libio/iovsprintf.c

   1 /* Copyright (C) 1993-2020 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 static int __THROW
  31 _IO_str_chk_overflow (FILE *fp, int c)
  32 {
  33   /* If we get here, the user-supplied buffer would be overrun by
  34      further output.  */
  35   __chk_fail ();
  36 }
  37
  38 static const struct _IO_jump_t _IO_str_chk_jumps libio_vtable =
  39 {
  40   JUMP_INIT_DUMMY,
  41   JUMP_INIT(finish, _IO_str_finish),
  42   JUMP_INIT(overflow, _IO_str_chk_overflow),
  43   JUMP_INIT(underflow, _IO_str_underflow),
  44   JUMP_INIT(uflow, _IO_default_uflow),
  45   JUMP_INIT(pbackfail, _IO_str_pbackfail),
  46   JUMP_INIT(xsputn, _IO_default_xsputn),
  47   JUMP_INIT(xsgetn, _IO_default_xsgetn),
  48   JUMP_INIT(seekoff, _IO_str_seekoff),
  49   JUMP_INIT(seekpos, _IO_default_seekpos),
  50   JUMP_INIT(setbuf, _IO_default_setbuf),
  51   JUMP_INIT(sync, _IO_default_sync),
  52   JUMP_INIT(doallocate, _IO_default_doallocate),
  53   JUMP_INIT(read, _IO_default_read),
  54   JUMP_INIT(write, _IO_default_write),
  55   JUMP_INIT(seek, _IO_default_seek),
  56   JUMP_INIT(close, _IO_default_close),
  57   JUMP_INIT(stat, _IO_default_stat),
  58   JUMP_INIT(showmanyc, _IO_default_showmanyc),
  59   JUMP_INIT(imbue, _IO_default_imbue)
  60 };
  61
  62 /* This function is called by regular vsprintf with maxlen set to -1,
  63    and by vsprintf_chk with maxlen set to the size of the output
  64    string.  In the former case, _IO_str_chk_overflow will never be
  65    called; in the latter case it will crash the program if the buffer
  66    overflows.  */
  67
  68 int
  69 __vsprintf_internal (char *string, size_t maxlen,
  70                      const char *format, va_list args,
  71                      unsigned int mode_flags)
  72 {
  73   _IO_strfile sf;
  74   int ret;
  75
  76 #ifdef _IO_MTSAFE_IO
  77   sf._sbf._f._lock = NULL;
  78 #endif
  79   _IO_no_init (&sf._sbf._f, _IO_USER_LOCK, -1, NULL, NULL);
  80   /* When called from fortified sprintf/vsprintf, erase the destination
  81      buffer and try to detect overflows.  When called from regular
  82      sprintf/vsprintf, do not erase the destination buffer, because
  83      known user code relies on this behavior (even though its undefined
  84      by ISO C), nor try to detect overflows.  */
  85   if ((mode_flags & PRINTF_CHK) != 0)
  86     {
  87       _IO_JUMPS (&sf._sbf) = &_IO_str_chk_jumps;
  88       string[0] = '\0';
  89     }
  90   else
  91     _IO_JUMPS (&sf._sbf) = &_IO_str_jumps;
  92   _IO_str_init_static_internal (&sf, string,
  93                                 (maxlen == -1) ? -1 : maxlen - 1,
  94                                 string);
  95
  96   ret = __vfprintf_internal (&sf._sbf._f, format, args, mode_flags);
  97
  98   *sf._sbf._f._IO_write_ptr = '\0';
  99   return ret;
 100 }
 101
 102 int
 103 __vsprintf (char *string, const char *format, va_list args)
 104 {
 105   return __vsprintf_internal (string, -1, format, args, 0);
 106 }
 107
 108 ldbl_strong_alias (__vsprintf, _IO_vsprintf)
 109 ldbl_weak_alias (__vsprintf, vsprintf)