1 /****************************************************************************
2 *
3 * Nagios plugins popen
4 *
5 * License: GPL
6 * Copyright (c) 2005 nagios-plugins team
7 *
8 * Last Modified: $Date$
9 *
10 * Description:
11 *
12 * A safe alternative to popen
13 *
14 * Provides spopen and spclose
15 *
16 * FILE * spopen(const char *);
17 * int spclose(FILE *);
18 *
19 *
20 * Code taken with liitle modification from "Advanced Programming for the Unix
21 * Environment" by W. Richard Stevens
22 *
23 * This is considered safe in that no shell is spawned, and the environment and
24 * path passed to the exec'd program are esstially empty. (popen create a shell
25 * and passes the environment to it).
26 *
27 * License Information:
28 *
29 * This program is free software; you can redistribute it and/or modify
30 * it under the terms of the GNU General Public License as published by
31 * the Free Software Foundation; either version 2 of the License, or
32 * (at your option) any later version.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * You should have received a copy of the GNU General Public License
40 * along with this program; if not, write to the Free Software
41 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
42 *
43 * $Id$
44 *
45 ******************************************************************************/
47 #include "common.h"
49 /* extern so plugin has pid to kill exec'd process on timeouts */
50 extern int timeout_interval;
51 extern pid_t *childpid;
52 extern int *child_stderr_array;
53 extern FILE *child_process;
55 FILE *spopen (const char *);
56 int spclose (FILE *);
57 #ifdef REDHAT_SPOPEN_ERROR
58 RETSIGTYPE popen_sigchld_handler (int);
59 #endif
60 RETSIGTYPE popen_timeout_alarm_handler (int);
62 #include <stdarg.h> /* ANSI C header file */
63 #include <fcntl.h>
65 #include <limits.h>
66 #include <sys/resource.h>
68 #ifdef HAVE_SYS_WAIT_H
69 #include <sys/wait.h>
70 #endif
72 #ifndef WEXITSTATUS
73 # define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
74 #endif
76 #ifndef WIFEXITED
77 # define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
78 #endif
80 /* 4.3BSD Reno <signal.h> doesn't define SIG_ERR */
81 #if defined(SIG_IGN) && !defined(SIG_ERR)
82 #define SIG_ERR ((Sigfunc *)-1)
83 #endif
85 #define min(a,b) ((a) < (b) ? (a) : (b))
86 #define max(a,b) ((a) > (b) ? (a) : (b))
87 int open_max (void); /* {Prog openmax} */
88 static void err_sys (const char *, ...) __attribute__((noreturn,format(printf, 1, 2)));
89 char *rtrim (char *, const char *);
91 char *pname = NULL; /* caller can set this from argv[0] */
93 /*int *childerr = NULL;*//* ptr to array allocated at run-time */
94 /*extern pid_t *childpid = NULL; *//* ptr to array allocated at run-time */
95 static int maxfd; /* from our open_max(), {Prog openmax} */
97 #ifdef REDHAT_SPOPEN_ERROR
98 static volatile int childtermd = 0;
99 #endif
101 FILE *
102 spopen (const char *cmdstring)
103 {
104 char *env[2];
105 char *cmd = NULL;
106 char **argv = NULL;
107 char *str;
108 int argc;
110 int i = 0, pfd[2], pfderr[2];
111 pid_t pid;
113 #ifdef RLIMIT_CORE
114 /* do not leave core files */
115 struct rlimit limit;
116 getrlimit (RLIMIT_CORE, &limit);
117 limit.rlim_cur = 0;
118 setrlimit (RLIMIT_CORE, &limit);
119 #endif
121 env[0] = strdup("LC_ALL=C");
122 env[1] = '\0';
124 /* if no command was passed, return with no error */
125 if (cmdstring == NULL)
126 return (NULL);
128 /* make copy of command string so strtok() doesn't silently modify it */
129 /* (the calling program may want to access it later) */
130 cmd = malloc (strlen (cmdstring) + 1);
131 if (cmd == NULL)
132 return NULL;
133 strcpy (cmd, cmdstring);
135 /* This is not a shell, so we don't handle "???" */
136 if (strstr (cmdstring, "\""))
137 return NULL;
139 /* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
140 if (strstr (cmdstring, " ' ") || strstr (cmdstring, "'''"))
141 return NULL;
143 /* there cannot be more args than characters */
144 argc = strlen (cmdstring) + 1; /* add 1 for NULL termination */
145 argv = malloc (sizeof(char*)*argc);
147 if (argv == NULL) {
148 printf ("%s\n", _("Could not malloc argv array in popen()"));
149 return NULL;
150 }
152 /* loop to get arguments to command */
153 while (cmd) {
154 str = cmd;
155 str += strspn (str, " \t\r\n"); /* trim any leading whitespace */
157 if (i >= argc - 2) {
158 printf ("%s\n",_("CRITICAL - You need more args!!!"));
159 return (NULL);
160 }
162 if (strstr (str, "'") == str) { /* handle SIMPLE quoted strings */
163 str++;
164 if (!strstr (str, "'"))
165 return NULL; /* balanced? */
166 cmd = 1 + strstr (str, "'");
167 str[strcspn (str, "'")] = 0;
