[PATCH 1/1] document posix_openpt

[PATCH 1/1] document posix_openpt

[Gavin Smith]

I copied the safety information from getpt, as I couldn't get this
information in full from anywhere else.

Your patch submission guide is contradictory as to whether to
use Signed-off-by or not
(https://sourceware.org/glibc/wiki/Contribution%20checklist):

> ... you just add a line saying:
>     Signed-off-by: ...

> The project does not support or use "Signed-off-by" lines


commit be1468aa984d91e55db7719034ca9b8e53a7a136
Author: Gavin Smith <gavinsmith0123@gmail.com>
Date:   Wed Apr 12 13:36:47 2023 +0100

    manual: document posix_openpt (bug 17010)
    
    * manual/terminal.texi (Allocation):
    Document posix_openpt.  State that getpt is similar to posix_openpt.
    Use posix_openpt instead of getpt in example.
    
    Signed-off-by: Gavin Smith <gavinsmith0123@gmail.com>

diff --git a/manual/terminal.texi b/manual/terminal.texi
index 7293bfb393..bdaee56053 100644
--- a/manual/terminal.texi
+++ b/manual/terminal.texi
@@ -1947,6 +1947,33 @@ This subsection describes functions for allocating a pseudo-terminal,
 and for making this pseudo-terminal available for actual use.  These
 functions are declared in the header file @file{stdlib.h}.
 
+@deftypefun int posix_openpt (int @var{flags})
+@standards{POSIX.1, stdlib.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
+
+@code{posix_openpt} returns a new file descriptor for the next
+available master pseudo-terminal.  In the case of an error, it returns
+a value of @math{-1} instead, and sets @code{errno} to indicate
+the error.  @xref{Opening and Closing Files} for possible values
+of @code{errno}.
+
+@var{flags} is a bit mask created from a bitwise OR of zero or more
+of the following flags:
+
+@table @code
+@item O_RDWR
+Open the device for both reading and writing.  It is usual to specify
+this flag.
+@item O_NOCTTY
+Do not make the device the controlling terminal for the process.
+@end table
+
+These flags are defined in @file{fcntl.h}.  @xref{Access Modes}.
+
+For this function to be available, @code{_XOPEN_SOURCE} must be defined
+to a value greater than @samp{600}.  @xref{Feature Test Macros}.
+@end deftypefun
+
 @deftypefun int getpt (void)
 @standards{GNU, stdlib.h}
 @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
@@ -1957,6 +1984,10 @@ functions are declared in the header file @file{stdlib.h}.
 @c a devfs, and returns the fd; static variables devpts_mounted and
 @c have_no_dev_ptmx are safely initialized so as to avoid repeated
 @c tests.
+
+@code{getpt} is similar to @code{posix_openpt}.  This function is a
+GNU extension and should not be used in portable programs.
+
 The @code{getpt} function returns a new file descriptor for the next
 available master pseudo-terminal.  The normal return value from
 @code{getpt} is a non-negative integer file descriptor.  In the case of
@@ -1967,8 +1998,6 @@ an error, a value of @math{-1} is returned instead.  The following
 @item ENOENT
 There are no free master pseudo-terminals available.
 @end table
-
-This function is a GNU extension.
 @end deftypefun
 
 @deftypefun int grantpt (int @var{filedes})
@@ -2118,6 +2147,7 @@ This function is a GNU extension.
 @end deftypefun
 
 Typical usage of these functions is illustrated by the following example:
+
 @smallexample
 int
 open_pty_pair (int *amaster, int *aslave)
@@ -2125,7 +2155,7 @@ open_pty_pair (int *amaster, int *aslave)
   int master, slave;
   char *name;
 
-  master = getpt ();
+  master = posix_openpt (O_RDWR | O_NOCTTY);
   if (master < 0)
     return 0;
 

Re: [PATCH 1/1] document posix_openpt

[Adhemerval Zanella Netto]

