/*****************************************************************************
*
* Monitoring run command utilities
*
* License: GPL
* Copyright (c) 2005-2024 Monitoring Plugins Development Team
*
* Description :
*
* A simple interface to executing programs from other programs, using an
* optimized and safe popen()-like implementation. It is considered safe
* in that no shell needs to be spawned and the environment passed to the
* execve()'d program is essentially empty.
*
* The code in this file is a derivative of popen.c which in turn was taken
* from "Advanced Programming for the Unix Environment" by W. Richard Stevens.
*
* Care has been taken to make sure the functions are async-safe. The one
* function which isn't is cmd_init() which it doesn't make sense to
* call twice anyway, so the api as a whole should be considered async-safe.
*
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
*
*****************************************************************************/
#define NAGIOSPLUG_API_C 1
/** includes **/
#include "common.h"
#include "utils.h"
#include "utils_cmd.h"
/* This variable must be global, since there's no way the caller
* can forcibly slay a dead or ungainly running program otherwise.
* Multithreading apps and plugins can initialize it (via CMD_INIT)
* in an async safe manner PRIOR to calling cmd_run() or cmd_run_array()
* for the first time.
*
* The check for initialized values is atomic and can
* occur in any number of threads simultaneously. */
static pid_t *_cmd_pids = NULL;
#include "utils_base.h"
#include "./maxfd.h"
#include
#ifdef HAVE_SYS_WAIT_H
# include
#endif
/* used in _cmd_open to pass the environment to commands */
extern char **environ;
/** macros **/
#ifndef WEXITSTATUS
# define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
#endif
#ifndef WIFEXITED
# define WIFEXITED(stat_val) (((stat_val)&255) == 0)
#endif
/* 4.3BSD Reno doesn't define SIG_ERR */
#if defined(SIG_IGN) && !defined(SIG_ERR)
# define SIG_ERR ((Sigfunc *)-1)
#endif
/** prototypes **/
static int _cmd_open(char *const *, int *, int *) __attribute__((__nonnull__(1, 2, 3)));
static int _cmd_fetch_output(int, output *, int) __attribute__((__nonnull__(2)));
static int _cmd_close(int);
/* prototype imported from utils.h */
extern void die(int, const char *, ...) __attribute__((__noreturn__, __format__(__printf__, 2, 3)));
/* this function is NOT async-safe. It is exported so multithreaded
* plugins (or other apps) can call it prior to running any commands
* through this api and thus achieve async-safeness throughout the api */
void cmd_init(void) {
long maxfd = mp_open_max();
/* if maxfd is unnaturally high, we force it to a lower value
* ( e.g. on SunOS, when ulimit is set to unlimited: 2147483647 this would cause
* a segfault when following calloc is called ... ) */
if (maxfd > MAXFD_LIMIT) {
maxfd = MAXFD_LIMIT;
}
if (!_cmd_pids)
_cmd_pids = calloc(maxfd, sizeof(pid_t));
}
/* Start running a command, array style */
static int _cmd_open(char *const *argv, int *pfd, int *pfderr) {
pid_t pid;
#ifdef RLIMIT_CORE
struct rlimit limit;
#endif
int i = 0;
if (!_cmd_pids)
CMD_INIT;
setenv("LC_ALL", "C", 1);
if (pipe(pfd) < 0 || pipe(pfderr) < 0 || (pid = fork()) < 0)
return -1; /* errno set by the failing function */
/* child runs exceve() and _exit. */
if (pid == 0) {
#ifdef RLIMIT_CORE
/* the program we execve shouldn't leave core files */
getrlimit(RLIMIT_CORE, &limit);
limit.rlim_cur = 0;
setrlimit(RLIMIT_CORE, &limit);
#endif
close(pfd[0]);
if (pfd[1] != STDOUT_FILENO) {
dup2(pfd[1], STDOUT_FILENO);
close(pfd[1]);
}
close(pfderr[0]);
if (pfderr[1] != STDERR_FILENO) {
dup2(pfderr[1], STDERR_FILENO);
close(pfderr[1]);
}
/* close all descriptors in _cmd_pids[]
* This is executed in a separate address space (pure child),
* so we don't have to worry about async safety */
long maxfd = mp_open_max();
for (i = 0; i < maxfd; i++)
if (_cmd_pids[i] > 0)
close(i);
execve(argv[0], argv, environ);
_exit(STATE_UNKNOWN);
}
/* parent picks up execution here */
/* close children descriptors in our address space */
close(pfd[1]);
close(pfderr[1]);
/* tag our file's entry in the pid-list and return it */
_cmd_pids[pfd[0]] = pid;
return pfd[0];
}
static int _cmd_close(int fd) {
int status;
pid_t pid;
/* make sure the provided fd was opened */
long maxfd = mp_open_max();
if (fd < 0 || fd > maxfd || !_cmd_pids || (pid = _cmd_pids[fd]) == 0)
return -1;
_cmd_pids[fd] = 0;
if (close(fd) == -1)
return -1;
/* EINTR is ok (sort of), everything else is bad */
while (waitpid(pid, &status, 0) < 0)
