1 /******************************************************************************
2 * popen.c
3 *
4 * A safe alternative to popen
5 *
6 * Provides spopen and spclose
8 FILE * spopen(const char *);
9 int spclose(FILE *);
11 *
12 * Code taken with liitle modification from "Advanced Programming for the Unix
13 * Environment" by W. Richard Stevens
14 *
15 * This is considered safe in that no shell is spawned, and the environment and
16 * path passed to the exec'd program are esstially empty. (popen create a shell
17 * and passes the environment to it).
18 *
19 ******************************************************************************/
21 #include <config.h>
22 #include <common.h>
24 /* extern so plugin has pid to kill exec'd process on timeouts */
25 extern int timeout_interval;
26 extern pid_t *childpid;
27 extern int *child_stderr_array;
28 extern FILE *child_process;
30 FILE *spopen (const char *);
31 int spclose (FILE *);
32 RETSIGTYPE popen_timeout_alarm_handler (int);
34 #include <stdarg.h> /* ANSI C header file */
35 #include <fcntl.h>
37 #include <limits.h>
38 #include <sys/resource.h>
40 #ifdef HAVE_SYS_WAIT_H
41 #include <sys/wait.h>
42 #endif
44 #ifndef WEXITSTATUS
45 # define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
46 #endif
48 #ifndef WIFEXITED
49 # define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
50 #endif
52 /* 4.3BSD Reno <signal.h> doesn't define SIG_ERR */
53 #if defined(SIG_IGN) && !defined(SIG_ERR)
54 #define SIG_ERR ((Sigfunc *)-1)
55 #endif
57 #define min(a,b) ((a) < (b) ? (a) : (b))
58 #define max(a,b) ((a) > (b) ? (a) : (b))
59 int open_max (void); /* {Prog openmax} */
60 static void err_sys (const char *, ...) __attribute__((noreturn,format(printf, 1, 2)));
61 char *rtrim (char *, const char *);
63 char *pname = NULL; /* caller can set this from argv[0] */
65 /*int *childerr = NULL;*//* ptr to array allocated at run-time */
66 /*extern pid_t *childpid = NULL; *//* ptr to array allocated at run-time */
67 static int maxfd; /* from our open_max(), {Prog openmax} */
69 FILE *
70 spopen (const char *cmdstring)
71 {
72 char *env[2];
73 char *cmd = NULL;
74 char **argv = NULL;
75 char *str;
76 int argc;
78 int i = 0, pfd[2], pfderr[2];
79 pid_t pid;
81 #ifdef RLIMIT_CORE
82 /* do not leave core files */
83 struct rlimit limit;
84 getrlimit (RLIMIT_CORE, &limit);
85 limit.rlim_cur = 0;
86 setrlimit (RLIMIT_CORE, &limit);
87 #endif
89 env[0] = strdup("LC_ALL=C");
90 env[1] = '\0';
92 /* if no command was passed, return with no error */
93 if (cmdstring == NULL)
94 return (NULL);
96 /* make copy of command string so strtok() doesn't silently modify it */
97 /* (the calling program may want to access it later) */
98 cmd = malloc (strlen (cmdstring) + 1);
99 if (cmd == NULL)
100 return NULL;
101 strcpy (cmd, cmdstring);
103 /* This is not a shell, so we don't handle "???" */
104 if (strstr (cmdstring, "\""))
105 return NULL;
107 /* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
108 if (strstr (cmdstring, " ' ") || strstr (cmdstring, "'''"))
109 return NULL;
111 /* there cannot be more args than characters */
112 argc = strlen (cmdstring) + 1; /* add 1 for NULL termination */
113 argv = malloc (sizeof(char*)*argc);
114 if (argv == NULL) {
115 printf ("Could not malloc argv array in popen()\n");
116 return NULL;
117 }
119 /* loop to get arguments to command */
120 while (cmd) {
121 str = cmd;
122 str += strspn (str, " \t\r\n"); /* trim any leading whitespace */
124 if (i >= argc - 2) {
125 printf ("You've got a big problem buddy! You need more args!!!\n");
126 return (NULL);
127 }
129 if (strstr (str, "'") == str) { /* handle SIMPLE quoted strings */
130 str++;
131 if (!strstr (str, "'"))
132 return NULL; /* balanced? */
133 cmd = 1 + strstr (str, "'");
134 str[strcspn (str, "'")] = 0;
135 }
136 else {
137 if (strpbrk (str, " \t\r\n")) {
138 cmd = 1 + strpbrk (str, " \t\r\n");
139 str[strcspn (str, " \t\r\n")] = 0;
