Hi Carl,
>>>>> "Carl" == Carl Worth <cworth at cworth.org> writes:
Carl> [1 <text/plain (quoted-printable)>]
Carl> On Mon, 23 Nov 2009 08:21:50 +0200, Dirk-Jan C. Binnema <djcb.bulk at
gmail.com> wrote:
>> -#define prompt(format, ...) \
>> - do { \
>> - printf (format, ##__VA_ARGS__); \
>> - fflush (stdout); \
>> - getline (&response, &response_size, stdin); \
>> - chomp_newline (response); \
>> +#define prompt(format, ...) \
>> + do { \
>> + int ignored; \
>> + printf (format, ##__VA_ARGS__); \
>> + fflush (stdout); \
>> + ignored = getline (&response, &response_size, stdin); \
>> + chomp_newline (response); \
>> } while (0)
Carl> This patch is incorrect. Ignoring the return value of getline results
in
Carl> the program invoking undefined behavior by reading uninitialized
Carl> memory. This is easily tested by, for example, typing Control-D to
Carl> provide EOF to a prompt from "notmuch setup".
Carl> How about just exiting in case of EOF as in the patch below?
Sure, that's the better solution, but note that my patch did not introduce the
undefined behavior -- it was there before. I was trying a minimal patch to
silencing the warning. Note that prompt seems to leak a bit, even after the
committed patch; attached are two more micro patches to fix this and another
small leak. I try to do minimal changes, but the prompt business gets a bit
unwieldy. The leaks are one-time at not critical, but anyway it's always good
stay vigilant.
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Best wishes,
Dirk.
--
Dirk-Jan C. Binnema Helsinki, Finland
e:djcb at djcbsoftware.nl w:www.djcbsoftware.nl
pgp: D09C E664 897D 7D39 5047 A178 E96A C7A1 017D DA3C
