2 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
24 #include <sys/resource.h>
29 #include "dynamic-string.h"
30 #include "fatal-signal.h"
32 #include "ovs-thread.h"
33 #include "poll-loop.h"
35 #include "socket-util.h"
39 VLOG_DEFINE_THIS_MODULE(process);
41 COVERAGE_DEFINE(process_start);
53 /* Pipe used to signal child termination. */
57 static struct list all_processes = LIST_INITIALIZER(&all_processes);
59 static void sigchld_handler(int signr OVS_UNUSED);
61 /* Initializes the process subsystem (if it is not already initialized). Calls
62 * exit() if initialization fails.
64 * This function may not be called after creating any additional threads.
66 * Calling this function is optional; it will be called automatically by
67 * process_start() if necessary. Calling it explicitly allows the client to
68 * prevent the process from exiting at an unexpected time. */
76 assert_single_threaded();
82 /* Create notification pipe. */
83 xpipe_nonblocking(fds);
85 /* Set up child termination signal handler. */
86 memset(&sa, 0, sizeof sa);
87 sa.sa_handler = sigchld_handler;
88 sigemptyset(&sa.sa_mask);
89 sa.sa_flags = SA_NOCLDSTOP | SA_RESTART;
90 xsigaction(SIGCHLD, &sa, NULL);
95 process_escape_args(char **argv)
97 struct ds ds = DS_EMPTY_INITIALIZER;
99 for (argp = argv; *argp; argp++) {
100 const char *arg = *argp;
103 ds_put_char(&ds, ' ');
105 if (arg[strcspn(arg, " \t\r\n\v\\\'\"")]) {
106 ds_put_char(&ds, '"');
107 for (p = arg; *p; p++) {
108 if (*p == '\\' || *p == '\"') {
109 ds_put_char(&ds, '\\');
111 ds_put_char(&ds, *p);
113 ds_put_char(&ds, '"');
115 ds_put_cstr(&ds, arg);
121 /* Prepare to start a process whose command-line arguments are given by the
122 * null-terminated 'argv' array. Returns 0 if successful, otherwise a
123 * positive errno value. */
125 process_prestart(char **argv)
131 /* Log the process to be started. */
132 if (VLOG_IS_DBG_ENABLED()) {
133 char *args = process_escape_args(argv);
134 VLOG_DBG("starting subprocess: %s", args);
138 /* execvp() will search PATH too, but the error in that case is more
139 * obscure, since it is only reported post-fork. */
140 binary = process_search_path(argv[0]);
142 VLOG_ERR("%s not found in PATH", argv[0]);
150 /* Creates and returns a new struct process with the specified 'name' and
152 static struct process *
153 process_register(const char *name, pid_t pid)
158 p = xzalloc(sizeof *p);
160 slash = strrchr(name, '/');
161 p->name = xstrdup(slash ? slash + 1 : name);
164 list_push_back(&all_processes, &p->node);
171 rlim_is_finite(rlim_t limit)
173 if (limit == RLIM_INFINITY) {
177 #ifdef RLIM_SAVED_CUR /* FreeBSD 8.0 lacks RLIM_SAVED_CUR. */
178 if (limit == RLIM_SAVED_CUR) {
183 #ifdef RLIM_SAVED_MAX /* FreeBSD 8.0 lacks RLIM_SAVED_MAX. */
184 if (limit == RLIM_SAVED_MAX) {
192 /* Returns the maximum valid FD value, plus 1. */
200 if (!getrlimit(RLIMIT_NOFILE, &r) && rlim_is_finite(r.rlim_cur)) {
201 max_fds = r.rlim_cur;
203 VLOG_WARN("failed to obtain fd limit, defaulting to 1024");
212 /* Starts a subprocess with the arguments in the null-terminated argv[] array.
213 * argv[0] is used as the name of the process. Searches the PATH environment
214 * variable to find the program to execute.
216 * This function may not be called after creating any additional threads.
