Date: Sun, 30 Nov 1997 14:49:30 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: DJ Delorie <dj AT delorie DOT com>
cc: djgpp-workers AT delorie DOT com
Subject: Patches for fpathconf and docs for pathconf
Message-ID: <Pine.SUN.3.91.971130144537.5999E-100000@is>
MIME-Version: 1.0
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Precedence: bulk

I became tired of looking into the sources and a bunch of headers every 
time I needed to know what exactly does `pathconf' return in its DJGPP 
incarnation.  So here are the docs patches that tell the full story.  This 
also fixes `fpathconf' so it reports the values from the filesystem where 
the handle belongs, if that can be determined by `fstat'.

*** src/libc/posix/unistd/pathconf.t~0	Mon Jul 10 05:42:40 1995
--- src/libc/posix/unistd/pathconf.txh	Sat Nov 29 15:30:22 1997
***************
*** 10,22 ****
  
  @subheading Description
  
! Returns configuration information on the filesystem that the
! open file resides on.  @xref{pathconf}.
  
  @subheading Return Value
  
! The configuration value, which are currently independent of the filesystem
! that the file is on.
  
  @c ----------------------------------------------------------------------
  @node pathconf, posix
--- 10,23 ----
  
  @subheading Description
  
! Returns configuration information on the filesystem that the open file
! resides on.  @xref{pathconf}.  If the filesystem cannot be determined
! from the file handle @var{fd} (e.g., for character devices),
! @code{fpathconf} will return the info for the current drive.
  
  @subheading Return Value
  
! The configuration value; for details, see @ref{pathconf}.
  
  @c ----------------------------------------------------------------------
  @node pathconf, posix
***************
*** 37,77 ****
  
  @item _PC_LINK_MAX
  
! The maximum number of directory entries that can refer to a single real file.
  
  @item _PC_MAX_CANON
  
! The maximum number of bytes in an editable input line.
  
  @item _PC_MAX_INPUT
  
! The maximum number of bytes in a non-editable input line.
  
  @item _PC_NAME_MAX
  
! The maximum length of an individual file name.
  
  @item _PC_PATH_MAX
  
! The maximum length of a complete path name.
  
  @item _PC_PIPE_BUF
  
! The size of a pipe's internal buffer.
  
  @item _PC_CHOWN_RESTRICTED
  
! If non-zero, only privileged user can chown() files, otherwise anyone may
! give away files.
  
  @item _PC_NO_TRUNC
  
! If false filenames longer than @code{_PC_NAME_MAX} are truncated, otherwise
! an error occurs if you use longer names.
  
  @item _PC_VDISABLE
  
! A character to use to disable tty special characters.
  
  @end table
  
--- 38,92 ----
  
  @item _PC_LINK_MAX
  
! The maximum number of directory entries that can refer to a single real
! file.  Always 1 in DJGPP.
  
  @item _PC_MAX_CANON
  
! The maximum number of bytes in an editable input line.  In DJGPP, this
! is 126 (DOS restriction).
  
  @item _PC_MAX_INPUT
  
! The maximum number of bytes in a non-editable input line.  Also 126 in
! DJGPP.
  
  @item _PC_NAME_MAX
  
! The maximum length of an individual file name.  If the filesystem where
! @var{filename} resides supports long file names, the result is whatever
! @code{_get_volume_info} returns (usually 255); otherwise 12 will be
! returned.  @xref{_use_lfn}.
  
  @item _PC_PATH_MAX
  
! The maximum length of a complete path name.  If the filesystem where
! @var{filename} resides supports long file names, the result is whatever
! @code{_get_volume_info} returns (usually 260); otherwise 80 will be
! returned.  @xref{_use_lfn}.
  
  @item _PC_PIPE_BUF
  
! The size of a pipe's internal buffer.  In DJGPP, this returns 512.
  
  @item _PC_CHOWN_RESTRICTED
  
! If non-zero, only priviledged user can change the ownership of files by
! calling @code{chown}, otherwise anyone may give away files.  The DJGPP
! version always returns zero, since MS-DOS files can be freely given
! away.
  
  @item _PC_NO_TRUNC
  
! If zero is returned, filenames longer than what 
! @w{@code{pathconf (filename, _PC_NAME_MAX)}} returns are truncated,
! otherwise an error occurs if you use longer names.  In DJGPP, this
! returns 0, since DOS always silently truncates long names.
  
  @item _PC_VDISABLE
  
! A character to use to disable tty special characters.  DJGPP currently
! doesn't support special characters, so this returns -1.
  
  @end table
  
*** src/libc/posix/unistd/fpathcon.c~0	Sat Apr  1 21:24:04 1995
--- src/libc/posix/unistd/fpathcon.c	Sat Nov 29 15:25:42 1997
***************
*** 1,11 ****
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
  #include <errno.h>
  #include <unistd.h>
  #include <limits.h>
  
- /* ARGSUSED */
  long
  fpathconf(int fildes, int name)
  {
!   return pathconf("/", name);
  }
--- 1,24 ----
+ /* Copyright (C) 1997 DJ Delorie, see COPYING.DJ for details */
  /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
  #include <errno.h>
  #include <unistd.h>
  #include <limits.h>
+ #include <sys/stat.h>
  
  long
  fpathconf(int fildes, int name)
  {
!   static char root_path[] = "/";
!   struct stat st_buf;
!   char fs_root[4];
!   char *p = root_path;
! 
!   /* `fstat' returns non-negative `st_dev' for regular disk files.  */
!   if (fstat(fildes, &st_buf) == 0 && st_buf.st_dev >= 0)
!   {
!     fs_root[0] = 'A' + st_buf.st_dev;
!     strcpy(fs_root + 1, ":\\");
!     p = fs_root;
!   }
!   return pathconf(p, name);
  }