Re: [PATCH v2] send-email: validate charset name in 8bit encoding prompt

> When a non-ASCII character is detected in the body or subject of the email
> the user is prompted with,
>
>   Which 8bit encoding should I declare [UTF-8]? foo
>
> After this the input string is validated by the regex, based on the fact
> that the charset string will be minimum 4 characters [1]. If the string is
> more than 4 letters the email is sent, if not then a second prompt to
> confirm is asked to the user,
>
>   Are you sure you want to use <foo> [y/N]? y
>
> This relies on a length based regex heuristic check to validate the user
> input, and can allow clearly invalid charset names to pass if the input is
> greater than 4 characters.
>
> Add a semantic validation of the charset name using the
> Encode::find_encoding() module of perl. If the encoding is not recognized,
> warn the user and ask for confirmation before proceeding. After this
> validation the lenght based validation becomes redundant and also breaks
> flow, so change the regex of valid input to any non blank string.
>
> Additionally, the wording of the first prompt can confuse the user if not
> read properly or under any default assumptions for a yes/no prompt. Change
> the wording to make it explicitly clear to the user that the prompt needs a
> string input, UTF-8 being the default.
>
> The intended flow is,
>
>   Declare which 8bit encoding to use [default: UTF-8]? foobar
>   warning: 'foobar' does not appear to be a valid charset name.
>   Are you sure you want to use <foobar> [y/N]?
>
> [1]- https://github.com/git/git/commit/852a15d748034eec87adbee73a72689c8936fb8b
>
> Signed-off-by: Shreyansh Paliwal <shreyanshpaliwalcmsmn@gmail.com>
> ---
> Changes in v2:
>  - Added braces in if-else block.
>
>  git-send-email.perl   | 17 ++++++++++++++---
>  t/t9001-send-email.sh |  2 +-
>  2 files changed, 15 insertions(+), 4 deletions(-)