lib/util/util_runcmd.c

   1 /*
   2    Unix SMB/CIFS mplementation.
   3
   4    run a child command
   5
   6    Copyright (C) Andrew Tridgell 2010
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 */
  22
  23 /*
  24   this runs a child command with stdout and stderr going to the Samba
  25   log
  26  */
  27
  28 #include "includes.h"
  29 #include "system/filesys.h"
  30 #include <tevent.h>
  31 #include "../lib/util/tevent_unix.h"
  32
  33 struct samba_runcmd_state {
  34         int stdout_log_level;
  35         int stderr_log_level;
  36         struct tevent_fd *fde_stdout;
  37         struct tevent_fd *fde_stderr;
  38         int fd_stdout, fd_stderr;
  39         char *arg0;
  40         pid_t pid;
  41         char buf[1024];
  42         uint16_t buf_used;
  43 };
  44
  45 static int samba_runcmd_state_destructor(struct samba_runcmd_state *state)
  46 {
  47         if (state->pid > 0) {
  48                 kill(state->pid, SIGKILL);
  49                 waitpid(state->pid, NULL, 0);
  50                 state->pid = -1;
  51         }
  52         return 0;
  53 }
  54
  55 static void samba_runcmd_io_handler(struct tevent_context *ev,
  56                                     struct tevent_fd *fde,
  57                                     uint16_t flags,
  58                                     void *private_data);
  59
  60 /*
  61   run a command as a child process, with a timeout.
  62
  63   any stdout/stderr from the child will appear in the Samba logs with
  64   the specified log levels
  65  */
  66 struct tevent_req *samba_runcmd_send(TALLOC_CTX *mem_ctx,
  67                                      struct tevent_context *ev,
  68                                      struct timeval endtime,
  69                                      int stdout_log_level,
  70                                      int stderr_log_level,
  71                                      const char * const *argv0, ...)
  72 {
  73         struct tevent_req *req;
  74         struct samba_runcmd_state *state;
  75         int p1[2], p2[2];
  76         char **argv;
  77         int ret;
  78         va_list ap;
  79
  80         req = tevent_req_create(mem_ctx, &state,
  81                                 struct samba_runcmd_state);
  82         if (req == NULL) {
  83                 return NULL;
  84         }
  85
  86         state->stdout_log_level = stdout_log_level;
  87         state->stderr_log_level = stderr_log_level;
  88
  89         state->arg0 = talloc_strdup(state, argv0[0]);
  90         if (tevent_req_nomem(state->arg0, req)) {
  91                 return tevent_req_post(req, ev);
  92         }
  93
  94         if (pipe(p1) != 0) {
  95                 tevent_req_error(req, errno);
  96                 return tevent_req_post(req, ev);
  97         }
  98         if (pipe(p2) != 0) {
  99                 close(p1[0]);
 100                 close(p1[1]);
 101                 tevent_req_error(req, errno);
 102                 return tevent_req_post(req, ev);
 103         }
 104
 105         state->pid = fork();
 106         if (state->pid == (pid_t)-1) {
 107                 close(p1[0]);
 108                 close(p1[1]);
 109                 close(p2[0]);
 110                 close(p2[1]);
 111                 tevent_req_error(req, errno);
 112                 return tevent_req_post(req, ev);
 113         }
 114
 115         if (state->pid != 0) {
 116                 /* the parent */
 117                 close(p1[1]);
 118                 close(p2[1]);
 119                 state->fd_stdout = p1[0];
 120                 state->fd_stderr = p2[0];
 121                 set_blocking(state->fd_stdout, false);
 122                 set_blocking(state->fd_stderr, false);
 123
 124                 talloc_set_destructor(state, samba_runcmd_state_destructor);
 125
 126                 state->fde_stdout = tevent_add_fd(ev, state,
 127                                                   state->fd_stdout,
 128                                                   TEVENT_FD_READ,
 129                                                   samba_runcmd_io_handler,
 130                                                   req);
 131                 if (tevent_req_nomem(state->fde_stdout, req)) {
 132                         close(p1[0]);
 133                         close(p2[0]);
 134                         return tevent_req_post(req, ev);
 135                 }
 136                 tevent_fd_set_auto_close(state->fde_stdout);
 137
 138                 state->fde_stderr = tevent_add_fd(ev, state,
 139                                                   state->fd_stderr,
 140                                                   TEVENT_FD_READ,
 141                                                   samba_runcmd_io_handler,
 142                                                   req);
 143                 if (tevent_req_nomem(state->fde_stdout, req)) {
 144                         close(p2[0]);
 145                         return tevent_req_post(req, ev);
 146                 }
 147                 tevent_fd_set_auto_close(state->fde_stderr);
 148
 149                 if (!timeval_is_zero(&endtime)) {
 150                         tevent_req_set_endtime(req, ev, endtime);
 151                 }
 152
 153                 return req;
 154         }
 155
 156         /* the child */
 157         close(p1[0]);
 158         close(p2[0]);
 159         close(0);
 160         close(1);
 161         close(2);
 162
 163         /* we want to ensure that all of the network sockets we had
 164            open are closed */
 165         tevent_re_initialise(ev);
 166
 167         /* setup for logging to go to the parents debug log */
 168         open("/dev/null", O_RDONLY); /* for stdin */
 169         dup2(p1[1], 1);
 170         dup2(p2[1], 2);
 171
 172         argv = str_list_copy(state, discard_const_p(const char *, argv0));
 173         if (!argv) {
 174                 fprintf(stderr, "Out of memory in child\n");
 175                 _exit(255);
