Absolute File Name: | /home/opencoverage/opencoverage/guest-scripts/coreutils/src/lib/malloca.c |
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1 | /* Safe automatic memory allocation. | - | ||||||
2 | Copyright (C) 2003, 2006-2007, 2009-2018 Free Software Foundation, Inc. | - | ||||||
3 | Written by Bruno Haible <bruno@clisp.org>, 2003, 2018. | - | ||||||
4 | - | |||||||
5 | This program is free software; you can redistribute it and/or modify | - | ||||||
6 | it under the terms of the GNU General Public License as published by | - | ||||||
7 | the Free Software Foundation; either version 3, or (at your option) | - | ||||||
8 | any later version. | - | ||||||
9 | - | |||||||
10 | This program 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 | - | ||||||
13 | GNU General Public License for more details. | - | ||||||
14 | - | |||||||
15 | You should have received a copy of the GNU General Public License | - | ||||||
16 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ | - | ||||||
17 | - | |||||||
18 | #define _GL_USE_STDLIB_ALLOC 1 | - | ||||||
19 | #include <config.h> | - | ||||||
20 | - | |||||||
21 | /* Specification. */ | - | ||||||
22 | #include "malloca.h" | - | ||||||
23 | - | |||||||
24 | #include "verify.h" | - | ||||||
25 | - | |||||||
26 | /* The speed critical point in this file is freea() applied to an alloca() | - | ||||||
27 | result: it must be fast, to match the speed of alloca(). The speed of | - | ||||||
28 | mmalloca() and freea() in the other case are not critical, because they | - | ||||||
29 | are only invoked for big memory sizes. | - | ||||||
30 | Here we use a bit in the address as an indicator, an idea by Ondřej Bílka. | - | ||||||
31 | malloca() can return three types of pointers: | - | ||||||
32 | - Pointers ≡ 0 mod 2*sa_alignment_max come from stack allocation. | - | ||||||
33 | - Pointers ≡ sa_alignment_max mod 2*sa_alignment_max come from heap | - | ||||||
34 | allocation. | - | ||||||
35 | - NULL comes from a failed heap allocation. */ | - | ||||||
36 | - | |||||||
37 | /* Type for holding very small pointer differences. */ | - | ||||||
38 | typedef unsigned char small_t; | - | ||||||
39 | /* Verify that it is wide enough. */ | - | ||||||
40 | verify (2 * sa_alignment_max - 1 <= (small_t) -1); | - | ||||||
41 | - | |||||||
42 | void * | - | ||||||
43 | mmalloca (size_t n) | - | ||||||
44 | { | - | ||||||
45 | #if HAVE_ALLOCA | - | ||||||
46 | /* Allocate one more word, used to determine the address to pass to freea(), | - | ||||||
47 | and room for the alignment ≡ sa_alignment_max mod 2*sa_alignment_max. */ | - | ||||||
48 | size_t nplus = n + sizeof (small_t) + 2 * sa_alignment_max - 1; | - | ||||||
49 | - | |||||||
50 | if (nplus >= n)
| 0 | ||||||
51 | { | - | ||||||
52 | char *mem = (char *) malloc (nplus); | - | ||||||
53 | - | |||||||
54 | if (mem != NULL)
| 0 | ||||||
55 | { | - | ||||||
56 | char *p = | - | ||||||
57 | (char *)((((uintptr_t)mem + sizeof (small_t) + sa_alignment_max - 1) | - | ||||||
58 | & ~(uintptr_t)(2 * sa_alignment_max - 1)) | - | ||||||
59 | + sa_alignment_max); | - | ||||||
60 | /* Here p >= mem + sizeof (small_t), | - | ||||||
61 | and p <= mem + sizeof (small_t) + 2 * sa_alignment_max - 1 | - | ||||||
62 | hence p + n <= mem + nplus. | - | ||||||
63 | So, the memory range [p, p+n) lies in the allocated memory range | - | ||||||
64 | [mem, mem + nplus). */ | - | ||||||
65 | ((small_t *) p)[-1] = p - mem; | - | ||||||
66 | /* p ≡ sa_alignment_max mod 2*sa_alignment_max. */ | - | ||||||
67 | return p; never executed: return p; | 0 | ||||||
68 | } | - | ||||||
69 | } never executed: end of block | 0 | ||||||
70 | /* Out of memory. */ | - | ||||||
71 | return NULL; never executed: return ((void *)0) ; | 0 | ||||||
72 | #else | - | ||||||
73 | # if !MALLOC_0_IS_NONNULL | - | ||||||
74 | if (n == 0) | - | ||||||
75 | n = 1; | - | ||||||
76 | # endif | - | ||||||
77 | return malloc (n); | - | ||||||
78 | #endif | - | ||||||
79 | } | - | ||||||
80 | - | |||||||
81 | #if HAVE_ALLOCA | - | ||||||
82 | void | - | ||||||
83 | freea (void *p) | - | ||||||
84 | { | - | ||||||
85 | /* Check argument. */ | - | ||||||
86 | if ((uintptr_t) p & (sa_alignment_max - 1))
| 0 | ||||||
87 | { | - | ||||||
88 | /* p was not the result of a malloca() call. Invalid argument. */ | - | ||||||
89 | abort (); never executed: abort (); | 0 | ||||||
90 | } | - | ||||||
91 | /* Determine whether p was a non-NULL pointer returned by mmalloca(). */ | - | ||||||
92 | if ((uintptr_t) p & sa_alignment_max)
| 0 | ||||||
93 | { | - | ||||||
94 | void *mem = (char *) p - ((small_t *) p)[-1]; | - | ||||||
95 | free (mem); | - | ||||||
96 | } never executed: end of block | 0 | ||||||
97 | } never executed: end of block | 0 | ||||||
98 | #endif | - | ||||||
99 | - | |||||||
100 | /* | - | ||||||
101 | * Hey Emacs! | - | ||||||
102 | * Local Variables: | - | ||||||
103 | * coding: utf-8 | - | ||||||
104 | * End: | - | ||||||
105 | */ | - | ||||||
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