X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Fshm.c;h=fb2df13bc11a5a1a43c0b5dc3394930fb8e1bd9a;hb=a9ff648cc;hp=873e6e87597311ae9a5cc03c3d1c27a53dae025c;hpb=afdf9825400f1b975a98202a3e9dcbec0a572a56;p=lttng-ust.git diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c index 873e6e87..fb2df13b 100644 --- a/libringbuffer/shm.c +++ b/libringbuffer/shm.c @@ -1,19 +1,75 @@ /* * libringbuffer/shm.c * - * Copyright 2011 (c) - Mathieu Desnoyers + * Copyright (C) 2005-2012 Mathieu Desnoyers * - * 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 "shm.h" #include #include #include +#include #include /* For mode constants */ #include /* For O_* constants */ #include -#include +#include +#include +#include +#include +#include +#include + +/* + * Ensure we have the required amount of space available by writing 0 + * into the entire buffer. Not doing so can trigger SIGBUS when going + * beyond the available shm space. + */ +static +int zero_file(int fd, size_t len) +{ + ssize_t retlen; + size_t written = 0; + char *zeropage; + long pagelen; + int ret; + + pagelen = sysconf(_SC_PAGESIZE); + if (pagelen < 0) + return (int) pagelen; + zeropage = calloc(pagelen, 1); + if (!zeropage) + return -ENOMEM; + + while (len > written) { + do { + retlen = write(fd, zeropage, + min_t(size_t, pagelen, len - written)); + } while (retlen == -1UL && errno == EINTR); + if (retlen < 0) { + ret = (int) retlen; + goto error; + } + written += retlen; + } + ret = 0; +error: + free(zeropage); + return ret; +} struct shm_object_table *shm_object_table_create(size_t max_nb_obj) { @@ -21,16 +77,76 @@ 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; } -struct shm_object *shm_object_table_append(struct shm_object_table *table, - size_t memory_map_size) +static +int create_posix_shm(void) { - int shmfd, waitfd[2], ret, i; + char tmp_name[NAME_MAX] = "/ust-shm-tmp-XXXXXX"; + int shmfd, ret; + + /* + * 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; + } + return shmfd; + +error_shm_release: + ret = close(shmfd); + if (ret) { + PERROR("close"); + assert(0); + } +error_shm_open: + return -1; +} + +static +int create_shared_file(const char *shm_path) +{ + return open(shm_path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); +} + +static +struct shm_object *_shm_object_table_alloc_shm(struct shm_object_table *table, + size_t memory_map_size, + const char *shm_path) +{ + int shmfd, waitfd[2], ret, i, sigblocked = 0; struct shm_object *obj; char *memory_map; + sigset_t all_sigs, orig_sigs; if (table->allocated_len >= table->size) return NULL; @@ -60,26 +176,43 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, /* shm_fd: create shm */ /* - * 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). + * 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. */ - do { - shmfd = shm_open("ust-shm-tmp", - O_CREAT | O_EXCL | O_RDWR, 0700); - } while (shmfd < 0 && errno == EEXIST); - if (shmfd < 0) { - PERROR("shm_open"); + sigfillset(&all_sigs); + ret = pthread_sigmask(SIG_BLOCK, &all_sigs, &orig_sigs); + if (ret == -1) { + PERROR("pthread_sigmask"); + goto error_pthread_sigmask; + } + sigblocked = 1; + + + if (!shm_path) { + obj->shm_path[0] = '\0'; + shmfd = create_posix_shm(); + } else { + strncpy(obj->shm_path, shm_path, + sizeof(obj->shm_path)); + obj->shm_path[sizeof(obj->shm_path) - 1] = '\0'; + + /* Path should already exist, but could fail. */ + shmfd = create_shared_file(shm_path); + } + if (shmfd < 0) goto error_shm_open; + + sigblocked = 0; + ret = pthread_sigmask(SIG_SETMASK, &orig_sigs, NULL); + if (ret == -1) { + PERROR("pthread_sigmask"); + goto error_sigmask_release; } - ret = shm_unlink("ust-shm-tmp"); + ret = zero_file(shmfd, memory_map_size); if (ret) { - PERROR("shm_unlink"); - goto error_unlink; + PERROR("zero_file"); + goto error_zero_file; } ret = ftruncate(shmfd, memory_map_size); if (ret) { @@ -95,6 +228,7 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, PERROR("mmap"); goto error_mmap; } + obj->type = SHM_OBJECT_SHM; obj->memory_map = memory_map; obj->memory_map_size = memory_map_size; obj->allocated_len = 0; @@ -104,13 +238,27 @@ struct shm_object *shm_object_table_append(struct shm_object_table *table, error_mmap: error_ftruncate: -error_unlink: +error_zero_file: +error_sigmask_release: ret = close(shmfd); if (ret) { PERROR("close"); assert(0); } + if (shm_path) { + ret = unlink(shm_path); + if (ret) { + PERROR("ret"); + } + } 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]); @@ -121,31 +269,235 @@ error_fcntl: } error_pipe: return NULL; - } static -void shmp_object_destroy(struct shm_object *obj) +struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table, + size_t