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Chris00 / ocaml-csv

CSV library for OCaml
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Fix must_quote call convention to avoid memory corruption when excel_tricks is enabled for output. #9

Closed bvaugon closed 9 years ago

bvaugon commented 9 years ago

The given patch fixes a bug that implied memory corruptions in some cases. The bug is observable on the following code:

Csv.output_all (Csv.to_channel ~excel_tricks:true stdout) [ [ "01234567" ] ]

In fact, it appears when excel_tricks is true and when a field starts with '0', do not contains any occurrence of '\n', '\r' or the separator, and have a length of the form (8 * n - 1). In this case, the function must_quote returns -1, and the buffer s allocated on csv.ml line 800 is too small by 1 to store all the characters. The last Byte.unsafe_set then corrupts the size tag of the string s (when String.length n mod 8 = 7) or looses the last char in the 0-padding of the string (when String.length n mod 8 < 7). This memory corruption implies funny bugs when the string s is used later.

Anyway, many thanks for this very useful and efficient code!

Benoît.

Chris00 commented 9 years ago

Thanks for analyzing the problem and the fix!

Chris00 commented 9 years ago

New release https://github.com/ocaml/opam-repository/pull/4525