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.
28 #include "dynamic-string.h"
29 #include "fatal-signal.h"
31 #include "poll-loop.h"
33 #include "socket-util.h"
37 VLOG_DEFINE_THIS_MODULE(process);
39 COVERAGE_DEFINE(process_sigchld);
40 COVERAGE_DEFINE(process_start);
52 /* Pipe used to signal child termination. */
56 static struct list all_processes = LIST_INITIALIZER(&all_processes);
58 static void sigchld_handler(int signr OVS_UNUSED);
60 /* Initializes the process subsystem (if it is not already initialized). Calls
61 * exit() if initialization fails.
63 * This function may not be called after creating any additional threads.
65 * Calling this function is optional; it will be called automatically by
66 * process_start() if necessary. Calling it explicitly allows the client to
67 * prevent the process from exiting at an unexpected time. */
79 /* Create notification pipe. */
80 xpipe_nonblocking(fds);
82 /* Set up child termination signal handler. */
83 memset(&sa, 0, sizeof sa);
84 sa.sa_handler = sigchld_handler;
85 sigemptyset(&sa.sa_mask);
86 sa.sa_flags = SA_NOCLDSTOP | SA_RESTART;
87 xsigaction(SIGCHLD, &sa, NULL);
91 process_escape_args(char **argv)
93 struct ds ds = DS_EMPTY_INITIALIZER;
95 for (argp = argv; *argp; argp++) {
96 const char *arg = *argp;
99 ds_put_char(&ds, ' ');
101 if (arg[strcspn(arg, " \t\r\n\v\\\'\"")]) {
102 ds_put_char(&ds, '"');
103 for (p = arg; *p; p++) {
104 if (*p == '\\' || *p == '\"') {
105 ds_put_char(&ds, '\\');
107 ds_put_char(&ds, *p);
109 ds_put_char(&ds, '"');
111 ds_put_cstr(&ds, arg);
117 /* Prepare to start a process whose command-line arguments are given by the
118 * null-terminated 'argv' array. Returns 0 if successful, otherwise a
119 * positive errno value. */
121 process_prestart(char **argv)
127 /* Log the process to be started. */
128 if (VLOG_IS_DBG_ENABLED()) {
129 char *args = process_escape_args(argv);
130 VLOG_DBG("starting subprocess: %s", args);
134 /* execvp() will search PATH too, but the error in that case is more
135 * obscure, since it is only reported post-fork. */
136 binary = process_search_path(argv[0]);
138 VLOG_ERR("%s not found in PATH", argv[0]);
146 /* Creates and returns a new struct process with the specified 'name' and
148 static struct process *
149 process_register(const char *name, pid_t pid)
154 p = xzalloc(sizeof *p);
156 slash = strrchr(name, '/');
157 p->name = xstrdup(slash ? slash + 1 : name);
160 list_push_back(&all_processes, &p->node);
165 /* Starts a subprocess with the arguments in the null-terminated argv[] array.
166 * argv[0] is used as the name of the process. Searches the PATH environment
167 * variable to find the program to execute.
169 * This function may not be called after creating any additional threads.
171 * All file descriptors are closed before executing the subprocess, except for
174 * Returns 0 if successful, otherwise a positive errno value indicating the
175 * error. If successful, '*pp' is assigned a new struct process that may be
176 * used to query the process's status. On failure, '*pp' is set to NULL. */
178 process_start(char **argv, struct process **pp)
184 COVERAGE_INC(process_start);
185 error = process_prestart(argv);
192 VLOG_WARN("fork failed: %s", strerror(errno));
195 /* Running in parent process. */
196 *pp = process_register(argv[0], pid);
199 /* Running in child process. */
200 int fd_max = get_max_fds();
204 for (fd = 3; fd < fd_max; fd++) {
207 execvp(argv[0], argv);
208 fprintf(stderr, "execvp(\"%s\") failed: %s\n",
209 argv[0], strerror(errno));
214 /* Destroys process 'p'. */
216 process_destroy(struct process *p)
219 list_remove(&p->node);
225 /* Sends signal 'signr' to process 'p'. Returns 0 if successful, otherwise a
226 * positive errno value. */
228 process_kill(const struct process *p, int signr)
230 return (p->exited ? ESRCH
231 : !kill(p->pid, signr) ? 0
235 /* Returns the pid of process 'p'. */
237 process_pid(const struct process *p)
242 /* Returns the name of process 'p' (the name passed to process_start() with any
243 * leading directories stripped). */
245 process_name(const struct process *p)
250 /* Returns true if process 'p' has exited, false otherwise. */
252 process_exited(struct process *p)
257 /* Returns process 'p''s exit status, as reported by waitpid(2).
258 * process_status(p) may be called only after process_exited(p) has returned
261 process_status(const struct process *p)
263 ovs_assert(p->exited);
267 /* Given 'status', which is a process status in the form reported by waitpid(2)
268 * and returned by process_status(), returns a string describing how the
269 * process terminated. The caller is responsible for freeing the string when
270 * it is no longer needed. */
272 process_status_msg(int status)
274 struct ds ds = DS_EMPTY_INITIALIZER;
275 if (WIFEXITED(status)) {
276 ds_put_format(&ds, "exit status %d", WEXITSTATUS(status));
277 } else if (WIFSIGNALED(status)) {
278 char namebuf[SIGNAL_NAME_BUFSIZE];
280 ds_put_format(&ds, "killed (%s)",
281 signal_name(WTERMSIG(status), namebuf, sizeof namebuf));
282 } else if (WIFSTOPPED(status)) {
283 char namebuf[SIGNAL_NAME_BUFSIZE];
285 ds_put_format(&ds, "stopped (%s)",
286 signal_name(WSTOPSIG(status), namebuf, sizeof namebuf));
288 ds_put_format(&ds, "terminated abnormally (%x)", status);
290 if (WCOREDUMP(status)) {
291 ds_put_cstr(&ds, ", core dumped");
296 /* Executes periodic maintenance activities required by the process module. */
300 char buf[_POSIX_PIPE_BUF];
302 if (!list_is_empty(&all_processes) && read(fds[0], buf, sizeof buf) > 0) {
305 LIST_FOR_EACH (p, node, &all_processes) {
309 retval = waitpid(p->pid, &status, WNOHANG);
310 } while (retval == -1 && errno == EINTR);
311 if (retval == p->pid) {
314 } else if (retval < 0) {
315 VLOG_WARN("waitpid: %s", strerror(errno));
325 /* Causes the next call to poll_block() to wake up when process 'p' has
328 process_wait(struct process *p)
331 poll_immediate_wake();
333 poll_fd_wait(fds[0], POLLIN);
338 process_search_path(const char *name)
340 char *save_ptr = NULL;
344 if (strchr(name, '/') || !getenv("PATH")) {
345 return stat(name, &s) == 0 ? xstrdup(name) : NULL;
348 path = xstrdup(getenv("PATH"));
349 for (dir = strtok_r(path, ":", &save_ptr); dir;
350 dir = strtok_r(NULL, ":", &save_ptr)) {
351 char *file = xasprintf("%s/%s", dir, name);
352 if (stat(file, &s) == 0) {
363 sigchld_handler(int signr OVS_UNUSED)
365 ignore(write(fds[1], "", 1));