2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
7 #ifndef _LIBRINGBUFFER_SHM_H
8 #define _LIBRINGBUFFER_SHM_H
13 #include <usterr-signal-safe.h>
14 #include <urcu/compiler.h>
15 #include "shm_types.h"
17 /* channel_handle_create - for UST. */
19 struct lttng_ust_shm_handle
*channel_handle_create(void *data
,
20 uint64_t memory_map_size
, int wakeup_fd
)
21 __attribute__((visibility("hidden")));
23 /* channel_handle_add_stream - for UST. */
25 int channel_handle_add_stream(struct lttng_ust_shm_handle
*handle
,
26 int shm_fd
, int wakeup_fd
, uint32_t stream_nr
,
27 uint64_t memory_map_size
)
28 __attribute__((visibility("hidden")));
30 unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle
*handle
)
31 __attribute__((visibility("hidden")));
34 * Pointer dereferencing. We don't trust the shm_ref, so we validate
35 * both the index and offset with known boundaries.
37 * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
38 * target type, even in the occurrence of shm_ref modification by an
39 * untrusted process having write access to the shm_ref. We return a
40 * NULL pointer if the ranges are invalid.
43 char *_shmp_offset(struct shm_object_table
*table
, struct shm_ref
*ref
,
44 size_t idx
, size_t elem_size
)
46 struct shm_object
*obj
;
47 size_t objindex
, ref_offset
;
49 objindex
= (size_t) ref
->index
;
50 if (caa_unlikely(objindex
>= table
->allocated_len
))
52 obj
= &table
->objects
[objindex
];
53 ref_offset
= (size_t) ref
->offset
;
54 ref_offset
+= idx
* elem_size
;
55 /* Check if part of the element returned would exceed the limits. */
56 if (caa_unlikely(ref_offset
+ elem_size
> obj
->memory_map_size
))
58 return &obj
->memory_map
[ref_offset
];
61 #define shmp_index(handle, ref, index) \
62 ((__typeof__((ref)._type)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*((ref)._type))))
64 #define shmp(handle, ref) shmp_index(handle, ref, 0)
67 void _set_shmp(struct shm_ref
*ref
, struct shm_ref src
)
72 #define set_shmp(ref, src) _set_shmp(&(ref)._ref, src)
74 struct shm_object_table
*shm_object_table_create(size_t max_nb_obj
)
75 __attribute__((visibility("hidden")));
77 struct shm_object
*shm_object_table_alloc(struct shm_object_table
*table
,
78 size_t memory_map_size
,
79 enum shm_object_type type
,
82 __attribute__((visibility("hidden")));
84 struct shm_object
*shm_object_table_append_shm(struct shm_object_table
*table
,
85 int shm_fd
, int wakeup_fd
, uint32_t stream_nr
,
86 size_t memory_map_size
)
87 __attribute__((visibility("hidden")));
89 /* mem ownership is passed to shm_object_table_append_mem(). */
90 struct shm_object
*shm_object_table_append_mem(struct shm_object_table
*table
,
91 void *mem
, size_t memory_map_size
, int wakeup_fd
)
92 __attribute__((visibility("hidden")));
94 void shm_object_table_destroy(struct shm_object_table
*table
, int consumer
)
95 __attribute__((visibility("hidden")));
98 * zalloc_shm - allocate memory within a shm object.
100 * Shared memory is already zeroed by shmget.
101 * *NOT* multithread-safe (should be protected by mutex).
102 * Returns a -1, -1 tuple on error.
104 struct shm_ref
zalloc_shm(struct shm_object
*obj
, size_t len
)
105 __attribute__((visibility("hidden")));
107 void align_shm(struct shm_object
*obj
, size_t align
)
108 __attribute__((visibility("hidden")));
111 int shm_get_wait_fd(struct lttng_ust_shm_handle
*handle
, struct shm_ref
*ref
)
113 struct shm_object_table
*table
= handle
->table
;
114 struct shm_object
*obj
;
117 index
= (size_t) ref
->index
;
118 if (caa_unlikely(index
>= table
->allocated_len
))
120 obj
= &table
->objects
[index
];
121 return obj
->wait_fd
[0];
125 int shm_get_wakeup_fd(struct lttng_ust_shm_handle
*handle
, struct shm_ref
*ref
)
127 struct shm_object_table
*table
= handle
->table
;
128 struct shm_object
*obj
;
131 index
= (size_t) ref
->index
;
132 if (caa_unlikely(index
>= table
->allocated_len
))
134 obj
= &table
->objects
[index
];
135 return obj
->wait_fd
[1];
139 int shm_close_wait_fd(struct lttng_ust_shm_handle
*handle
,
142 struct shm_object_table
*table
= handle
->table
;
143 struct shm_object
*obj
;
148 index
= (size_t) ref
->index
;
149 if (caa_unlikely(index
>= table
->allocated_len
))
151 obj
= &table
->objects
[index
];
152 wait_fd
= obj
->wait_fd
[0];
155 obj
->wait_fd
[0] = -1;
156 ret
= close(wait_fd
);
165 int shm_close_wakeup_fd(struct lttng_ust_shm_handle
*handle
,
168 struct shm_object_table
*table
= handle
->table
;
169 struct shm_object
*obj
;
174 index
= (size_t) ref
->index
;
175 if (caa_unlikely(index
>= table
->allocated_len
))
177 obj
= &table
->objects
[index
];
178 wakeup_fd
= obj
->wait_fd
[1];
181 obj
->wait_fd
[1] = -1;
182 ret
= close(wakeup_fd
);
191 int shm_get_shm_fd(struct lttng_ust_shm_handle
*handle
, struct shm_ref
*ref
)
193 struct shm_object_table
*table
= handle
->table
;
194 struct shm_object
*obj
;
197 index
= (size_t) ref
->index
;
198 if (caa_unlikely(index
>= table
->allocated_len
))
200 obj
= &table
->objects
[index
];
206 int shm_get_shm_size(struct lttng_ust_shm_handle
*handle
, struct shm_ref
*ref
,
209 struct shm_object_table
*table
= handle
->table
;
210 struct shm_object
*obj
;
213 index
= (size_t) ref
->index
;
214 if (caa_unlikely(index
>= table
->allocated_len
))
216 obj
= &table
->objects
[index
];
217 *size
= obj
->memory_map_size
;
221 #endif /* _LIBRINGBUFFER_SHM_H */
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