Re: Error in Wireshark (tshark.c:646)

[Pascal Quantin <pascal.quantin () gmail com>]

2017-04-20 14:03 GMT+02:00 Pascal Quantin <pascal.quantin () gmail com>:

> Hi Rémy,
>
> 2017-04-20 13:57 GMT+02:00 Remy Leone <remy.leone () inria fr>:
>
> > Hello,
> >
> > I've noticed that master broke recently:
> > tshark.c:646:24: error: variable ‘exp_pdu_filename’ might be clobbered by
> > ‘longjmp’ or ‘vfork’ [-Werror=clobbered]
> >    const char          *exp_pdu_filename = NULL;
> >                         ^
> > Is a fix on the way? How could this bug passed through CI ?
>
> This kind of warnings is highly dependent on the compiler version used.
> That's why it was not spotted so far, and why you are the first one to
> report the issue (for example I'm using gcc 6.3.1 and I do not have this
> warning).
> Does replacing the line by the code below allows you to build?
> const volatile char *exp_pdu_filename = NULL;

Short answer: it will not as it will create other errors:

/mnt/data/tools/wireshark/git/tshark.c: In function ‘main’:
/mnt/data/tools/wireshark/git/tshark.c:1902:24: error: passing argument 1
of ‘open’ discards ‘volatile’ qualifier from pointer target type
[-Werror=discarded-qualifiers]
       exp_fd = ws_open(exp_pdu_filename, O_WRONLY | O_CREAT | O_TRUNC |
O_BINARY, 0644);
                        ^~~~~~~~~~~~~~~~
In file included from /mnt/data/tools/wireshark/git/wsutil/file_util.h:40:0,
                 from /mnt/data/tools/wireshark/git/tshark.c:61:
/usr/include/fcntl.h:181:12: note: expected ‘const char *’ but argument is
of type ‘const volatile char *’
 extern int open (const char *__file, int __oflag, ...) __nonnull ((1));
            ^~~~
/mnt/data/tools/wireshark/git/tshark.c:1913:48: error: passing argument 2
of ‘cfile_open_failure_message’ discards ‘volatile’ qualifier from pointer
target type [-Werror=discarded-qualifiers]
           cfile_open_failure_message("TShark", exp_pdu_filename, err, NULL,
                                                ^~~~~~~~~~~~~~~~
In file included from /mnt/data/tools/wireshark/git/tshark.c:92:0:
/mnt/data/tools/wireshark/git/ui/failure_message.h:41:13: note: expected
‘const char *’ but argument is of type ‘const volatile char *’
 extern void cfile_open_failure_message(const char *progname,
             ^~~~~~~~~~~~~~~~~~~~~~~~~~
/mnt/data/tools/wireshark/git/tshark.c:1981:41: error: passing argument 1
of ‘cfile_close_failure_message’ discards ‘volatile’ qualifier from pointer
target type [-Werror=discarded-qualifiers]
             cfile_close_failure_message(exp_pdu_filename, err);
                                         ^~~~~~~~~~~~~~~~
In file included from /mnt/data/tools/wireshark/git/tshark.c:92:0:
/mnt/data/tools/wireshark/git/ui/failure_message.h:93:13: note: expected
‘const char *’ but argument is of type ‘const volatile char *’
 extern void cfile_close_failure_message(const char *filename, int err);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors


> BR,
> Pascal.
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