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Fix parser bug for empty string allocation #496

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merged 1 commit into from
May 16, 2022
Merged

Fix parser bug for empty string allocation #496

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8 changes: 8 additions & 0 deletions ext/json/ext/parser/parser.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2363,9 +2363,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
char buf[4];

if (bufferSize > MAX_STACK_BUFFER_SIZE) {
# ifdef HAVE_RB_ENC_INTERNED_STR
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note, i've wrapped the fix with this HAVE_RB_ENC_INTERNED_STR guard as the issue only pertains to the call to rb_enc_interned_str below. Saves allocating the extra byte unnecessarily. Although, if there was concern about the extra allocation this would likely look like:

bufferStart = buffer = ALLOC_N(char, !intern || bufferSize ? bufferSize : 1);

Or would you prefer for simplicities sake to just go with the suggestion in #475 from @jeremyevans (ie without the HAVE_RB_ENC_INTERNED_STR guards)?

Of course the safest solution would be to simply allocate room for the null terminator all of the time (bufferSize + 1) but that's likely unnecessary given how the pointers are being used.

bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
# else
bufferStart = buffer = ALLOC_N(char, bufferSize);
# endif
} else {
# ifdef HAVE_RB_ENC_INTERNED_STR
bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
# else
bufferStart = buffer = ALLOCA_N(char, bufferSize);
# endif
}

while (pe < stringEnd) {
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8 changes: 8 additions & 0 deletions ext/json/ext/parser/parser.rl
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Expand Up @@ -462,9 +462,17 @@ static VALUE json_string_unescape(char *string, char *stringEnd, int intern, int
char buf[4];

if (bufferSize > MAX_STACK_BUFFER_SIZE) {
# ifdef HAVE_RB_ENC_INTERNED_STR
bufferStart = buffer = ALLOC_N(char, bufferSize ? bufferSize : 1);
# else
bufferStart = buffer = ALLOC_N(char, bufferSize);
# endif
} else {
# ifdef HAVE_RB_ENC_INTERNED_STR
bufferStart = buffer = ALLOCA_N(char, bufferSize ? bufferSize : 1);
# else
bufferStart = buffer = ALLOCA_N(char, bufferSize);
# endif
}

while (pe < stringEnd) {
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1 change: 1 addition & 0 deletions tests/json_parser_test.rb
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Expand Up @@ -84,6 +84,7 @@ def test_parse_simple_objects
assert_equal({ "a" => 23 }, parse(' { "a" : 23 } '))
assert_equal({ "a" => 0.23 }, parse(' { "a" : 0.23 } '))
assert_equal({ "a" => 0.23 }, parse(' { "a" : 0.23 } '))
assert_equal({ "" => 123 }, parse('{"":123}'))
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Technically this test is a duplicate given https://github.com/flori/json/blob/master/tests/fixtures/pass1.json#L15 however it seems reasonable to have an explicit test for this case here too.

end

def test_parse_numbers
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