X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=libringbuffer%2Fshm.c;h=53b2b6ec3f1819ba69d2b328f83f224d1d0b220d;hb=99b99b470fddbc81b9c7d01320616efdbe1cb55b;hp=995665ae16f4ee0b4836b3ffaf047bfb76ec3193;hpb=af21f7816739b0f9db8b4006ef4378ddc2de0157;p=lttng-ust.git diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c index 995665ae..53b2b6ec 100644 --- a/libringbuffer/shm.c +++ b/libringbuffer/shm.c @@ -22,6 +22,7 @@ #include #include #include +#include #include /* For mode constants */ #include /* For O_* constants */ #include @@ -29,7 +30,6 @@ #include #include #include -#include #include #include @@ -77,20 +77,23 @@ struct shm_object_table *shm_object_table_create(size_t max_nb_obj) table = zmalloc(sizeof(struct shm_object_table) + max_nb_obj * sizeof(table->objects[0])); + if (!table) + return NULL; table->size = max_nb_obj; return table; } static struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, - size_t memory_map_size) + size_t memory_map_size, + int stream_fd) { - int shmfd, waitfd[2], ret, i, sigblocked = 0; + int shmfd, waitfd[2], ret, i; struct shm_object *obj; char *memory_map; - char tmp_name[NAME_MAX] = "/ust-shm-tmp-XXXXXX"; - sigset_t all_sigs, orig_sigs; + if (stream_fd < 0) + return NULL; if (table->allocated_len >= table->size) return NULL; obj = &table->objects[table->allocated_len]; @@ -116,58 +119,9 @@ struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, } memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); - /* shm_fd: create shm */ - - /* - * Theoretically, we could leak a shm if the application crashes - * between open and unlink. Disable signals on this thread for - * increased safety against this scenario. - */ - sigfillset(&all_sigs); - ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs); - if (ret == -1) { - PERROR("pthread_sigmask"); - goto error_pthread_sigmask; - } - sigblocked = 1; - - /* - * Allocate shm, and immediately unlink its shm oject, keeping - * only the file descriptor as a reference to the object. If it - * already exists (caused by short race window during which the - * global object exists in a concurrent shm_open), simply retry. - * We specifically do _not_ use the / at the beginning of the - * pathname so that some OS implementations can keep it local to - * the process (POSIX leaves this implementation-defined). - */ - do { - /* - * Using mktemp filename with O_CREAT | O_EXCL open - * flags. - */ - (void) mktemp(tmp_name); - if (tmp_name[0] == '\0') { - PERROR("mktemp"); - goto error_shm_open; - } - shmfd = shm_open(tmp_name, - O_CREAT | O_EXCL | O_RDWR, 0700); - } while (shmfd < 0 && (errno == EEXIST || errno == EACCES)); - if (shmfd < 0) { - PERROR("shm_open"); - goto error_shm_open; - } - ret = shm_unlink(tmp_name); - if (ret < 0 && errno != ENOENT) { - PERROR("shm_unlink"); - goto error_shm_release; - } - sigblocked = 0; - ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); - if (ret == -1) { - PERROR("pthread_sigmask"); - goto error_sigmask_release; - } + /* create shm */ + + shmfd = stream_fd; ret = zero_file(shmfd, memory_map_size); if (ret) { PERROR("zero_file"); @@ -178,6 +132,7 @@ struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, PERROR("ftruncate"); goto error_ftruncate; } + obj->shm_fd_ownership = 0; obj->shm_fd = shmfd; /* memory_map: mmap */ @@ -197,22 +152,7 @@ struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, error_mmap: error_ftruncate: -error_shm_release: error_zero_file: -error_sigmask_release: - ret = close(shmfd); - if (ret) { - PERROR("close"); - assert(0); - } -error_shm_open: - if (sigblocked) { - ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); - if (ret == -1) { - PERROR("pthread_sigmask"); - } - } -error_pthread_sigmask: error_fcntl: for (i = 0; i < 2; i++) { ret = close(waitfd[i]); @@ -264,6 +204,7 @@ struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table, /* no shm_fd */ obj->shm_fd = -1; + obj->shm_fd_ownership = 0; obj->type = SHM_OBJECT_MEM; obj->memory_map = memory_map; @@ -289,11 +230,13 @@ alloc_error: struct shm_object *shm_object_table_alloc(struct shm_object_table *table, size_t memory_map_size, - enum shm_object_type type) + enum shm_object_type type, + int stream_fd) { switch (type) { case SHM_OBJECT_SHM: - return _shm_object_table_alloc_shm(table, memory_map_size); + return _shm_object_table_alloc_shm(table, memory_map_size, + stream_fd); case SHM_OBJECT_MEM: return _shm_object_table_alloc_mem(table, memory_map_size); default: @@ -322,6 +265,7 @@ struct shm_object *shm_object_table_append_shm(struct shm_object_table *table, obj->wait_fd[0] = -1; /* read end is unset */ obj->wait_fd[1] = wakeup_fd; obj->shm_fd = shm_fd; + obj->shm_fd_ownership = 1; ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); if (ret < 0) { @@ -371,6 +315,7 @@ struct shm_object *shm_object_table_append_mem(struct shm_object_table *table, obj->wait_fd[0] = -1; /* read end is unset */ obj->wait_fd[1] = wakeup_fd; obj->shm_fd = -1; + obj->shm_fd_ownership = 0; ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); if (ret < 0) { @@ -409,10 +354,12 @@ void shmp_object_destroy(struct shm_object *obj) PERROR("umnmap"); assert(0); } - ret = close(obj->shm_fd); - if (ret) { - PERROR("close"); - assert(0); + if (obj->shm_fd_ownership) { + ret = close(obj->shm_fd); + if (ret) { + PERROR("close"); + assert(0); + } } for (i = 0; i < 2; i++) { if (obj->wait_fd[i] < 0)