GNU bug report logs - #16782
date: reject invalid %[X] format characters

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: fuz <at> fuz.su
To: bug-coreutils <at> gnu.org
Subject: Insensitive behavior in date when given invalid fomatting string
Date: Mon, 17 Feb 2014 18:42:01 +0100

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Consider the following set of date invocations:

    $ date --version
    date (GNU coreutils) 8.20
    Copyright (C) 2012 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

    Written by David MacKenzie.
    $ date +%05
    00%05
    $ date +%Y%#05
    20140%#05
    $ date +x%7
    x     %7
    $ date "+%7 xyz"
        %7 xyz
    $ date "+%7q xyz"
        %7q xyz

GNU date behaves strangely when given an invalid formatting string. GNU date
does not inform the user about the invalid formatting string; instead it outputs
padding as if the flags and field-width, flags and E/O modifier were the whole
formatting string, then the unchanged formatting string. This behavior is not
incorrect as of POSIX.1-2008, as the standard does not specify the behavior of
date in case of an invalid format string, yet it is highly unexpected and weird.

I suggest changing GNU date to output incorrect parts of a formatting string
as-is (as done by the date shipped with Solaris) and possibly exiting with a
non-zero exit status.

Yours sincerely,
Robert Clausecker

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Message #8 received at 16782 <at> debbugs.gnu.org (full text, mbox):

From: Assaf Gordon <assafgordon <at> gmail.com>
To: 16782 <at> debbugs.gnu.org
Subject: Re: bug#16782: Insensitive behavior in date when given invalid
 fomatting string
Date: Sun, 21 Oct 2018 15:31:37 -0600

severity 16782 wishlist
retitle 16782 date: reject invalid %[X] format characters
stop

(triaging old bugs)

Hello,

On 17/02/14 10:42 AM, fuz <at> fuz.su wrote:
> Consider the following set of date invocations:
> 
>      $ date +%05
>      00%05
>      $ date +%Y%#05
>      20140%#05
>      $ date +x%7
>      x     %7
>      $ date "+%7 xyz"
>          %7 xyz
>      $ date "+%7q xyz"
>          %7q xyz
> 
> GNU date behaves strangely when given an invalid formatting string. GNU date
> does not inform the user about the invalid formatting string; instead it outputs
> padding as if the flags and field-width

It seems your message was never replied to. Sorry about that.

Indeed, this would be a nice improvement, contrast:

  $ printf "+%7 xyz"
  -bash: printf: ` ': invalid format character

  $ /src/printf "+%7 xyz"
  +./src/printf: %7 : invalid conversion specification

  $ ./src/printf "+%7q xyz"
  +./src/printf: %7q: invalid conversion specification

Marking this as a "wishlist" item.

-assaf

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