Forgot to attach the proposed patch.
Best,
Dominik
On 11.02.2018 17:02, Dominik Derigs wrote:
> Hey Andy (and list),
>
> According to the inotify man page, the name buffer will always be
> null-terminated. Furthermore, the name buffer seems to be allocated in
> chunks of 16 bytes. I have not found an official confirmation for that.
>
> I the way to go would be: char lastchar = in->name[strlen(in->name)-1];
>
> I have extended your test code by the following two lines:
>
> if(in->name == NULL) continue;
> printf("DD: strlen: %lu\n", strlen(in->name));
> char lastchar = in->name[strlen(in->name)-1];
> printf("DD: strlen last char: %c\n", lastchar);
>
> Here are results obtained with your + my debug output:
>
> For a short filename without ~
>
> ADH: len: 16
> ADH: name: shortfilename
> ADH: last char:
> DD: strlen: 13
> DD: strlen last char: e
>
> For a short filename with ~
>
> ADH: len: 16
> ADH: name: shortfilename~
> ADH: last char:
> DD: strlen: 14
> DD: strlen last char: ~
>
> For a long filename without ~
>
> ADH: len: 32
> ADH: name: veryverylongfilename
> ADH: last char:
> DD: strlen: 20
> DD: strlen last char: e
>
> For a long filename with ~
>
> ADH: len: 32
> ADH: name: veryverylongfilename~
> ADH: last char:
> DD: strlen: 21
> DD: strlen last char: ~
>
> Best regards,
> Dominik
>
>
> On 11.02.2018 12:57, Andy Hawkins wrote:
>> Hi,
>>
>> In article <slrnp80aau.nkj.a...@xcp-mailnews.gently.org.uk>,
>> Andy Hawkins<a...@gently.org.uk> wrote:
>>> In inotify.c, around line 236 is the following code block:
>>>
>>> /* ignore emacs backups and dotfiles */
>>> if (in->len == 0 ||
>>> in->name[in->len - 1] == '~' ||
>>> (in->name[0] == '#' && in->name[in->len - 1] == '#') ||
>>> in->name[0] == '.')
>>> continue;
>>>
>>> However, if I create a file called 'fred~' in the directory I've specified
>>> using dhcp-hostsdir I still get an event in syslog that shows this file is
>>> being processed:
>>>
>>> Feb 11 11:14:34 xcp-gateway dnsmasq[1039]: inotify, new or changed file
>>> /etc/dnsmasq/dhcp-hosts.d/fred~
>> Ok, I've done some debugging. I added the following lines:
>>
>> my_syslog(LOG_INFO, "ADH: len: %d", in->len);
>> my_syslog(LOG_INFO, "ADH: name: %s", in->name);
>> my_syslog(LOG_INFO, "ADH: last char: %c", in->name[in->len - 1]);
>>
>> And I get the following output:
>>
>> dnsmasq: ADH: len: 16
>> dnsmasq: ADH: name: fred4~
>> dnsmasq: ADH: last char:
>>
>> So, it appears that the length in in->len is being interpreted correctly.
>>
>> According to the inotify man page:
>>
>> The len field counts all of the bytes in name, including the null
>> bytes; the length of each inotify_event structure is thus
>> sizeof(struct inotify_event)+len.
>>
>> So in fact, 'len' seems to be a fixed length, irrespective of the length of
>> the file name in the 'name' field.
>>
>> It looks like the check should actually be something like:
>>
>> /* ignore emacs backups and dotfiles */
>> if (in->len == 0 ||
>> in->name[strlen(in->name) - 1] == '~' ||
>> (in->name[0] == '#' && in->name[strlen(in->name) - 1] == '#')
>> ||
>> in->name[0] == '.')
>>
>> I guess you may need to check that there's a null in the name somewhere
>> before using strlen, otherwise you might end up running off the end of the
>> string. I don't know inotify well enough to know if there's guaranteed to be
>> a null in there somewhere. The manpage does say that the name field is null
>> terminated, but I don't know if that's guaranteed or not.
>>
>> I could have a look at submitting a patch, but my editor is showing some
>> very strange indentation of the source, so I suspect I have my tab settings
>> incorrect. What is the standard setting for tabs on the dnasmasq source
>> files?
>>
>> Thanks
>>
>> Andy
>>
>>
>> _______________________________________________
>> Dnsmasq-discuss mailing list
>> Dnsmasq-discuss@lists.thekelleys.org.uk
>> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
diff --git a/inotify.c b/inotify.c
index b5a17dd..51d13be 100644
--- a/inotify.c
+++ b/inotify.c
@@ -234,9 +234,10 @@ int inotify_check(time_t now)
hit = 1;
/* ignore emacs backups and dotfiles */
+ char lastchar = in->name[strlen(in->name)-1];
if (in->len == 0 ||
- in->name[in->len - 1] == '~' ||
- (in->name[0] == '#' && in->name[in->len - 1] == '#') ||
+ lastchar == '~' ||
+ (in->name[0] == '#' && lastchar == '#') ||
in->name[0] == '.')
continue;
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