Hi,
On Wed, Aug 1, 2012 at 11:58 AM, Måns Rullgård <[email protected]> wrote:
> Luca Barbato <[email protected]> writes:
>
>> +#if !HAVE_SNPRINTF
>> +#ifdef _MSC_VER
>> +#define vsnprintf _vsnprintf
>> +#endif
>> +
>> +int snprintf(char *buffer, size_t bufsize, const char *fmt, ...)
>> +{
>> + va_list ap;
>> + int ret;
>> +
>> + if ((int)bufsize <= 0) return -1;
>> + va_start(ap, fmt);
>> + ret = vsnprintf(buffer, bufsize-1, fmt, ap);
>> + if (ret < 0) {
>> + buffer[bufsize - 1] = '\0';
>> + ret = bufsize - 1;
>> + }
>> + va_end(ap);
>> + return ret;
>> +}
>
> This assumes that any system without snprintf will have vsnprintf with
> microsoft semantics. That's a pretty bold assumption.
As for vsnprintf behaviour, from MSDN:
"vsnprintf, _vsnprintf, and _vsnwprintf return the number of
characters written if the number of characters to write is less than
or equal to count; if the number of characters to write is greater
than count, these functions return -1 indicating that output has been
truncated. The return value does not include the terminating null, if
one is written."
So if format, buffer != NULL and count > 0, a return value of -1 means
that the buffer was overrun and is filled with data ("truncated"), so
writing a '\0' at the end and returning count should be OK then.
As you pointed out, if the return value equals count, no zero was
written and we should add that.
Do we care that the return value of this snprintf() drop-in will not
be the amount of characters that would have been written, but is
simply count, if the output was truncated? If so, this should be
relatively easy to finish.
Ronald
_______________________________________________
libav-devel mailing list
[email protected]
https://lists.libav.org/mailman/listinfo/libav-devel