218 * All file descriptors are closed before executing the subprocess, except for
221 * Returns 0 if successful, otherwise a positive errno value indicating the
222 * error. If successful, '*pp' is assigned a new struct process that may be
223 * used to query the process's status. On failure, '*pp' is set to NULL. */
225 process_start(char **argv, struct process **pp)
231 assert_single_threaded();
234 COVERAGE_INC(process_start);
235 error = process_prestart(argv);
242 VLOG_WARN("fork failed: %s", ovs_strerror(errno));
245 /* Running in parent process. */
246 *pp = process_register(argv[0], pid);
249 /* Running in child process. */
250 int fd_max = get_max_fds();
254 for (fd = 3; fd < fd_max; fd++) {
257 execvp(argv[0], argv);
258 fprintf(stderr, "execvp(\"%s\") failed: %s\n",
259 argv[0], ovs_strerror(errno));
268 /* Destroys process 'p'. */
270 process_destroy(struct process *p)
273 list_remove(&p->node);
279 /* Sends signal 'signr' to process 'p'. Returns 0 if successful, otherwise a
280 * positive errno value. */
282 process_kill(const struct process *p, int signr)
285 return (p->exited ? ESRCH
286 : !kill(p->pid, signr) ? 0
293 /* Returns the pid of process 'p'. */
295 process_pid(const struct process *p)
300 /* Returns the name of process 'p' (the name passed to process_start() with any
301 * leading directories stripped). */
303 process_name(const struct process *p)
308 /* Returns true if process 'p' has exited, false otherwise. */
310 process_exited(struct process *p)
315 /* Returns process 'p''s exit status, as reported by waitpid(2).
316 * process_status(p) may be called only after process_exited(p) has returned
319 process_status(const struct process *p)
321 ovs_assert(p->exited);
325 /* Given 'status', which is a process status in the form reported by waitpid(2)
326 * and returned by process_status(), returns a string describing how the
327 * process terminated. The caller is responsible for freeing the string when
328 * it is no longer needed. */
330 process_status_msg(int status)
332 struct ds ds = DS_EMPTY_INITIALIZER;
334 if (WIFEXITED(status)) {
335 ds_put_format(&ds, "exit status %d", WEXITSTATUS(status));
336 } else if (WIFSIGNALED(status)) {
337 char namebuf[SIGNAL_NAME_BUFSIZE];
339 ds_put_format(&ds, "killed (%s)",
340 signal_name(WTERMSIG(status), namebuf, sizeof namebuf));
341 } else if (WIFSTOPPED(status)) {
342 char namebuf[SIGNAL_NAME_BUFSIZE];
344 ds_put_format(&ds, "stopped (%s)",
345 signal_name(WSTOPSIG(status), namebuf, sizeof namebuf));
347 ds_put_format(&ds, "terminated abnormally (%x)", status);
349 if (WCOREDUMP(status)) {
350 ds_put_cstr(&ds, ", core dumped");
353 ds_put_cstr(&ds, "function not supported.");
358 /* Executes periodic maintenance activities required by the process module. */
363 char buf[_POSIX_PIPE_BUF];
365 if (!list_is_empty(&all_processes) && read(fds[0], buf, sizeof buf) > 0) {
368 LIST_FOR_EACH (p, node, &all_processes) {
372 retval = waitpid(p->pid, &status, WNOHANG);
373 } while (retval == -1 && errno == EINTR);
374 if (retval == p->pid) {
377 } else if (retval < 0) {
378 VLOG_WARN("waitpid: %s", ovs_strerror(errno));
389 /* Causes the next call to poll_block() to wake up when process 'p' has
392 process_wait(struct process *p)
396 poll_immediate_wake();
398 poll_fd_wait(fds[0], POLLIN);
406 process_search_path(const char *name)
408 char *save_ptr = NULL;
412 if (strchr(name, '/') || !getenv("PATH")) {
413 return stat(name, &s) == 0 ? xstrdup(name) : NULL;
416 path = xstrdup(getenv("PATH"));
417 for (dir = strtok_r(path, ":", &save_ptr); dir;
418 dir = strtok_r(NULL, ":", &save_ptr)) {
419 char *file = xasprintf("%s/%s", dir, name);
420 if (stat(file, &s) == 0) {
431 sigchld_handler(int signr OVS_UNUSED)
433 ignore(write(fds[1], "", 1));