,
126                             cpu_types, &ocount) == -1) {
127         err(1, "posix_spawnattr_setbinpref");
128         /* NOTREACHTED */
129     }
130     if (count != ocount) {
131         fprintf(stderr, "posix_spawnattr_setbinpref failed to copy\n");
132         exit(1);
133         /* NOTREACHTED */
134     }
135 
136 
137     /*
138      * Set flag that causes posix_spawn to behave like execv
139      */
140     flags |= POSIX_SPAWN_SETEXEC;
141     if ((errno = posix_spawnattr_setflags(spawnattr, flags)) != 0) {
142         err(1, "posix_spawnattr_setflags");
143         /* NOTREACHTED */
144     }
145 }
146 #endif
147 
148 int
main(int argc,char ** argv)149 main(int argc, char **argv) {
150     char* exec_path = get_python_path();
151 
152     /*
153      * Let argv[0] refer to the new interpreter. This is needed to
154      * get the effect we want on OSX 10.5 or earlier. That is, without
155      * changing argv[0] the real interpreter won't have access to
156      * the Window Server.
157      */
158     argv[0] = exec_path;
159 
160 #ifdef HAVE_SPAWN_H
161 
162     /* We're weak-linking to posix-spawnv to ensure that
163      * an executable build on 10.5 can work on 10.4.
164      */
165     if (posix_spawn != NULL) {
166         posix_spawnattr_t spawnattr = NULL;
167 
168 
169         setup_spawnattr(&spawnattr);
170         posix_spawn(NULL, exec_path, NULL,
171             &spawnattr, argv, environ);
172         err(1, "posix_spawn: %s", exec_path);
173     }
174 #endif
175     execve(exec_path, argv, environ);
176     err(1, "execve: %s", argv[0]);
177     /* NOTREACHED */
178 }
179