From 5f51c19502709228d5f6520412fb35167f078030 Mon Sep 17 00:00:00 2001
From: Roumen Petrov <local@example.net>
Date: Tue, 26 Feb 2013 23:56:16 +0200
Subject: [PATCH 06/24] MINGW: implement exec prefix

use content of pybuilddir.txt to find just build extentions
---
 PC/getpathp.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)

diff --git a/PC/getpathp.c b/PC/getpathp.c
index af77a2d..5ee058d 100644
--- a/PC/getpathp.c
+++ b/PC/getpathp.c
@@ -104,10 +104,17 @@ static wchar_t *lib_python = L"lib\\python" VERSION;
 
 #  define USE_POSIX_PREFIX
 
+#  ifdef Py_ENABLE_SHARED
+#    define USE_EXEC_PREFIX
+#  endif
+
 #endif
 
 
 static wchar_t prefix[MAXPATHLEN+1];
+#ifdef USE_EXEC_PREFIX
+static wchar_t exec_prefix[MAXPATHLEN+1];
+#endif
 static wchar_t progpath[MAXPATHLEN+1];
 static wchar_t dllpath[MAXPATHLEN+1];
 static wchar_t *module_search_path = NULL;
@@ -290,6 +297,82 @@ search_for_prefix(wchar_t *argv0_path, wchar_t *landmark)
 /* a string loaded from the DLL at startup.*/
 extern const char *PyWin_DLLVersionString;
 
+#ifdef USE_EXEC_PREFIX
+
+/* based on getpath.c but with path relative to executabe */
+/* search_for exec_prefix requires that paths be no more than
+   MAXPATHLEN bytes long.
+   return: 1 if found; -1 if found build directory
+*/
+static int
+search_for_exec_prefix(wchar_t *argv0_path, wchar_t *home, wchar_t *_exec_prefix)
+{
+    size_t n;
+
+    /* If PYTHONHOME is set, we believe it unconditionally */
+    if (home) {
+        wchar_t *delim;
+        delim = wcschr(home, DELIM);
+        if (delim)
+            wcsncpy(exec_prefix, delim+1, MAXPATHLEN);
+        else
+            wcsncpy(exec_prefix, home, MAXPATHLEN);
+        join(exec_prefix, lib_python);
+        join(exec_prefix, L"lib-dynload");
+        return 1;
+    }
+
+    /* Check to see if argv[0] is in the build directory. "pybuilddir.txt"
+       is written by setup.py and contains the relative path to the location
+       of shared library modules. */
+    wcscpy(exec_prefix, argv0_path);
+    join(exec_prefix, L"pybuilddir.txt");
+    if (exists(exec_prefix)) {
+        FILE *f = _Py_wfopen(exec_prefix, L"rb");
+        if (f == NULL)
+            errno = 0;
+        else {
+            char buf[MAXPATHLEN+1];
+            PyObject *decoded;
+            wchar_t rel_builddir_path[MAXPATHLEN+1];
+            n = fread(buf, 1, MAXPATHLEN, f);
+            buf[n] = '\0';
+            fclose(f);
+            decoded = PyUnicode_DecodeMBCS(buf, n, NULL);
+            if (decoded != NULL) {
+                Py_ssize_t k;
+                k = PyUnicode_AsWideChar(decoded,
+                                         rel_builddir_path, MAXPATHLEN);
+                Py_DECREF(decoded);
+                if (k >= 0) {
+                    rel_builddir_path[k] = L'\0';
+                    wcscpy(exec_prefix, argv0_path);
+                    join(exec_prefix, rel_builddir_path);
+                    return -1;
+                }
+            }
+        }
+    }
+
+    /* Search from argv0_path, until root is found */
+    wcscpy(exec_prefix, argv0_path);
+    do {
+        n = wcslen(exec_prefix);
+        join(exec_prefix, lib_python);
+        join(exec_prefix, L"lib-dynload");
+        if (exists(exec_prefix))
+            return 1;
+        exec_prefix[n] = L'\0';
+        reduce(exec_prefix);
+    } while (exec_prefix[0]);
+
+    /* Configure exec_prefix is unused */
+    (void)_exec_prefix;
+
+    /* Fail */
+    return 0;
+}
+#endif /*def USE_EXEC_PREFIX*/
 
 /* Load a PYTHONPATH value from the registry.
    Load from either HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER.
@@ -559,6 +642,9 @@ calculate_path(void)
 #ifdef USE_POSIX_PREFIX
     int pfound;
 #endif
+#ifdef USE_EXEC_PREFIX
+    int efound;
+#endif
 
 #ifdef MS_WINDOWS
     int skiphome, skipdefault;
@@ -642,6 +728,16 @@ calculate_path(void)
     if (envpath && *envpath == '\0')
         envpath = NULL;
 
+#ifdef USE_EXEC_PREFIX
+    efound = search_for_exec_prefix(argv0_path, pythonhome, NULL);
+    if (!efound) {
+        wcsncpy(exec_prefix, argv0_path, MAXPATHLEN);
+        reduce(exec_prefix);
+        join(exec_prefix, lib_python);
+        join(exec_prefix, L"lib-dynload");
+    }
+#endif
+
 #ifdef MS_WINDOWS
     /* Calculate zip archive path */
     if (dllpath[0])             /* use name of python DLL */
@@ -698,6 +794,9 @@ calculate_path(void)
 #ifdef USE_POSIX_PREFIX
     bufsz += wcslen(prefix) + 1;
 #endif
+#ifdef USE_EXEC_PREFIX
+    bufsz += wcslen(exec_prefix) + 1;
+#endif
     bufsz += wcslen(PYTHONPATH) + 1;
     bufsz += wcslen(argv0_path) + 1;
 #ifdef MS_WINDOWS
@@ -745,6 +844,11 @@ calculate_path(void)
     buf = wcschr(buf, L'\0');
     *buf++ = DELIM;
 #endif
+#ifdef USE_EXEC_PREFIX
+    wcscpy(buf, exec_prefix);
+    buf = wcschr(buf, L'\0');
+    *buf++ = DELIM;
+#endif
     if (userpath) {
         wcscpy(buf, userpath);
         buf = wcschr(buf, L'\0');
@@ -812,6 +916,17 @@ calculate_path(void)
         reduce(prefix);
         reduce(prefix);
     }
+    else
+        wcscpy(prefix, argv0_path);
+#endif
+#ifdef USE_EXEC_PREFIX
+    if (efound > 0) {
+        reduce(exec_prefix);
+        reduce(exec_prefix);
+        reduce(exec_prefix);
+    }
+    else
+        wcscpy(exec_prefix, argv0_path);
 #endif
     if (*prefix==L'\0') {
         wchar_t lookBuf[MAXPATHLEN+1];
@@ -881,7 +996,13 @@ Py_GetPrefix(void)
 wchar_t *
 Py_GetExecPrefix(void)
 {
+#ifdef USE_EXEC_PREFIX
+    if (!module_search_path)
+        calculate_path();
+    return exec_prefix;
+#else
     return Py_GetPrefix();
+#endif
 }
 
 wchar_t *
-- 
1.7.12.1