On Sat, Oct 08, 2016 at 16:14 -0400, Gaitan D'Antoni wrote:
>
> I just built libserialport on Windows 10 and while stepping through the
> code I noticed a bug so I created the following patch:
>
> --- serialport.c 2016-10-08 13:41:23.269484000 -0400
> +++ serialport1.c 2016-10-08 13:43:10.958994300 -0400
> @@ -459,8 +459,8 @@
> char *escaped_port_name;
> COMSTAT status;
>
> - /* Prefix port name with '\\.\' to work with ports above COM9. */
> - if (!(escaped_port_name = malloc(strlen(port->name) + 5)))
> + /* Prefix port name with '\\\\.\\' to work with ports above COM9. */
> + if (!(escaped_port_name = malloc(strlen(port->name) + 8)))
> RETURN_ERROR(SP_ERR_MEM, "Escaped port name malloc failed");
> sprintf(escaped_port_name, "\\\\.\\%s", port->name);
Can you expand on what's the issue? I cannot see an obvious
problem in the original source from looking at the patch. And
there is no comment / commit message that comes with your patch,
explaining what the problem was and what the consequences might
be, or how the changed version has improved.
Consider that strlen("\\") == 1, and thus strlen("\\\\.\\") == 4.
The first backslash escapes the subsequent one, the resulting
string after resolving the escaped sequence is a single backslash
(or three backslashes plus a dot in the second term).
Also note the different quote characters. The _source code_ uses
double quotes, because that's how strings are phrased in the C
programming language. The _comment_ uses single quotes, which by
convention denote "citations" or strict terms in the verbatim
sense.
So it's really \\.\ which needs to get prepended (that's a "UNC"
style Windows path name). It just happens to get phrased as
"\\\\.\\" in the specific programming language.
Did I miss something?
virtually yours
Gerhard Sittig
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