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272
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1 /* xalloc.h -- malloc with out-of-memory checking
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2
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3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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4 1999, 2000, 2003, 2004, 2006, 2007, 2008 Free Software Foundation, Inc.
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5
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6 This program is free software: you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3 of the License, or
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9 (at your option) any later version.
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10
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11 This program is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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18
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19 #ifndef XALLOC_H_
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20 # define XALLOC_H_
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21
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22 # include <stddef.h>
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23
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24
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25 # ifdef __cplusplus
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26 extern "C" {
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27 # endif
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28
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29
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30 # ifndef __attribute__
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31 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8)
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32 # define __attribute__(x)
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33 # endif
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34 # endif
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35
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36 # ifndef ATTRIBUTE_NORETURN
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37 # define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
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38 # endif
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39
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40 # ifndef ATTRIBUTE_MALLOC
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41 # if __GNUC__ >= 3
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42 # define ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
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43 # else
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44 # define ATTRIBUTE_MALLOC
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45 # endif
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46 # endif
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47
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48 /* This function is always triggered when memory is exhausted.
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49 It must be defined by the application, either explicitly
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50 or by using gnulib's xalloc-die module. This is the
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51 function to call when one wants the program to die because of a
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52 memory allocation failure. */
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53 extern void xalloc_die (void) ATTRIBUTE_NORETURN;
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54
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55 void *xmalloc (size_t s) ATTRIBUTE_MALLOC;
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56 void *xzalloc (size_t s) ATTRIBUTE_MALLOC;
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57 void *xcalloc (size_t n, size_t s) ATTRIBUTE_MALLOC;
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58 void *xrealloc (void *p, size_t s);
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59 void *x2realloc (void *p, size_t *pn);
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60 void *xmemdup (void const *p, size_t s) ATTRIBUTE_MALLOC;
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61 char *xstrdup (char const *str) ATTRIBUTE_MALLOC;
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62
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63 /* Return 1 if an array of N objects, each of size S, cannot exist due
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64 to size arithmetic overflow. S must be positive and N must be
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65 nonnegative. This is a macro, not an inline function, so that it
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66 works correctly even when SIZE_MAX < N.
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67
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68 By gnulib convention, SIZE_MAX represents overflow in size
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69 calculations, so the conservative dividend to use here is
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70 SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
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71 However, malloc (SIZE_MAX) fails on all known hosts where
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72 sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
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73 exactly-SIZE_MAX allocations on such hosts; this avoids a test and
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74 branch when S is known to be 1. */
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75 # define xalloc_oversized(n, s) \
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76 ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
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77
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78
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79 /* In the following macros, T must be an elementary or structure/union or
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80 typedef'ed type, or a pointer to such a type. To apply one of the
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81 following macros to a function pointer or array type, you need to typedef
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82 it first and use the typedef name. */
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83
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84 /* Allocate an object of type T dynamically, with error checking. */
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85 /* extern t *XMALLOC (typename t); */
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86 # define XMALLOC(t) ((t *) xmalloc (sizeof (t)))
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87
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88 /* Allocate memory for N elements of type T, with error checking. */
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89 /* extern t *XNMALLOC (size_t n, typename t); */
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90 # define XNMALLOC(n, t) \
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91 ((t *) (sizeof (t) == 1 ? xmalloc (n) : xnmalloc (n, sizeof (t))))
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92
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93 /* Allocate an object of type T dynamically, with error checking,
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94 and zero it. */
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95 /* extern t *XZALLOC (typename t); */
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96 # define XZALLOC(t) ((t *) xzalloc (sizeof (t)))
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97
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98 /* Allocate memory for N elements of type T, with error checking,
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99 and zero it. */
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100 /* extern t *XCALLOC (size_t n, typename t); */
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101 # define XCALLOC(n, t) \
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102 ((t *) (sizeof (t) == 1 ? xzalloc (n) : xcalloc (n, sizeof (t))))
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103
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104
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105 # if HAVE_INLINE
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106 # define static_inline static inline
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107 # else
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108 void *xnmalloc (size_t n, size_t s) ATTRIBUTE_MALLOC;
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109 void *xnrealloc (void *p, size_t n, size_t s);
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110 void *x2nrealloc (void *p, size_t *pn, size_t s);
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111 char *xcharalloc (size_t n) ATTRIBUTE_MALLOC;
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112 # endif
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113
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114 # ifdef static_inline
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115
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116 /* Allocate an array of N objects, each with S bytes of memory,
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117 dynamically, with error checking. S must be nonzero. */
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118
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119 static_inline void *xnmalloc (size_t n, size_t s) ATTRIBUTE_MALLOC;
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120 static_inline void *
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121 xnmalloc (size_t n, size_t s)
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122 {
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123 if (xalloc_oversized (n, s))
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124 xalloc_die ();
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125 return xmalloc (n * s);
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126 }
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127
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128 /* Change the size of an allocated block of memory P to an array of N
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129 objects each of S bytes, with error checking. S must be nonzero. */
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130
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131 static_inline void *
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132 xnrealloc (void *p, size_t n, size_t s)
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133 {
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134 if (xalloc_oversized (n, s))
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135 xalloc_die ();
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136 return xrealloc (p, n * s);
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137 }
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138
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139 /* If P is null, allocate a block of at least *PN such objects;
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140 otherwise, reallocate P so that it contains more than *PN objects
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141 each of S bytes. *PN must be nonzero unless P is null, and S must
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142 be nonzero. Set *PN to the new number of objects, and return the
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143 pointer to the new block. *PN is never set to zero, and the
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144 returned pointer is never null.
