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Re: [PATCH c++ 06/12] Fix constness problem in ioscm_make_gdb_stdio_port
- From: Simon Marchi <simon dot marchi at polymtl dot ca>
- To: Pedro Alves <palves at redhat dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Mon, 26 Oct 2015 13:27:59 -0400
- Subject: Re: [PATCH c++ 06/12] Fix constness problem in ioscm_make_gdb_stdio_port
- Authentication-results: sourceware.org; auth=none
- References: <1445831204-16588-1-git-send-email-simon dot marchi at polymtl dot ca> <1445831204-16588-6-git-send-email-simon dot marchi at polymtl dot ca> <562E5050 dot 6010909 at redhat dot com>
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(-)
diff --git a/gdb/guile/scm-ports.c b/gdb/guile/scm-ports.c
index 5d529b3..ffaa3fd 100644
--- a/gdb/guile/scm-ports.c
+++ b/gdb/guile/scm-ports.c
@@ -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));
--
2.5.1