libio/vswprintf.c

   1 /* Copyright (C) 1994-2021 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, see
  16    <https://www.gnu.org/licenses/>.
  17
  18    As a special exception, if you link the code in this file with
  19    files compiled with a GNU compiler to produce an executable,
  20    that does not cause the resulting executable to be covered by
  21    the GNU Lesser General Public License.  This exception does not
  22    however invalidate any other reasons why the executable file
  23    might be covered by the GNU Lesser General Public License.
  24    This exception applies to code released by its copyright holders
  25    in files containing the exception.  */
  26
  27 #include "libioP.h"
  28 #include "strfile.h"
  29
  30
  31 static wint_t _IO_wstrn_overflow (FILE *fp, wint_t c) __THROW;
  32
  33 static wint_t
  34 _IO_wstrn_overflow (FILE *fp, wint_t c)
  35 {
  36   /* When we come to here this means the user supplied buffer is
  37      filled.  But since we must return the number of characters which
  38      would have been written in total we must provide a buffer for
  39      further use.  We can do this by writing on and on in the overflow
  40      buffer in the _IO_wstrnfile structure.  */
  41   _IO_wstrnfile *snf = (_IO_wstrnfile *) fp;
  42
  43   if (fp->_wide_data->_IO_buf_base != snf->overflow_buf)
  44     {
  45       _IO_wsetb (fp, snf->overflow_buf,
  46                  snf->overflow_buf + (sizeof (snf->overflow_buf)
  47                                       / sizeof (wchar_t)), 0);
  48
  49       fp->_wide_data->_IO_write_base = snf->overflow_buf;
  50       fp->_wide_data->_IO_read_base = snf->overflow_buf;
  51       fp->_wide_data->_IO_read_ptr = snf->overflow_buf;
  52       fp->_wide_data->_IO_read_end = (snf->overflow_buf
  53                                       + (sizeof (snf->overflow_buf)
  54                                          / sizeof (wchar_t)));
  55     }
  56
  57   fp->_wide_data->_IO_write_ptr = snf->overflow_buf;
  58   fp->_wide_data->_IO_write_end = snf->overflow_buf;
  59
  60   /* Since we are not really interested in storing the characters
  61      which do not fit in the buffer we simply ignore it.  */
  62   return c;
  63 }
  64
  65
  66 const struct _IO_jump_t _IO_wstrn_jumps libio_vtable attribute_hidden =
  67 {
  68   JUMP_INIT_DUMMY,
  69   JUMP_INIT(finish, _IO_wstr_finish),
  70   JUMP_INIT(overflow, (_IO_overflow_t) _IO_wstrn_overflow),
  71   JUMP_INIT(underflow, (_IO_underflow_t) _IO_wstr_underflow),
  72   JUMP_INIT(uflow, (_IO_underflow_t) _IO_wdefault_uflow),
  73   JUMP_INIT(pbackfail, (_IO_pbackfail_t) _IO_wstr_pbackfail),
  74   JUMP_INIT(xsputn, _IO_wdefault_xsputn),
  75   JUMP_INIT(xsgetn, _IO_wdefault_xsgetn),
  76   JUMP_INIT(seekoff, _IO_wstr_seekoff),
  77   JUMP_INIT(seekpos, _IO_default_seekpos),
  78   JUMP_INIT(setbuf, _IO_default_setbuf),
  79   JUMP_INIT(sync, _IO_default_sync),
  80   JUMP_INIT(doallocate, _IO_wdefault_doallocate),
  81   JUMP_INIT(read, _IO_default_read),
  82   JUMP_INIT(write, _IO_default_write),
  83   JUMP_INIT(seek, _IO_default_seek),
  84   JUMP_INIT(close, _IO_default_close),
  85   JUMP_INIT(stat, _IO_default_stat),
  86   JUMP_INIT(showmanyc, _IO_default_showmanyc),
  87   JUMP_INIT(imbue, _IO_default_imbue)
  88 };
  89
  90
  91 int
  92 __vswprintf_internal (wchar_t *string, size_t maxlen, const wchar_t *format,
  93                       va_list args, unsigned int mode_flags)
  94 {
  95   _IO_wstrnfile sf;
  96   int ret;
  97   struct _IO_wide_data wd;
  98 #ifdef _IO_MTSAFE_IO
  99   sf.f._sbf._f._lock = NULL;
 100 #endif
 101
 102   if (maxlen == 0)
 103     /* Since we have to write at least the terminating L'\0' a buffer
 104        length of zero always makes the function fail.  */
 105     return -1;
 106
 107   _IO_no_init (&sf.f._sbf._f, _IO_USER_LOCK, 0, &wd, &_IO_wstrn_jumps);
 108   _IO_fwide (&sf.f._sbf._f, 1);
 109   string[0] = L'\0';
 110   _IO_wstr_init_static (&sf.f._sbf._f, string, maxlen - 1, string);
 111   ret = __vfwprintf_internal ((FILE *) &sf.f._sbf, format, args, mode_flags);
 112
 113   if (sf.f._sbf._f._wide_data->_IO_buf_base == sf.overflow_buf)
 114     /* ISO C99 requires swprintf/vswprintf to return an error if the
 115        output does not fit in the provided buffer.  */
 116     return -1;
 117
 118   /* Terminate the string.  */
 119   *sf.f._sbf._f._wide_data->_IO_write_ptr = '\0';
 120
 121   return ret;
 122 }
 123
 124 int
 125 __vswprintf (wchar_t *string, size_t maxlen, const wchar_t *format,
 126              va_list args)
 127 {
 128   return __vswprintf_internal (string, maxlen, format, args, 0);
 129 }
 130 ldbl_weak_alias (__vswprintf, vswprintf)