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git.proxmox.com Git - ovs.git/blob - lib/process.c
2 * Copyright (c) 2008, 2009 Nicira Networks.
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.
29 #include "dynamic-string.h"
31 #include "poll-loop.h"
32 #include "socket-util.h"
35 #define THIS_MODULE VLM_process
43 /* Modified by signal handler. */
48 /* Pipe used to signal child termination. */
52 static struct list all_processes
= LIST_INITIALIZER(&all_processes
);
54 static void block_sigchld(sigset_t
*);
55 static void unblock_sigchld(const sigset_t
*);
56 static void sigchld_handler(int signr UNUSED
);
57 static bool is_member(int x
, const int *array
, size_t);
59 /* Initializes the process subsystem (if it is not already initialized). Calls
60 * exit() if initialization fails.
62 * Calling this function is optional; it will be called automatically by
63 * process_start() if necessary. Calling it explicitly allows the client to
64 * prevent the process from exiting at an unexpected time. */
76 /* Create notification pipe. */
78 ovs_fatal(errno
, "could not create pipe");
80 set_nonblocking(fds
[0]);
81 set_nonblocking(fds
[1]);
83 /* Set up child termination signal handler. */
84 memset(&sa
, 0, sizeof sa
);
85 sa
.sa_handler
= sigchld_handler
;
86 sigemptyset(&sa
.sa_mask
);
87 sa
.sa_flags
= SA_NOCLDSTOP
| SA_RESTART
;
88 if (sigaction(SIGCHLD
, &sa
, NULL
)) {
89 ovs_fatal(errno
, "sigaction(SIGCHLD) failed");
94 process_escape_args(char **argv
)
96 struct ds ds
= DS_EMPTY_INITIALIZER
;
98 for (argp
= argv
; *argp
; argp
++) {
99 const char *arg
= *argp
;
102 ds_put_char(&ds
, ' ');
104 if (arg
[strcspn(arg
, " \t\r\n\v\\")]) {
105 ds_put_char(&ds
, '"');
106 for (p
= arg
; *p
; p
++) {
107 if (*p
== '\\' || *p
== '\"') {
108 ds_put_char(&ds
, '\\');
110 ds_put_char(&ds
, *p
);
112 ds_put_char(&ds
, '"');
114 ds_put_cstr(&ds
, arg
);
120 /* Starts a subprocess with the arguments in the null-terminated argv[] array.
121 * argv[0] is used as the name of the process. Searches the PATH environment
122 * variable to find the program to execute.
124 * All file descriptors are closed before executing the subprocess, except for
125 * fds 0, 1, and 2 and the 'n_keep_fds' fds listed in 'keep_fds'. Also, any of
126 * the 'n_null_fds' fds listed in 'null_fds' are replaced by /dev/null.
128 * Returns 0 if successful, otherwise a positive errno value indicating the
129 * error. If successful, '*pp' is assigned a new struct process that may be
130 * used to query the process's status. On failure, '*pp' is set to NULL. */
132 process_start(char **argv
,
133 const int keep_fds
[], size_t n_keep_fds
,
134 const int null_fds
[], size_t n_null_fds
,
143 COVERAGE_INC(process_start
);
145 if (VLOG_IS_DBG_ENABLED()) {
146 char *args
= process_escape_args(argv
);
147 VLOG_DBG("starting subprocess: %s", args
);
151 /* execvp() will search PATH too, but the error in that case is more
152 * obscure, since it is only reported post-fork. */
153 binary
= process_search_path(argv
[0]);
155 VLOG_ERR("%s not found in PATH", argv
[0]);
160 block_sigchld(&oldsigs
);
163 unblock_sigchld(&oldsigs
);
164 VLOG_WARN("fork failed: %s", strerror(errno
));
167 /* Running in parent process. */
171 p
= xcalloc(1, sizeof *p
);
173 slash
= strrchr(argv
[0], '/');
174 p
->name
= xstrdup(slash
? slash
+ 1 : argv
[0]);
177 list_push_back(&all_processes
, &p
->node
);
178 unblock_sigchld(&oldsigs
);
183 /* Running in child process. */
184 int fd_max
= get_max_fds();
187 unblock_sigchld(&oldsigs
);
188 for (fd
= 0; fd
< fd_max
; fd
++) {
189 if (is_member(fd
, null_fds
, n_null_fds
)) {
190 int nullfd
= open("/dev/null", O_RDWR
);
193 } else if (fd
>= 3 && !is_member(fd
, keep_fds
, n_keep_fds
)) {
197 execvp(argv
[0], argv
);
198 fprintf(stderr
, "execvp(\"%s\") failed: %s\n",
199 argv
[0], strerror(errno
));
204 /* Destroys process 'p'. */
206 process_destroy(struct process
*p
)
211 block_sigchld(&oldsigs
);
212 list_remove(&p
->node
);
213 unblock_sigchld(&oldsigs
);
220 /* Sends signal 'signr' to process 'p'. Returns 0 if successful, otherwise a
221 * positive errno value. */
223 process_kill(const struct process
*p
, int signr
)
225 return (p
->exited
? ESRCH
226 : !kill(p
->pid
, signr
) ? 0
230 /* Returns the pid of process 'p'. */
232 process_pid(const struct process
*p
)
237 /* Returns the name of process 'p' (the name passed to process_start() with any
238 * leading directories stripped). */
240 process_name(const struct process
*p
)
245 /* Returns true if process 'p' has exited, false otherwise. */
247 process_exited(struct process
*p
)
252 char buf
[_POSIX_PIPE_BUF
];
253 read(fds
[0], buf
, sizeof buf
);
258 /* Returns process 'p''s exit status, as reported by waitpid(2).
