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_stdin, 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
  53         if (state->fd_stdin != -1) {
  54                 close(state->fd_stdin);
  55         }
  56         return 0;
  57 }
  58
  59 static void samba_runcmd_io_handler(struct tevent_context *ev,
  60                                     struct tevent_fd *fde,
  61                                     uint16_t flags,
  62                                     void *private_data);
  63
  64 /*
  65   run a command as a child process, with a timeout.
  66
  67   any stdout/stderr from the child will appear in the Samba logs with
  68   the specified log levels
  69  */
  70 struct tevent_req *samba_runcmd_send(TALLOC_CTX *mem_ctx,
  71                                      struct tevent_context *ev,
  72                                      struct timeval endtime,
  73                                      int stdout_log_level,
  74                                      int stderr_log_level,
  75                                      const char * const *argv0, ...)
  76 {
  77         struct tevent_req *req;
  78         struct samba_runcmd_state *state;
  79         int p1[2], p2[2], p3[2];
  80         char **argv;
  81         va_list ap;
  82
  83         if (argv0 == NULL) {
  84                 return NULL;
  85         }
  86
  87         req = tevent_req_create(mem_ctx, &state,
  88                                 struct samba_runcmd_state);
  89         if (req == NULL) {
  90                 return NULL;
  91         }
  92
  93         state->stdout_log_level = stdout_log_level;
  94         state->stderr_log_level = stderr_log_level;
  95         state->fd_stdin = -1;
  96
  97         state->arg0 = talloc_strdup(state, argv0[0]);
  98         if (tevent_req_nomem(state->arg0, req)) {
  99                 return tevent_req_post(req, ev);
 100         }
 101
 102         if (pipe(p1) != 0) {
 103                 tevent_req_error(req, errno);
 104                 return tevent_req_post(req, ev);
 105         }
 106         if (pipe(p2) != 0) {
 107                 close(p1[0]);
 108                 close(p1[1]);
 109                 tevent_req_error(req, errno);
 110                 return tevent_req_post(req, ev);
 111         }
 112         if (pipe(p3) != 0) {
 113                 close(p1[0]);
 114                 close(p1[1]);
 115                 close(p2[0]);
 116                 close(p2[1]);
 117                 tevent_req_error(req, errno);
 118                 return tevent_req_post(req, ev);
 119         }
 120
 121         state->pid = fork();
 122         if (state->pid == (pid_t)-1) {
 123                 close(p1[0]);
 124                 close(p1[1]);
 125                 close(p2[0]);
 126                 close(p2[1]);
 127                 close(p3[0]);
 128                 close(p3[1]);
 129                 tevent_req_error(req, errno);
 130                 return tevent_req_post(req, ev);
 131         }
 132
 133         if (state->pid != 0) {
 134                 /* the parent */
 135                 close(p1[1]);
 136                 close(p2[1]);
 137                 close(p3[0]);
 138                 state->fd_stdout = p1[0];
 139                 state->fd_stderr = p2[0];
 140                 state->fd_stdin  = p3[1];
 141
 142                 set_blocking(state->fd_stdout, false);
 143                 set_blocking(state->fd_stderr, false);
 144                 set_blocking(state->fd_stdin,  false);
 145
 146                 smb_set_close_on_exec(state->fd_stdin);
 147                 smb_set_close_on_exec(state->fd_stdout);
 148                 smb_set_close_on_exec(state->fd_stderr);
 149
 150                 talloc_set_destructor(state, samba_runcmd_state_destructor);
 151
 152                 state->fde_stdout = tevent_add_fd(ev, state,
 153                                                   state->fd_stdout,
 154                                                   TEVENT_FD_READ,
 155                                                   samba_runcmd_io_handler,
 156                                                   req);
 157                 if (tevent_req_nomem(state->fde_stdout, req)) {
 158                         close(state->fd_stdout);
 159                         close(state->fd_stderr);
 160                         return tevent_req_post(req, ev);
 161                 }
 162                 tevent_fd_set_auto_close(state->fde_stdout);
 163
 164                 state->fde_stderr = tevent_add_fd(ev, state,
 165                                                   state->fd_stderr,
 166                                                   TEVENT_FD_READ,
 167                                                   samba_runcmd_io_handler,
 168                                                   req);
 169                 if (tevent_req_nomem(state->fde_stdout, req)) {
 170                         close(state->fd_stderr);
 171                         return tevent_req_post(req, ev);
 172                 }
 173                 tevent_fd_set_auto_close(state->fde_stderr);
 174
 175                 if (!timeval_is_zero(&endtime)) {
 176                         tevent_req_set_endtime(req, ev, endtime);
 177                 }
 178
 179                 return req;
 180         }
 181
 182         /* the child */
 183         close(p1[0]);
 184         close(p2[0]);
 185         close(p3[1]);
 186         close(0);
 187         close(1);
 188         close(2);
 189
 190         /* we want to ensure that all of the network sockets we had
 191            open are closed */
 192         tevent_re_initialise(ev);
 193
 194         /* setup for logging to go to the parents debug log */
 195         dup2(p3[0], 0);
 196         dup2(p1[1], 1);
 197         dup2(p2[1], 2);
 198
 199         close(p1[1]);
 200         close(p2[1]);
 201         close(p3[0]);
 202
 203         argv = str_list_copy(state, discard_const_p(const char *, argv0));
 204         if (!argv) {
 205                 fprintf(stderr, "Out of memory in child\n");
 206                 _exit(255);
 207         }
 208
 209         va_start(ap, argv0);
 210         while (1) {
 211                 const char **l;
 212                 char *arg = va_arg(ap, char *);
 213                 if (arg == NULL) break;