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145
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146 Repeated reallocations are guaranteed to make progress, either by
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147 allocating an initial block with a nonzero size, or by allocating a
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148 larger block.
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149
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150 In the following implementation, nonzero sizes are increased by a
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151 factor of approximately 1.5 so that repeated reallocations have
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152 O(N) overall cost rather than O(N**2) cost, but the
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153 specification for this function does not guarantee that rate.
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154
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155 Here is an example of use:
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156
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157 int *p = NULL;
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158 size_t used = 0;
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159 size_t allocated = 0;
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160
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161 void
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162 append_int (int value)
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163 {
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164 if (used == allocated)
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165 p = x2nrealloc (p, &allocated, sizeof *p);
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166 p[used++] = value;
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167 }
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168
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169 This causes x2nrealloc to allocate a block of some nonzero size the
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170 first time it is called.
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171
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172 To have finer-grained control over the initial size, set *PN to a
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173 nonzero value before calling this function with P == NULL. For
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174 example:
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175
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176 int *p = NULL;
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177 size_t used = 0;
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178 size_t allocated = 0;
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179 size_t allocated1 = 1000;
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180
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181 void
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182 append_int (int value)
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183 {
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184 if (used == allocated)
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185 {
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186 p = x2nrealloc (p, &allocated1, sizeof *p);
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187 allocated = allocated1;
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188 }
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189 p[used++] = value;
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190 }
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191
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192 */
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193
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194 static_inline void *
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195 x2nrealloc (void *p, size_t *pn, size_t s)
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196 {
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197 size_t n = *pn;
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198
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199 if (! p)
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200 {
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201 if (! n)
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202 {
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203 /* The approximate size to use for initial small allocation
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204 requests, when the invoking code specifies an old size of
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205 zero. 64 bytes is the largest "small" request for the
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206 GNU C library malloc. */
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207 enum { DEFAULT_MXFAST = 64 };
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208
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209 n = DEFAULT_MXFAST / s;
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210 n += !n;
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211 }
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212 }
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213 else
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214 {
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215 /* Set N = ceil (1.5 * N) so that progress is made if N == 1.
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216 Check for overflow, so that N * S stays in size_t range.
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217 The check is slightly conservative, but an exact check isn't
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218 worth the trouble. */
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219 if ((size_t) -1 / 3 * 2 / s <= n)
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220 xalloc_die ();
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221 n += (n + 1) / 2;
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222 }
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223
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224 *pn = n;
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225 return xrealloc (p, n * s);
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226 }
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227
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228 /* Return a pointer to a new buffer of N bytes. This is like xmalloc,
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229 except it returns char *. */
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230
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231 static_inline char *xcharalloc (size_t n) ATTRIBUTE_MALLOC;
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232 static_inline char *
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233 xcharalloc (size_t n)
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234 {
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235 return XNMALLOC (n, char);
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236 }
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237
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238 # endif
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239
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240 # ifdef __cplusplus
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241 }
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242
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243 /* C++ does not allow conversions from void * to other pointer types
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244 without a cast. Use templates to work around the problem when
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245 possible. */
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246
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247 template <typename T> inline T *
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248 xrealloc (T *p, size_t s)
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249 {
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250 return (T *) xrealloc ((void *) p, s);
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251 }
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252
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253 template <typename T> inline T *
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254 xnrealloc (T *p, size_t n, size_t s)
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255 {
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256 return (T *) xnrealloc ((void *) p, n, s);
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257 }
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258
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259 template <typename T> inline T *
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260 x2realloc (T *p, size_t *pn)
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261 {
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262 return (T *) x2realloc ((void *) p, pn);
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263 }
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264
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265 template <typename T> inline T *
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266 x2nrealloc (T *p, size_t *pn, size_t s)
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267 {
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268 return (T *) x2nrealloc ((void *) p, pn, s);
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269 }
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270
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271 template <typename T> inline T *
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272 xmemdup (T const *p, size_t s)
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273 {
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274 return (T *) xmemdup ((void const *) p, s);
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275 }
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276
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277 # endif
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278
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279
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280 #endif /* !XALLOC_H_ */
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