lib/sh/fpurge.c

   1 /* fpurge - Flushing buffers of a FILE stream. */
   2
   3 /* Copyright (C) 2007 Free Software Foundation, Inc.
   4
   5    This file is part of GNU Bash, the Bourne Again SHell.
   6
   7    Bash is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    Bash is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include <config.h>
  22
  23 #include "stdc.h"
  24
  25 #include <stdio.h>
  26
  27 /* Specification.  Same as in ../../externs.h.  */
  28 #define NEED_FPURGE_DECL
  29 #if HAVE_FPURGE
  30 #  define fpurge _bash_fpurge
  31 #endif
  32 extern int fpurge __P((FILE *stream));
  33
  34 #if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7 */
  35 # include <stdio_ext.h>
  36 #endif
  37 #include <stdlib.h>
  38
  39 int
  40 fpurge (FILE *fp)
  41 {
  42 #if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7 */
  43
  44   __fpurge (fp);
  45   /* The __fpurge function does not have a return value.  */
  46   return 0;
  47
  48 #elif HAVE_FPURGE                   /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X */
  49
  50   /* Call the system's fpurge function.  */
  51 # undef fpurge
  52 # if !HAVE_DECL_FPURGE
  53   extern int fpurge (FILE *);
  54 # endif
  55   int result = fpurge (fp);
  56 # if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
  57   if (result == 0)
  58     /* Correct the invariants that fpurge broke.
  59        <stdio.h> on BSD systems says:
  60          "The following always hold: if _flags & __SRD, _w is 0."
  61        If this invariant is not fulfilled and the stream is read-write but
  62        currently writing, subsequent putc or fputc calls will write directly
  63        into the buffer, although they shouldn't be allowed to.  */
  64     if ((fp->_flags & __SRD) != 0)
  65       fp->_w = 0;
  66 # endif
  67   return result;
  68
  69 #else
  70
  71   /* Most systems provide FILE as a struct and the necessary bitmask in
  72      <stdio.h>, because they need it for implementing getc() and putc() as
  73      fast macros.  */
  74 # if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
  75   fp->_IO_read_end = fp->_IO_read_ptr;
  76   fp->_IO_write_ptr = fp->_IO_write_base;
  77   /* Avoid memory leak when there is an active ungetc buffer.  */
  78   if (fp->_IO_save_base != NULL)
  79     {
  80       free (fp->_IO_save_base);
  81       fp->_IO_save_base = NULL;
  82     }
  83   return 0;
  84 # elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
  85   fp_->_p = fp_->_bf._base;
  86   fp_->_r = 0;
  87   fp_->_w = ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
  88              ? fp_->_bf._size
  89              : 0);
  90   /* Avoid memory leak when there is an active ungetc buffer.  */
  91   if (fp_ub._base != NULL)
  92     {
  93       if (fp_ub._base != fp_->_ubuf)
  94         free (fp_ub._base);
  95       fp_ub._base = NULL;
  96     }
  97   return 0;
  98 # elif defined __EMX__              /* emx+gcc */
  99   fp->_ptr = fp->_buffer;
 100   fp->_rcount = 0;
 101   fp->_wcount = 0;
 102   fp->_ungetc_count = 0;
 103   return 0;
 104 # elif defined _IOERR               /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
 105   fp->_ptr = fp->_base;
 106   if (fp->_ptr != NULL)
 107     fp->_cnt = 0;
 108   return 0;
 109 # elif defined __UCLIBC__           /* uClibc */
 110 #  ifdef __STDIO_BUFFERS
 111   if (fp->__modeflags & __FLAG_WRITING)
 112     fp->__bufpos = fp->__bufstart;
 113   else if (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING))
 114     fp->__bufpos = fp->__bufread;
 115 #  endif
 116   return 0;
 117 # elif defined __QNX__              /* QNX */
 118   fp->_Rback = fp->_Back + sizeof (fp->_Back);
 119   fp->_Rsave = NULL;
 120   if (fp->_Mode & 0x2000 /* _MWRITE */)
 121     /* fp->_Buf <= fp->_Next <= fp->_Wend */
 122     fp->_Next = fp->_Buf;
 123   else
 124     /* fp->_Buf <= fp->_Next <= fp->_Rend */
 125     fp->_Rend = fp->_Next;
 126   return 0;
 127 # elif defined __MINT__             /* Atari FreeMiNT */
 128   if (fp->__pushed_back)
 129     {
 130       fp->__bufp = fp->__pushback_bufp;
 131       fp->__pushed_back = 0;
 132     }
 133   /* Preserve the current file position.  */
 134   if (fp->__target != -1)
 135     fp->__target += fp->__bufp - fp->__buffer;
 136   fp->__bufp = fp->__buffer;
 137   /* Nothing in the buffer, next getc is nontrivial.  */
 138   fp->__get_limit = fp->__bufp;
 139   /* Nothing in the buffer, next putc is nontrivial.  */
 140   fp->__put_limit = fp->__buffer;
 141   return 0;
 142 # else
 143 # warning "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."
 144   return 0;
 145 # endif
 146
 147 #endif
 148 }