Patch #1542451: fix crash with continue in nested try/finally

  (backport from rev. 51439)

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index dc7a16d1e26330867e79be93b48697f61fff6ad3..bc9cb127ea7a53a9cb68dcda1a238c7c0ced5be7 100644 (file)
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -235,6 +235,90 @@ SyntaxError: assignment to None (<doctest test.test_syntax[32]>, line 1)
 >>> f() += 1
 Traceback (most recent call last):
 SyntaxError: illegal expression for augmented assignment (<doctest test.test_syntax[33]>, line 1)
+
+
+Test continue in finally in weird combinations.
+
+continue in for loop under finally shouuld be ok.
+
+    >>> def test():
+    ...     try:
+    ...         pass
+    ...     finally:
+    ...         for abc in range(10):
+    ...             continue
+    ...     print abc
+    >>> test()
+    9
+
+Start simple, a continue in a finally should not be allowed.
+
+    >>> def test():
+    ...    for abc in range(10):
+    ...        try:
+    ...            pass
+    ...        finally:
+    ...            continue
+    ...
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[36]>, line 6)
+
+This is essentially a continue in a finally which should not be allowed.
+
+    >>> def test():
+    ...    for abc in range(10):
+    ...        try:
+    ...            pass
+    ...        finally:
+    ...            try:
+    ...                continue
+    ...            except:
+    ...                pass
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[37]>, line 7)
+
+    >>> def foo():
+    ...   try:
+    ...     pass
+    ...   finally:
+    ...     continue
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[38]>, line 5)
+
+    >>> def foo():
+    ...   for a in ():
+    ...     try: pass
+    ...     finally: continue
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[39]>, line 4)
+
+    >>> def foo():
+    ...  for a in ():
+    ...   try: pass
+    ...   finally:
+    ...    try:
+    ...     continue
+    ...    finally: pass
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[40]>, line 6)
+
+    >>> def foo():
+    ...  for a in ():
+    ...   try: pass
+    ...   finally:
+    ...    try:
+    ...     pass
+    ...    except:
+    ...     continue
+    Traceback (most recent call last):
+      ...
+    SyntaxError: 'continue' not supported inside 'finally' clause (<doctest test.test_syntax[41]>, line 8)
+
 """
 
 import re

diff --git a/Misc/NEWS b/Misc/NEWS
index 7a8e4de2f1b84d9a4f7c0eb2cec8f6728087a129..9bccc28b69548dd3b012972e2c9c6ea39f73c19d 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@ What's New in Python 2.5.1c1?
 Core and builtins
 -----------------
 
+- Patch #1542451: disallow continue anywhere under a finally.
+
 - list.pop(x) accepts any object x following the __index__ protocol.
 
 - Fix some leftovers from the conversion from int to Py_ssize_t

diff --git a/Python/compile.c b/Python/compile.c
index 92eff00732ca454f5f0129f835c0a1251c05e656..76c462829dc21458668b01adf6e336bcce15cf3f 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2288,6 +2288,8 @@ static int
 compiler_continue(struct compiler *c)
 {
        static const char LOOP_ERROR_MSG[] = "'continue' not properly in loop";
+       static const char IN_FINALLY_ERROR_MSG[] = 
+                       "'continue' not supported inside 'finally' clause";
        int i;
 
        if (!c->u->u_nfblocks)
@@ -2299,15 +2301,19 @@ compiler_continue(struct compiler *c)
                break;
        case EXCEPT:
        case FINALLY_TRY:
-               while (--i >= 0 && c->u->u_fblock[i].fb_type != LOOP)
-                       ;
+               while (--i >= 0 && c->u->u_fblock[i].fb_type != LOOP) {
+                       /* Prevent try: ... finally:
+                             try: continue ...  or
+                             try: ... except: continue */
+                       if (c->u->u_fblock[i].fb_type == FINALLY_END)
+                               return compiler_error(c, IN_FINALLY_ERROR_MSG);
+               }
                if (i == -1)
                        return compiler_error(c, LOOP_ERROR_MSG);
                ADDOP_JABS(c, CONTINUE_LOOP, c->u->u_fblock[i].fb_block);
                break;
        case FINALLY_END:
-               return compiler_error(c,
-                       "'continue' not supported inside 'finally' clause");
+               return compiler_error(c, IN_FINALLY_ERROR_MSG);
        }
 
        return 1;