On 12/04/23 09:45, Gavin Smith via Libc-alpha wrote:
> I copied the safety information from getpt, as I couldn't get this
> information in full from anywhere else.
> 
> Your patch submission guide is contradictory as to whether to
> use Signed-off-by or not
> (https://sourceware.org/glibc/wiki/Contribution%20checklist):
> 
>> ... you just add a line saying:
>>     Signed-off-by: ...
> 
>> The project does not support or use "Signed-off-by" lines
> 
> 
> commit be1468aa984d91e55db7719034ca9b8e53a7a136
> Author: Gavin Smith <gavinsmith0123@gmail.com>
> Date:   Wed Apr 12 13:36:47 2023 +0100
> 
>     manual: document posix_openpt (bug 17010)
>     
>     * manual/terminal.texi (Allocation):
>     Document posix_openpt.  State that getpt is similar to posix_openpt.
>     Use posix_openpt instead of getpt in example.
>     
>     Signed-off-by: Gavin Smith <gavinsmith0123@gmail.com>

LGTM, I am just no sure which standard to use.

> 
> diff --git a/manual/terminal.texi b/manual/terminal.texi
> index 7293bfb393..bdaee56053 100644
> --- a/manual/terminal.texi
> +++ b/manual/terminal.texi
> @@ -1947,6 +1947,33 @@ This subsection describes functions for allocating a pseudo-terminal,
>  and for making this pseudo-terminal available for actual use.  These
>  functions are declared in the header file @file{stdlib.h}.
>  
> +@deftypefun int posix_openpt (int @var{flags})
> +@standards{POSIX.1, stdlib.h}

Shouldn't it be POSIX.2, since it is define for _XOPEN_SOURCE >= 600?

> +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
> +
> +@code{posix_openpt} returns a new file descriptor for the next
> +available master pseudo-terminal.  In the case of an error, it returns
> +a value of @math{-1} instead, and sets @code{errno} to indicate
> +the error.  @xref{Opening and Closing Files} for possible values
> +of @code{errno}.
> +
> +@var{flags} is a bit mask created from a bitwise OR of zero or more
> +of the following flags:
> +
> +@table @code
> +@item O_RDWR
> +Open the device for both reading and writing.  It is usual to specify
> +this flag.
> +@item O_NOCTTY
> +Do not make the device the controlling terminal for the process.
> +@end table
> +
> +These flags are defined in @file{fcntl.h}.  @xref{Access Modes}.
> +
> +For this function to be available, @code{_XOPEN_SOURCE} must be defined
> +to a value greater than @samp{600}.  @xref{Feature Test Macros}.
> +@end deftypefun
> +
>  @deftypefun int getpt (void)
>  @standards{GNU, stdlib.h}
>  @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
> @@ -1957,6 +1984,10 @@ functions are declared in the header file @file{stdlib.h}.
>  @c a devfs, and returns the fd; static variables devpts_mounted and
>  @c have_no_dev_ptmx are safely initialized so as to avoid repeated
>  @c tests.
> +
> +@code{getpt} is similar to @code{posix_openpt}.  This function is a
> +GNU extension and should not be used in portable programs.
> +
>  The @code{getpt} function returns a new file descriptor for the next
>  available master pseudo-terminal.  The normal return value from
>  @code{getpt} is a non-negative integer file descriptor.  In the case of
> @@ -1967,8 +1998,6 @@ an error, a value of @math{-1} is returned instead.  The following
>  @item ENOENT
>  There are no free master pseudo-terminals available.
>  @end table
> -
> -This function is a GNU extension.
>  @end deftypefun
>  
>  @deftypefun int grantpt (int @var{filedes})
> @@ -2118,6 +2147,7 @@ This function is a GNU extension.
>  @end deftypefun
>  
>  Typical usage of these functions is illustrated by the following example:
> +
>  @smallexample
>  int
>  open_pty_pair (int *amaster, int *aslave)
> @@ -2125,7 +2155,7 @@ open_pty_pair (int *amaster, int *aslave)
>    int master, slave;
>    char *name;
>  
> -  master = getpt ();
> +  master = posix_openpt (O_RDWR | O_NOCTTY);
>    if (master < 0)
>      return 0;
>  
> 

Ok.

