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authorM. Sean Finney <seanius@users.sourceforge.net>2005-06-29 04:11:29 (GMT)
committerM. Sean Finney <seanius@users.sourceforge.net>2005-06-29 04:11:29 (GMT)
commit290c9b1077eeb1a3acc2b2e1ffacca3571acf30d (patch)
tree814629ebb1980142c7d468cf5563cc86ac9f0630
parent49b7afb02704b8d37b0e863efb2651c5ca1cb70f (diff)
downloadmonitoring-plugins-290c9b1077eeb1a3acc2b2e1ffacca3571acf30d.tar.gz
initial versions of the runcmd framework by andreas
git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1197 f882894a-f735-0410-b71e-b25c423dba1c
-rw-r--r--plugins/runcmd.c339
-rw-r--r--plugins/runcmd.h39
2 files changed, 378 insertions, 0 deletions
diff --git a/plugins/runcmd.c b/plugins/runcmd.c
new file mode 100644
index 0000000..14300ee
--- /dev/null
+++ b/plugins/runcmd.c
@@ -0,0 +1,339 @@
1/*
2 * $Id$
3 *
4 * A simple interface to executing programs from other programs, using an
5 * optimized and safe popen()-like implementation. It is considered safe
6 * in that no shell needs to be spawned and the environment passed to the
7 * execve()'d program is essentially empty.
8 *
9 *
10 * The code in this file is a derivative of popen.c which in turn was taken
11 * from "Advanced Programming for the Unix Environment" by W. Richard Stevens.
12 *
13 * Care has been taken to make sure the functions are async-safe. The one
14 * function which isn't is np_runcmd_init() which it doesn't make sense to
15 * call twice anyway, so the api as a whole should be considered async-safe.
16 *
17 */
18
19/** includes **/
20#include "runcmd.h"
21#ifdef HAVE_SYS_WAIT_H
22# include <sys/wait.h>
23#endif
24
25/** macros **/
26#ifndef WEXITSTATUS
27# define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
28#endif
29
30#ifndef WIFEXITED
31# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
32#endif
33
34/* 4.3BSD Reno <signal.h> doesn't define SIG_ERR */
35#if defined(SIG_IGN) && !defined(SIG_ERR)
36# define SIG_ERR ((Sigfunc *)-1)
37#endif
38
39/* This variable must be global, since there's no way the caller
40 * can forcibly slay a dead or ungainly running program otherwise.
41 * Multithreading apps and plugins can initialize it (via NP_RUNCMD_INIT)
42 * in an async safe manner PRIOR to calling np_runcmd() for the first time.
43 *
44 * The check for initialized values is atomic and can
45 * occur in any number of threads simultaneously. */
46static pid_t *np_pids = NULL;
47
48/* If OPEN_MAX isn't defined, we try the sysconf syscall first.
49 * If that fails, we fall back to an educated guess which is accurate
50 * on Linux and some other systems. There's no guarantee that our guess is
51 * adequate and the program will die with SIGSEGV if it isn't and the
52 * upper boundary is breached. */
53#ifdef OPEN_MAX
54# define maxfd OPEN_MAX
55#else
56# ifndef _SC_OPEN_MAX /* sysconf macro unavailable, so guess */
57# define maxfd 256
58# else
59static int maxfd = 0;
60# endif /* _SC_OPEN_MAX */
61#endif /* OPEN_MAX */
62
63
64/** prototypes **/
65static int np_runcmd_open(const char *, int *, int *)
66 __attribute__((__nonnull__(1, 2, 3)));
67
68static int np_fetch_output(int, output *, int)
69 __attribute__((__nonnull__(2)));
70
71static int np_runcmd_close(int);
72
73/* imported from utils.h */
74extern void die (int, const char *, ...)
