lib/fpurge.c

   1 /* Flushing buffers of a FILE stream.
   2    Copyright (C) 2007-2020 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <stdio.h>
  21
  22 #if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7, Android API >= 23 */
  23 # include <stdio_ext.h>
  24 #endif
  25 #include <stdlib.h>
  26
  27 #include "stdio-impl.h"
  28
  29 int
  30 fpurge (FILE *fp)
  31 {
  32 #if HAVE___FPURGE                   /* glibc >= 2.2, Haiku, Solaris >= 7, Android API >= 23, musl libc */
  33
  34   __fpurge (fp);
  35   /* The __fpurge function does not have a return value.  */
  36   return 0;
  37
  38 #elif HAVE_FPURGE                   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin 1.7 */
  39
  40   /* Call the system's fpurge function.  */
  41 # undef fpurge
  42 # if !HAVE_DECL_FPURGE
  43   extern int fpurge (FILE *);
  44 # endif
  45   int result = fpurge (fp);
  46 # if defined __sferror || defined __DragonFly__ || defined __ANDROID__
  47   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
  48   if (result == 0)
  49     /* Correct the invariants that fpurge broke.
  50        <stdio.h> on BSD systems says:
  51          "The following always hold: if _flags & __SRD, _w is 0."
  52        If this invariant is not fulfilled and the stream is read-write but
  53        currently reading, subsequent putc or fputc calls will write directly
  54        into the buffer, although they shouldn't be allowed to.  */
  55     if ((fp_->_flags & __SRD) != 0)
  56       fp_->_w = 0;
  57 # endif
  58   return result;
  59
  60 #else
  61
  62   /* Most systems provide FILE as a struct and the necessary bitmask in
  63      <stdio.h>, because they need it for implementing getc() and putc() as
  64      fast macros.  */
  65 # if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
  66   /* GNU libc, BeOS, Haiku, Linux libc5 */
  67   fp->_IO_read_end = fp->_IO_read_ptr;
  68   fp->_IO_write_ptr = fp->_IO_write_base;
  69   /* Avoid memory leak when there is an active ungetc buffer.  */
  70   if (fp->_IO_save_base != NULL)
  71     {
  72       free (fp->_IO_save_base);
  73       fp->_IO_save_base = NULL;
  74     }
  75   return 0;
  76 # elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
  77   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
  78   fp_->_p = fp_->_bf._base;
  79   fp_->_r = 0;
  80   fp_->_w = ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
  81              ? fp_->_bf._size
  82              : 0);
  83   /* Avoid memory leak when there is an active ungetc buffer.  */
  84   if (fp_ub._base != NULL)
  85     {
  86       if (fp_ub._base != fp_->_ubuf)
  87         free (fp_ub._base);
  88       fp_ub._base = NULL;
  89     }
  90   return 0;
  91 # elif defined __EMX__              /* emx+gcc */
  92   fp->_ptr = fp->_buffer;
  93   fp->_rcount = 0;
  94   fp->_wcount = 0;
  95   fp->_ungetc_count = 0;
  96   return 0;
  97 # elif defined __minix              /* Minix */
  98   fp->_ptr = fp->_buf;
  99   if (fp->_ptr != NULL)
 100     fp->_count = 0;
 101   return 0;
 102 # elif defined _IOERR               /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, MSVC, NonStop Kernel, OpenVMS */
 103   fp_->_ptr = fp_->_base;
 104   if (fp_->_ptr != NULL)
 105     fp_->_cnt = 0;
 106   return 0;
 107 # elif defined __UCLIBC__           /* uClibc */
 108 #  ifdef __STDIO_BUFFERS
 109   if (fp->__modeflags & __FLAG_WRITING)
 110     fp->__bufpos = fp->__bufstart;
 111   else if (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING))
 112     fp->__bufpos = fp->__bufread;
 113 #  endif
 114   return 0;
 115 # elif defined __QNX__              /* QNX */
 116   fp->_Rback = fp->_Back + sizeof (fp->_Back);
 117   fp->_Rsave = NULL;
 118   if (fp->_Mode & 0x2000 /* _MWRITE */)
 119     /* fp->_Buf <= fp->_Next <= fp->_Wend */
 120     fp->_Next = fp->_Buf;
 121   else
 122     /* fp->_Buf <= fp->_Next <= fp->_Rend */
 123     fp->_Rend = fp->_Next;
 124   return 0;
 125 # elif defined __MINT__             /* Atari FreeMiNT */
 126   if (fp->__pushed_back)
 127     {
 128       fp->__bufp = fp->__pushback_bufp;
 129       fp->__pushed_back = 0;
 130     }
 131   /* Preserve the current file position.  */
 132   if (fp->__target != -1)
 133     fp->__target += fp->__bufp - fp->__buffer;
 134   fp->__bufp = fp->__buffer;
 135   /* Nothing in the buffer, next getc is nontrivial.  */
 136   fp->__get_limit = fp->__bufp;
 137   /* Nothing in the buffer, next putc is nontrivial.  */
 138   fp->__put_limit = fp->__buffer;
 139   return 0;
 140 # elif defined EPLAN9               /* Plan9 */
 141   fp->rp = fp->wp = fp->lp = fp->buf;
 142   return 0;
 143 # else
 144 #  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."
 145 # endif
 146
 147 #endif
 148 }