259 * process_status(p) may be called only after process_exited(p) has returned
262 process_status(const struct process
*p
)
269 process_run(char **argv
,
270 const int keep_fds
[], size_t n_keep_fds
,
271 const int null_fds
[], size_t n_null_fds
,
277 COVERAGE_INC(process_run
);
278 retval
= process_start(argv
, keep_fds
, n_keep_fds
, null_fds
, n_null_fds
,
285 while (!process_exited(p
)) {
289 *status
= process_status(p
);
294 /* Given 'status', which is a process status in the form reported by waitpid(2)
295 * and returned by process_status(), returns a string describing how the
296 * process terminated. The caller is responsible for freeing the string when
297 * it is no longer needed. */
299 process_status_msg(int status
)
301 struct ds ds
= DS_EMPTY_INITIALIZER
;
302 if (WIFEXITED(status
)) {
303 ds_put_format(&ds
, "exit status %d", WEXITSTATUS(status
));
304 } else if (WIFSIGNALED(status
) || WIFSTOPPED(status
)) {
305 int signr
= WIFSIGNALED(status
) ? WTERMSIG(status
) : WSTOPSIG(status
);
306 const char *name
= NULL
;
307 #ifdef HAVE_STRSIGNAL
308 name
= strsignal(signr
);
310 ds_put_format(&ds
, "%s by signal %d",
311 WIFSIGNALED(status
) ? "killed" : "stopped", signr
);
313 ds_put_format(&ds
, " (%s)", name
);
316 ds_put_format(&ds
, "terminated abnormally (%x)", status
);
318 if (WCOREDUMP(status
)) {
319 ds_put_cstr(&ds
, ", core dumped");
324 /* Causes the next call to poll_block() to wake up when process 'p' has
327 process_wait(struct process
*p
)
330 poll_immediate_wake();
332 poll_fd_wait(fds
[0], POLLIN
);
337 process_search_path(const char *name
)
339 char *save_ptr
= NULL
;
343 if (strchr(name
, '/') || !getenv("PATH")) {
344 return stat(name
, &s
) == 0 ? xstrdup(name
) : NULL
;
347 path
= xstrdup(getenv("PATH"));
348 for (dir
= strtok_r(path
, ":", &save_ptr
); dir
;
349 dir
= strtok_r(NULL
, ":", &save_ptr
)) {
350 char *file
= xasprintf("%s/%s", dir
, name
);
351 if (stat(file
, &s
) == 0) {
362 sigchld_handler(int signr UNUSED
)
366 COVERAGE_INC(process_sigchld
);
367 LIST_FOR_EACH (p
, struct process
, node
, &all_processes
) {
371 retval
= waitpid(p
->pid
, &status
, WNOHANG
);
372 } while (retval
== -1 && errno
== EINTR
);
373 if (retval
== p
->pid
) {
376 } else if (retval
< 0) {
377 /* XXX We want to log something but we're in a signal
384 write(fds
[1], "", 1);
388 is_member(int x
, const int *array
, size_t n
)
392 for (i
= 0; i
< n
; i
++) {
401 block_sigchld(sigset_t
*oldsigs
)
404 sigemptyset(&sigchld
);
405 sigaddset(&sigchld
, SIGCHLD
);
406 if (sigprocmask(SIG_BLOCK
, &sigchld
, oldsigs
)) {
407 ovs_fatal(errno
, "sigprocmask");
412 unblock_sigchld(const sigset_t
*oldsigs
)
414 if (sigprocmask(SIG_SETMASK
, oldsigs
, NULL
)) {
415 ovs_fatal(errno
, "sigprocmask");