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1d498196 MD |
1 | /* |
2 | * libringbuffer/shm.c | |
3 | * | |
e92f3e28 | 4 | * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
1d498196 | 5 | * |
e92f3e28 MD |
6 | * This library is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; only | |
9 | * version 2.1 of the License. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
1d498196 MD |
19 | */ |
20 | ||
21 | #include "shm.h" | |
22 | #include <unistd.h> | |
23 | #include <fcntl.h> | |
24 | #include <sys/mman.h> | |
25 | #include <sys/stat.h> /* For mode constants */ | |
26 | #include <fcntl.h> /* For O_* constants */ | |
27 | #include <assert.h> | |
8da6cd6d MD |
28 | #include <stdio.h> |
29 | #include <signal.h> | |
30 | #include <dirent.h> | |
4318ae1b | 31 | #include <lttng/align.h> |
35897f8b | 32 | #include <helper.h> |
96e80018 | 33 | #include <limits.h> |
1d498196 MD |
34 | |
35 | struct shm_object_table *shm_object_table_create(size_t max_nb_obj) | |
36 | { | |
37 | struct shm_object_table *table; | |
38 | ||
39 | table = zmalloc(sizeof(struct shm_object_table) + | |
40 | max_nb_obj * sizeof(table->objects[0])); | |
41 | table->size = max_nb_obj; | |
42 | return table; | |
43 | } | |
44 | ||
45 | struct shm_object *shm_object_table_append(struct shm_object_table *table, | |
46 | size_t memory_map_size) | |
47 | { | |
5a61337d | 48 | int shmfd, waitfd[2], ret, i, sigblocked = 0; |
1d498196 MD |
49 | struct shm_object *obj; |
50 | char *memory_map; | |
dda4784f | 51 | char tmp_name[NAME_MAX] = "/ust-shm-tmp-XXXXXX"; |
8da6cd6d | 52 | sigset_t all_sigs, orig_sigs; |
1d498196 MD |
53 | |
54 | if (table->allocated_len >= table->size) | |
55 | return NULL; | |
7a9c21bd | 56 | obj = &table->objects[table->allocated_len]; |
1d498196 MD |
57 | |
58 | /* wait_fd: create pipe */ | |
59 | ret = pipe(waitfd); | |
60 | if (ret < 0) { | |
61 | PERROR("pipe"); | |
62 | goto error_pipe; | |
63 | } | |
64 | for (i = 0; i < 2; i++) { | |
65 | ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC); | |
66 | if (ret < 0) { | |
67 | PERROR("fcntl"); | |
68 | goto error_fcntl; | |
69 | } | |
70 | } | |
5d61a504 MD |
71 | /* The write end of the pipe needs to be non-blocking */ |
72 | ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK); | |
73 | if (ret < 0) { | |
74 | PERROR("fcntl"); | |
75 | goto error_fcntl; | |
76 | } | |
7a9c21bd | 77 | memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); |
1d498196 MD |
78 | |
79 | /* shm_fd: create shm */ | |
80 | ||
8da6cd6d MD |
81 | /* |
82 | * Theoretically, we could leak a shm if the application crashes | |
83 | * between open and unlink. Disable signals on this thread for | |
84 | * increased safety against this scenario. | |
85 | */ | |
86 | sigfillset(&all_sigs); | |
87 | ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs); | |
88 | if (ret == -1) { | |
89 | PERROR("pthread_sigmask"); | |
90 | goto error_pthread_sigmask; | |
91 | } | |
5a61337d | 92 | sigblocked = 1; |
8da6cd6d | 93 | |
1d498196 MD |
94 | /* |
95 | * Allocate shm, and immediately unlink its shm oject, keeping | |
96 | * only the file descriptor as a reference to the object. If it | |
97 | * already exists (caused by short race window during which the | |
98 | * global object exists in a concurrent shm_open), simply retry. | |
99 | * We specifically do _not_ use the / at the beginning of the | |
100 | * pathname so that some OS implementations can keep it local to | |
101 | * the process (POSIX leaves this implementation-defined). | |
102 | */ | |
103 | do { | |
8da6cd6d MD |
104 | /* |
105 | * Using mktemp filename with O_CREAT | O_EXCL open | |
106 | * flags. | |
107 | */ | |
108 | mktemp(tmp_name); | |
109 | if (tmp_name[0] == '\0') { | |
110 | PERROR("mktemp"); | |
111 | goto error_shm_open; | |
a8803897 | 112 | } |
8da6cd6d | 113 | shmfd = shm_open(tmp_name, |
1d498196 | 114 | O_CREAT | O_EXCL | O_RDWR, 0700); |
8da6cd6d | 115 | } while (shmfd < 0 && (errno == EEXIST || errno == EACCES)); |
1d498196 MD |
116 | if (shmfd < 0) { |
117 | PERROR("shm_open"); | |
118 | goto error_shm_open; | |
119 | } | |
8da6cd6d | 120 | ret = shm_unlink(tmp_name); |
a8803897 MD |
121 | if (ret < 0 && errno != ENOENT) { |
122 | PERROR("shm_unlink"); | |
123 | goto error_shm_release; | |
124 | } | |
5a61337d | 125 | sigblocked = 0; |
8da6cd6d MD |
126 | ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); |
127 | if (ret == -1) { | |
128 | PERROR("pthread_sigmask"); | |
5a61337d | 129 | goto error_sigmask_release; |
