ctdb/server/ctdb_event_helper.c

   1 /*
   2    ctdb event script helper
   3
   4    Copyright (C) Amitay Isaacs  2013
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "replace.h"
  21 #include "system/filesys.h"
  22 #include "system/network.h"
  23 #include "system/wait.h"
  24
  25 #include <talloc.h>
  26
  27 #include "lib/util/blocking.h"
  28
  29 #include "ctdb_private.h"
  30
  31 #include "common/system.h"
  32
  33 static char *progname = NULL;
  34
  35
  36 /* CTDB sends SIGTERM, when process must die */
  37 static void sigterm(int sig)
  38 {
  39         pid_t pid;
  40
  41         /* all the child processes are running in the same process group */
  42         pid = getpgrp();
  43         if (pid == -1) {
  44                 kill(-getpid(), SIGKILL);
  45         } else {
  46                 kill(-pid, SIGKILL);
  47         }
  48         _exit(0);
  49 }
  50
  51 static int check_executable(const char *path)
  52 {
  53         struct stat st;
  54
  55         if (stat(path, &st) != 0) {
  56                 fprintf(stderr, "Failed to access '%s' - %s\n",
  57                         path, strerror(errno));
  58                 return errno;
  59         }
  60
  61         if (!(st.st_mode & S_IXUSR)) {
  62                 return ENOEXEC;
  63         }
  64
  65         return 0;
  66 }
  67
  68 static void usage(void)
  69 {
  70         fprintf(stderr, "\n");
  71         fprintf(stderr, "Usage: %s <log-fd> <output-fd> <script_path> <event> [<args>]\n",
  72                 progname);
  73 }
  74
  75 int main(int argc, char *argv[])
  76 {
  77         int log_fd, write_fd;
  78         pid_t pid;
  79         int status, output, ret;
  80
  81         progname = argv[0];
  82
  83         if (argc < 5) {
  84                 usage();
  85                 exit(1);
  86         }
  87
  88         reset_scheduler();
  89
  90         log_fd = atoi(argv[1]);
  91         write_fd = atoi(argv[2]);
  92
  93         set_close_on_exec(write_fd);
  94
  95         close(STDOUT_FILENO);
  96         close(STDERR_FILENO);
  97         dup2(log_fd, STDOUT_FILENO);
  98         dup2(log_fd, STDERR_FILENO);
  99         close(log_fd);
 100
 101         if (setpgid(0, 0) != 0) {
 102                 fprintf(stderr, "Failed to create process group for event script - %s\n",
 103                         strerror(errno));
 104                 exit(1);
 105         }
 106
 107         signal(SIGTERM, sigterm);
 108
 109         pid = fork();
 110         if (pid < 0) {
 111                 int save_errno = errno;
 112                 fprintf(stderr, "Failed to fork - %s\n", strerror(errno));
 113                 sys_write(write_fd, &save_errno, sizeof(save_errno));
 114                 exit(1);
 115         }
 116
 117         if (pid == 0) {
 118                 ret = check_executable(argv[3]);
 119                 if (ret != 0) {
 120                         _exit(ret);
 121                 }
 122                 ret = execv(argv[3], &argv[3]);
 123                 if (ret != 0) {
 124                         int save_errno = errno;
 125                         fprintf(stderr, "Error executing '%s' - %s\n",
 126                                 argv[3], strerror(save_errno));
 127                 }
 128                 /* This should never happen */
 129                 _exit(ENOEXEC);
 130         }
 131
 132         ret = waitpid(pid, &status, 0);
 133         if (ret == -1) {
 134                 output = -errno;
 135                 fprintf(stderr, "waitpid() failed - %s\n", strerror(errno));
 136                 sys_write(write_fd, &output, sizeof(output));
 137                 exit(1);
 138         }
 139         if (WIFEXITED(status)) {
 140                 output = WEXITSTATUS(status);
 141                 /* Only errors should be returned as -ve values */
 142                 if (output == ENOENT || output == ENOEXEC) {
 143                         output = -output;
 144                 }
 145                 sys_write(write_fd, &output, sizeof(output));
 146                 exit(0);
 147         }
 148         if (WIFSIGNALED(status)) {
 149                 output = -EINTR;
 150                 fprintf(stderr, "Process terminated with signal - %d\n",
 151                         WTERMSIG(status));
 152                 sys_write(write_fd, &output, sizeof(output));
 153                 exit(0);
 154         }
 155
 156         fprintf(stderr, "waitpid() status=%d\n", status);
 157         exit(1);
 158 }