1 /*****************************************************************************
2 *
3 * Monitoring run command utilities
4 *
5 * License: GPL
6 * Copyright (c) 2005-2006 Monitoring Plugins Development Team
7 *
8 * Description :
9 *
10 * A simple interface to executing programs from other programs, using an
11 * optimized and safe popen()-like implementation. It is considered safe
12 * in that no shell needs to be spawned and the environment passed to the
13 * execve()'d program is essentially empty.
14 *
15 * The code in this file is a derivative of popen.c which in turn was taken
16 * from "Advanced Programming for the Unix Environment" by W. Richard Stevens.
17 *
18 * Care has been taken to make sure the functions are async-safe. The one
19 * function which isn't is cmd_init() which it doesn't make sense to
20 * call twice anyway, so the api as a whole should be considered async-safe.
21 *
22 *
23 * This program is free software: you can redistribute it and/or modify
24 * it under the terms of the GNU General Public License as published by
25 * the Free Software Foundation, either version 3 of the License, or
26 * (at your option) any later version.
27 *
28 * This program is distributed in the hope that it will be useful,
29 * but WITHOUT ANY WARRANTY; without even the implied warranty of
30 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
31 * GNU General Public License for more details.
32 *
33 * You should have received a copy of the GNU General Public License
34 * along with this program. If not, see <http://www.gnu.org/licenses/>.
35 *
36 *
37 *****************************************************************************/
38
39 #define NAGIOSPLUG_API_C 1
40
41 /** includes **/
42 #include "common.h"
43 #include "utils.h"
44 #include "utils_cmd.h"
45 #include "utils_base.h"
46 #include <fcntl.h>
47
48 #ifdef HAVE_SYS_WAIT_H
49 # include <sys/wait.h>
50 #endif
51
52 /* used in _cmd_open to pass the environment to commands */
53 extern char **environ;
54
55 /** macros **/
56 #ifndef WEXITSTATUS
57 # define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
58 #endif
59
60 #ifndef WIFEXITED
61 # define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
62 #endif
63
64 /* 4.3BSD Reno <signal.h> doesn't define SIG_ERR */
65 #if defined(SIG_IGN) && !defined(SIG_ERR)
66 # define SIG_ERR ((Sigfunc *)-1)
67 #endif
68
69 /** prototypes **/
70 static int _cmd_open (char *const *, int *, int *)
71 __attribute__ ((__nonnull__ (1, 2, 3)));
72
73 static int _cmd_fetch_output (int, output *, int)
74 __attribute__ ((__nonnull__ (2)));
75
76 static int _cmd_close (int);
77
78 /* prototype imported from utils.h */
79 extern void die (int, const char *, ...)
80 __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3)));
81
82
83 /* this function is NOT async-safe. It is exported so multithreaded
84 * plugins (or other apps) can call it prior to running any commands
85 * through this api and thus achieve async-safeness throughout the api */
86 void
cmd_init(void)87 cmd_init (void)
88 {
89 #ifndef maxfd
90 if (!maxfd && (maxfd = sysconf (_SC_OPEN_MAX)) < 0) {
91 /* possibly log or emit a warning here, since there's no
92 * guarantee that our guess at maxfd will be adequate */
93 maxfd = DEFAULT_MAXFD;
94 }
95 #endif
96
97 /* if maxfd is unnaturally high, we force it to a lower value
98 * ( e.g. on SunOS, when ulimit is set to unlimited: 2147483647 this would cause
99 * a segfault when following calloc is called ... ) */
100
101 if ( maxfd > MAXFD_LIMIT ) {
102 maxfd = MAXFD_LIMIT;
103 }
104
105 if (!_cmd_pids)
106 _cmd_pids = calloc (maxfd, sizeof (pid_t));
107 }
108
109
110 /* Start running a command, array style */
111 static int
_cmd_open(char * const * argv,int * pfd,int * pfderr)112 _cmd_open (char *const *argv, int *pfd, int *pfderr)
