projects / lttng-ust.git / blame
| Commit | Line | Data |
|---|---|---|
| a6352fd4 MD |
1 | #ifndef _LIBRINGBUFFER_SHM_H |
| 2 | #define _LIBRINGBUFFER_SHM_H | |
| 3 | ||
| 4 | /* | |
| 5 | * libringbuffer/shm.h | |
| 6 | * | |
| 7 | * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
| 8 | * | |
| 9 | * Dual LGPL v2.1/GPL v2 license. | |
| 10 | */ | |
| 11 | ||
| 12 | #include <stdint.h> | |
| 1dbfff0c | 13 | #include <ust/usterr-signal-safe.h> |
| a6352fd4 MD |
14 | #include "ust/core.h" |
| 15 | ||
| 16 | #define SHM_MAGIC 0x54335433 | |
| 17 | #define SHM_MAJOR 0 | |
| 18 | #define SHM_MINOR 1 | |
| 19 | ||
| 20 | /* | |
| 21 | * Defining a max shm offset, for debugging purposes. | |
| 22 | */ | |
| 23 | #if (CAA_BITS_PER_LONG == 32) | |
| 24 | /* Define the maximum shared memory size to 128MB on 32-bit machines */ | |
| 25 | #define MAX_SHM_SIZE 134217728 | |
| 26 | #else | |
| 27 | /* Define the maximum shared memory size to 8GB on 64-bit machines */ | |
| 28 | #define MAX_SHM_SIZE 8589934592 | |
| 29 | #endif | |
| 30 | ||
| 31 | #define DECLARE_SHMP(type, name) type *****name | |
| 32 | ||
| 33 | struct shm_header { | |
| 34 | uint32_t magic; | |
| 35 | uint8_t major; | |
| 36 | uint8_t minor; | |
| 37 | uint8_t bits_per_long; | |
| 38 | size_t shm_size, shm_allocated; | |
| 39 | ||
| 40 | DECLARE_SHMP(struct channel, chan); | |
| 41 | }; | |
| 42 | ||
| 431d5cf0 MD |
43 | struct shm_handle { |
| 44 | struct shm_header *header; /* beginning of mapping */ | |
| 45 | int shmfd; /* process-local file descriptor */ | |
| 46 | }; | |
| 47 | ||
| a6352fd4 MD |
48 | #define shmp(shm_offset) \ |
| 49 | ((__typeof__(****(shm_offset))) (((char *) &(shm_offset)) + (ptrdiff_t) (shm_offset))) | |
| 50 | ||
| 51 | #define _shmp_abs(a) ((a < 0) ? -(a) : (a)) | |
| 52 | ||
| 53 | static inline | |
| 54 | void _set_shmp(ptrdiff_t *shm_offset, void *ptr) | |
| 55 | { | |
| 56 | *shm_offset = (((char *) ptr) - ((char *) shm_offset)); | |
| 57 | assert(_shmp_abs(*shm_offset) < MAX_SHM_SIZE); | |
| 58 | } | |
| 59 | ||
| 60 | #define set_shmp(shm_offset, ptr) \ | |
| 61 | _set_shmp((ptrdiff_t *) ****(shm_offset), ptr) | |
| 62 | ||
| 63 | /* Shared memory is already zeroed by shmget */ | |
| 64 | /* *NOT* multithread-safe (should be protected by mutex) */ | |
| 65 | static inline | |
| 66 | void *zalloc_shm(struct shm_header *shm_header, size_t len) | |
| 67 | { | |
| 68 | void *ret; | |
| 69 | ||
| 70 | if (shm_header->shm_size - shm_header->shm_allocated < len) | |
| 71 | return NULL; | |
| 72 | ret = (char *) shm_header + shm_header->shm_allocated; | |
| 73 | shm_header->shm_allocated += len; | |
| 74 | return ret; | |
| 75 | } | |
| 76 | ||
| 431d5cf0 MD |
77 | static inline |
| 78 | void align_shm(struct shm_header *shm_header, size_t align) | |
| 79 | { | |
| 80 | size_t offset_len = offset_align(shm_header->shm_allocated, align); | |
| 81 | shm_header->shm_allocated += offset_len; | |
| 82 | } | |
| 83 | ||
| a6352fd4 | 84 | #endif /* _LIBRINGBUFFER_SHM_H */ |