if (errno != EINTR)
return -1;
/* return child's termination status */
return (WIFEXITED(status)) ? WEXITSTATUS(status) : -1;
}
static int _cmd_fetch_output(int fd, output *op, int flags) {
size_t len = 0, i = 0, lineno = 0;
size_t rsf = 6, ary_size = 0; /* rsf = right shift factor, dec'ed uncond once */
char *buf = NULL;
int ret;
char tmpbuf[4096];
op->buf = NULL;
op->buflen = 0;
while ((ret = read(fd, tmpbuf, sizeof(tmpbuf))) > 0) {
len = (size_t)ret;
op->buf = realloc(op->buf, op->buflen + len + 1);
memcpy(op->buf + op->buflen, tmpbuf, len);
op->buflen += len;
i++;
}
if (ret < 0) {
printf("read() returned %d: %s\n", ret, strerror(errno));
return ret;
}
/* some plugins may want to keep output unbroken, and some commands
* will yield no output, so return here for those */
if (flags & CMD_NO_ARRAYS || !op->buf || !op->buflen)
return op->buflen;
/* and some may want both */
if (flags & CMD_NO_ASSOC) {
buf = malloc(op->buflen);
memcpy(buf, op->buf, op->buflen);
} else
buf = op->buf;
op->line = NULL;
op->lens = NULL;
i = 0;
while (i < op->buflen) {
/* make sure we have enough memory */
if (lineno >= ary_size) {
/* ary_size must never be zero */
do {
ary_size = op->buflen >> --rsf;
} while (!ary_size);
op->line = realloc(op->line, ary_size * sizeof(char *));
op->lens = realloc(op->lens, ary_size * sizeof(size_t));
}
/* set the pointer to the string */
op->line[lineno] = &buf[i];
/* hop to next newline or end of buffer */
while (buf[i] != '\n' && i < op->buflen)
i++;
buf[i] = '\0';
/* calculate the string length using pointer difference */
op->lens[lineno] = (size_t)&buf[i] - (size_t)op->line[lineno];
lineno++;
i++;
}
return lineno;
}
int cmd_run(const char *cmdstring, output *out, output *err, int flags) {
int i = 0, argc;
size_t cmdlen;
char **argv = NULL;
char *cmd = NULL;
char *str = NULL;
if (cmdstring == NULL)
return -1;
/* initialize the structs */
if (out)
memset(out, 0, sizeof(output));
if (err)
memset(err, 0, sizeof(output));
/* make copy of command string so strtok() doesn't silently modify it */
/* (the calling program may want to access it later) */
cmdlen = strlen(cmdstring);
if ((cmd = malloc(cmdlen + 1)) == NULL)
return -1;
memcpy(cmd, cmdstring, cmdlen);
cmd[cmdlen] = '\0';
/* This is not a shell, so we don't handle "???" */
if (strstr(cmdstring, "\""))
return -1;
/* allow single quotes, but only if non-whitesapce doesn't occur on both sides */
if (strstr(cmdstring, " ' ") || strstr(cmdstring, "'''"))
return -1;
/* each arg must be whitespace-separated, so args can be a maximum
* of (len / 2) + 1. We add 1 extra to the mix for NULL termination */
argc = (cmdlen >> 1) + 2;
argv = calloc((size_t)argc, sizeof(char *));
if (argv == NULL) {
printf("%s\n", _("Could not malloc argv array in popen()"));
return -1;
}
/* get command arguments (stupidly, but fairly quickly) */
while (cmd) {
str = cmd;
str += strspn(str, " \t\r\n"); /* trim any leading whitespace */
if (strstr(str, "'") == str) { /* handle SIMPLE quoted strings */
str++;
if (!strstr(str, "'"))
return -1; /* balanced? */
cmd = 1 + strstr(str, "'");
str[strcspn(str, "'")] = 0;
} else {
if (strpbrk(str, " \t\r\n")) {
cmd = 1 + strpbrk(str, " \t\r\n");
str[strcspn(str, " \t\r\n")] = 0;
} else {
cmd = NULL;
}
}
if (cmd && strlen(cmd) == strspn(cmd, " \t\r\n"))
cmd = NULL;
argv[i++] = str;
}
return cmd_run_array(argv, out, err, flags);
}
int cmd_run_array(char *const *argv, output *out, output *err, int flags) {
int fd, pfd_out[2], pfd_err[2];
/* initialize the structs */
if (out)
memset(out, 0, sizeof(output));
if (err)
memset(err, 0, sizeof(output));
if ((fd = _cmd_open(argv, pfd_out, pfd_err)) == -1)
die(STATE_UNKNOWN, _("Could not open pipe: %s\n"), argv[0]);
if (out)
out->lines = _cmd_fetch_output(pfd_out[0], out, flags);
if (err)
err->lines = _cmd_fetch_output(pfd_err[0], err, flags);
return _cmd_close(fd);
}
int cmd_file_read(char *filename, output *out, int flags) {
int fd;
if (out)
memset(out, 0, sizeof(output));
if ((fd = open(filename, O_RDONLY)) == -1) {
die(STATE_UNKNOWN, _("Error opening %s: %s"), filename, strerror(errno));
}
if (out)
out->lines = _cmd_fetch_output(fd, out, flags);
if (close(fd) == -1)
die(STATE_UNKNOWN, _("Error closing %s: %s"), filename, strerror(errno));
return 0;
}
void timeout_alarm_handler(int signo) {
if (signo == SIGALRM) {
printf(_("%s - Plugin timed out after %d seconds\n"), state_text(timeout_state), timeout_interval);
long maxfd = mp_open_max();
if (_cmd_pids)
for (long int i = 0; i < maxfd; i++) {
if (_cmd_pids[i] != 0)
kill(_cmd_pids[i], SIGKILL);
}
exit(timeout_state);
}
}