75 __attribute__((__noreturn__,__format__(__printf__, 2, 3)));
76
77
78/* this function is NOT async-safe. It is exported so multithreaded
79 * plugins (or other apps) can call it prior to running any commands
80 * through this api and thus achieve async-safeness throughout the api */
81void np_runcmd_init(void)
82{
83#if !defined(OPEN_MAX) && defined(_SC_OPEN_MAX)
84 if(!maxfd) {
85 if((maxfd = sysconf(_SC_OPEN_MAX)) < 0) {
86 /* possibly log or emit a warning here, since there's no
87 * guarantee that our guess at maxfd will be adequate */
88 maxfd = 256;
89 }
90 }
91#endif
92
93 if(!np_pids) np_pids = calloc(maxfd, sizeof(pid_t));
94}
95
96
97/* Start running a command */
98static int
99np_runcmd_open(const char *cmdstring, int *pfd, int *pfderr)
100{
101 char *env[2];
102 char *cmd = NULL;
103 char **argv = NULL;
104 char *str;
105 int argc;
106 size_t cmdlen;
107 pid_t pid;
108#ifdef RLIMIT_CORE
109 struct rlimit limit;
110#endif
111
112 int i = 0;
113
114 if(!np_pids) NP_RUNCMD_INIT;
115
116 env[0] = strdup("LC_ALL=C");
117 env[1] = '\0';
118
119 /* if no command was passed, return with no error */
120 if (cmdstring == NULL)
121 return -1;
122
123 /* make copy of command string so strtok() doesn't silently modify it */
124 /* (the calling program may want to access it later) */
125 cmdlen = strlen(cmdstring);
126 cmd = malloc(cmdlen + 1);
127 if (cmd == NULL) return -1;
128 memcpy(cmd, cmdstring, cmdlen);
129
130 /* This is not a shell, so we don't handle "???" */
131 if (strstr (cmdstring, "\"")) return -1;
132
133 /* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
134 if (strstr (cmdstring, " ' ") || strstr (cmdstring, "'''"))
135 return -1;
136
137 /* each arg must be whitespace-separated, so args can be a maximum
138 * of (len / 2) + 1. We add 1 extra to the mix for NULL termination */
139 argc = (cmdlen >> 1) + 2;
140 argv = calloc(sizeof(char *), argc);
141
142 if (argv == NULL) {
143 printf (_("Could not malloc argv array in popen()\n"));
144 return -1;
145 }
146
147 /* get command arguments (stupidly, but fairly quickly) */
148 while (cmd) {
149 str = cmd;
150 str += strspn (str, " \t\r\n"); /* trim any leading whitespace */
151
152 if (strstr (str, "'") == str) { /* handle SIMPLE quoted strings */
153 str++;
154 if (!strstr (str, "'")) return -1; /* balanced? */
155 cmd = 1 + strstr (str, "'");
156 str[strcspn (str, "'")] = 0;
157 }
158 else {
159 if (strpbrk (str, " \t\r\n")) {
160 cmd = 1 + strpbrk (str, " \t\r\n");
161 str[strcspn (str, " \t\r\n")] = 0;
162 }
163 else {
164 cmd = NULL;
165 }
166 }
167
168 if (cmd && strlen (cmd) == strspn (cmd, " \t\r\n"))
169 cmd = NULL;
170
171 argv[i++] = str;
172 }
173
174 if (pipe(pfd) < 0 || pipe(pfderr) < 0 || (pid = fork()) < 0)
175 return -1; /* errno set by the failing function */
176
177 /* child runs exceve() and _exit. */
178 if (pid == 0) {
179#ifdef RLIMIT_CORE
180 /* the program we execve shouldn't leave core files */
181 getrlimit (RLIMIT_CORE, &limit);
182 limit.rlim_cur = 0;
183 setrlimit (RLIMIT_CORE, &limit);
184#endif
185 close (pfd[0]);
186 if (pfd[1] != STDOUT_FILENO) {
187 dup2 (pfd[1], STDOUT_FILENO);
188 close (pfd[1]);
189 }
190 close (pfderr[0]);
191 if (pfderr[1] != STDERR_FILENO) {
192 dup2 (pfderr[1], STDERR_FILENO);
193 close (pfderr[1]);
194 }
195
196 /* close all descriptors in np_pids[]
197 * This is executed in a separate address space (pure child),
198 * so we don't have to worry about async safety */
199 for (i = 0; i < maxfd; i++)
200 if(np_pids[i] > 0)
201 close (i);
202
203 execve (argv[0], argv, env);
204 _exit (0);
205 }
206
207 /* parent picks up execution here */
208 /* close childs descriptors in our address space */
209 close(pfd[1]);
210 close(pfderr[1]);
211
212 /* tag our file's entry in the pid-list and return it */
213 np_pids[pfd[0]] = pid;
214
215 return pfd[0];
216}
217
218
219static int
220np_runcmd_close(int fd)
221{
222 int status;
223 pid_t pid;
224
225 /* make sure this fd was opened by popen() */
226 if(fd < 0 || fd > maxfd || !np_pids || (pid = np_pids[fd]) == 0)