140 }
141 else {
142 cmd = NULL;
143 }
144 }
146 if (cmd && strlen (cmd) == strspn (cmd, " \t\r\n"))
147 cmd = NULL;
149 argv[i++] = str;
151 }
152 argv[i] = NULL;
154 if (childpid == NULL) { /* first time through */
155 maxfd = open_max (); /* allocate zeroed out array for child pids */
156 if ((childpid = calloc ((size_t)maxfd, sizeof (pid_t))) == NULL)
157 return (NULL);
158 }
160 if (child_stderr_array == NULL) { /* first time through */
161 maxfd = open_max (); /* allocate zeroed out array for child pids */
162 if ((child_stderr_array = calloc ((size_t)maxfd, sizeof (int))) == NULL)
163 return (NULL);
164 }
166 if (pipe (pfd) < 0)
167 return (NULL); /* errno set by pipe() */
169 if (pipe (pfderr) < 0)
170 return (NULL); /* errno set by pipe() */
172 if ((pid = fork ()) < 0)
173 return (NULL); /* errno set by fork() */
174 else if (pid == 0) { /* child */
175 close (pfd[0]);
176 if (pfd[1] != STDOUT_FILENO) {
177 dup2 (pfd[1], STDOUT_FILENO);
178 close (pfd[1]);
179 }
180 close (pfderr[0]);
181 if (pfderr[1] != STDERR_FILENO) {
182 dup2 (pfderr[1], STDERR_FILENO);
183 close (pfderr[1]);
184 }
185 /* close all descriptors in childpid[] */
186 for (i = 0; i < maxfd; i++)
187 if (childpid[i] > 0)
188 close (i);
190 execve (argv[0], argv, env);
191 _exit (0);
192 }
194 close (pfd[1]); /* parent */
195 if ((child_process = fdopen (pfd[0], "r")) == NULL)
196 return (NULL);
197 close (pfderr[1]);
199 childpid[fileno (child_process)] = pid; /* remember child pid for this fd */
200 child_stderr_array[fileno (child_process)] = pfderr[0]; /* remember STDERR */
201 return (child_process);
202 }
204 int
205 spclose (FILE * fp)
206 {
207 int fd, status;
208 pid_t pid;
210 if (childpid == NULL)
211 return (1); /* popen() has never been called */
213 fd = fileno (fp);
214 if ((pid = childpid[fd]) == 0)
215 return (1); /* fp wasn't opened by popen() */
217 childpid[fd] = 0;
218 if (fclose (fp) == EOF)
219 return (1);
221 while (waitpid (pid, &status, 0) < 0)
222 if (errno != EINTR)
223 return (1); /* error other than EINTR from waitpid() */
225 if (WIFEXITED (status))
226 return (WEXITSTATUS (status)); /* return child's termination status */
228 return (1);
229 }
231 #ifdef OPEN_MAX
232 static int openmax = OPEN_MAX;
233 #else
234 static int openmax = 0;
235 #endif
237 #define OPEN_MAX_GUESS 256 /* if OPEN_MAX is indeterminate */
238 /* no guarantee this is adequate */
240 void
241 popen_timeout_alarm_handler (int signo)
242 {
243 if (signo == SIGALRM) {
244 kill (childpid[fileno (child_process)], SIGKILL);
245 printf ("CRITICAL - Plugin timed out after %d seconds\n",
246 timeout_interval);
247 exit (STATE_CRITICAL);
248 }
249 }
251 int
252 open_max (void)
253 {
254 if (openmax == 0) { /* first time through */
255 errno = 0;
256 if ((openmax = sysconf (_SC_OPEN_MAX)) < 0) {
257 if (errno == 0)
258 openmax = OPEN_MAX_GUESS; /* it's indeterminate */
259 else
260 err_sys ("sysconf error for _SC_OPEN_MAX");
261 }
262 }
263 return (openmax);
264 }
268 /* Fatal error related to a system call.
269 * Print a message and die. */
271 #define MAXLINE 2048
272 static void
273 err_sys (const char *fmt, ...)
274 {
275 int errnoflag = 1;
276 int errno_save;
277 char buf[MAXLINE];
279 va_list ap;
281 va_start (ap, fmt);
282 /* err_doit (1, fmt, ap); */
283 errno_save = errno; /* value caller might want printed */
284 vsprintf (buf, fmt, ap);
285 if (errnoflag)
286 sprintf (buf + strlen (buf), ": %s", strerror (errno_save));
287 strcat (buf, "\n");
288 fflush (stdout); /* in case stdout and stderr are the same */
289 fputs (buf, stderr);
290 fflush (NULL); /* flushes all stdio output streams */
291 va_end (ap);
292 exit (1);
293 }
295 char *
296 rtrim (char *str, const char *tok)
297 {
298 int i = 0;
299 int j = sizeof (str);
301 while (str != NULL && i < j) {
302 if (*(str + i) == *tok) {
303 sprintf (str + i, "%s", "\0");
304 return str;
305 }
306 i++;
307 }
308 return str;
309 }