Re: fpurge.c on Plan9/APE

[Bruno Haible]

Jens Staal wrote:
> I think the problem basically is that I do not fully understand what is 
> done in all those other OSes defined in fpurge.c and what is expected 
> from this function....

Yes, it's not easy to understand the various stdioext operations.

Here is a tentative port to Plan9. Before you can assume that it is usable
for GNU m4 or GNU coreutils, you need to run the testsuite, though.
I have prepared a testdir for you, through

  $ ./gnulib-tool --create-testdir --dir=/tmp/testdir-stdioext \
    --with-tests --single-configure \
    fseterr freadable fwritable fbufmode freading fwriting freadptr \
    freadseek freadahead fpurge fseeko ftello fpending

Please download it from
  http://www.haible.de/bruno/gnu/testdir-stdioext.tar.gz
and report the test suite results from
  $ ./configure
  $ make
  $ make check



2012-02-03  Bruno Haible  <address@hidden>

        stdioext: Add tentative support for Plan9.
        * lib/stdio-impl.h: Include <errno.h>.
        * lib/fseterr.c (fseterr) [EPLAN9]: Add conditional code.
        * lib/freadable.c (freadable): Likewise.
        * lib/fwritable.c (fwritable): Likewise.
        * lib/fbufmode.c (fbufmode): Likewise.
        * lib/freading.c (freading): Likewise.
        * lib/fwriting.c (fwriting): Likewise.
        * lib/freadptr.c (freadptr): Likewise.
        * lib/freadseek.c (freadptrinc): Likewise.
        * lib/freadahead.c (freadahead): Likewise.
        * lib/fpurge.c (fpurge): Likewise.
        * lib/fseeko.c (rpl_fseeko): Likewise.
        * m4/fpending.m4 (gl_PREREQ_FPENDING): Add a variant for Plan9.
        Reported by Jens Staal <address@hidden>.

--- lib/fbufmode.c.orig Fri Feb  3 22:54:04 2012
+++ lib/fbufmode.c      Fri Feb  3 21:30:15 2012
@@ -79,6 +79,12 @@
   if (fp->__linebuf)
     return _IOLBF;
   return (fp->__bufsize > 0 ? _IOFBF : _IONBF);
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->flags & 2 /* LINEBUF */)
+    return _IOLBF;
+  if (fp->bufl)
+    return _IOFBF;
+  return _IONBF;
 #else
 # error "Please port gnulib fbufmode.c to your platform! Look at the setvbuf 
implementation."
 #endif
--- lib/fpurge.c.orig   Fri Feb  3 22:54:04 2012
+++ lib/fpurge.c        Fri Feb  3 22:30:44 2012
@@ -134,6 +134,9 @@
   /* Nothing in the buffer, next putc is nontrivial.  */
   fp->__put_limit = fp->__buffer;
   return 0;
+# elif defined EPLAN9               /* Plan9 */
+  fp->rp = fp->wp = fp->lp = fp->buf;
+  return 0;
 # else
 #  error "Please port gnulib fpurge.c to your platform! Look at the 
definitions of fflush, setvbuf and ungetc on your system, then report this to 
bug-gnulib."
 # endif
--- lib/freadable.c.orig        Fri Feb  3 22:54:04 2012
+++ lib/freadable.c     Fri Feb  3 21:25:10 2012
@@ -21,6 +21,10 @@
 
 #include "stdio-impl.h"
 
