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_stdin;
  37         struct tevent_fd *fde_stdout;
  38         struct tevent_fd *fde_stderr;
  39         int fd_stdin, fd_stdout, fd_stderr;
  40         char *arg0;
  41         pid_t pid;
  42         char buf[1024];
  43         uint16_t buf_used;
  44 };
  45
  46 static int samba_runcmd_state_destructor(struct samba_runcmd_state *state)
  47 {
  48         if (state->pid > 0) {
  49                 kill(state->pid, SIGKILL);
  50                 waitpid(state->pid, NULL, 0);
  51                 state->pid = -1;
  52         }
  53         return 0;
  54 }
  55
  56 static void samba_runcmd_io_handler(struct tevent_context *ev,
  57                                     struct tevent_fd *fde,
  58                                     uint16_t flags,
  59                                     void *private_data);
  60
  61 /*
  62   run a command as a child process, with a timeout.
  63
  64   any stdout/stderr from the child will appear in the Samba logs with
  65   the specified log levels
  66  */
  67 struct tevent_req *samba_runcmd_send(TALLOC_CTX *mem_ctx,
  68                                      struct tevent_context *ev,
  69                                      struct timeval endtime,
  70                                      int stdout_log_level,
  71                                      int stderr_log_level,
  72                                      const char * const *argv0, ...)
  73 {
  74         struct tevent_req *req;
  75         struct samba_runcmd_state *state;
  76         int p1[2], p2[2], p3[2];
  77         char **argv;
  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         if (pipe(p3) != 0) {
 105                 close(p1[0]);
 106                 close(p1[1]);
 107                 close(p2[0]);
 108                 close(p2[1]);
 109                 tevent_req_error(req, errno);
 110                 return tevent_req_post(req, ev);
 111         }
 112
 113         state->pid = fork();
 114         if (state->pid == (pid_t)-1) {
 115                 close(p1[0]);
 116                 close(p1[1]);
 117                 close(p2[0]);
 118                 close(p2[1]);
 119                 close(p3[0]);
 120                 close(p3[1]);
 121                 tevent_req_error(req, errno);
 122                 return tevent_req_post(req, ev);
 123         }
 124
 125         if (state->pid != 0) {
 126                 /* the parent */
 127                 close(p1[1]);
 128                 close(p2[1]);
 129                 close(p3[0]);
 130                 state->fd_stdout = p1[0];
 131                 state->fd_stderr = p2[0];
 132                 state->fd_stdin  = p3[1];
 133
 134                 set_blocking(state->fd_stdout, false);
 135                 set_blocking(state->fd_stderr, false);
 136                 set_blocking(state->fd_stdin,  false);
 137
 138                 smb_set_close_on_exec(state->fd_stdin);
 139                 smb_set_close_on_exec(state->fd_stdout);
 140                 smb_set_close_on_exec(state->fd_stderr);
 141
 142                 talloc_set_destructor(state, samba_runcmd_state_destructor);
 143
 144                 state->fde_stdout = tevent_add_fd(ev, state,
 145                                                   state->fd_stdout,
 146                                                   TEVENT_FD_READ,
 147                                                   samba_runcmd_io_handler,
 148                                                   req);
 149                 if (tevent_req_nomem(state->fde_stdout, req)) {
 150                         close(state->fd_stdout);
 151                         close(state->fd_stderr);
 152                         close(state->fd_stdin);
 153                         return tevent_req_post(req, ev);
 154                 }
 155                 tevent_fd_set_auto_close(state->fde_stdout);
 156
 157                 state->fde_stderr = tevent_add_fd(ev, state,
 158                                                   state->fd_stderr,
 159                                                   TEVENT_FD_READ,
 160                                                   samba_runcmd_io_handler,
 161                                                   req);
 162                 if (tevent_req_nomem(state->fde_stdout, req)) {
 163                         close(state->fd_stderr);
 164                         close(state->fd_stdin);
 165                         return tevent_req_post(req, ev);
 166                 }
 167                 tevent_fd_set_auto_close(state->fde_stderr);
 168
 169                 state->fde_stdin = tevent_add_fd(ev, state,
 170                                                  state->fd_stdin,
 171                                                  0,
 172                                                  samba_runcmd_io_handler,
 173                                                  req);
 174                 if (tevent_req_nomem(state->fde_stdin, req)) {
 175                         close(state->fd_stdin);
 176                         return tevent_req_post(req, ev);
 177                 }
 178                 tevent_fd_set_auto_close(state->fde_stdin);
 179
 180                 if (!timeval_is_zero(&endtime)) {
 181                         tevent_req_set_endtime(req, ev, endtime);
 182                 }
 183
 184                 return req;
 185         }
 186
 187         /* the child */
 188         close(p1[0]);
 189         close(p2[0]);
 190         close(p3[1]);
 191         close(0);
 192         close(1);
 193         close(2);
 194
 195         /* we want to ensure that all of the network sockets we had
 196            open are closed */
 197         tevent_re_initialise(ev);
 198
 199         /* setup for logging to go to the parents debug log */
 200         dup2(p3[0], 0);
 201         dup2(p1[1], 1);
 202         dup2(p2[1], 2);
 203
 204         close(p1[1]);
 205         close(p2[1]);
 206         close(p3[0]);
 207
 208         argv = str_list_copy(state, discard_const_p(const char *, argv0));
 209         if (!argv) {
 210                 fprintf(stderr, "Out of memory in child\n");
 211                 _exit(255);
 212         }
 213
 214         va_start(ap, argv0);
 215         while (1) {
 216                 char *arg = va_arg(ap, char *);
