[Bug tapsets/25686] user_buffer_quoted incorrectly octal-escapes non-printable characters

["craig.ringer at 2ndquadrant dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=25686

--- Comment #2 from Craig Ringer <craig.ringer at 2ndquadrant dot com> ---
Proposed patch attached

```
Author: Craig Ringer <craig@2ndquadrant.com>
Date:   Tue Mar 17 22:20:56 2020 +0800

    Fix ambiguous octal escapes in _stp_text_str

    Tapset functions like user_buffer_quoted that use the _stp_text_str
function
    for octal escaping would produce incorrect output if a null byte was
followed
    by a byte that represents a printable digit in US-ASCII. The null byte
would
    be emitted in the shorthand \0 form, then the printable digit would be
emitted
    literally, resulting in (e.g.) \06 instead of \0006 for the two input bytes
    "0x00 0x06".

    Fix by disabling shorthand escapes for null bytes. The alternatives are to:

    (a) look ahead in the buffer to see if the next byte is a digit and only
        expand the \0 to \000 if it would be ambiguous; or
    (b) octal-escape all printable digits

    The second would be woeful for the intended function of human-readable-ish
    buffer representations. The former seems potentially fragile and risky,
    so I just went with simple.

    Fixes bug #25686
```

-- 
You are receiving this mail because:
You are the assignee for the bug.