Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup

[andrzej zaborowski]

2008/10/25 Blue Swirl <address@hidden>:
> On 10/25/08, andrzej zaborowski <address@hidden> wrote:
>> 2008/10/25 Blue Swirl <address@hidden>:
>>
>> > Revision: 5532
>>  >          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5532
>>  > Author:   blueswir1
>>  > Date:     2008-10-25 11:23:27 +0000 (Sat, 25 Oct 2008)
>>  >
>>  > Log Message:
>>  > -----------
>>  > Replace uses of strndup (a GNU extension) with Qemu pstrdup
>>  >
>>  > Modified Paths:
>>  > --------------
>>  >    trunk/cutils.c
>>  >    trunk/hw/bt-hci.c
>>  >    trunk/qemu-common.h
>>  >
>>  > Modified: trunk/cutils.c
>>  > ===================================================================
>>  > --- trunk/cutils.c      2008-10-25 11:21:28 UTC (rev 5531)
>>  > +++ trunk/cutils.c      2008-10-25 11:23:27 UTC (rev 5532)
>>  > @@ -50,6 +50,18 @@
>>  >     return buf;
>>  >  }
>>  >
>>  > +/* strdup with a limit */
>>  > +char *pstrdup(const char *str, size_t buf_size)
>>  > +{
>>  > +    size_t len;
>>  > +    char *buf;
>>  > +
>>  > +    len = MIN(buf_size, strlen(str));
>>  > +    buf = qemu_malloc(len);
>>  > +    pstrcpy(buf, len, str);
>>  > +    return buf;
>>  > +}
>>
>>
>> I think here also pstrcpy will only copy up to buf_size - 1 characters
>>  while strndup would copy buf_size chars.
>
> That is actually safer if we always want the strings to be NUL terminated.

strndup also always NUL terminates the string so it's just as safe,
the length is just different.

>
> But the allocation length is wrong, it should be MIN(buf_size, strlen(str) + 
> 1).

By my reading of the manual, it should rather be MIN(buf_size, strlen(str)) + 1.

Now that I think of it, note that this changed malloc to qemu_malloc
so you need to change the respective free()s to qemu_free()s.
Cheers