1  /* Variable-sized buffer with on-stack default allocation.
       2     Copyright (C) 2015-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _LIBC
      20  # include <libc-config.h>
      21  #endif
      22  
      23  #include <scratch_buffer.h>
      24  #include <errno.h>
      25  
      26  bool
      27  __libc_scratch_buffer_grow (struct scratch_buffer *buffer)
      28  {
      29    void *new_ptr;
      30    size_t new_length = buffer->length * 2;
      31  
      32    /* Discard old buffer.  */
      33    scratch_buffer_free (buffer);
      34  
      35    /* Check for overflow.  */
      36    if (__glibc_likely (new_length >= buffer->length))
      37      new_ptr = malloc (new_length);
      38    else
      39      {
      40        __set_errno (ENOMEM);
      41        new_ptr = NULL;
      42      }
      43  
      44    if (__glibc_unlikely (new_ptr == NULL))
      45      {
      46        /* Buffer must remain valid to free.  */
      47        scratch_buffer_init (buffer);
      48        return false;
      49      }
      50  
      51    /* Install new heap-based buffer.  */
      52    buffer->data = new_ptr;
      53    buffer->length = new_length;
      54    return true;
      55  }
      56  libc_hidden_def (__libc_scratch_buffer_grow)