/*
* libringbuffer/shm.h
*
- * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
- * Dual LGPL v2.1/GPL v2 license.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
-#include "ust/core.h"
-#include "usterr_signal_safe.h"
-
-#define SHM_MAGIC 0x54335433
-#define SHM_MAJOR 0
-#define SHM_MINOR 1
+#include <usterr-signal-safe.h>
+#include <urcu/compiler.h>
+#include "shm_types.h"
/*
- * Defining a max shm offset, for debugging purposes.
+ * Pointer dereferencing. We don't trust the shm_ref, so we validate
+ * both the index and offset with known boundaries.
+ *
+ * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
+ * target type, even in the occurrence of shm_ref modification by an
+ * untrusted process having write access to the shm_ref. We return a
+ * NULL pointer if the ranges are invalid.
*/
-#if (CAA_BITS_PER_LONG == 32)
-/* Define the maximum shared memory size to 128MB on 32-bit machines */
-#define MAX_SHM_SIZE 134217728
-#else
-/* Define the maximum shared memory size to 8GB on 64-bit machines */
-#define MAX_SHM_SIZE 8589934592
-#endif
+static inline
+char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
+ size_t idx, size_t elem_size)
+{
+ struct shm_object *obj;
+ size_t objindex, ref_offset;
-#define DECLARE_SHMP(type, name) type *****name
+ objindex = (size_t) ref->index;
+ if (caa_unlikely(objindex >= table->allocated_len))
+ return NULL;
+ obj = &table->objects[objindex];
+ ref_offset = (size_t) ref->offset;
+ ref_offset += idx * elem_size;
+ /* Check if part of the element returned would exceed the limits. */
+ if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
+ return NULL;
+ return &obj->memory_map[ref_offset];
+}
-struct shm_header {
- uint32_t magic;
- uint8_t major;
- uint8_t minor;
- uint8_t bits_per_long;
- size_t shm_size, shm_allocated;
+#define shmp_index(handle, ref, index) \
+ ({ \
+ __typeof__((ref)._type) ____ptr_ret; \
+ ____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret)); \
+ ____ptr_ret; \
+ })
- DECLARE_SHMP(struct channel, chan);
-};
+#define shmp(handle, ref) shmp_index(handle, ref, 0)
-struct shm_handle {
- struct shm_header *header; /* beginning of mapping */
- int shmfd; /* process-local file descriptor */
-};
+static inline
+void _set_shmp(struct shm_ref *ref, struct shm_ref src)
+{
+ *ref = src;
+}
+
+#define set_shmp(ref, src) _set_shmp(&(ref)._ref, src)
-#define shmp(shm_offset) \
- ((__typeof__(****(shm_offset))) (((char *) &(shm_offset)) + (ptrdiff_t) (shm_offset)))
+struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
+struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
+ int shm_fd, int wait_fd, size_t memory_map_size);
+void shm_object_table_destroy(struct shm_object_table *table);
+struct shm_object *shm_object_table_append(struct shm_object_table *table,
+ size_t memory_map_size);
-#define _shmp_abs(a) ((a < 0) ? -(a) : (a))
+/*
+ * zalloc_shm - allocate memory within a shm object.
+ *
+ * Shared memory is already zeroed by shmget.
+ * *NOT* multithread-safe (should be protected by mutex).
+ * Returns a -1, -1 tuple on error.
+ */
+struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
+void align_shm(struct shm_object *obj, size_t align);
static inline
-void _set_shmp(ptrdiff_t *shm_offset, void *ptr)
+int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
{
- *shm_offset = (((char *) ptr) - ((char *) shm_offset));
- assert(_shmp_abs(*shm_offset) < MAX_SHM_SIZE);
-}
+ struct shm_object_table *table = handle->table;
+ struct shm_object *obj;
+ size_t index;
+
+ index = (size_t) ref->index;
+ if (caa_unlikely(index >= table->allocated_len))
+ return -EPERM;
+ obj = &table->objects[index];
+ return obj->wait_fd[1];
-#define set_shmp(shm_offset, ptr) \
- _set_shmp((ptrdiff_t *) ****(shm_offset), ptr)
+}
-/* Shared memory is already zeroed by shmget */
-/* *NOT* multithread-safe (should be protected by mutex) */
static inline
-void *zalloc_shm(struct shm_header *shm_header, size_t len)
+int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
{
- void *ret;
-
- if (shm_header->shm_size - shm_header->shm_allocated < len)
- return NULL;
- ret = (char *) shm_header + shm_header->shm_allocated;
- shm_header->shm_allocated += len;
- return ret;
+ struct shm_object_table *table = handle->table;
+ struct shm_object *obj;
+ size_t index;
+
+ index = (size_t) ref->index;
+ if (caa_unlikely(index >= table->allocated_len))
+ return -EPERM;
+ obj = &table->objects[index];
+ return obj->wait_fd[0];
}
static inline
-void align_shm(struct shm_header *shm_header, size_t align)
+int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
+ int **shm_fd, char **shm_path,
+ int **wait_fd, char **wait_pipe_path,
+ uint64_t **memory_map_size)
{
- size_t offset_len = offset_align(shm_header->shm_allocated, align);
- shm_header->shm_allocated += offset_len;
+ struct shm_object_table *table = handle->table;
+ struct shm_object *obj;
+ size_t index;
+
+ index = (size_t) ref->index;
+ if (caa_unlikely(index >= table->allocated_len))
+ return -EPERM;
+ obj = &table->objects[index];
+ *shm_fd = &obj->shm_fd;
+ *shm_path = obj->shm_path;
+ *wait_fd = &obj->wait_fd[0];
+ *wait_pipe_path = obj->wait_pipe_path;
+ *memory_map_size = &obj->allocated_len;
+ return 0;
}
#endif /* _LIBRINGBUFFER_SHM_H */
projects / lttng-ust.git / blobdiff