1 files changed, 84 insertions, 3 deletions

diff --git a/PC/getpathp.c b/PC/getpathp.c
index cd3a4b2..b5bf325 100644
--- a/PC/getpathp.c
+++ b/PC/getpathp.c
@@ -251,7 +251,7 @@ getpythonregpath(HKEY keyBase, int skipcore)
     if (keyBuf==NULL) goto done;
 
     memcpy(keyBufPtr, keyPrefix, sizeof(keyPrefix)-sizeof(WCHAR));
-    keyBufPtr += sizeof(keyPrefix)/sizeof(WCHAR) - 1;
+    keyBufPtr += Py_ARRAY_LENGTH(keyPrefix) - 1;
     mbstowcs(keyBufPtr, PyWin_DLLVersionString, versionLen);
     keyBufPtr += versionLen;
     /* NULL comes with this one! */
@@ -423,6 +423,53 @@ get_progpath(void)
         progpath[0] = '\0';
 }
 
+static int
+find_env_config_value(FILE * env_file, const wchar_t * key, wchar_t * value)
+{
+    int result = 0; /* meaning not found */
+    char buffer[MAXPATHLEN*2+1];  /* allow extra for key, '=', etc. */
+
+    fseek(env_file, 0, SEEK_SET);
+    while (!feof(env_file)) {
+        char * p = fgets(buffer, MAXPATHLEN*2, env_file);
+        wchar_t tmpbuffer[MAXPATHLEN*2+1];
+        PyObject * decoded;
+        int n;
+
+        if (p == NULL)
+            break;
+        n = strlen(p);
+        if (p[n - 1] != '\n') {
+            /* line has overflowed - bail */
+            break;
+        }
+        if (p[0] == '#')    /* Comment - skip */
+            continue;
+        decoded = PyUnicode_DecodeUTF8(buffer, n, "surrogateescape");
+        if (decoded != NULL) {
+            Py_ssize_t k;
+            k = PyUnicode_AsWideChar(decoded,
+                                     tmpbuffer, MAXPATHLEN * 2);
+            Py_DECREF(decoded);
+            if (k >= 0) {
+                wchar_t * tok = wcstok(tmpbuffer, L" \t\r\n");
+                if ((tok != NULL) && !wcscmp(tok, key)) {
+                    tok = wcstok(NULL, L" \t");
+                    if ((tok != NULL) && !wcscmp(tok, L"=")) {
+                        tok = wcstok(NULL, L"\r\n");
+                        if (tok != NULL) {
+                            wcsncpy(value, tok, MAXPATHLEN);
+                            result = 1;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return result;
+}
+
 static void
 calculate_path(void)
 {
@@ -457,6 +504,40 @@ calculate_path(void)
     /* progpath guaranteed \0 terminated in MAXPATH+1 bytes. */
     wcscpy(argv0_path, progpath);
     reduce(argv0_path);
+
+    /* Search for an environment configuration file, first in the
+       executable's directory and then in the parent directory.
+       If found, open it for use when searching for prefixes.
+    */
+
+    {
+        wchar_t tmpbuffer[MAXPATHLEN+1];
+        wchar_t *env_cfg = L"pyvenv.cfg";
+        FILE * env_file = NULL;
+
+        wcscpy(tmpbuffer, argv0_path);
+        join(tmpbuffer, env_cfg);
+        env_file = _Py_wfopen(tmpbuffer, L"r");
+        if (env_file == NULL) {
+            errno = 0;
+            reduce(tmpbuffer);
+            reduce(tmpbuffer);
+            join(tmpbuffer, env_cfg);
+            env_file = _Py_wfopen(tmpbuffer, L"r");
+            if (env_file == NULL) {
+                errno = 0;
+            }
+        }
+        if (env_file != NULL) {
+            /* Look for a 'home' variable and set argv0_path to it, if found */
+            if (find_env_config_value(env_file, L"home", tmpbuffer)) {
+                wcscpy(argv0_path, tmpbuffer);
+            }
+            fclose(env_file);
+            env_file = NULL;
+        }
+    }
+
     if (pythonhome == NULL || *pythonhome == '\0') {
         if (search_for_prefix(argv0_path, LANDMARK))
             pythonhome = prefix;
@@ -708,8 +789,8 @@ Py_GetProgramFullPath(void)
     return progpath;
 }
 
-/* Load python3.dll before loading any extension module that might refer 
-   to it. That way, we can be sure that always the python3.dll corresponding 
+/* Load python3.dll before loading any extension module that might refer
+   to it. That way, we can be sure that always the python3.dll corresponding
    to this python DLL is loaded, not a python3.dll that might be on the path
    by chance.
    Return whether the DLL was found.