8da6cd6d | 130 | } |
1d498196 MD |
131 | ret = ftruncate(shmfd, memory_map_size); |
132 | if (ret) { | |
133 | PERROR("ftruncate"); | |
134 | goto error_ftruncate; | |
135 | } | |
136 | obj->shm_fd = shmfd; | |
137 | ||
138 | /* memory_map: mmap */ | |
139 | memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, | |
140 | MAP_SHARED, shmfd, 0); | |
141 | if (memory_map == MAP_FAILED) { | |
142 | PERROR("mmap"); | |
143 | goto error_mmap; | |
144 | } | |
145 | obj->memory_map = memory_map; | |
146 | obj->memory_map_size = memory_map_size; | |
147 | obj->allocated_len = 0; | |
dc613eb9 | 148 | obj->index = table->allocated_len++; |
7a9c21bd | 149 | |
1d498196 MD |
150 | return obj; |
151 | ||
152 | error_mmap: | |
153 | error_ftruncate: | |
a8803897 | 154 | error_shm_release: |
5a61337d | 155 | error_sigmask_release: |
1d498196 MD |
156 | ret = close(shmfd); |
157 | if (ret) { | |
158 | PERROR("close"); | |
159 | assert(0); | |
160 | } | |
161 | error_shm_open: | |
5a61337d MD |
162 | if (sigblocked) { |
163 | ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); | |
164 | if (ret == -1) { | |
165 | PERROR("pthread_sigmask"); | |
166 | } | |
167 | } | |
8da6cd6d | 168 | error_pthread_sigmask: |
1d498196 MD |
169 | error_fcntl: |
170 | for (i = 0; i < 2; i++) { | |
171 | ret = close(waitfd[i]); | |
172 | if (ret) { | |
173 | PERROR("close"); | |
174 | assert(0); | |
175 | } | |
176 | } | |
177 | error_pipe: | |
1d498196 MD |
178 | return NULL; |
179 | ||
180 | } | |
181 | ||
193183fb MD |
182 | struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table, |
183 | int shm_fd, int wait_fd, size_t memory_map_size) | |
184 | { | |
185 | struct shm_object *obj; | |
186 | char *memory_map; | |
187 | ||
188 | if (table->allocated_len >= table->size) | |
189 | return NULL; | |
190 | obj = &table->objects[table->allocated_len]; | |
191 | ||
192 | /* wait_fd: set read end of the pipe. */ | |
193 | obj->wait_fd[0] = wait_fd; | |
194 | obj->wait_fd[1] = -1; /* write end is unset. */ | |
195 | obj->shm_fd = shm_fd; | |
196 | ||
197 | /* memory_map: mmap */ | |
198 | memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, | |
199 | MAP_SHARED, shm_fd, 0); | |
200 | if (memory_map == MAP_FAILED) { | |
201 | PERROR("mmap"); | |
202 | goto error_mmap; | |
203 | } | |
204 | obj->memory_map = memory_map; | |
205 | obj->memory_map_size = memory_map_size; | |
206 | obj->allocated_len = memory_map_size; | |
207 | obj->index = table->allocated_len++; | |
208 | ||
209 | return obj; | |
210 | ||
211 | error_mmap: | |
212 | return NULL; | |
213 | } | |
214 | ||
1d498196 MD |
215 | static |
216 | void shmp_object_destroy(struct shm_object *obj) | |
217 | { | |
218 | int ret, i; | |
219 | ||
7a784989 MD |
220 | if (!obj->is_shadow) { |
221 | ret = munmap(obj->memory_map, obj->memory_map_size); | |
222 | if (ret) { | |
223 | PERROR("umnmap"); | |
224 | assert(0); | |
225 | } | |
226 | } | |
ef9ff354 MD |
227 | if (obj->shm_fd >= 0) { |
228 | ret = close(obj->shm_fd); | |
229 | if (ret) { | |
230 | PERROR("close"); | |
231 | assert(0); | |
232 | } | |
1d498196 MD |
233 | } |
234 | for (i = 0; i < 2; i++) { | |
824f40b8 MD |
235 | if (obj->wait_fd[i] < 0) |
236 | continue; | |
1d498196 MD |
237 | ret = close(obj->wait_fd[i]); |
238 | if (ret) { | |
239 | PERROR("close"); | |
240 | assert(0); | |
241 | } | |
242 | } | |
243 | } | |
244 | ||
245 | void shm_object_table_destroy(struct shm_object_table *table) | |
246 | { | |
247 | int i; | |
248 | ||
249 | for (i = 0; i < table->allocated_len; i++) | |
250 | shmp_object_destroy(&table->objects[i]); | |
251 | free(table); | |
252 | } | |
253 | ||
254 | /* | |
255 | * zalloc_shm - allocate memory within a shm object. | |
256 | * | |
257 | * Shared memory is already zeroed by shmget. | |
258 | * *NOT* multithread-safe (should be protected by mutex). | |
259 | * Returns a -1, -1 tuple on error. | |
260 | */ | |
261 | struct shm_ref zalloc_shm(struct shm_object *obj, size_t len) | |
262 | { | |
263 | struct shm_ref ref; | |
264 | struct shm_ref shm_ref_error = { -1, -1 }; | |
265 | ||
266 | if (obj->memory_map_size - obj->allocated_len < len) | |
267 | return shm_ref_error; | |
268 | ref.index = obj->index; | |
269 | ref.offset = obj->allocated_len; | |
270 | obj->allocated_len += len; | |
271 | return ref; | |
272 | } | |
273 | ||
274 | void align_shm(struct shm_object *obj, size_t align) | |
275 | { | |
276 | size_t offset_len = offset_align(obj->allocated_len, align); | |
277 | obj->allocated_len += offset_len; | |
278 | } |