+++ /dev/null
-/*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2 only,
- * as published by the Free Software Foundation.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#define _GNU_SOURCE
-#include <fcntl.h>
-#include <limits.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-#include <urcu.h>
-
-#include <common/error.h>
-
-#include "shm.h"
-
-/*
- * Using fork to set umask in the child process (not multi-thread safe). We
- * deal with the shm_open vs ftruncate race (happening when the sessiond owns
- * the shm and does not let everybody modify it, to ensure safety against
- * shm_unlink) by simply letting the mmap fail and retrying after a few
- * seconds. For global shm, everybody has rw access to it until the sessiond
- * starts.
- */
-static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
-{
- int wait_shm_fd, ret;
- mode_t mode;
-
- assert(shm_path);
-
- /* Default permissions */
- mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
-
- /*
- * Change owner of the shm path.
- */
- if (global) {
- /*
- * If global session daemon, any application can
- * register. Make it initially writeable so applications
- * registering concurrently can do ftruncate() by
- * themselves.
- */
- mode |= S_IROTH | S_IWOTH;
- }
-
- /*
- * We're alone in a child process, so we can modify the process-wide
- * umask.
- */
- umask(~mode);
-
- /*
- * Try creating shm (or get rw access). We don't do an exclusive open,
- * because we allow other processes to create+ftruncate it concurrently.
- */
- wait_shm_fd = shm_open(shm_path, O_RDWR | O_CREAT, mode);
- if (wait_shm_fd < 0) {
- PERROR("shm_open wait shm");
- goto error;
- }
-
- ret = ftruncate(wait_shm_fd, mmap_size);
- if (ret < 0) {
- PERROR("ftruncate wait shm");
- exit(EXIT_FAILURE);
- }
-
-#ifndef __FreeBSD__
- if (global) {
- ret = fchown(wait_shm_fd, 0, 0);
- if (ret < 0) {
- PERROR("fchown");
- exit(EXIT_FAILURE);
- }
- /*
- * If global session daemon, any application can
- * register so the shm needs to be set in read-only mode
- * for others.
- */
- mode &= ~S_IWOTH;
- ret = fchmod(wait_shm_fd, mode);
- if (ret < 0) {
- PERROR("fchmod");
- exit(EXIT_FAILURE);
- }
- } else {
- ret = fchown(wait_shm_fd, getuid(), getgid());
- if (ret < 0) {
- PERROR("fchown");
- exit(EXIT_FAILURE);
- }
- }
-#else
-#warning "FreeBSD does not support setting file mode on shm FD."
-#endif
-
- DBG("Got the wait shm fd %d", wait_shm_fd);
-
- return wait_shm_fd;
-
-error:
- DBG("Failing to get the wait shm fd");
-
- return -1;
-}
-
-/*
- * Return the wait shm mmap for UST application notification. The global
- * variable is used to indicate if the the session daemon is global
- * (root:tracing) or running with an unprivileged user.
- *
- * This returned value is used by futex_wait_update() in futex.c to WAKE all
- * waiters which are UST application waiting for a session daemon.
- */
-char *shm_ust_get_mmap(char *shm_path, int global)
-{
- size_t mmap_size = sysconf(_SC_PAGE_SIZE);
- int wait_shm_fd, ret;
- char *wait_shm_mmap;
-
- assert(shm_path);
-
- wait_shm_fd = get_wait_shm(shm_path, mmap_size, global);
- if (wait_shm_fd < 0) {
- goto error;
- }
-
- wait_shm_mmap = mmap(NULL, mmap_size, PROT_WRITE | PROT_READ,
- MAP_SHARED, wait_shm_fd, 0);
-
- /* close shm fd immediately after taking the mmap reference */
- ret = close(wait_shm_fd);
- if (ret) {
- PERROR("Error closing fd");
- }
-
- if (wait_shm_mmap == MAP_FAILED) {
- DBG("mmap error (can be caused by race with ust).");
- goto error;
- }
-
- return wait_shm_mmap;
-
-error:
- return NULL;
-}