168 }
169 else {
170 if (strpbrk (str, " \t\r\n")) {
171 cmd = 1 + strpbrk (str, " \t\r\n");
172 str[strcspn (str, " \t\r\n")] = 0;
173 }
174 else {
175 cmd = NULL;
176 }
177 }
179 if (cmd && strlen (cmd) == strspn (cmd, " \t\r\n"))
180 cmd = NULL;
182 argv[i++] = str;
184 }
185 argv[i] = NULL;
187 if (childpid == NULL) { /* first time through */
188 maxfd = open_max (); /* allocate zeroed out array for child pids */
189 if ((childpid = calloc ((size_t)maxfd, sizeof (pid_t))) == NULL)
190 return (NULL);
191 }
193 if (child_stderr_array == NULL) { /* first time through */
194 maxfd = open_max (); /* allocate zeroed out array for child pids */
195 if ((child_stderr_array = calloc ((size_t)maxfd, sizeof (int))) == NULL)
196 return (NULL);
197 }
199 if (pipe (pfd) < 0)
200 return (NULL); /* errno set by pipe() */
202 if (pipe (pfderr) < 0)
203 return (NULL); /* errno set by pipe() */
205 #ifdef REDHAT_SPOPEN_ERROR
206 if (signal (SIGCHLD, popen_sigchld_handler) == SIG_ERR) {
207 usage4 (_("Cannot catch SIGCHLD"));
208 }
209 #endif
211 if ((pid = fork ()) < 0)
212 return (NULL); /* errno set by fork() */
213 else if (pid == 0) { /* child */
214 close (pfd[0]);
215 if (pfd[1] != STDOUT_FILENO) {
216 dup2 (pfd[1], STDOUT_FILENO);
217 close (pfd[1]);
218 }
219 close (pfderr[0]);
220 if (pfderr[1] != STDERR_FILENO) {
221 dup2 (pfderr[1], STDERR_FILENO);
222 close (pfderr[1]);
223 }
224 /* close all descriptors in childpid[] */
225 for (i = 0; i < maxfd; i++)
226 if (childpid[i] > 0)
227 close (i);
229 execve (argv[0], argv, env);
230 _exit (0);
231 }
233 close (pfd[1]); /* parent */
234 if ((child_process = fdopen (pfd[0], "r")) == NULL)
235 return (NULL);
236 close (pfderr[1]);
238 childpid[fileno (child_process)] = pid; /* remember child pid for this fd */
239 child_stderr_array[fileno (child_process)] = pfderr[0]; /* remember STDERR */
240 return (child_process);
241 }
243 int
244 spclose (FILE * fp)
245 {
246 int fd, status;
247 pid_t pid;
249 if (childpid == NULL)
250 return (1); /* popen() has never been called */
252 fd = fileno (fp);
253 if ((pid = childpid[fd]) == 0)
254 return (1); /* fp wasn't opened by popen() */
256 childpid[fd] = 0;
257 if (fclose (fp) == EOF)
258 return (1);
260 #ifdef REDHAT_SPOPEN_ERROR
261 while (!childtermd); /* wait until SIGCHLD */
262 #endif
264 while (waitpid (pid, &status, 0) < 0)
265 if (errno != EINTR)
266 return (1); /* error other than EINTR from waitpid() */
268 if (WIFEXITED (status))
269 return (WEXITSTATUS (status)); /* return child's termination status */
271 return (1);
272 }
274 #ifdef OPEN_MAX
275 static int openmax = OPEN_MAX;
276 #else
277 static int openmax = 0;
278 #endif
280 #define OPEN_MAX_GUESS 256 /* if OPEN_MAX is indeterminate */
281 /* no guarantee this is adequate */
283 #ifdef REDHAT_SPOPEN_ERROR
284 RETSIGTYPE
285 popen_sigchld_handler (int signo)
286 {
287 if (signo == SIGCHLD)
288 childtermd = 1;
289 }
290 #endif
292 RETSIGTYPE
293 popen_timeout_alarm_handler (int signo)
294 {
295 int fh;
296 if (signo == SIGALRM) {
297 if (child_process != NULL) {
298 fh=fileno (child_process);
299 if(fh >= 0){
300 kill (childpid[fh], SIGKILL);
301 }
302 printf (_("CRITICAL - Plugin timed out after %d seconds\n"),
303 timeout_interval);
304 } else {
305 printf ("%s\n", _("CRITICAL - popen timeout received, but no child process"));
306 }
307 exit (STATE_CRITICAL);
308 }
309 }
312 int
313 open_max (void)
314 {
315 if (openmax == 0) { /* first time through */
316 errno = 0;
317 if ((openmax = sysconf (_SC_OPEN_MAX)) < 0) {
318 if (errno == 0)
319 openmax = OPEN_MAX_GUESS; /* it's indeterminate */
320 else
321 err_sys (_("sysconf error for _SC_OPEN_MAX"));
322 }
323 }
324 return (openmax);
325 }
328 /* Fatal error related to a system call.
329 * Print a message and die. */
331 #define MAXLINE 2048
332 static void
333 err_sys (const char *fmt, ...)
334 {
335 int errnoflag = 1;
336 int errno_save;
337 char buf[MAXLINE];
339 va_list ap;
341 va_start (ap, fmt);
342 /* err_doit (1, fmt, ap); */
343 errno_save = errno; /* value caller might want printed */
344 vsprintf (buf, fmt, ap);
345 if (errnoflag)
346 sprintf (buf + strlen (buf), ": %s", strerror (errno_save));
347 strcat (buf, "\n");
348 fflush (stdout); /* in case stdout and stderr are the same */
349 fputs (buf, stderr);
350 fflush (NULL); /* flushes all stdio output streams */
351 va_end (ap);
352 exit (1);
353 }
355 char *
356 rtrim (char *str, const char *tok)
357 {
358 int i = 0;
359 int j = sizeof (str);
361 while (str != NULL && i < j) {
362 if (*(str + i) == *tok) {
363 sprintf (str + i, "%s", "\0");
364 return str;
365 }
366 i++;
367 }
368 return str;
369 }