1  /* alloc.c -- Memory allocation without mmap.
       2     Copyright (C) 2012-2023 Free Software Foundation, Inc.
       3     Written by Ian Lance Taylor, Google.
       4  
       5  Redistribution and use in source and binary forms, with or without
       6  modification, are permitted provided that the following conditions are
       7  met:
       8  
       9      (1) Redistributions of source code must retain the above copyright
      10      notice, this list of conditions and the following disclaimer.
      11  
      12      (2) Redistributions in binary form must reproduce the above copyright
      13      notice, this list of conditions and the following disclaimer in
      14      the documentation and/or other materials provided with the
      15      distribution.
      16  
      17      (3) The name of the author may not be used to
      18      endorse or promote products derived from this software without
      19      specific prior written permission.
      20  
      21  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
      22  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
      23  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
      24  DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
      25  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
      26  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
      27  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      28  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
      29  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
      30  IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      31  POSSIBILITY OF SUCH DAMAGE.  */
      32  
      33  #include "config.h"
      34  
      35  #include <errno.h>
      36  #include <stdlib.h>
      37  #include <sys/types.h>
      38  
      39  #include "backtrace.h"
      40  #include "internal.h"
      41  
      42  /* Allocation routines to use on systems that do not support anonymous
      43     mmap.  This implementation just uses malloc, which means that the
      44     backtrace functions may not be safely invoked from a signal
      45     handler.  */
      46  
      47  /* Allocate memory like malloc.  If ERROR_CALLBACK is NULL, don't
      48     report an error.  */
      49  
      50  void *
      51  backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
      52  		 size_t size, backtrace_error_callback error_callback,
      53  		 void *data)
      54  {
      55    void *ret;
      56  
      57    ret = malloc (size);
      58    if (ret == NULL)
      59      {
      60        if (error_callback)
      61  	error_callback (data, "malloc", errno);
      62      }
      63    return ret;
      64  }
      65  
      66  /* Free memory.  */
      67  
      68  void
      69  backtrace_free (struct backtrace_state *state ATTRIBUTE_UNUSED,
      70  		void *p, size_t size ATTRIBUTE_UNUSED,
      71  		backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
      72  		void *data ATTRIBUTE_UNUSED)
      73  {
      74    free (p);
      75  }
      76  
      77  /* Grow VEC by SIZE bytes.  */
      78  
      79  void *
      80  backtrace_vector_grow (struct backtrace_state *state ATTRIBUTE_UNUSED,
      81  		       size_t size, backtrace_error_callback error_callback,
      82  		       void *data, struct backtrace_vector *vec)
      83  {
      84    void *ret;
      85  
      86    if (size > vec->alc)
      87      {
      88        size_t alc;
      89        void *base;
      90  
      91        if (vec->size == 0)
      92  	alc = 32 * size;
      93        else if (vec->size >= 4096)
      94  	alc = vec->size + 4096;
      95        else
      96  	alc = 2 * vec->size;
      97  
      98        if (alc < vec->size + size)
      99  	alc = vec->size + size;
     100  
     101        base = realloc (vec->base, alc);
     102        if (base == NULL)
     103  	{
     104  	  error_callback (data, "realloc", errno);
     105  	  return NULL;
     106  	}
     107  
     108        vec->base = base;
     109        vec->alc = alc - vec->size;
     110      }
     111  
     112    ret = (char *) vec->base + vec->size;
     113    vec->size += size;
     114    vec->alc -= size;
     115    return ret;
     116  }
     117  
     118  /* Finish the current allocation on VEC.  */
     119  
     120  void *
     121  backtrace_vector_finish (struct backtrace_state *state,
     122  			 struct backtrace_vector *vec,
     123  			 backtrace_error_callback error_callback,
     124  			 void *data)
     125  {
     126    void *ret;
     127  
     128    /* With this allocator we call realloc in backtrace_vector_grow,
     129       which means we can't easily reuse the memory here.  So just
     130       release it.  */
     131    if (!backtrace_vector_release (state, vec, error_callback, data))
     132      return NULL;
     133    ret = vec->base;
     134    vec->base = NULL;
     135    vec->size = 0;
     136    vec->alc = 0;
     137    return ret;
     138  }
     139  
     140  /* Release any extra space allocated for VEC.  */
     141  
     142  int
     143  backtrace_vector_release (struct backtrace_state *state ATTRIBUTE_UNUSED,
     144  			  struct backtrace_vector *vec,
     145  			  backtrace_error_callback error_callback,
     146  			  void *data)
     147  {
     148    vec->alc = 0;
     149  
     150    if (vec->size == 0)
     151      {
     152        /* As of C17, realloc with size 0 is marked as an obsolescent feature, use
     153  	 free instead.  */
     154        free (vec->base);
     155        vec->base = NULL;
     156        return 1;
     157      }
     158  
     159    vec->base = realloc (vec->base, vec->size);
     160    if (vec->base == NULL)
     161      {
     162        error_callback (data, "realloc", errno);
     163        return 0;
     164      }
     165  
     166    return 1;
     167  }