libio/vsnprintf.c

   1 /* Copyright (C) 1994,1997,1999-2004,2006,2009 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.
  18
  19    As a special exception, if you link the code in this file with
  20    files compiled with a GNU compiler to produce an executable,
  21    that does not cause the resulting executable to be covered by
  22    the GNU Lesser General Public License.  This exception does not
  23    however invalidate any other reasons why the executable file
  24    might be covered by the GNU Lesser General Public License.
  25    This exception applies to code released by its copyright holders
  26    in files containing the exception.  */
  27
  28 #include "libioP.h"
  29 #include "strfile.h"
  30
  31 static int _IO_strn_overflow (_IO_FILE *fp, int c) __THROW;
  32
  33 static int
  34 _IO_strn_overflow (fp, c)
  35      _IO_FILE *fp;
  36      int c;
  37 {
  38   /* When we come to here this means the user supplied buffer is
  39      filled.  But since we must return the number of characters which
  40      would have been written in total we must provide a buffer for
  41      further use.  We can do this by writing on and on in the overflow
  42      buffer in the _IO_strnfile structure.  */
  43   _IO_strnfile *snf = (_IO_strnfile *) fp;
  44
  45   if (fp->_IO_buf_base != snf->overflow_buf)
  46     {
  47       /* Terminate the string.  We know that there is room for at
  48          least one more character since we initialized the stream with
  49          a size to make this possible.  */
  50       *fp->_IO_write_ptr = '\0';
  51
  52       INTUSE(_IO_setb) (fp, snf->overflow_buf,
  53                         snf->overflow_buf + sizeof (snf->overflow_buf), 0);
  54
  55       fp->_IO_write_base = snf->overflow_buf;
  56       fp->_IO_read_base = snf->overflow_buf;
  57       fp->_IO_read_ptr = snf->overflow_buf;
  58       fp->_IO_read_end = snf->overflow_buf + sizeof (snf->overflow_buf);
  59     }
  60
  61   fp->_IO_write_ptr = snf->overflow_buf;
  62   fp->_IO_write_end = snf->overflow_buf;
  63
  64   /* Since we are not really interested in storing the characters
  65      which do not fit in the buffer we simply ignore it.  */
  66   return c;
  67 }
  68
  69
  70 const struct _IO_jump_t _IO_strn_jumps attribute_hidden =
  71 {
  72   JUMP_INIT_DUMMY,
  73   JUMP_INIT(finish, _IO_str_finish),
  74   JUMP_INIT(overflow, _IO_strn_overflow),
  75   JUMP_INIT(underflow, INTUSE(_IO_str_underflow)),
  76   JUMP_INIT(uflow, INTUSE(_IO_default_uflow)),
  77   JUMP_INIT(pbackfail, INTUSE(_IO_str_pbackfail)),
  78   JUMP_INIT(xsputn, INTUSE(_IO_default_xsputn)),
  79   JUMP_INIT(xsgetn, INTUSE(_IO_default_xsgetn)),
  80   JUMP_INIT(seekoff, INTUSE(_IO_str_seekoff)),
  81   JUMP_INIT(seekpos, _IO_default_seekpos),
  82   JUMP_INIT(setbuf, _IO_default_setbuf),
  83   JUMP_INIT(sync, _IO_default_sync),
  84   JUMP_INIT(doallocate, INTUSE(_IO_default_doallocate)),
  85   JUMP_INIT(read, _IO_default_read),
  86   JUMP_INIT(write, _IO_default_write),
  87   JUMP_INIT(seek, _IO_default_seek),
  88   JUMP_INIT(close, _IO_default_close),
  89   JUMP_INIT(stat, _IO_default_stat),
  90   JUMP_INIT(showmanyc, _IO_default_showmanyc),
  91   JUMP_INIT(imbue, _IO_default_imbue)
  92 };
  93
  94
  95 int
  96 _IO_vsnprintf (string, maxlen, format, args)
  97      char *string;
  98      _IO_size_t maxlen;
  99      const char *format;
 100      _IO_va_list args;
 101 {
 102   _IO_strnfile sf;
 103   int ret;
 104 #ifdef _IO_MTSAFE_IO
 105   sf.f._sbf._f._lock = NULL;
 106 #endif
 107
 108   /* We need to handle the special case where MAXLEN is 0.  Use the
 109      overflow buffer right from the start.  */
 110   if (maxlen == 0)
 111     {
 112       string = sf.overflow_buf;
 113       maxlen = sizeof (sf.overflow_buf);
 114     }
 115
 116   _IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, -1, NULL, NULL);
 117   _IO_JUMPS (&sf.f._sbf) = &_IO_strn_jumps;
 118   string[0] = '\0';
 119   _IO_str_init_static_internal (&sf.f, string, maxlen - 1, string);
 120   ret = INTUSE(_IO_vfprintf) (&sf.f._sbf._f, format, args);
 121
 122   if (sf.f._sbf._f._IO_buf_base != sf.overflow_buf)
 123     *sf.f._sbf._f._IO_write_ptr = '\0';
 124   return ret;
 125 }
 126 ldbl_weak_alias (_IO_vsnprintf, __vsnprintf)
 127 ldbl_weak_alias (_IO_vsnprintf, vsnprintf)