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gh-104016: Fixed off by 1 error in f string tokenizer #104047

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merged 9 commits into from
May 1, 2023
Merged

gh-104016: Fixed off by 1 error in f string tokenizer #104047

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9d72066
Fixed off by 1 error in f string tokenizer
jx124 May 1, 2023
ab38fd2
📜🤖 Added by blurb_it.
blurb-it[bot] May 1, 2023
eb4b729
Update test_fstring.py
jx124 May 1, 2023
d5f4a3d
Fixed tabs and assert
jx124 May 1, 2023
ef0a1c2
Merge branch 'fix-issue-104016' of https://github.com/jx124/cpython i…
jx124 May 1, 2023
d07ddb4
Undo accidental reformat
jx124 May 1, 2023
2c48eae
Removed whitespace.
jx124 May 1, 2023
de9a495
Use two separate limits and update tests
pablogsal May 1, 2023
d3a2fca
delete news entry
pablogsal May 1, 2023
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16 changes: 16 additions & 0 deletions Lib/test/test_fstring.py
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Original file line number Diff line number Diff line change
Expand Up @@ -565,7 +565,23 @@ def test_fstring_nested_too_deeply(self):
self.assertAllRaise(SyntaxError,
"f-string: expressions nested too deeply",
['f"{1+2:{1+2:{1+1:{1}}}}"'])

def create_nested_fstring(n):
if n == 0:
return "1+1"
prev = create_nested_fstring(n-1)
return f'f"{{{prev}}}"'

self.assertAllRaise(SyntaxError,
"too many nested f-strings",
[create_nested_fstring(160)])

def test_syntax_error_in_nested_fstring(self):
# See gh-104016 for more information on this crash
self.assertAllRaise(SyntaxError,
"invalid syntax",
['f"{1 1:' + ('{f"1:' * 199)])

def test_double_braces(self):
self.assertEqual(f'{{', '{')
self.assertEqual(f'a{{', 'a{')
Expand Down
7 changes: 5 additions & 2 deletions Parser/tokenizer.c
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Expand Up @@ -43,12 +43,12 @@
#ifdef Py_DEBUG
static inline tokenizer_mode* TOK_GET_MODE(struct tok_state* tok) {
assert(tok->tok_mode_stack_index >= 0);
assert(tok->tok_mode_stack_index < MAXLEVEL);
assert(tok->tok_mode_stack_index < MAXFSTRINGLEVEL);
return &(tok->tok_mode_stack[tok->tok_mode_stack_index]);
}
static inline tokenizer_mode* TOK_NEXT_MODE(struct tok_state* tok) {
assert(tok->tok_mode_stack_index >= 0);
assert(tok->tok_mode_stack_index < MAXLEVEL);
assert(tok->tok_mode_stack_index + 1 < MAXFSTRINGLEVEL);
return &(tok->tok_mode_stack[++tok->tok_mode_stack_index]);
}
#else
Expand Down Expand Up @@ -2235,6 +2235,9 @@ tok_get_normal_mode(struct tok_state *tok, tokenizer_mode* current_tok, struct t

p_start = tok->start;
p_end = tok->cur;
if (tok->tok_mode_stack_index + 1 >= MAXFSTRINGLEVEL) {
return MAKE_TOKEN(syntaxerror(tok, "too many nested f-strings"));
}
tokenizer_mode *the_current_tok = TOK_NEXT_MODE(tok);
the_current_tok->kind = TOK_FSTRING_MODE;
the_current_tok->f_string_quote = quote;
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7 changes: 4 additions & 3 deletions Parser/tokenizer.h
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Expand Up @@ -10,8 +10,9 @@ extern "C" {

#include "pycore_token.h" /* For token types */

#define MAXINDENT 100 /* Max indentation level */
#define MAXLEVEL 200 /* Max parentheses level */
#define MAXINDENT 100 /* Max indentation level */
#define MAXLEVEL 200 /* Max parentheses level */
#define MAXFSTRINGLEVEL 150 /* Max f-string nesting level */

enum decoding_state {
STATE_INIT,
Expand Down Expand Up @@ -123,7 +124,7 @@ struct tok_state {
enum interactive_underflow_t interactive_underflow;
int report_warnings;
// TODO: Factor this into its own thing
tokenizer_mode tok_mode_stack[MAXLEVEL];
tokenizer_mode tok_mode_stack[MAXFSTRINGLEVEL];
int tok_mode_stack_index;
int tok_report_warnings;
#ifdef Py_DEBUG
Expand Down