X-Git-Url: http://git.lttng.org/?p=lttng-ust.git;a=blobdiff_plain;f=libringbuffer%2Fshm.c;h=06724e58999aad7169a232bdff91866e66413e97;hp=79977017904308c4f5c05046f176caa7e07fb612;hb=bf5ff35ed0a3a7f60e92d654a5b97e73b94da852;hpb=cbd7f39d9267e24159023db91712ca91558c5cc8 diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c index 79977017..06724e58 100644 --- a/libringbuffer/shm.c +++ b/libringbuffer/shm.c @@ -20,6 +20,7 @@ #include "shm.h" #include +#include #include #include #include /* For mode constants */ @@ -32,6 +33,8 @@ #include #include #include +/* FIXME: Include UUID the proper way, e.g. config.h... */ +#include /* * Ensure we have the required amount of space available by writing 0 @@ -81,39 +84,95 @@ struct shm_object_table *shm_object_table_create(size_t max_nb_obj) return table; } +/* + * Generate a unique name with the desired prefix. + * Pattern is as follow: prefix-pid-uuid. + * Caller is responsible of freeing the resulting string. + */ +static +char *gen_unique_name(const char *prefix) +{ + int written; + pid_t pid; + uuid_t uuid; + char uuid_str[37]; + char tmp_name[NAME_MAX]; + char *name; + + if (!prefix) + return NULL; + + pid = getpid(); + + uuid_generate(uuid); + uuid_unparse(uuid, uuid_str); + + written = snprintf(tmp_name, NAME_MAX, + "%s-%d-%s", prefix, pid, uuid_str); + + if (written < 0 || written >= NAME_MAX) + return NULL; + + name = zmalloc(written + 1); + + if (!name) + return NULL; + + return strncpy(name, tmp_name, written); +} + struct shm_object *shm_object_table_append(struct shm_object_table *table, size_t memory_map_size) { - int shmfd, waitfd[2], ret, i, sigblocked = 0; + int shmfd, ret, sigblocked = 0; struct shm_object *obj; char *memory_map; + + const char *base_shm = "/dev/shm/"; + const char *base_path = "/tmp/lttng-fds/"; + const char *waitfd_prefix = "ust-wait"; + const char *shm_prefix = "ust-shm"; + + char *wait_pipe_path, *wait_pipe_file; + char *shm_path, *shm_symlink_path, *shm_file; + char tmp_name[NAME_MAX] = "ust-shm-tmp-XXXXXX"; + sigset_t all_sigs, orig_sigs; if (table->allocated_len >= table->size) return NULL; obj = &table->objects[table->allocated_len]; - /* wait_fd: create pipe */ - ret = pipe(waitfd); - if (ret < 0) { - PERROR("pipe"); - goto error_pipe; + wait_pipe_file = gen_unique_name(waitfd_prefix); + + if (!wait_pipe_file) { + goto error_gen_unique_wait; } - for (i = 0; i < 2; i++) { - ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC); - if (ret < 0) { - PERROR("fcntl"); - goto error_fcntl; - } + + wait_pipe_path = zmalloc(strlen(base_path) + + strlen(wait_pipe_file) + 1); + + if (!wait_pipe_path) { + free(wait_pipe_file); + goto error_wait_alloc; } - /* The write end of the pipe needs to be non-blocking */ - ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK); + + strncat(wait_pipe_path, base_path, strlen(base_path)); + strncat(wait_pipe_path, wait_pipe_file, strlen(wait_pipe_file)); + + free(wait_pipe_file); + + /* wait_fd: create named pipe */ + ret = mkfifo(wait_pipe_path, 0777); if (ret < 0) { - PERROR("fcntl"); - goto error_fcntl; + PERROR("mkfifo"); + goto error_mkfifo; } - memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); + + obj->wait_fd[0] = -1; + obj->wait_fd[1] = -1; + obj->wait_pipe_path = wait_pipe_path; /* shm_fd: create shm */ @@ -131,10 +190,6 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, 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). @@ -156,17 +211,54 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, 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 unique symlink to shm */ + shm_path = zmalloc(strlen(base_shm) + strlen(tmp_name) + 1); + + if (!shm_path) { + goto error_shm_alloc; + } + + strncat(shm_path, base_shm, strlen(base_shm)); + strncat(shm_path, tmp_name, strlen(tmp_name)); + + shm_file = gen_unique_name(shm_prefix); + + if (!shm_file) { + free(shm_path); + goto error_gen_unique_shm; + } + + shm_symlink_path = zmalloc(strlen(base_path) + strlen(shm_file) + 1); + + if (!shm_symlink_path) { + free(shm_path); + free(shm_file); + goto error_symlink_alloc; + } + + strncat(shm_symlink_path, base_path, strlen(base_path)); + strncat(shm_symlink_path, shm_file, strlen(shm_file)); + + free(shm_file); + + ret = symlink(shm_path, shm_symlink_path); + if (ret < 0) { + PERROR("symlink"); + free(shm_path); + free(shm_symlink_path); + goto error_symlink_shm; + } + + free(shm_path); + ret = zero_file(shmfd, memory_map_size); if (ret) { PERROR("zero_file"); @@ -178,6 +270,7 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, goto error_ftruncate; } obj->shm_fd = shmfd; + obj->shm_path = shm_symlink_path; /* memory_map: mmap */ memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, @@ -195,8 +288,12 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, error_mmap: error_ftruncate: -error_shm_release: error_zero_file: + free(shm_symlink_path); +error_symlink_shm: +error_symlink_alloc: +error_gen_unique_shm: +error_shm_alloc: error_sigmask_release: ret = close(shmfd); if (ret) { @@ -211,17 +308,11 @@ error_shm_open: } } error_pthread_sigmask: -error_fcntl: - for (i = 0; i < 2; i++) { - ret = close(waitfd[i]); - if (ret) { - PERROR("close"); - assert(0); - } - } -error_pipe: +error_mkfifo: + free(wait_pipe_path); +error_wait_alloc: +error_gen_unique_wait: return NULL; - } struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table, @@ -276,6 +367,11 @@ void shmp_object_destroy(struct shm_object *obj) assert(0); } } + + if (obj->shm_path) { + free(obj->shm_path); + } + for (i = 0; i < 2; i++) { if (obj->wait_fd[i] < 0) continue; @@ -285,6 +381,10 @@ void shmp_object_destroy(struct shm_object *obj) assert(0); } } + + if (obj->wait_pipe_path) { + free(obj->wait_pipe_path); + } } void shm_object_table_destroy(struct shm_object_table *table)