* Correctly pre-check for int-to-str conversion (#96537)
Converting a large enough `int` to a decimal string raises `ValueError` as expected. However, the raise comes _after_ the quadratic-time base-conversion algorithm has run to completion. For effective DOS prevention, we need some kind of check before entering the quadratic-time loop. Oops! =)
The quick fix: essentially we catch _most_ values that exceed the threshold up front. Those that slip through will still be on the small side (read: sufficiently fast), and will get caught by the existing check so that the limit remains exact.
The justification for the current check. The C code check is:
```c
max_str_digits / (3 * PyLong_SHIFT) <= (size_a - 11) / 10
```
In GitHub markdown math-speak, writing $M$ for `max_str_digits`, $L$ for `PyLong_SHIFT` and $s$ for `size_a`, that check is:
$$\left\lfloor\frac{M}{3L}\right\rfloor \le \left\lfloor\frac{s - 11}{10}\right\rfloor$$
From this it follows that
$$\frac{M}{3L} < \frac{s-1}{10}$$
hence that
$$\frac{L(s-1)}{M} > \frac{10}{3} > \log_2(10).$$
So
$$2^{L(s-1)} > 10^M.$$
But our input integer $a$ satisfies $|a| \ge 2^{L(s-1)}$, so $|a|$ is larger than $10^M$. This shows that we don't accidentally capture anything _below_ the intended limit in the check.
<!-- gh-issue-number: gh-95778 -->
* Issue: gh-95778
<!-- /gh-issue-number -->
Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>
Co-authored-by: Christian Heimes <christian@python.org>
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
* bpo-46503: Prevent an assert from firing. Also fix one nearby tiny PEP-7 nit.
* Added blurb.
(cherry picked from commit 0daf72194bd4e31de7f12020685bb39a14d6f45e)
Co-authored-by: Eric V. Smith <ericvsmith@users.noreply.github.com>
Co-authored-by: Eric V. Smith <ericvsmith@users.noreply.github.com>
"make regen-all" now produces the same output when run from a
directory other than the source tree: when building Python out of the
source tree.
(cherry picked from commit 253b7a0a9fef1d72a4cb87b837885576e68e917c)
(cherry picked from commit b6defde2afe656db830d6fedf74ca5f6225f5928)
There are two errors that this commit fixes:
* The parser was not correctly computing the offset and the string
source for E_LINECONT errors due to the incorrect usage of strtok().
* The parser was not correctly unwinding the call stack when a tokenizer
exception happened in rules involving optionals ('?', [...]) as we
always make them return valid results by using the comma operator. We
need to check first if we don't have an error before continuing..
(cherry picked from commit a106343f632a99c8ebb0136fa140cf189b4a6a57)
Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
NOTE: unlike the cherry-picked original, this commit points at a crazy location
due to a bug in the tokenizer that required a big refactor in 3.10 to fix.
We are leaving as-is for 3.9.
They support now splitting escape sequences between input chunks.
Add the third parameter "final" in codecs.unicode_escape_decode().
It is True by default to match the former behavior.
(cherry picked from commit c96d1546b11b4c282a7e21737cb1f5d16349656d)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
When compiling an AST object with a direct / indirect reference
cycles, on the conversion phase because of exceeding amount of
calls, a segfault was raised. This patch adds recursion guards to
places for preventing user inputs to not to crash AST but instead
raise a RecursionError..
(cherry picked from commit f3491242e41933aa9529add7102edb68b80a25e9)
Co-authored-by: Batuhan Taskaya <batuhan@python.org>
(cherry picked from commit 96eeff516204b7cc751103fa33dcc665e387846e)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
Currently walruses are not allowerd in set literals and set comprehensions:
>>> {y := 4, 4**2, 3**3}
File "<stdin>", line 1
{y := 4, 4**2, 3**3}
^
SyntaxError: invalid syntax
but they should be allowed as well per PEP 572.
(cherry picked from commit b0aba1fcdc3da952698d99aec2334faa79a8b68c)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
Signed-off-by: Christian Heimes <christian@python.org>
Automerge-Triggered-By: GH:tiran
(cherry picked from commit 07f2adedf0940b06d136208ec386d69b7d2d5b43)
Co-authored-by: Christian Heimes <christian@python.org>
Left-recursive rules need to check for errors explicitly, since
even if the rule returns NULL, the parsing might continue and lead
to long-distance failures.
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
(cherry picked from commit 02cdfc93f82fecdb7eae97a868d4ee222b9875d9)
Automerge-Triggered-By: GH:lysnikolaou
* Implement running the parser a second time for the errors messages
The first parser run is only responsible for detecting whether
there is a `SyntaxError` or not. If there isn't the AST gets returned.
Otherwise, the parser is run a second time with all the `invalid_*`
rules enabled so that all the customized error messages get produced.
(cherry picked from commit bca701403253379409dece03053dbd739c0bd059)
Partially revert commit ac46eb4ad6662cf6d771b20d8963658b2186c48c:
"bpo-38113: Update the Python-ast.c generator to PEP384 (gh-15957)".
Using a module state per module instance is causing subtle practical
problems.
