libringbuffer/shm.h

   1 #ifndef _LIBRINGBUFFER_SHM_H
   2 #define _LIBRINGBUFFER_SHM_H
   3
   4 /*
   5  * libringbuffer/shm.h
   6  *
   7  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   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
  22  */
  23
  24 #include <stddef.h>
  25 #include <stdint.h>
  26 #include <usterr-signal-safe.h>
  27 #include <urcu/compiler.h>
  28 #include "shm_types.h"
  29
  30 /* channel_handle_create - for UST. */
  31 extern
  32 struct lttng_ust_shm_handle *channel_handle_create(void *data,
  33                                 uint64_t memory_map_size, int wakeup_fd);
  34 /* channel_handle_add_stream - for UST. */
  35 extern
  36 int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
  37                 int shm_fd, int wakeup_fd, uint32_t stream_nr,
  38                 uint64_t memory_map_size);
  39 unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle *handle);
  40 extern
  41 void channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
  42                 int consumer);
  43
  44 /*
  45  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  46  * both the index and offset with known boundaries.
  47  *
  48  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  49  * target type, even in the occurrence of shm_ref modification by an
  50  * untrusted process having write access to the shm_ref. We return a
  51  * NULL pointer if the ranges are invalid.
  52  */
  53 static inline
  54 char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
  55                    size_t idx, size_t elem_size)
  56 {
  57         struct shm_object *obj;
  58         size_t objindex, ref_offset;
  59
  60         objindex = (size_t) ref->index;
  61         if (caa_unlikely(objindex >= table->allocated_len))
  62                 return NULL;
  63         obj = &table->objects[objindex];
  64         ref_offset = (size_t) ref->offset;
  65         ref_offset += idx * elem_size;
  66         /* Check if part of the element returned would exceed the limits. */
  67         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  68                 return NULL;
  69         return &obj->memory_map[ref_offset];
  70 }
  71
  72 #define shmp_index(handle, ref, index)                                  \
  73         ({                                                              \
  74                 __typeof__((ref)._type) ____ptr_ret;                    \
  75                 ____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));        \
  76                 ____ptr_ret;                                            \
  77         })
  78
  79 #define shmp(handle, ref)       shmp_index(handle, ref, 0)
  80
  81 static inline
  82 void _set_shmp(struct shm_ref *ref, struct shm_ref src)
  83 {
  84         *ref = src;
  85 }
  86
  87 #define set_shmp(ref, src)      _set_shmp(&(ref)._ref, src)
  88
  89 struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
  90 struct shm_object *shm_object_table_alloc(struct shm_object_table *table,
  91                         size_t memory_map_size,
  92                         enum shm_object_type type,
  93                         const int stream_fd,
  94                         int cpu);
  95 struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
  96                         int shm_fd, int wakeup_fd, uint32_t stream_nr,
  97                         size_t memory_map_size);
  98 /* mem ownership is passed to shm_object_table_append_mem(). */
  99 struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
 100                         void *mem, size_t memory_map_size, int wakeup_fd);
 101 void shm_object_table_destroy(struct shm_object_table *table, int consumer);
 102
 103 /*
 104  * zalloc_shm - allocate memory within a shm object.
 105  *
 106  * Shared memory is already zeroed by shmget.
 107  * *NOT* multithread-safe (should be protected by mutex).
 108  * Returns a -1, -1 tuple on error.
 109  */
 110 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 111 void align_shm(struct shm_object *obj, size_t align);
 112
 113 static inline
 114 int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 115 {
 116         struct shm_object_table *table = handle->table;
 117         struct shm_object *obj;
 118         size_t index;
 119
 120         index = (size_t) ref->index;
 121         if (caa_unlikely(index >= table->allocated_len))
 122                 return -EPERM;
 123         obj = &table->objects[index];
 124         return obj->wait_fd[0];
 125 }
 126
 127 static inline
 128 int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 129 {
 130         struct shm_object_table *table = handle->table;
 131         struct shm_object *obj;
 132         size_t index;
 133
 134         index = (size_t) ref->index;
 135         if (caa_unlikely(index >= table->allocated_len))
 136                 return -EPERM;
 137         obj = &table->objects[index];
 138         return obj->wait_fd[1];
 139 }
 140
 141 static inline
 142 int shm_close_wait_fd(struct lttng_ust_shm_handle *handle,
 143                 struct shm_ref *ref)
 144 {
 145         struct shm_object_table *table = handle->table;
 146         struct shm_object *obj;
 147         int wait_fd;
 148         size_t index;
 149         int ret;
 150
 151         index = (size_t) ref->index;
 152         if (caa_unlikely(index >= table->allocated_len))
 153                 return -EPERM;
 154         obj = &table->objects[index];
 155         wait_fd = obj->wait_fd[0];
 156         if (wait_fd < 0)
 157                 return -ENOENT;
 158         obj->wait_fd[0] = -1;
 159         ret = close(wait_fd);
 160         if (ret) {
 161                 ret = -errno;
 162                 return ret;
 163         }
 164         return 0;
 165 }
 166
 167 static inline
 168 int shm_close_wakeup_fd(struct lttng_ust_shm_handle *handle,
 169                 struct shm_ref *ref)
 170 {
 171         struct shm_object_table *table = handle->table;
 172         struct shm_object *obj;
 173         int wakeup_fd;
 174         size_t index;
 175         int ret;
 176
 177         index = (size_t) ref->index;
 178         if (caa_unlikely(index >= table->allocated_len))
 179                 return -EPERM;
 180         obj = &table->objects[index];
 181         wakeup_fd = obj->wait_fd[1];
 182         if (wakeup_fd < 0)
 183                 return -ENOENT;
 184         obj->wait_fd[1] = -1;
 185         ret = close(wakeup_fd);
 186         if (ret) {
 187                 ret = -errno;
 188                 return ret;
 189         }
 190         return 0;
 191 }
 192
 193 static inline
 194 int shm_get_shm_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 195 {
 196         struct shm_object_table *table = handle->table;
 197         struct shm_object *obj;
 198         size_t index;
 199
 200         index = (size_t) ref->index;
 201         if (caa_unlikely(index >= table->allocated_len))
 202                 return -EPERM;
 203         obj = &table->objects[index];
 204         return obj->shm_fd;
 205 }
 206
 207
 208 static inline
 209 int shm_get_shm_size(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
 210                 uint64_t *size)
 211 {
 212         struct shm_object_table *table = handle->table;
 213         struct shm_object *obj;
 214         size_t index;
 215
 216         index = (size_t) ref->index;
 217         if (caa_unlikely(index >= table->allocated_len))
 218                 return -EPERM;
 219         obj = &table->objects[index];
 220         *size = obj->memory_map_size;
 221         return 0;
 222 }
 223
 224 #endif /* _LIBRINGBUFFER_SHM_H */