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a6352fd4 MD |
1 | #ifndef _LIBRINGBUFFER_SHM_H |
2 | #define _LIBRINGBUFFER_SHM_H | |
3 | ||
4 | /* | |
5 | * libringbuffer/shm.h | |
6 | * | |
e92f3e28 | 7 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
a6352fd4 | 8 | * |
e92f3e28 MD |
9 | * This library is free software; you can redistribute it and/or |
10 | * modify it under the terms of the GNU Lesser General Public | |
11 | * License as published by the Free Software Foundation; only | |
12 | * version 2.1 of the License. | |
13 | * | |
14 | * This library is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | * Lesser General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU Lesser General Public | |
20 | * License along with this library; if not, write to the Free Software | |
21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
a6352fd4 MD |
22 | */ |
23 | ||
24 | #include <stdint.h> | |
44c72f10 | 25 | #include <usterr-signal-safe.h> |
35897f8b | 26 | #include <urcu/compiler.h> |
1d498196 | 27 | #include "shm_types.h" |
a6352fd4 | 28 | |
a6352fd4 | 29 | /* |
1d498196 MD |
30 | * Pointer dereferencing. We don't trust the shm_ref, so we validate |
31 | * both the index and offset with known boundaries. | |
ed5426d3 MD |
32 | * |
33 | * "shmp" and "shmp_index" guarantee that it's safe to use the pointer | |
34 | * target type, even in the occurrence of shm_ref modification by an | |
35 | * untrusted process having write access to the shm_ref. We return a | |
36 | * NULL pointer if the ranges are invalid. | |
a6352fd4 | 37 | */ |
a6352fd4 | 38 | static inline |
4746ae29 | 39 | char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref, |
cba4b7a3 | 40 | size_t idx, size_t elem_size) |
a6352fd4 | 41 | { |
1d498196 | 42 | struct shm_object *obj; |
cba4b7a3 | 43 | size_t objindex, ref_offset; |
a6352fd4 | 44 | |
cba4b7a3 | 45 | objindex = (size_t) ref->index; |
b5a3dfa5 | 46 | if (caa_unlikely(objindex >= table->allocated_len)) |
1d498196 | 47 | return NULL; |
cba4b7a3 | 48 | obj = &table->objects[objindex]; |
4746ae29 | 49 | ref_offset = (size_t) ref->offset; |
cba4b7a3 MD |
50 | ref_offset += idx * elem_size; |
51 | /* Check if part of the element returned would exceed the limits. */ | |
b5a3dfa5 | 52 | if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size)) |
a6352fd4 | 53 | return NULL; |
4746ae29 | 54 | return &obj->memory_map[ref_offset]; |
a6352fd4 MD |
55 | } |
56 | ||
cba4b7a3 | 57 | #define shmp_index(handle, ref, index) \ |
1d498196 MD |
58 | ({ \ |
59 | __typeof__((ref)._type) ____ptr_ret; \ | |
cba4b7a3 | 60 | ____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret)); \ |
1d498196 MD |
61 | ____ptr_ret; \ |
62 | }) | |
63 | ||
4746ae29 MD |
64 | #define shmp(handle, ref) shmp_index(handle, ref, 0) |
65 | ||
431d5cf0 | 66 | static inline |
1d498196 | 67 | void _set_shmp(struct shm_ref *ref, struct shm_ref src) |
431d5cf0 | 68 | { |
1d498196 | 69 | *ref = src; |
431d5cf0 MD |
70 | } |
71 | ||
1d498196 MD |
72 | #define set_shmp(ref, src) _set_shmp(&(ref)._ref, src) |
73 | ||
74 | struct shm_object_table *shm_object_table_create(size_t max_nb_obj); | |
193183fb MD |
75 | struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table, |
76 | int shm_fd, int wait_fd, size_t memory_map_size); | |
1d498196 MD |
77 | void shm_object_table_destroy(struct shm_object_table *table); |
78 | struct shm_object *shm_object_table_append(struct shm_object_table *table, | |
79 | size_t memory_map_size); | |
80 | ||
81 | /* | |
82 | * zalloc_shm - allocate memory within a shm object. | |
83 | * | |
84 | * Shared memory is already zeroed by shmget. | |
85 | * *NOT* multithread-safe (should be protected by mutex). | |
86 | * Returns a -1, -1 tuple on error. | |
87 | */ | |
88 | struct shm_ref zalloc_shm(struct shm_object *obj, size_t len); | |
89 | void align_shm(struct shm_object *obj, size_t align); | |
90 | ||
5d61a504 | 91 | static inline |
38fae1d3 | 92 | int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref) |
5d61a504 MD |
93 | { |
94 | struct shm_object_table *table = handle->table; | |
95 | struct shm_object *obj; | |
96 | size_t index; | |
97 | ||
98 | index = (size_t) ref->index; | |
b5a3dfa5 | 99 | if (caa_unlikely(index >= table->allocated_len)) |
5d61a504 MD |
100 | return -EPERM; |
101 | obj = &table->objects[index]; | |
102 | return obj->wait_fd[1]; | |
103 | ||
104 | } | |
105 | ||
106 | static inline | |
38fae1d3 | 107 | int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref) |
5d61a504 MD |
108 | { |
109 | struct shm_object_table *table = handle->table; | |
110 | struct shm_object *obj; | |
111 | size_t index; | |
112 | ||
113 | index = (size_t) ref->index; | |
b5a3dfa5 | 114 | if (caa_unlikely(index >= table->allocated_len)) |
5d61a504 MD |
115 | return -EPERM; |
116 | obj = &table->objects[index]; | |
117 | return obj->wait_fd[0]; | |
118 | } | |
119 | ||
381c0f1e | 120 | static inline |
38fae1d3 | 121 | int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref, |
ef9ff354 | 122 | int **shm_fd, int **wait_fd, uint64_t **memory_map_size) |
381c0f1e MD |
123 | { |
124 | struct shm_object_table *table = handle->table; | |
125 | struct shm_object *obj; | |
126 | size_t index; | |
127 | ||
128 | index = (size_t) ref->index; | |
b5a3dfa5 | 129 | if (caa_unlikely(index >= table->allocated_len)) |
381c0f1e MD |
130 | return -EPERM; |
131 | obj = &table->objects[index]; | |
ef9ff354 MD |
132 | *shm_fd = &obj->shm_fd; |
133 | *wait_fd = &obj->wait_fd[0]; | |
134 | *memory_map_size = &obj->allocated_len; | |
381c0f1e MD |
135 | return 0; |
136 | } | |
137 | ||
a6352fd4 | 138 | #endif /* _LIBRINGBUFFER_SHM_H */ |