MyMalloc/malloc.c at master · Antoine340/MyMalloc · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
/*
** malloc.c for malloc in /home/chenne_a/rendu/tech2/PSU_2016_malloc
**
** Made by chennetier
** Login   <arthur.chennetier@epitech.eu>
**
** Started on  Wed Jan 25 11:24:28 2017 chennetier
** Last update Fri Jan 27 10:44:54 2017 chauvin
*/

#include <stdio.h>
#include <limits.h>
#include "malloc.h"

t_meta *head = NULL;
t_meta *last = NULL;

t_meta		*check_size_init(t_meta *prev_elem, size_t size)
{
  t_meta	*to_malloc;

  to_malloc = (void *)prev_elem + SIZE_META + size;
  to_malloc->free = 1;
  to_malloc->prev = prev_elem;
  to_malloc->next = prev_elem->next;
  to_malloc->size = prev_elem->size - SIZE_META - size;
  return  (to_malloc);
}

void		check_size(t_meta *prev_elem, size_t size)
{
  t_meta	*to_malloc;
  t_meta	*tmp;

  to_malloc = NULL;
  tmp = head;
  while ((tmp->free != 1 || tmp->next != prev_elem) && tmp->next != NULL)
    tmp = tmp->next;
  if (size + (SIZE_META * 2) + 8 < prev_elem->size)
    {
      to_malloc = check_size_init(prev_elem, size);
      tmp->next = to_malloc;
      if (prev_elem != last)
	{
	  tmp = (void *) prev_elem + prev_elem->size + SIZE_META;
	  tmp->prev = to_malloc;
	}
      else
	{
	  last = to_malloc;
	  to_malloc->next = NULL;
	}
      prev_elem->size = size;
    }
  else
    tmp->next = prev_elem->next;
}

void		*check_memory(size_t size, int check)
{
  t_meta	*tmp;
  t_meta	*smallest;
  void		*ptr;

  tmp = head->next;
  smallest = tmp;
  while (tmp != NULL && smallest != NULL && check != 0)
    {
      if (tmp->size >= size)
	{
	  smallest = tmp;
	  check = 0;
	}
      else if (tmp->size >= size && tmp->size < smallest->size && check == 0)
	  smallest = tmp;
      tmp = tmp->next;
    }
  if (smallest == NULL)
    return (NULL);
  if (smallest->size < size || smallest->free != 1)
    return (NULL);
  ptr = (void *)smallest + SIZE_META;
  smallest->free = 0;
  check_size(smallest, size);
  return (ptr);
}

void		*init_head(size_t size)
{
  void		*ptr;

  if ((size + SIZE_META * 2) % SIZE_PAGE != 0 ||
      (size + SIZE_META * 2) / SIZE_PAGE == 0)
    {
      if ((head = sbrk(SIZE_PAGE * (((size + SIZE_META * 2)
				     / SIZE_PAGE) + 1))) == (void *) - 1)
	return (NULL);
    }
  else
    {
      if ((head = sbrk(SIZE_PAGE * (size + SIZE_META * 2)
		       / SIZE_PAGE)) == (void *) -1)
	return (NULL);
    }
  head->free = 1;
  head->prev = NULL;
  head->size = 0;
  if ((ptr = new_space(NULL, size)) == NULL)
    return (NULL);
  return (ptr);
}

void 	*mallo(size_t size)
{
  void	*ptr;

  size = (size + 7) & ~7;
  if (size >= LONG_MAX)
    return (NULL);
  if (!head)
    {
      if ((ptr = init_head(size)) == NULL)
	{
	  head = NULL;
	  last = NULL;
	  return (NULL);
	}
      return (ptr);
    }
  else
    {
      if ((ptr = check_memory(size, 1)) == NULL)
	{
	  if ((ptr = new_space(last, size)) == NULL)
	    return (NULL);
	}
    }
  return (ptr);
}