113 {
114 pid_t pid;
115 #ifdef RLIMIT_CORE
116 struct rlimit limit;
117 #endif
118
119 int i = 0;
120
121 /* if no command was passed, return with no error */
122 if (argv == NULL)
123 return -1;
124
125 if (!_cmd_pids)
126 CMD_INIT;
127
128 setenv("LC_ALL", "C", 1);
129
130 if (pipe (pfd) < 0 || pipe (pfderr) < 0 || (pid = fork ()) < 0)
131 return -1; /* errno set by the failing function */
132
133 /* child runs exceve() and _exit. */
134 if (pid == 0) {
135 #ifdef RLIMIT_CORE
136 /* the program we execve shouldn't leave core files */
137 getrlimit (RLIMIT_CORE, &limit);
138 limit.rlim_cur = 0;
139 setrlimit (RLIMIT_CORE, &limit);
140 #endif
141 close (pfd[0]);
142 if (pfd[1] != STDOUT_FILENO) {
143 dup2 (pfd[1], STDOUT_FILENO);
144 close (pfd[1]);
145 }
146 close (pfderr[0]);
147 if (pfderr[1] != STDERR_FILENO) {
148 dup2 (pfderr[1], STDERR_FILENO);
149 close (pfderr[1]);
150 }
151
152 /* close all descriptors in _cmd_pids[]
153 * This is executed in a separate address space (pure child),
154 * so we don't have to worry about async safety */
155 for (i = 0; i < maxfd; i++)
156 if (_cmd_pids[i] > 0)
157 close (i);
158
159 execve (argv[0], argv, environ);
160 _exit (STATE_UNKNOWN);
161 }
162
163 /* parent picks up execution here */
164 /* close childs descriptors in our address space */
165 close (pfd[1]);
166 close (pfderr[1]);
167
168 /* tag our file's entry in the pid-list and return it */
169 _cmd_pids[pfd[0]] = pid;
170
171 return pfd[0];
172 }
173
174 static int
_cmd_close(int fd)175 _cmd_close (int fd)
176 {
177 int status;
178 pid_t pid;
179
180 /* make sure the provided fd was opened */
181 if (fd < 0 || fd > maxfd || !_cmd_pids || (pid = _cmd_pids[fd]) == 0)
182 return -1;
183
184 _cmd_pids[fd] = 0;
185 if (close (fd) == -1)
186 return -1;
187
188 /* EINTR is ok (sort of), everything else is bad */
189 while (waitpid (pid, &status, 0) < 0)
190 if (errno != EINTR)
191 return -1;
192
193 /* return child's termination status */
194 return (WIFEXITED (status)) ? WEXITSTATUS (status) : -1;
195 }
196
197
198 static int
_cmd_fetch_output(int fd,output * op,int flags)199 _cmd_fetch_output (int fd, output * op, int flags)
200 {
201 size_t len = 0, i = 0, lineno = 0;
202 size_t rsf = 6, ary_size = 0; /* rsf = right shift factor, dec'ed uncond once */
203 char *buf = NULL;
204 int ret;
205 char tmpbuf[4096];
206
207 op->buf = NULL;
208 op->buflen = 0;
209 while ((ret = read (fd, tmpbuf, sizeof (tmpbuf))) > 0) {
210 len = (size_t) ret;
211 op->buf = realloc (op->buf, op->buflen + len + 1);
212 memcpy (op->buf + op->buflen, tmpbuf, len);
213 op->buflen += len;
214 i++;
215 }
216
217 if (ret < 0) {
218 printf ("read() returned %d: %s\n", ret, strerror (errno));
219 return ret;
220 }
221
222 /* some plugins may want to keep output unbroken, and some commands
223 * will yield no output, so return here for those */
224 if (flags & CMD_NO_ARRAYS || !op->buf || !op->buflen)
225 return op->buflen;
226
227 /* and some may want both */
228 if (flags & CMD_NO_ASSOC) {
229 buf = malloc (op->buflen);
230 memcpy (buf, op->buf, op->buflen);
231 }
232 else
233 buf = op->buf;
234
235 op->line = NULL;
236 op->lens = NULL;
237 i = 0;
238 while (i < op->buflen) {
239 /* make sure we have enough memory */
240 if (lineno >= ary_size) {
241 /* ary_size must never be zero */
242 do {
243 ary_size = op->buflen >> --rsf;
244 } while (!ary_size);
245
246 op->line = realloc (op->line, ary_size * sizeof (char *));
247 op->lens = realloc (op->lens, ary_size * sizeof (size_t));
248 }
249
250 /* set the pointer to the string */
251 op->line[lineno] = &buf[i];
252
253 /* hop to next newline or end of buffer */
254 while (buf[i] != '\n' && i < op->buflen)
255 i++;
256 buf[i] = '\0';
257
258 /* calculate the string length using pointer difference */
