Re: lib/53640: getnstr(3) shall read at most n characters, not n-1

[Kamil Rytarowski <n54%gmx.com@localhost>]

The following reply was made to PR lib/53640; it has been noted by GNATS.

From: Kamil Rytarowski <n54%gmx.com@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: lib/53640: getnstr(3) shall read at most n characters, not n-1
Date: Sat, 29 Sep 2018 16:05:39 +0200

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 From: Kamil Rytarowski <n54%gmx.com@localhost>
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 Subject: Re: lib/53640: getnstr(3) shall read at most n characters, not n-1
 References: <pr-lib-53640%gnats.netbsd.org@localhost>
  <20180929102931.2AB207A232%mollari.NetBSD.org@localhost>
  <20180929135001.4DC9B7A276%mollari.NetBSD.org@localhost>
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 On 29.09.2018 15:50, Valery Ushakov wrote:
 > The following reply was made to PR lib/53640; it has been noted by GNAT=
 S.
 >=20
 > From: Valery Ushakov <uwe%stderr.spb.ru@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc:=20
 > Subject: Re: lib/53640: getnstr(3) shall read at most n characters, not=
  n-1
 > Date: Sat, 29 Sep 2018 16:46:42 +0300
 >=20
 >  On Sat, Sep 29, 2018 at 10:30:01 +0000, n54%gmx.com@localhost wrote:
 > =20
 >  > It's documented in POSIX to reat at most N bytes; but the NetBSD
 >  > curses(3) version reads at most N-1 bytes.
 >  >=20
 >  > http://pubs.opengroup.org/onlinepubs/7908799/xcurses/getnstr.html
 > =20
 >  I don't think that definition is precise enough.  It doesn't
 >  explicitly say if the buffer is NUL terminated on overflow.
 > =20
 
 It's specified that the input string is terminated by a \0 byte.
 
 "The resulting value is placed in the area pointed to by str. The string
 is then terminated with a null byte. "
 
 In combination of "functions read at most n bytes" I assume that I can
 enter n characters (bytes) and a string is always terminated with a NUL
 character.
 
 > =20
 >  > While the NetBSD curses(3) behavior might be defendable it diverges
 >  > from the idiom of gets(3) + fgets(3). fgets(3) is documented to read=
 
 >  > at most N-1 characters and it does so.
 > =20
 >  > >How-To-Repeat:
 > =20
 >  Is it really that hard to explicitly quote the results you observe
 >  with these tests?  I find it rather disingenuous.  Can't you
 >  explicitly state your point?
 > =20
 
 This is an interactive program. You cannot enter N characters into it,
 only up to N-1.
 
 NetBSD curses(3) permits to enter only up to n-1 characters (bytes),
 while ncurses allows n.
 
 POSIX specifies that we shall be able read up to n bytes.
 
 > =20
 >  -uwe
 > =20
 >=20
 
 
 
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