xref: /PHP-7.2/ext/opcache/shared_alloc_shm.c (revision 7a7ec01a)
1 /*
2    +----------------------------------------------------------------------+
3    | Zend OPcache                                                         |
4    +----------------------------------------------------------------------+
5    | Copyright (c) 1998-2018 The PHP Group                                |
6    +----------------------------------------------------------------------+
7    | This source file is subject to version 3.01 of the PHP license,      |
8    | that is bundled with this package in the file LICENSE, and is        |
9    | available through the world-wide-web at the following url:           |
10    | http://www.php.net/license/3_01.txt                                  |
11    | If you did not receive a copy of the PHP license and are unable to   |
12    | obtain it through the world-wide-web, please send a note to          |
13    | license@php.net so we can mail you a copy immediately.               |
14    +----------------------------------------------------------------------+
15    | Authors: Andi Gutmans <andi@zend.com>                                |
16    |          Zeev Suraski <zeev@zend.com>                                |
17    |          Stanislav Malyshev <stas@zend.com>                          |
18    |          Dmitry Stogov <dmitry@zend.com>                             |
19    +----------------------------------------------------------------------+
20 */
21 
22 #include "zend_shared_alloc.h"
23 
24 #ifdef USE_SHM
25 
26 #if defined(__FreeBSD__)
27 # include <machine/param.h>
28 #endif
29 #include <sys/types.h>
30 #include <sys/shm.h>
31 #include <sys/ipc.h>
32 #include <dirent.h>
33 #include <signal.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <unistd.h>
37 #include <errno.h>
38 
39 #include <sys/stat.h>
40 #include <fcntl.h>
41 
42 #ifndef MIN
43 # define MIN(x, y) ((x) > (y)? (y) : (x))
44 #endif
45 
46 #define SEG_ALLOC_SIZE_MAX 32*1024*1024
47 #define SEG_ALLOC_SIZE_MIN 2*1024*1024
48 
49 typedef struct  {
50     zend_shared_segment common;
51     int shm_id;
52 } zend_shared_segment_shm;
53 
create_segments(size_t requested_size,zend_shared_segment_shm *** shared_segments_p,int * shared_segments_count,char ** error_in)54 static int create_segments(size_t requested_size, zend_shared_segment_shm ***shared_segments_p, int *shared_segments_count, char **error_in)
55 {
56 	int i;
57 	size_t allocate_size = 0, remaining_bytes = requested_size, seg_allocate_size;
58 	int first_segment_id = -1;
59 	key_t first_segment_key = -1;
60 	struct shmid_ds sds;
61 	int shmget_flags;
62 	zend_shared_segment_shm *shared_segments;
63 
64     seg_allocate_size = SEG_ALLOC_SIZE_MAX;
65     /* determine segment size we _really_ need:
66      * no more than to include requested_size
67      */
68     while (requested_size * 2 <= seg_allocate_size && seg_allocate_size > SEG_ALLOC_SIZE_MIN) {
69         seg_allocate_size >>= 1;
70     }
71 
72 	shmget_flags = IPC_CREAT|SHM_R|SHM_W|IPC_EXCL;
73 
74 	/* try allocating this much, if not - try shrinking */
75 	while (seg_allocate_size >= SEG_ALLOC_SIZE_MIN) {
76 		allocate_size = MIN(requested_size, seg_allocate_size);
77 		first_segment_id = shmget(first_segment_key, allocate_size, shmget_flags);
78 		if (first_segment_id != -1) {
79 			break;
80 		}
81 		seg_allocate_size >>= 1; /* shrink the allocated block */
82 	}
83 
84 	if (first_segment_id == -1) {
85 		*error_in = "shmget";
86 		return ALLOC_FAILURE;
87 	}
88 
89 	*shared_segments_count = ((requested_size - 1) / seg_allocate_size) + 1;
90 	*shared_segments_p = (zend_shared_segment_shm **) calloc(1, (*shared_segments_count) * sizeof(zend_shared_segment_shm) + sizeof(void *) * (*shared_segments_count));
91 	if (!*shared_segments_p) {
92 		*error_in = "calloc";
93 		return ALLOC_FAILURE;
94 	}
95 	shared_segments = (zend_shared_segment_shm *)((char *)(*shared_segments_p) + sizeof(void *) * (*shared_segments_count));
96 	for (i = 0; i < *shared_segments_count; i++) {
97 		(*shared_segments_p)[i] = shared_segments + i;
98 	}
99 
100 	remaining_bytes = requested_size;
101 	for (i = 0; i < *shared_segments_count; i++) {
102 		allocate_size = MIN(remaining_bytes, seg_allocate_size);
103 		if (i != 0) {
104 			shared_segments[i].shm_id = shmget(IPC_PRIVATE, allocate_size, shmget_flags);
105 		} else {
106 			shared_segments[i].shm_id = first_segment_id;
107 		}
108 
109 		if (shared_segments[i].shm_id == -1) {
110 			return ALLOC_FAILURE;
111 		}
112 
113 		shared_segments[i].common.p = shmat(shared_segments[i].shm_id, NULL, 0);
114 		if (shared_segments[i].common.p == (void *)-1) {
115 			*error_in = "shmat";
116 			shmctl(shared_segments[i].shm_id, IPC_RMID, &sds);
117 			return ALLOC_FAILURE;
118 		}
119 		shmctl(shared_segments[i].shm_id, IPC_RMID, &sds);
120 
121 		shared_segments[i].common.pos = 0;
122 		shared_segments[i].common.size = allocate_size;
123 		remaining_bytes -= allocate_size;
124 	}
125 	return ALLOC_SUCCESS;
126 }
127 
detach_segment(zend_shared_segment_shm * shared_segment)128 static int detach_segment(zend_shared_segment_shm *shared_segment)
129 {
130 	shmdt(shared_segment->common.p);
131 	return 0;
132 }
133 
segment_type_size(void)134 static size_t segment_type_size(void)
135 {
136 	return sizeof(zend_shared_segment_shm);
137 }
138 
139 zend_shared_memory_handlers zend_alloc_shm_handlers = {
140 	(create_segments_t)create_segments,
141 	(detach_segment_t)detach_segment,
142 	segment_type_size
143 };
144 
145 #endif /* USE_SHM */
146