 217                 if (arg == NULL) break;
 218                 argv = discard_const_p(char *, str_list_add((const char **)argv, arg));
 219                 if (!argv) {
 220                         fprintf(stderr, "Out of memory in child\n");
 221                         _exit(255);
 222                 }
 223         }
 224         va_end(ap);
 225
 226         (void)execvp(state->arg0, argv);
 227         fprintf(stderr, "Failed to exec child - %s\n", strerror(errno));
 228         _exit(255);
 229         return NULL;
 230 }
 231
 232 /*
 233   handle stdout/stderr from the child
 234  */
 235 static void samba_runcmd_io_handler(struct tevent_context *ev,
 236                                     struct tevent_fd *fde,
 237                                     uint16_t flags,
 238                                     void *private_data)
 239 {
 240         struct tevent_req *req = talloc_get_type_abort(private_data,
 241                                  struct tevent_req);
 242         struct samba_runcmd_state *state = tevent_req_data(req,
 243                                            struct samba_runcmd_state);
 244         int level;
 245         char *p;
 246         int n, fd;
 247
 248         if (fde == state->fde_stdout) {
 249                 level = state->stdout_log_level;
 250                 fd = state->fd_stdout;
 251         } else if (fde == state->fde_stderr) {
 252                 level = state->stderr_log_level;
 253                 fd = state->fd_stderr;
 254         } else if (fde == state->fde_stdin) {
 255                 char c;
 256                 if (read(state->fd_stdin, &c, 1) != 1) {
 257                         /* the child has closed its stdin */
 258                         talloc_free(fde);
 259                         state->fde_stdin = NULL;
 260                         return;
 261                 }
 262         } else {
 263                 return;
 264         }
 265
 266         if (!(flags & TEVENT_FD_READ)) {
 267                 return;
 268         }
 269
 270         n = read(fd, &state->buf[state->buf_used],
 271                  sizeof(state->buf) - state->buf_used);
 272         if (n > 0) {
 273                 state->buf_used += n;
 274         } else if (n == 0) {
 275                 if (fde == state->fde_stdout) {
 276                         talloc_free(fde);
 277                         state->fde_stdout = NULL;
 278                 }
 279                 if (fde == state->fde_stderr) {
 280                         talloc_free(fde);
 281                         state->fde_stderr = NULL;
 282                 }
 283                 if (state->fde_stdout == NULL &&
 284                     state->fde_stderr == NULL) {
 285                         int status;
 286                         /* the child has closed both stdout and
 287                          * stderr, assume its dead */
 288                         pid_t pid = waitpid(state->pid, &status, 0);
 289                         if (pid != state->pid) {
 290                                 if (errno == ECHILD) {
 291                                         /* this happens when the
 292                                            parent has set SIGCHLD to
 293                                            SIG_IGN. In that case we
 294                                            can only get error
 295                                            information for the child
 296                                            via its logging. We should
 297                                            stop using SIG_IGN on
 298                                            SIGCHLD in the standard
 299                                            process model.
 300                                         */
 301                                         tevent_req_done(req);
 302                                         return;
 303                                 }
 304                                 DEBUG(0,("Error in waitpid() for child %s - %s \n",
 305                                          state->arg0, strerror(errno)));
 306                                 if (errno == 0) {
 307                                         errno = ECHILD;
 308                                 }
 309                                 tevent_req_error(req, errno);
 310                                 return;
 311                         }
 312                         status = WEXITSTATUS(status);
 313                         DEBUG(3,("Child %s exited with status %d - %s\n",
 314                                  state->arg0, status, strerror(status)));
 315                         if (status != 0) {
 316                                 tevent_req_error(req, status);
 317                                 return;
 318                         }
 319
 320                         tevent_req_done(req);
 321                         return;
 322                 }
 323                 return;
 324         }
 325
 326         while (state->buf_used > 0 &&
 327                (p = (char *)memchr(state->buf, '\n', state->buf_used)) != NULL) {
 328                 int n1 = (p - state->buf)+1;
 329                 int n2 = n1 - 1;
 330                 /* swallow \r from child processes */
 331                 if (n2 > 0 && state->buf[n2-1] == '\r') {
 332                         n2--;
 333                 }
 334                 DEBUG(level,("%s: %*.*s\n", state->arg0, n2, n2, state->buf));
 335                 memmove(state->buf, p+1, sizeof(state->buf) - n1);
 336                 state->buf_used -= n1;
 337         }
 338
 339         /* the buffer could have completely filled - unfortunately we have
 340            no choice but to dump it out straight away */
 341         if (state->buf_used == sizeof(state->buf)) {
 342                 DEBUG(level,("%s: %*.*s\n",
 343                              state->arg0, state->buf_used,
 344                              state->buf_used, state->buf));
 345                 state->buf_used = 0;
 346         }
 347 }
 348
 349 int samba_runcmd_recv(struct tevent_req *req, int *perrno)
 350 {
 351         if (tevent_req_is_unix_error(req, perrno)) {
 352                 tevent_req_received(req);
 353                 return -1;
 354         }
 355
 356         tevent_req_received(req);
 357         return 0;
 358 }