1  /* Copyright (C) 1994-2023 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  
      29  #include <array_length.h>
      30  #include <printf.h>
      31  #include <printf_buffer.h>
      32  
      33  void
      34  __printf_buffer_flush_snprintf (struct __printf_buffer_snprintf *buf)
      35  {
      36    /* Record the bytes written so far, before switching buffers.  */
      37    buf->base.written += buf->base.write_ptr - buf->base.write_base;
      38  
      39    if (buf->base.write_base != buf->discard)
      40      {
      41        /* We just finished writing the caller-supplied buffer.  Force
      42  	 NUL termination if the string length is not zero.  */
      43        if (buf->base.write_base != buf->base.write_end)
      44  	buf->base.write_end[-1] = '\0';
      45  
      46  
      47        /* Switch to the discard buffer.  */
      48        buf->base.write_base = buf->discard;
      49        buf->base.write_ptr = buf->discard;
      50        buf->base.write_end = array_end (buf->discard);
      51      }
      52  
      53    buf->base.write_base = buf->discard;
      54    buf->base.write_ptr = buf->discard;
      55  }
      56  
      57  void
      58  __printf_buffer_snprintf_init (struct __printf_buffer_snprintf *buf,
      59  			       char *buffer, size_t length)
      60  {
      61    __printf_buffer_init (&buf->base, buffer, length,
      62  			__printf_buffer_mode_snprintf);
      63    if (length > 0)
      64      /* Historic behavior for trivially overlapping buffers (checked by
      65         the test suite).  */
      66      *buffer = '\0';
      67  }
      68  
      69  int
      70  __printf_buffer_snprintf_done (struct __printf_buffer_snprintf *buf)
      71  {
      72    /* NB: Do not check for buf->base.fail here.  Write the null
      73       terminator even in case of errors. */
      74  
      75    if (buf->base.write_ptr < buf->base.write_end)
      76      *buf->base.write_ptr = '\0';
      77    else if (buf->base.write_ptr > buf->base.write_base)
      78      /* If write_ptr == write_base, nothing has been written.  No null
      79         termination is needed because of the early truncation in
      80         __printf_buffer_snprintf_init (the historic behavior).
      81  
      82         We might also be at the start of the discard buffer, but in
      83         this case __printf_buffer_flush_snprintf has already written
      84         the NUL terminator.  */
      85      buf->base.write_ptr[-1] = '\0';
      86  
      87    return __printf_buffer_done (&buf->base);
      88  }
      89  
      90  int
      91  __vsnprintf_internal (char *string, size_t maxlen, const char *format,
      92  		      va_list args, unsigned int mode_flags)
      93  {
      94    struct __printf_buffer_snprintf buf;
      95    __printf_buffer_snprintf_init (&buf, string, maxlen);
      96    __printf_buffer (&buf.base, format, args, mode_flags);
      97    return __printf_buffer_snprintf_done (&buf);
      98  }
      99  
     100  int
     101  ___vsnprintf (char *string, size_t maxlen, const char *format, va_list args)
     102  {
     103    return __vsnprintf_internal (string, maxlen, format, args, 0);
     104  }
     105  ldbl_weak_alias (___vsnprintf, __vsnprintf)
     106  ldbl_weak_alias (___vsnprintf, vsnprintf)