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Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Q
From: |
andrzej zaborowski |
Subject: |
Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup |
Date: |
Sat, 25 Oct 2008 16:48:34 +0200 |
2008/10/25 Blue Swirl <address@hidden>:
> On 10/25/08, andrzej zaborowski <address@hidden> wrote:
>> 2008/10/25 Blue Swirl <address@hidden>:
>> > On 10/25/08, andrzej zaborowski <address@hidden> wrote:
>> >> 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.
>> >
>> > But then the length could be incorrect: buf_size + 1.
>>
>>
>> That's what it should be in case lmp_name is 248 chars long. I think
>> the confusion is because you called the parameter buf_size while
>> strndup calls it n (the number of characters.. not buffer size).
>
> If strlen(lmp_name) >= 248, only first 247 should be copied and the
> final character should be NUL, because sizeof(read_local_name_rp.name)
> == buf_size == 248.
Nope, actually now I notice that I assumed that strndup never executes
strlen() on the parameter... I think it's a sane assumption (?).
read_local_name_rp.name format is specified by the bluetooth "Volume 2
Core system package, part E - Host Controller Interface Functional
Specification" on pg. 394:
6.24 LOCAL NAME
<...>
If the name contained in the parameter is shorter than 248 octets, the
end of the name is indicated by a NULL octet (0x00), and the following
octets (to fill up 248 octets, which is the length of the parameter) do not
have valid values.
- [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Blue Swirl, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, andrzej zaborowski, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Blue Swirl, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, andrzej zaborowski, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Blue Swirl, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, andrzej zaborowski, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Blue Swirl, 2008/10/25
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup,
andrzej zaborowski <=
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Blue Swirl, 2008/10/26
- Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, andrzej zaborowski, 2008/10/26
Re: [Qemu-devel] [5532] Replace uses of strndup (a GNU extension) with Qemu pstrdup, Warner Losh, 2008/10/25