argp: argp.doc prints incorrectly when it starts with "\v" [BZ #19038]

  In argp-help.c `char *vt` is being initialized only once. It needs to
be initialized for every child in the doc and it needs to be printed
only in two cases.
1. There are no children and the doc does not starts with '\v'.
2. Argument `first_only` to the function `argp_doc` is false and the
complete doc needs to be printed.

     }
@@ -1498,8 +1499,11 @@ argp_doc (const struct argp *argp, const struct
argp_state *state,

       if (text == inp_text && inp_text_limit)
        __argp_fmtstream_write (stream, inp_text, inp_text_limit);
-      else
-       __argp_fmtstream_puts (stream, text);
+      else{
+        if((!vt && !child) || (text == inp_text && !first_only)){
+          __argp_fmtstream_puts (stream, text);
+       }
+      }

       if (__argp_fmtstream_point (stream) > __argp_fmtstream_lmargin (stream))
        __argp_fmtstream_putc (stream, '\n');
  

* Girish Joshi:

> In argp-help.c `char *vt` is being initialized only once. It needs to
> be initialized for every child in the doc and it needs to be printed
> only in two cases.

> 1. There are no children and the doc does not starts with '\v'.
> 2. Argument `first_only` to the function `argp_doc` is false and the
> complete doc needs to be printed.

I assume this bug user-visible, so it should have a bug in Bugzilla
<https://sourceware.org/bugzilla/>.  Would you please file one?

Could you write a test case for this?  Or at least post how to reproduce
the issue in a minimal program?

Thanks,
Florian
  

Hi Florian,

> I assume this bug user-visible, so it should have a bug in Bugzilla
> <https://sourceware.org/bugzilla/>.  Would you please file one?
>
Here[1] is a Bugzilla entry for this.

> Could you write a test case for this?  Or at least post how to reproduce
> the issue in a minimal program?
>
It can be reproduced with following code.

#include<stdlib.h>
#include<argp.h>

static char doc[] = "\vthis is post_doc";
static struct argp argp = {NULL, NULL, NULL, doc};

int main(int argc, char *args[]){
     argp_parse(&argp, argc, args, 0, 0, NULL);
}

the output of the above code looks like:

this is post_doc

  -?, --help                 Give this help list
      --usage                Give a short usage message

this is post_doc

In this case the doc is being printed two times.
As mentioned in the comment by Kenny Stauffer on Bugzilla the first
occurrence of `this is post_doc` is erroneous.

If we change the doc[] in the above code to something else like

static char doc[] = "this is pre_doc\vthis is post_doc";

We get the output like:

this is pre_doc

  -?, --help                 Give this help list
      --usage                Give a short usage message

this is post_doc

[1]: https://sourceware.org/bugzilla/show_bug.cgi?id=19038
  

Could someone please review this patch?
Thanks.
  

On 30/05/2019 05:14, Girish Joshi wrote:
> Could someone please review this patch?
> Thanks.
> 

My understanding is Florian has asked if you could write a testcase
using glibc libsupport and resend the patch along with the testcase.
It will also need a ChangeLog entry.