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