Re: [PATCH 1/1] document posix_openpt

[Gavin Smith]

On Wed, Apr 19, 2023 at 09:43:01AM -0300, Adhemerval Zanella Netto wrote:

> LGTM, I am just no sure which standard to use.
> 
> > 
> > diff --git a/manual/terminal.texi b/manual/terminal.texi
> > index 7293bfb393..bdaee56053 100644
> > --- a/manual/terminal.texi
> > +++ b/manual/terminal.texi
> > @@ -1947,6 +1947,33 @@ This subsection describes functions for allocating a pseudo-terminal,
> >  and for making this pseudo-terminal available for actual use.  These
> >  functions are declared in the header file @file{stdlib.h}.
> >  
> > +@deftypefun int posix_openpt (int @var{flags})
> > +@standards{POSIX.1, stdlib.h}
> 
> Shouldn't it be POSIX.2, since it is define for _XOPEN_SOURCE >= 600?

I got from the "feature_test_macros" manpage:

  (Since glibc 2.2) The value 600 or greater additionally  ex‐
  poses definitions for SUSv3 (UNIX 03; i.e., the POSIX.1-2001
  base specification plus the XSI extension) and  C99  defini‐
  tions.

This is why I thought "POSIX.1" was the most appropriate.

POSIX.2 is mentioned in the libc manual, but it doesn't appear to cover
pseudo-terminal functionality:

     Some facilities from ‘ISO/IEC 9945-2:1993, the POSIX Shell and
  Utilities standard’ (POSIX.2) are also implemented in the GNU C Library.
  These include utilities for dealing with regular expressions and other
  pattern matching facilities

Existing uses of @standards{POSIX.2, ...} in the manual are consistent
with this.

'./summary.pl --help' doesn't offer any further guidance.

Re: [PATCH 1/1] document posix_openpt

[Adhemerval Zanella Netto]

On 23/04/23 06:35, Gavin Smith wrote:
> On Wed, Apr 19, 2023 at 09:43:01AM -0300, Adhemerval Zanella Netto wrote:
> 
>> LGTM, I am just no sure which standard to use.
>>
>>>
>>> diff --git a/manual/terminal.texi b/manual/terminal.texi
>>> index 7293bfb393..bdaee56053 100644
>>> --- a/manual/terminal.texi
>>> +++ b/manual/terminal.texi
>>> @@ -1947,6 +1947,33 @@ This subsection describes functions for allocating a pseudo-terminal,
>>>  and for making this pseudo-terminal available for actual use.  These
>>>  functions are declared in the header file @file{stdlib.h}.
>>>  
>>> +@deftypefun int posix_openpt (int @var{flags})
>>> +@standards{POSIX.1, stdlib.h}
>>
>> Shouldn't it be POSIX.2, since it is define for _XOPEN_SOURCE >= 600?
> 
> I got from the "feature_test_macros" manpage:
> 
>   (Since glibc 2.2) The value 600 or greater additionally  ex‐
>   poses definitions for SUSv3 (UNIX 03; i.e., the POSIX.1-2001
>   base specification plus the XSI extension) and  C99  defini‐
>   tions.
> 
> This is why I thought "POSIX.1" was the most appropriate.
> 
> POSIX.2 is mentioned in the libc manual, but it doesn't appear to cover
> pseudo-terminal functionality:
> 
>      Some facilities from ‘ISO/IEC 9945-2:1993, the POSIX Shell and
>   Utilities standard’ (POSIX.2) are also implemented in the GNU C Library.
>   These include utilities for dealing with regular expressions and other
>   pattern matching facilities
> 
> Existing uses of @standards{POSIX.2, ...} in the manual are consistent
> with this.
> 
> './summary.pl --help' doesn't offer any further guidance
The posix_openpt was originally added with XPG6 XSI (__USE_XOPEN2KXSI),
which I think it indeed falls on POSIX.1 (although for 2008).  So I think
it is correct.  I will apply this patch, thanks.

Re: [PATCH 1/1] document posix_openpt

[Gavin Smith]

On Wed, Apr 26, 2023 at 01:20:45PM +0100, Adhemerval Zanella Netto wrote:
> The posix_openpt was originally added with XPG6 XSI (__USE_XOPEN2KXSI),
> which I think it indeed falls on POSIX.1 (although for 2008).  So I think
> it is correct.  I will apply this patch, thanks.

Thank you!