memory_map_size) { - int ret, i; - - ret = munmap(obj->memory_map, obj->memory_map_size); - if (ret) { - PERROR("umnmap"); - assert(0); - } - ret = close(obj->shm_fd); - if (ret) { - PERROR("close"); - assert(0); + struct shm_object *obj; + void *memory_map; + int waitfd[2], i, ret; + + if (table->allocated_len >= table->size) + return NULL; + obj = &table->objects[table->allocated_len]; + + memory_map = zmalloc(memory_map_size); + if (!memory_map) + goto alloc_error; + + /* wait_fd: create pipe */ + ret = pipe(waitfd); + if (ret < 0) { + PERROR("pipe"); + goto error_pipe; + } + for (i = 0; i < 2; i++) { + ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } } + /* The write end of the pipe needs to be non-blocking */ + ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } + memcpy(obj->wait_fd, waitfd, sizeof(waitfd)); + + /* no shm_fd */ + obj->shm_fd = -1; + + obj->type = SHM_OBJECT_MEM; + obj->memory_map = memory_map; + obj->memory_map_size = memory_map_size; + obj->allocated_len = 0; + obj->index = table->allocated_len++; + + return obj; + +error_fcntl: for (i = 0; i < 2; i++) { - ret = close(obj->wait_fd[i]); + ret = close(waitfd[i]); if (ret) { PERROR("close"); assert(0); } } +error_pipe: + free(memory_map); +alloc_error: + return NULL; +} + +struct shm_object *shm_object_table_alloc(struct shm_object_table *table, + size_t memory_map_size, + enum shm_object_type type, + const char *shm_path) +{ + switch (type) { + case SHM_OBJECT_SHM: + return _shm_object_table_alloc_shm(table, memory_map_size, + shm_path); + case SHM_OBJECT_MEM: + return _shm_object_table_alloc_mem(table, memory_map_size); + default: + assert(0); + } + return NULL; +} + +struct shm_object *shm_object_table_append_shm(struct shm_object_table *table, + int shm_fd, int wakeup_fd, uint32_t stream_nr, + size_t memory_map_size) +{ + struct shm_object *obj; + char *memory_map; + int ret; + + if (table->allocated_len >= table->size) + return NULL; + /* streams _must_ be received in sequential order, else fail. */ + if (stream_nr + 1 != table->allocated_len) + return NULL; + + obj = &table->objects[table->allocated_len]; + + /* wait_fd: set write end of the pipe. */ + obj->wait_fd[0] = -1; /* read end is unset */ + obj->wait_fd[1] = wakeup_fd; + obj->shm_fd = shm_fd; + + ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } + /* The write end of the pipe needs to be non-blocking */ + ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } + + /* memory_map: mmap */ + memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE, + MAP_SHARED, shm_fd, 0); + if (memory_map == MAP_FAILED) { + PERROR("mmap"); + goto error_mmap; + } + obj->type = SHM_OBJECT_SHM; + obj->memory_map = memory_map; + obj->memory_map_size = memory_map_size; + obj->allocated_len = memory_map_size; + obj->index = table->allocated_len++; + + return obj; + +error_fcntl: +error_mmap: + return NULL; +} + +/* + * Passing ownership of mem to object. + */ +struct shm_object *shm_object_table_append_mem(struct shm_object_table *table, + void *mem, size_t memory_map_size, int wakeup_fd) +{ + struct shm_object *obj; + int ret; + + if (table->allocated_len >= table->size) + return NULL; + obj = &table->objects[table->allocated_len]; + + obj->wait_fd[0] = -1; /* read end is unset */ + obj->wait_fd[1] = wakeup_fd; + obj->shm_fd = -1; + + ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } + /* The write end of the pipe needs to be non-blocking */ + ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK); + if (ret < 0) { + PERROR("fcntl"); + goto error_fcntl; + } + + obj->type = SHM_OBJECT_MEM; + obj->memory_map = mem; + obj->memory_map_size = memory_map_size; + obj->allocated_len = memory_map_size; + obj->index = table->allocated_len++; + + return obj; + +error_fcntl: + return NULL; +} + +static +void shmp_object_destroy(struct shm_object *obj) +{ + switch (obj->type) { + case SHM_OBJECT_SHM: + { + int ret, i; + + ret = munmap(obj->memory_map, obj->memory_map_size); + if (ret) { + PERROR("umnmap"); + assert(0); + } + ret = close(obj->shm_fd); + if (ret) { + PERROR("close"); + assert(0); + } + if (obj->shm_path[0]) { + ret = unlink(obj->shm_path); + if (ret) { + PERROR("ret"); + } + } + for (i = 0; i < 2; i++) { + if (obj->wait_fd[i] < 0) + continue; + ret = close(obj->wait_fd[i]); + if (ret) { + PERROR("close"); + assert(0); + } + } + break; + } + case SHM_OBJECT_MEM: + { + int ret, i; + + for (i = 0; i < 2; i++) { + if (obj->wait_fd[i] < 0) + continue; + ret = close(obj->wait_fd[i]); + if (ret) { + PERROR("close"); + assert(0); + } + } + free(obj->memory_map); + break; + } + default: + assert(0); + } } void shm_object_table_destroy(struct shm_object_table *table)