 214                 l = discard_const_p(const char *, argv);
 215                 l = str_list_add(l, arg);
 216                 if (l == NULL) {
 217                         fprintf(stderr, "Out of memory in child\n");
 218                         _exit(255);
 219                 }
 220                 argv = discard_const_p(char *, l);
 221         }
 222         va_end(ap);
 223
 224         (void)execvp(state->arg0, argv);
 225         fprintf(stderr, "Failed to exec child - %s\n", strerror(errno));
 226         _exit(255);
 227         return NULL;
 228 }
 229
 230 /*
 231   handle stdout/stderr from the child
 232  */
 233 static void samba_runcmd_io_handler(struct tevent_context *ev,
 234                                     struct tevent_fd *fde,
 235                                     uint16_t flags,
 236                                     void *private_data)
 237 {
 238         struct tevent_req *req = talloc_get_type_abort(private_data,
 239                                  struct tevent_req);
 240         struct samba_runcmd_state *state = tevent_req_data(req,
 241                                            struct samba_runcmd_state);
 242         int level;
 243         char *p;
 244         int n, fd;
 245
 246         if (fde == state->fde_stdout) {
 247                 level = state->stdout_log_level;
 248                 fd = state->fd_stdout;
 249         } else if (fde == state->fde_stderr) {
 250                 level = state->stderr_log_level;
 251                 fd = state->fd_stderr;
 252         } else {
 253                 return;
 254         }
 255
 256         if (!(flags & TEVENT_FD_READ)) {
 257                 return;
 258         }
 259
 260         n = read(fd, &state->buf[state->buf_used],
 261                  sizeof(state->buf) - state->buf_used);
 262         if (n > 0) {
 263                 state->buf_used += n;
 264         } else if (n == 0) {
 265                 if (fde == state->fde_stdout) {
 266                         talloc_free(fde);
 267                         state->fde_stdout = NULL;
 268                 }
 269                 if (fde == state->fde_stderr) {
 270                         talloc_free(fde);
 271                         state->fde_stderr = NULL;
 272                 }
 273                 if (state->fde_stdout == NULL &&
 274                     state->fde_stderr == NULL) {
 275                         int status;
 276                         /* the child has closed both stdout and
 277                          * stderr, assume its dead */
 278                         pid_t pid = waitpid(state->pid, &status, 0);
 279                         if (pid != state->pid) {
 280                                 if (errno == ECHILD) {
 281                                         /* this happens when the
 282                                            parent has set SIGCHLD to
 283                                            SIG_IGN. In that case we
 284                                            can only get error
 285                                            information for the child
 286                                            via its logging. We should
 287                                            stop using SIG_IGN on
 288                                            SIGCHLD in the standard
 289                                            process model.
 290                                         */
 291                                         DEBUG(0, ("Error in waitpid() unexpectedly got ECHILD "
 292                                                   "for %s child %d - %s, "
 293                                                   "someone has set SIGCHLD to SIG_IGN!\n",
 294                                         state->arg0, (int)state->pid, strerror(errno)));
 295                                         tevent_req_error(req, errno);
 296                                         return;
 297                                 }
 298                                 DEBUG(0,("Error in waitpid() for child %s - %s \n",
 299                                          state->arg0, strerror(errno)));
 300                                 if (errno == 0) {
 301                                         errno = ECHILD;
 302                                 }
 303                                 tevent_req_error(req, errno);
 304                                 return;
 305                         }
 306                         status = WEXITSTATUS(status);
 307                         DEBUG(3,("Child %s exited with status %d - %s\n",
 308                                  state->arg0, status, strerror(status)));
 309                         if (status != 0) {
 310                                 tevent_req_error(req, status);
 311                                 return;
 312                         }
 313
 314                         tevent_req_done(req);
 315                         return;
 316                 }
 317                 return;
 318         }
 319
 320         while (state->buf_used > 0 &&
 321                (p = (char *)memchr(state->buf, '\n', state->buf_used)) != NULL) {
 322                 int n1 = (p - state->buf)+1;
 323                 int n2 = n1 - 1;
 324                 /* swallow \r from child processes */
 325                 if (n2 > 0 && state->buf[n2-1] == '\r') {
 326                         n2--;
 327                 }
 328                 DEBUG(level,("%s: %*.*s\n", state->arg0, n2, n2, state->buf));
 329                 memmove(state->buf, p+1, sizeof(state->buf) - n1);
 330                 state->buf_used -= n1;
 331         }
 332
 333         /* the buffer could have completely filled - unfortunately we have
 334            no choice but to dump it out straight away */
 335         if (state->buf_used == sizeof(state->buf)) {
 336                 DEBUG(level,("%s: %*.*s\n",
 337                              state->arg0, state->buf_used,
 338                              state->buf_used, state->buf));
 339                 state->buf_used = 0;
 340         }
 341 }
 342
 343 int samba_runcmd_recv(struct tevent_req *req, int *perrno)
 344 {
 345         if (tevent_req_is_unix_error(req, perrno)) {
 346                 tevent_req_received(req);
 347                 return -1;
 348         }
 349
 350         tevent_req_received(req);
 351         return 0;
 352 }