For example, the Mercurial project replaces the __import__() function
to implement lazy import, whereas Python expected that "import _ast"
always return a fully initialized _ast module.
Add _PyAST_Fini() to clear the state at exit.
The _ast module has no state (set _astmodule.m_size to 0). Remove
astmodule_traverse(), astmodule_clear() and astmodule_free()
functions..
(cherry picked from commit e5fbe0cbd4be99ced5f000ad382208ad2a561c90)
Co-authored-by: Victor Stinner <vstinner@python.org>
This program can segfault the parser by stack overflow:
```
import ast
code = "f(" + ",".join(['a' for _ in range(100000)]) + ")"
print("Ready!")
ast.parse(code)
```
the reason is that the rule for arguments has a simple recursion when collecting args:
args[expr_ty]:
[...]
| a=named_expression b=[',' c=args { c }] {
[...] }.
(cherry picked from commit 4a97b1517a6b5ff22e2984b677a680b07ff0ce11)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
* bpo-41194: Convert _ast extension to PEP 489 (GH-21293)
Convert the _ast extension module to PEP 489 "Multiphase
initialization". Replace the global _ast state with a module state.
(cherry picked from commit b1cc6ba73a51d5cc3aeb113b5e7378fb50a0e20a)
* bpo-41204: Fix compiler warning in ast_type_init() (GH-21307)
(cherry picked from commit 1f76453173267887ed05bb3783e862cb22365ae8)
incr cannot be larger than INT_MAX: downcast to int explicitly.
(cherry picked from commit bde48fd8110cc5f128d5db44810d17811e328a24)
Co-authored-by: Victor Stinner <vstinner@python.org>
This consolidates the handling of my_fgets return values, so that interrupts are always handled, even if they come after EOF.
I believe PyOS_StdioReadline is still buggy in that I/O errors will not result in a proper Python exception being set. However, that is a separate issue.
(cherry picked from commit a74eea238f5baba15797e2e8b570d153bc8690a7)
Co-authored-by: Benjamin Peterson <benjamin@python.org>
This will improve the debug experience if something fails in the produced AST. Previously, errors in the produced AST can be felt much later like in the garbage collector or the compiler, making debugging them much more difficult..
(cherry picked from commit 1332226b32da44087a55e1d71990ee6899dfd28a)
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
GCC says
```
../cpython/Parser/string_parser.c: In function ‘fstring_find_expr’:
../cpython/Parser/string_parser.c:404:93: warning: ‘cols’ may be used uninitialized in this function [-Wmaybe-uninitialized]
404 | p2->starting_col_offset = p->tok->first_lineno == p->tok->lineno ? t->col_offset + cols : cols;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../cpython/Parser/string_parser.c:384:16: note: ‘cols’ was declared here
384 | int lines, cols;
| ^~~~
../cpython/Parser/string_parser.c:403:45: warning: ‘lines’ may be used uninitialized in this function [-Wmaybe-uninitialized]
403 | p2->starting_lineno = t->lineno + lines - 1;
| ~~~~~~~~~~~~~~~~~~^~~
../cpython/Parser/string_parser.c:384:9: note: ‘lines’ was declared here
384 | int lines, cols;
| ^~~~~
```
and, indeed, if `PyBytes_AsString` somehow fails, lines & cols will not be initialized.
(cherry picked from commit 2ad7e9c011b7606c5c7307176df07419a0e60134)
Co-authored-by: Benjamin Peterson <benjamin@python.org>
* bpo-41194: Pass module state in Python-ast.c (GH-21284)
Rework asdl_c.py to pass the module state to functions in
Python-ast.c, instead of using astmodulestate_global.
Handle also PyState_AddModule() failure in init_types().
(cherry picked from commit 74419f0c64959bb8392fcf3659058410423038e1)
* bpo-41194: The _ast module cannot be loaded more than once (GH-21290)
Fix a crash in the _ast module: it can no longer be loaded more than
once. It now uses a global state rather than a module state.
* Move _ast module state: use a global state instead.
* Set _astmodule.m_size to -1, so the extension cannot be loaded more
than once.
(cherry picked from commit 91e1bc18bd467a13bceb62e16fbc435b33381c82)
This commit changes the parsing of f-string expressions with the new parser. The parser gets pre-fed with the location of the expression itself (not the f-string, which was what we were doing before). This allows us to completely skip the shifting of the AST nodes after the parsing is completed..
(cherry picked from commit 1f0f4abb110b9fbade6175842b6a26ab0b8df6dd)
Prefix the error message with `fstring: `, when parsing an f-string expression throws a `SyntaxError`.
(cherry picked from commit 2e0a920e9eb540654c0bb2298143b00637dc5961)
Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
`GET_INVALID_TARGET` might unexpectedly return `NULL`, which if not
caught will cause a SEGFAULT. Therefore, this commit introduces a new
inline function `RAISE_SYNTAX_ERROR_INVALID_TARGET` that always
checks for `GET_INVALID_TARGET` returning NULL and can be used in
the grammar, replacing the long C ternary operation used till now.
(cherry picked from commit 6c4e0bd974f2895d42b63d9d004587e74b286c88)
Automerge-Triggered-By: @pablogsal
