Fix [ 616716 ] Bug in PyErr_SetExcFromWindows

Ensure that even if FormatMessage fails we (a) don't crash, and (b) provide something useful.

Bugfix candidate.

diff --git a/Python/errors.c b/Python/errors.c
index 9a2597b0ce1dabb5d0e74abb9ef0555e273d4cb5..95c24a685ea6a864c064b51ceb54052f465566a0 100644 (file)
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -269,6 +269,7 @@ PyErr_SetFromErrnoWithFilenameObject(PyObject *exc, PyObject *filenameObject)
 #endif
 #ifdef MS_WINDOWS
        char *s_buf = NULL;
+       char s_small_buf[28]; /* Room for "Windows Error 0xFFFFFFFF" */
 #endif
 #ifdef EINTR
        if (i == EINTR && PyErr_CheckSignals())
@@ -306,10 +307,18 @@ PyErr_SetFromErrnoWithFilenameObject(PyObject *exc, PyObject *filenameObject)
                                (LPTSTR) &s_buf,
                                0,      /* size not used */
                                NULL);  /* no args */
-                       s = s_buf;
-                       /* remove trailing cr/lf and dots */
-                       while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
-                               s[--len] = '\0';
+                       if (len==0) {
+                               /* Only ever seen this in out-of-mem 
+                                  situations */
+                               sprintf(s_small_buf, "Windows Error 0x%X", i);
+                               s = s_small_buf;
+                               s_buf = NULL;
+                       } else {
+                               s = s_buf;
+                               /* remove trailing cr/lf and dots */
+                               while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
+                                       s[--len] = '\0';
+                       }
                }
        }
 #endif /* Unix/Windows */
@@ -366,6 +375,8 @@ PyObject *PyErr_SetExcFromWindowsErrWithFilenameObject(
 {
        int len;
        char *s;
+       char *s_buf = NULL; /* Free via LocalFree */
+       char s_small_buf[28]; /* Room for "Windows Error 0xFFFFFFFF" */
        PyObject *v;
        DWORD err = (DWORD)ierr;
        if (err==0) err = GetLastError();
@@ -378,12 +389,20 @@ PyObject *PyErr_SetExcFromWindowsErrWithFilenameObject(
                err,
                MAKELANGID(LANG_NEUTRAL,
                SUBLANG_DEFAULT), /* Default language */
-               (LPTSTR) &s,
+               (LPTSTR) &s_buf,
                0,      /* size not used */
                NULL);  /* no args */
-       /* remove trailing cr/lf and dots */
-       while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
-               s[--len] = '\0';
+       if (len==0) {
+               /* Only seen this in out of mem situations */
+               sprintf(s_small_buf, "Windows Error 0x%X", err);
+               s = s_small_buf;
+               s_buf = NULL;
+       } else {
+               s = s_buf;
+               /* remove trailing cr/lf and dots */
+               while (len > 0 && (s[len-1] <= ' ' || s[len-1] == '.'))
+                       s[--len] = '\0';
+       }
        if (filenameObject != NULL)
                v = Py_BuildValue("(isO)", err, s, filenameObject);
        else
@@ -392,7 +411,7 @@ PyObject *PyErr_SetExcFromWindowsErrWithFilenameObject(
                PyErr_SetObject(exc, v);
                Py_DECREF(v);
        }
-       LocalFree(s);
+       LocalFree(s_buf);
        return NULL;
 }