+#if defined EPLAN9                  /* Plan9 */
+# include <fcntl.h>
+#endif
+
 bool
 freadable (FILE *fp)
 {
@@ -41,6 +45,18 @@
   return (fp->_Mode & 0x1 /* _MOPENR */) != 0;
 #elif defined __MINT__              /* Atari FreeMiNT */
   return fp->__mode.__read;
+#elif defined EPLAN9                /* Plan9 */
+  int fd = fp->fd;
+  if (fd >= 0)
+    {
+      int flags = fcntl (fd, F_GETFL, NULL);
+      if (flags >= 0)
+        {
+          flags &= O_ACCMODE;
+          return (flags == O_RDONLY || flags == O_RDWR);
+        }
+    }
+  return 0;
 #else
 # error "Please port gnulib freadable.c to your platform! Look at the 
definition of fopen, fdopen on your system, then report this to bug-gnulib."
 #endif
--- lib/freadahead.c.orig       Fri Feb  3 22:54:04 2012
+++ lib/freadahead.c    Fri Feb  3 22:21:18 2012
@@ -80,6 +80,10 @@
   return (fp->__pushed_back
           ? fp->__get_limit - fp->__pushback_bufp + 1
           : fp->__get_limit - fp->__bufp);
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->state == 4 /* WR */ || fp->rp >= fp->wp)
+    return 0;
+  return fp->wp - fp->rp;
 #elif defined SLOW_BUT_NO_HACKS     /* users can define this */
   abort ();
   return 0;
--- lib/freading.c.orig Fri Feb  3 22:54:04 2012
+++ lib/freading.c      Fri Feb  3 22:01:21 2012
@@ -62,6 +62,10 @@
 #  else
   return (fp->__buffer < fp->__get_limit /*|| fp->__bufp == fp->__put_limit 
??*/);
 #  endif
+# elif defined EPLAN9                /* Plan9 */
+  if (fp->state == 0 /* CLOSED */ || fp->state == 4 /* WR */)
+    return 0;
+  return (fp->state == 3 /* RD */ && (fp->bufl == 0 || fp->rp < fp->wp));
 # else
 #  error "Please port gnulib freading.c to your platform!"
 # endif
--- lib/freadptr.c.orig Fri Feb  3 22:54:04 2012
+++ lib/freadptr.c      Fri Feb  3 22:06:58 2012
@@ -101,6 +101,13 @@
     return NULL;
   *sizep = size;
   return fp->__bufp;
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->state == 4 /* WR */)
+    return NULL;
+  if (fp->rp >= fp->wp)
+    return NULL;
+  *sizep = fp->wp - fp->rp;
+  return fp->rp;
 #elif defined SLOW_BUT_NO_HACKS     /* users can define this */
   /* This implementation is correct on any ANSI C platform.  It is just
      awfully slow.  */
--- lib/freadseek.c.orig        Fri Feb  3 22:54:04 2012
+++ lib/freadseek.c     Fri Feb  3 22:07:42 2012
@@ -58,6 +58,8 @@
   fp->_Next += increment;
 #elif defined __MINT__              /* Atari FreeMiNT */
   fp->__bufp += increment;
+#elif defined EPLAN9                /* Plan9 */
+  fp->rp += increment;
 #elif defined SLOW_BUT_NO_HACKS     /* users can define this */
 #else
  #error "Please port gnulib freadseek.c to your platform! Look at the 
definition of getc, getc_unlocked on your system, then report this to 
bug-gnulib."
--- lib/fseeko.c.orig   Fri Feb  3 22:54:04 2012
+++ lib/fseeko.c        Fri Feb  3 22:41:25 2012
@@ -89,6 +89,9 @@
       && fp->__get_limit == fp->__bufp
       && fp->__put_limit == fp->__bufp
       && !fp->__pushed_back)
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->rp == fp->buf
+      && fp->wp == fp->buf)
 #else
   #error "Please port gnulib fseeko.c to your platform! Look at the code in 
fpurge.c, then report this to bug-gnulib."
 #endif
--- lib/fseterr.c.orig  Fri Feb  3 22:54:04 2012
+++ lib/fseterr.c       Fri Feb  3 21:10:30 2012
@@ -45,6 +45,9 @@
   fp->_Mode |= 0x200 /* _MERR */;
 #elif defined __MINT__              /* Atari FreeMiNT */
   fp->__error = 1;
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->state != 0 /* CLOSED */)
+    fp->state = 5 /* ERR */;
 #elif 0                             /* unknown  */
   /* Portable fallback, based on an idea by Rich Felker.
      Wow! 6 system calls for something that is just a bit operation!
--- lib/fwritable.c.orig        Fri Feb  3 22:54:04 2012
+++ lib/fwritable.c     Fri Feb  3 21:24:52 2012
@@ -41,6 +41,18 @@
   return (fp->_Mode & 0x2 /* _MOPENW */) != 0;
 #elif defined __MINT__              /* Atari FreeMiNT */
   return fp->__mode.__write;
+#elif defined EPLAN9                /* Plan9 */
+  int fd = fp->fd;
+  if (fd >= 0)
+    {
+      int flags = fcntl (fd, F_GETFL, NULL);
+      if (flags >= 0)
+        {
+          flags &= O_ACCMODE;
+          return (flags == O_WRONLY || flags == O_RDWR);
+        }
+    }
+  return 0;
 #else
 # error "Please port gnulib fwritable.c to your platform! Look at the 
definition of fopen, fdopen on your system, then report this to bug-gnulib."
 #endif
--- lib/fwriting.c.orig Fri Feb  3 22:54:04 2012
+++ lib/fwriting.c      Fri Feb  3 22:00:28 2012
@@ -52,6 +52,10 @@
 # else
   return (fp->__buffer < fp->__put_limit /*|| fp->__bufp == fp->__get_limit 
??*/);
 # endif
+#elif defined EPLAN9                /* Plan9 */
+  if (fp->state == 0 /* CLOSED */ || fp->state == 3 /* RD */)
+    return 0;
+  return (fp->state == 4 /* WR */ && (fp->bufl == 0 || fp->wp < fp->rp));
 #else
 # error "Please port gnulib fwriting.c to your platform!"
 #endif
--- lib/stdio-impl.h.orig       Fri Feb  3 22:54:04 2012
+++ lib/stdio-impl.h    Fri Feb  3 21:02:41 2012
@@ -26,6 +26,8 @@
 # include <sys/param.h>
 #endif
 
+#include <errno.h>                             /* For detecting Plan9.  */
+
 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, 
DragonFly, MacOS X, Cygwin */
 
 # if defined __DragonFly__          /* DragonFly */
--- m4/fpending.m4.orig Fri Feb  3 22:54:04 2012
+++ m4/fpending.m4      Fri Feb  3 22:53:44 2012
@@ -1,4 +1,4 @@
-# serial 18
+# serial 19
 
 # Copyright (C) 2000-2001, 2004-2012 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
@@ -61,6 +61,9 @@
           '# Minix'                                                     \
           'fp->_ptr - fp->_buf'                                         \
                                                                         \
+          '# Plan9'                                                     \
+          'fp->wp - fp->buf'                                            \
+                                                                        \
           '# VMS'                                                       \
           '(*fp)->_ptr - (*fp)->_base'                                  \
                                                                         \