 176         }
 177
 178         va_start(ap, argv0);
 179         while (1) {
 180                 char *arg = va_arg(ap, char *);
 181                 if (arg == NULL) break;
 182                 argv = discard_const_p(char *, str_list_add((const char **)argv, arg));
 183                 if (!argv) {
 184                         fprintf(stderr, "Out of memory in child\n");
 185                         _exit(255);
 186                 }
 187         }
 188         va_end(ap);
 189
 190         ret = execvp(state->arg0, argv);
 191         fprintf(stderr, "Failed to exec child - %s\n", strerror(errno));
 192         _exit(255);
 193         return NULL;
 194 }
 195
 196 /*
 197   handle stdout/stderr from the child
 198  */
 199 static void samba_runcmd_io_handler(struct tevent_context *ev,
 200                                     struct tevent_fd *fde,
 201                                     uint16_t flags,
 202                                     void *private_data)
 203 {
 204         struct tevent_req *req = talloc_get_type_abort(private_data,
 205                                  struct tevent_req);
 206         struct samba_runcmd_state *state = tevent_req_data(req,
 207                                            struct samba_runcmd_state);
 208         int level;
 209         char *p;
 210         int n, fd;
 211
 212         if (fde == state->fde_stdout) {
 213                 level = state->stdout_log_level;
 214                 fd = state->fd_stdout;
 215         } else {
 216                 level = state->stderr_log_level;
 217                 fd = state->fd_stderr;
 218         }
 219
 220         if (!(flags & TEVENT_FD_READ)) {
 221                 return;
 222         }
 223
 224         n = read(fd, &state->buf[state->buf_used],
 225                  sizeof(state->buf) - state->buf_used);
 226         if (n > 0) {
 227                 state->buf_used += n;
 228         } else if (n == 0) {
 229                 if (fde == state->fde_stdout) {
 230                         talloc_free(fde);
 231                         state->fde_stdout = NULL;
 232                 }
 233                 if (fde == state->fde_stderr) {
 234                         talloc_free(fde);
 235                         state->fde_stderr = NULL;
 236                 }
 237                 if (state->fde_stdout == NULL &&
 238                     state->fde_stderr == NULL) {
 239                         int status;
 240                         /* the child has closed both stdout and
 241                          * stderr, assume its dead */
 242                         pid_t pid = waitpid(state->pid, &status, 0);
 243                         if (pid != state->pid) {
 244                                 if (errno == ECHILD) {
 245                                         /* this happens when the
 246                                            parent has set SIGCHLD to
 247                                            SIG_IGN. In that case we
 248                                            can only get error
 249                                            information for the child
 250                                            via its logging. We should
 251                                            stop using SIG_IGN on
 252                                            SIGCHLD in the standard
 253                                            process model.
 254                                         */
 255                                         tevent_req_done(req);
 256                                         return;
 257                                 }
 258                                 DEBUG(0,("Error in waitpid() for child %s - %s \n",
 259                                          state->arg0, strerror(errno)));
 260                                 if (errno == 0) {
 261                                         errno = ECHILD;
 262                                 }
 263                                 tevent_req_error(req, errno);
 264                                 return;
 265                         }
 266                         status = WEXITSTATUS(status);
 267                         DEBUG(3,("Child %s exited with status %d - %s\n",
 268                                  state->arg0, status, strerror(status)));
 269                         if (status != 0) {
 270                                 tevent_req_error(req, status);
 271                                 return;
 272                         }
 273
 274                         tevent_req_done(req);
 275                         return;
 276                 }
 277                 return;
 278         }
 279
 280         while (state->buf_used > 0 &&
 281                (p = (char *)memchr(state->buf, '\n', state->buf_used)) != NULL) {
 282                 int n1 = (p - state->buf)+1;
 283                 int n2 = n1 - 1;
 284                 /* swallow \r from child processes */
 285                 if (n2 > 0 && state->buf[n2-1] == '\r') {
 286                         n2--;
 287                 }
 288                 DEBUG(level,("%s: %*.*s\n", state->arg0, n2, n2, state->buf));
 289                 memmove(state->buf, p+1, sizeof(state->buf) - n1);
 290                 state->buf_used -= n1;
 291         }
 292
 293         /* the buffer could have completely filled - unfortunately we have
 294            no choice but to dump it out straight away */
 295         if (state->buf_used == sizeof(state->buf)) {
 296                 DEBUG(level,("%s: %*.*s\n",
 297                              state->arg0, state->buf_used,
 298                              state->buf_used, state->buf));
 299                 state->buf_used = 0;
 300         }
 301 }
 302
 303 int samba_runcmd_recv(struct tevent_req *req, int *perrno)
 304 {
 305         if (tevent_req_is_unix_error(req, perrno)) {
 306                 tevent_req_received(req);
 307                 return -1;
 308         }
 309
 310         tevent_req_received(req);
 311         return 0;
 312 }