On 10/10/2017 01:48 PM, Corinna Vinschen wrote:
> Hi Michael,
>
> On Oct 9 18:58, Michael Haubenwallner wrote:
>> When fork fails, we can use "%s" now with system_sprintf for the errmsg
>> rather than a (potentially too small) buffer for the format string.
>
> How could buf be too small?
See below.
Actually I've found this by searching for suspect char array definitions
while hunting the "uninitialized variable for RtlLookupFunctionEntry" bug.
>> * fork.cc (fork): Use "%s" with system_printf now.
>> ---
>> winsup/cygwin/fork.cc | 9 ++-------
>> 1 file changed, 2 insertions(+), 7 deletions(-)
>>
>> diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc
>> index 73a72f530..bcbef12d8 100644
>> --- a/winsup/cygwin/fork.cc
>> +++ b/winsup/cygwin/fork.cc
>> @@ -618,13 +618,8 @@ fork ()
>> if (!grouped.errmsg)
>> syscall_printf ("fork failed - child pid %d, errno %d",
>> grouped.child_pid, grouped.this_errno);
>> else
>> - {
>> - char buf[strlen (grouped.errmsg) + sizeof ("child %d - , errno
>> 4294967295 ")];
Usually child_pid is longer than the 2 characters counted by "%d", but
errno usually is shorther than the 10 characters counted by "4294967295",
and there is another 2 reserved characters counted by trailing " ".
In practice the buffer unlikely will be too small, so this is merely cosmetics.
>> - strcpy (buf, "child %d - ");
>> - strcat (buf, grouped.errmsg);
>> - strcat (buf, ", errno %d");
>> - system_printf (buf, grouped.child_pid, grouped.this_errno);
>> - }
>> + system_printf ("child %d - %s, errno %d", grouped.child_pid,
>> + grouped.errmsg, grouped.this_errno);
>>
>> set_errno (grouped.this_errno);
>> }
>> --
>> 2.14.2
>
> I guess this also means we can drop the if/else, kind of like
>
> system_printf ("child %d %s%s, errno %d",
> grouped.child_pid,
> grouped.errmsg ? "- " : "",
> grouped.errmsg ?: "",
> grouped.this_errno);
>
> What do you think?
Nothing I really take care of - yet suggesting:
system_printf ("fork failed - child %d%s%s, errno %d",
grouped.child_pid,
grouped.errmsg ? " - " : "",
grouped.errmsg ?: "",
grouped.this_errno);
But wait, what's the difference between syscall_printf and system_printf?
/haubi/
