Re: a few more patches

Hi Jim,
  They're both pushed thanks.

I can't find an email if I gave specifics about the warnings or not, but
they are below.

This seems a bit of a bogus warning. You are using snprintf() with a %s
which could be a long string and limiting it to 4 characters.
The issue is, not checking the return value. But! you know what the source
string is (another window name) so it won't be larger than 4 and truncate.

There are probably three ways ahead with this:
 * Disable the warning when using --enable-harden-flags
 * Add a compiler note to not complain
 * Change the top.c code to check the return value

I see not a lot of value of this warning, especially in this context;
what's your view?
I found
https://stackoverflow.com/questions/51534284/how-to-circumvent-format-truncation-warning-in-gcc/51536663
quite useful too.

  CC       top/top.o
top/top.c: In function ‘keys_window’:
top/top.c:4163:55: warning: ‘%s’ directive output may be truncated writing
up to 127 bytes into a region of size 4 [-Wformat-truncation=]
 4163 |       snprintf(q->rc.winname, sizeof(q->rc.winname), "%s", name);
      |                                                       ^~
......
 5403 |             if (tmp[0] && tmp[0] != kbd_ESC) win_names(w, tmp);
      |                                                           ~~~
top/top.c:4163:7: note: ‘snprintf’ output between 1 and 128 bytes into a
destination of size 4
 4163 |       snprintf(q->rc.winname, sizeof(q->rc.winname), "%s", name);
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
top/top.c:4164:49: warning: ‘%s’ directive output may be truncated writing
up to 127 bytes into a region of size between 0 and 4 [-Wformat-truncation=]
 4164 |    snprintf(q->grpname, sizeof(q->grpname), "%d:%s", q->winnum,
name);
      |                                                 ^~
......
 5403 |             if (tmp[0] && tmp[0] != kbd_ESC) win_names(w, tmp);
      |                                                           ~~~
top/top.c:4164:4: note: ‘snprintf’ output between 3 and 140 bytes into a
destination of size 6
 4164 |    snprintf(q->grpname, sizeof(q->grpname), "%d:%s", q->winnum,
name);
      |
 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  CCLD     top/top



If you want to see how it happens:
$ gcc -Wformat -o test1 test1.c
test1.c: In function ‘main’:
test1.c:8:43: warning: ‘%s’ directive output may be truncated writing up to
99 bytes into a region of size 4 [-Wformat-truncation=]
    8 |     snprintf(smallbuf, sizeof(smallbuf), "%s", buf);
      |                                           ^~   ~~~
test1.c:8:5: note: ‘snprintf’ output between 1 and 100 bytes into a
destination of size 4
    8 |     snprintf(smallbuf, sizeof(smallbuf), "%s", buf);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

$ cat test1.c
#include <stdio.h>

int main()
{
    char buf[100] = "123";
    char smallbuf[4];

    snprintf(smallbuf, sizeof(smallbuf), "%s", buf);
    printf("Small buffer is >%s<\n", smallbuf);
    return 0;
}


On Wed, 16 Feb 2022 at 07:26, Jim Warner <[email protected]> wrote:

> Hi Craig,
>
> Here are some more minor patches for our two branches.
>
> Thanks in advance for the pushes.
>
> Regards,
>
> Jim