259 op->lens[lineno] = (size_t) & buf[i] - (size_t) op->line[lineno];
260
261 lineno++;
262 i++;
263 }
264
265 return lineno;
266 }
267
268
269 int
cmd_run(const char * cmdstring,output * out,output * err,int flags)270 cmd_run (const char *cmdstring, output * out, output * err, int flags)
271 {
272 int fd, pfd_out[2], pfd_err[2];
273 int i = 0, argc;
274 size_t cmdlen;
275 char **argv = NULL;
276 char *cmd = NULL;
277 char *str = NULL;
278
279 if (cmdstring == NULL)
280 return -1;
281
282 /* initialize the structs */
283 if (out)
284 memset (out, 0, sizeof (output));
285 if (err)
286 memset (err, 0, sizeof (output));
287
288 /* make copy of command string so strtok() doesn't silently modify it */
289 /* (the calling program may want to access it later) */
290 cmdlen = strlen (cmdstring);
291 if ((cmd = malloc (cmdlen + 1)) == NULL)
292 return -1;
293 memcpy (cmd, cmdstring, cmdlen);
294 cmd[cmdlen] = '\0';
295
296 /* This is not a shell, so we don't handle "???" */
297 if (strstr (cmdstring, "\"")) return -1;
298
299 /* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
300 if (strstr (cmdstring, " ' ") || strstr (cmdstring, "'''"))
301 return -1;
302
303 /* each arg must be whitespace-separated, so args can be a maximum
304 * of (len / 2) + 1. We add 1 extra to the mix for NULL termination */
305 argc = (cmdlen >> 1) + 2;
306 argv = calloc (sizeof (char *), argc);
307
308 if (argv == NULL) {
309 printf ("%s\n", _("Could not malloc argv array in popen()"));
310 return -1;
311 }
312
313 /* get command arguments (stupidly, but fairly quickly) */
314 while (cmd) {
315 str = cmd;
316 str += strspn (str, " \t\r\n"); /* trim any leading whitespace */
317
318 if (strstr (str, "'") == str) { /* handle SIMPLE quoted strings */
319 str++;
320 if (!strstr (str, "'"))
321 return -1; /* balanced? */
322 cmd = 1 + strstr (str, "'");
323 str[strcspn (str, "'")] = 0;
324 }
325 else {
326 if (strpbrk (str, " \t\r\n")) {
327 cmd = 1 + strpbrk (str, " \t\r\n");
328 str[strcspn (str, " \t\r\n")] = 0;
329 }
330 else {
331 cmd = NULL;
332 }
333 }
334
335 if (cmd && strlen (cmd) == strspn (cmd, " \t\r\n"))
336 cmd = NULL;
337
338 argv[i++] = str;
339 }
340
341 return cmd_run_array (argv, out, err, flags);
342 }
343
344 int
cmd_run_array(char * const * argv,output * out,output * err,int flags)345 cmd_run_array (char *const *argv, output * out, output * err, int flags)
346 {
347 int fd, pfd_out[2], pfd_err[2];
348
349 /* initialize the structs */
350 if (out)
351 memset (out, 0, sizeof (output));
352 if (err)
353 memset (err, 0, sizeof (output));
354
355 if ((fd = _cmd_open (argv, pfd_out, pfd_err)) == -1)
356 die (STATE_UNKNOWN, _("Could not open pipe: %s\n"), argv[0]);
357
358 if (out)
359 out->lines = _cmd_fetch_output (pfd_out[0], out, flags);
360 if (err)
361 err->lines = _cmd_fetch_output (pfd_err[0], err, flags);
362
363 return _cmd_close (fd);
364 }
365
366 int
cmd_file_read(char * filename,output * out,int flags)367 cmd_file_read ( char *filename, output *out, int flags)
368 {
369 int fd;
370 if(out)
371 memset (out, 0, sizeof(output));
372
373 if ((fd = open(filename, O_RDONLY)) == -1) {
374 die( STATE_UNKNOWN, _("Error opening %s: %s"), filename, strerror(errno) );
375 }
376
377 if(out)
378 out->lines = _cmd_fetch_output (fd, out, flags);
379
380 if (close(fd) == -1)
381 die( STATE_UNKNOWN, _("Error closing %s: %s"), filename, strerror(errno) );
382
383 return 0;
384 }
385
386 void
timeout_alarm_handler(int signo)387 timeout_alarm_handler (int signo)
388 {
389 size_t i;
390 if (signo == SIGALRM) {
391 printf (_("%s - Plugin timed out after %d seconds\n"),
392 state_text(timeout_state), timeout_interval);
393
394 if(_cmd_pids) for(i = 0; i < maxfd; i++) {
395 if(_cmd_pids[i] != 0) kill(_cmd_pids[i], SIGKILL);
396 }
397
398 exit (timeout_state);
399 }
400 }
401