[c++,06/12] Fix constness problem in ioscm_make_gdb_stdio_port
Commit Message
On 26 October 2015 at 12:09, Pedro Alves <palves@redhat.com> wrote:
> WDYT?
Sounds good to me. I wanted to avoid passing a string literal to
something that wasn't explicitely const (since if it tries to modify
the string, the program just crashes). But if we are sure that
scm_mode_bits does not do that, we can keep the simpler code.
Here's a ready to push patch (not guaranteed to be well-formatted,
because gmail).
From ff3fa55ca1cf6bd23de87eb26687ad48fb2b3806 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Mon, 26 Oct 2015 13:26:51 -0400
Subject: [PATCH] guile: Simplify ioscm_make_gdb_stdio_port
As pointed out by Pedro, it's clearer to do it this way. We can trust
that scm_mode_bits won't try to modify our string, even though it takes
a non-const char *.
gdb/ChangeLog:
* guile/scm-ports.c (ioscm_make_gdb_stdio_port): Do not pass a
local char array to scm_mode_bits, use a cast instead.
---
gdb/guile/scm-ports.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)
Comments
On 10/26/2015 05:27 PM, Simon Marchi wrote:
> On 26 October 2015 at 12:09, Pedro Alves <palves@redhat.com> wrote:
>> WDYT?
>
> Sounds good to me. I wanted to avoid passing a string literal to
> something that wasn't explicitely const (since if it tries to modify
> the string, the program just crashes). But if we are sure that
> scm_mode_bits does not do that, we can keep the simpler code.
>
> Here's a ready to push patch (not guaranteed to be well-formatted,
> because gmail).
>
>
> From ff3fa55ca1cf6bd23de87eb26687ad48fb2b3806 Mon Sep 17 00:00:00 2001
> From: Simon Marchi <simon.marchi@polymtl.ca>
> Date: Mon, 26 Oct 2015 13:26:51 -0400
> Subject: [PATCH] guile: Simplify ioscm_make_gdb_stdio_port
>
> As pointed out by Pedro, it's clearer to do it this way. We can trust
> that scm_mode_bits won't try to modify our string, even though it takes
> a non-const char *.
LGTM, though it's Doug's call.
Thanks,
Pedro Alves
On Mon, Oct 26, 2015 at 10:39 AM, Pedro Alves <palves@redhat.com> wrote:
> On 10/26/2015 05:27 PM, Simon Marchi wrote:
>> On 26 October 2015 at 12:09, Pedro Alves <palves@redhat.com> wrote:
>>> WDYT?
>>
>> Sounds good to me. I wanted to avoid passing a string literal to
>> something that wasn't explicitely const (since if it tries to modify
>> the string, the program just crashes). But if we are sure that
>> scm_mode_bits does not do that, we can keep the simpler code.
>>
>> Here's a ready to push patch (not guaranteed to be well-formatted,
>> because gmail).
>>
>>
>> From ff3fa55ca1cf6bd23de87eb26687ad48fb2b3806 Mon Sep 17 00:00:00 2001
>> From: Simon Marchi <simon.marchi@polymtl.ca>
>> Date: Mon, 26 Oct 2015 13:26:51 -0400
>> Subject: [PATCH] guile: Simplify ioscm_make_gdb_stdio_port
>>
>> As pointed out by Pedro, it's clearer to do it this way. We can trust
>> that scm_mode_bits won't try to modify our string, even though it takes
>> a non-const char *.
>
> LGTM, though it's Doug's call.
Fine by me.
On 26 October 2015 at 14:36, Doug Evans <xdje42@gmail.com> wrote:
> Fine by me.
Thanks, pushed.
@@ -357,36 +357,31 @@ ioscm_init_stdio_buffers (SCM port, long mode_bits)
static SCM
ioscm_make_gdb_stdio_port (int fd)
{
+ int is_a_tty = isatty (fd);
const char *name;
+ const char *mode_str;
long mode_bits;
SCM port;
- char buf[3];
-
- memset (buf, 0, sizeof (buf));
switch (fd)
{
case 0:
name = input_port_name;
- buf[0] = 'r';
+ mode_str = is_a_tty ? "r0" : "r";
break;
case 1:
name = output_port_name;
- buf[0] = 'w';
+ mode_str = is_a_tty ? "w0" : "w";
break;
case 2:
name = error_port_name;
- buf[0] = 'w';
+ mode_str = is_a_tty ? "w0" : "w";
break;
default:
gdb_assert_not_reached ("bad stdio file descriptor");
}
- if (isatty (fd))
- buf[1] = '0';
-
- mode_bits = scm_mode_bits (buf);
-
+ mode_bits = scm_mode_bits ((char *) mode_str);
port = ioscm_open_port (stdio_port_desc, mode_bits);
scm_set_port_filename_x (port, gdbscm_scm_from_c_string (name));