227 return -1;
228
229 np_pids[fd] = 0;
230 if (close (fd) == -1) return -1;
231
232 /* EINTR is ok (sort of), everything else is bad */
233 while (waitpid (pid, &status, 0) < 0)
234 if (errno != EINTR) return -1;
235
236 /* return child's termination status */
237 return (WIFEXITED(status)) ? WEXITSTATUS(status) : -1;
238}
239
240
241void
242popen_timeout_alarm_handler (int signo)
243{
244 size_t i;
245
246 if (signo == SIGALRM)
247 puts(_("CRITICAL - Plugin timed out while executing system call\n"));
248
249 if(np_pids) for(i = 0; i < maxfd; i++) {
250 if(np_pids[i] != 0) kill(np_pids[i], SIGKILL);
251 }
252
253 exit (STATE_CRITICAL);
254}
255
256
257static int
258np_fetch_output(int fd, output *op, int flags)
259{
260 size_t len = 0, i = 0;
261 size_t rsf = 6, ary_size = 0; /* rsf = right shift factor, dec'ed uncond once */
262 char *buf = NULL;
263 int ret;
264 char tmpbuf[4096];
265
266 op->buf = NULL;
267 op->buflen = 0;
268 while((ret = read(fd, tmpbuf, sizeof(tmpbuf))) > 0) {
269 len = (size_t)ret;
270 op->buf = realloc(op->buf, op->buflen + len + 1);
271 memcpy(op->buf + op->buflen, tmpbuf, len);
272 op->buflen += len;
273 i++;
274 }
275
276 if(ret < 0) {
277 printf("read() returned %d: %s\n", ret, strerror(errno));
278 return ret;
279 }
280
281 if(!op->buf || !op->buflen) return 0;
282
283 /* some plugins may want to keep output unbroken */
284 if(flags & RUNCMD_NO_ARRAYS)
285 return op->buflen;
286
287 /* and some may want both (*sigh*) */
288 if(flags & RUNCMD_NO_ASSOC) {
289 buf = malloc(op->buflen);
290 memcpy(buf, op->buf, op->buflen);
291 }
292 else buf = op->buf;
293
294 op->line = NULL;
295 op->lens = NULL;
296 len = i = 0;
297 while(i < op->buflen) {
298 /* make sure we have enough memory */
299 if(len >= ary_size) {
300 ary_size = op->buflen >> --rsf;
301 op->line = realloc(op->line, ary_size * sizeof(char *));
302 op->lens = realloc(op->lens, ary_size * sizeof(size_t));
303 }
304
305 /* set the pointer to the string */
306 op->line[len] = &buf[i];
307
308 /* hop to next newline or end of buffer */
309 while(buf[i] != '\n' && i < op->buflen) i++;
310 buf[i] = '\0';
311
312 /* calculate the string length using pointer difference */
313 op->lens[len] = (size_t)&buf[i] - (size_t)op->line[len];
314
315 len++;
316 i++;
317 }
318
319 return len;
320}
321
322
323int
324np_runcmd(const char *cmd, output *out, output *err, int flags)
325{
326 int fd, pfd_out[2], pfd_err[2];
327
328 /* initialize the structs */
329 if(out) memset(out, 0, sizeof(output));
330 if(err) memset(err, 0, sizeof(output));
331
332 if((fd = np_runcmd_open(cmd, pfd_out, pfd_err)) == -1)
333 die (STATE_UNKNOWN, _("Could not open pipe: %s\n"), cmd);
334
335 if(out) out->lines = np_fetch_output(pfd_out[0], out, flags);
336 if(err) err->lines = np_fetch_output(pfd_err[0], err, flags);
337
338 return np_runcmd_close(fd);
339}
diff --git a/plugins/runcmd.h b/plugins/runcmd.h
new file mode 100644
index 0000000..35ebc25
--- /dev/null
+++ b/plugins/runcmd.h
@@ -0,0 +1,39 @@
1/*
2 * $Id$
3 *
4 * Author: Andreas Ericsson <ae@op5.se>
5 *
6 * Copyright: GNU GPL v2 or any later version.
7 *
8 */
9
10#ifndef NAGIOSPLUG_RUNCMD_H
11#define NAGIOSPLUG_RUNCMD_H
12
13#include "common.h"
14
15/** types **/
16struct output {
17 char *buf; /* output buffer */
18 size_t buflen; /* output buffer content length */
19 char **line; /* array of lines (points to buf) */
20 size_t *lens; /* string lengths */
21 size_t lines; /* lines of output */
22};
23
24typedef struct output output;
25
26/** prototypes **/
27int np_runcmd(const char *, output *, output *, int);
28void popen_timeout_alarm_handler(int)
29 __attribute__((__noreturn__));
30
31/* only multi-threaded plugins need to bother with this */
32void np_runcmd_init(void);
33#define NP_RUNCMD_INIT np_runcmd_init()
34
35/* possible flags for np_runcmd()'s fourth argument */
36#define RUNCMD_NO_ARRAYS 0x01 /* don't populate arrays at all */
37#define RUNCMD_NO_ASSOC 0x02 /* output.line won't point to buf */
38
39#endif /* NAGIOSPLUG_RUNCMD_H */