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                 talloc_set_destructor(state, samba_runcmd_state_destructor);
 139
 140                 state->fde_stdout = tevent_add_fd(ev, state,
 141                                                   state->fd_stdout,
 142                                                   TEVENT_FD_READ,
 143                                                   samba_runcmd_io_handler,
 144                                                   req);
 145                 if (tevent_req_nomem(state->fde_stdout, req)) {
 146                         close(state->fd_stdout);
 147                         close(state->fd_stderr);
 148                         close(state->fd_stdin);
 149                         return tevent_req_post(req, ev);
 150                 }
 151                 tevent_fd_set_auto_close(state->fde_stdout);
 152
 153                 state->fde_stderr = tevent_add_fd(ev, state,
 154                                                   state->fd_stderr,
 155                                                   TEVENT_FD_READ,
 156                                                   samba_runcmd_io_handler,
 157                                                   req);
 158                 if (tevent_req_nomem(state->fde_stdout, req)) {
 159                         close(state->fd_stderr);
 160                         close(state->fd_stdin);
 161                         return tevent_req_post(req, ev);
 162                 }
 163                 tevent_fd_set_auto_close(state->fde_stderr);
 164
 165                 state->fde_stdin = tevent_add_fd(ev, state,
 166                                                  state->fd_stdin,
 167                                                  0,
 168                                                  samba_runcmd_io_handler,
 169                                                  req);
 170                 if (tevent_req_nomem(state->fde_stdin, req)) {
 171                         close(state->fd_stdin);
 172                         return tevent_req_post(req, ev);
 173                 }
 174                 tevent_fd_set_auto_close(state->fde_stdin);
 175
 176                 if (!timeval_is_zero(&endtime)) {
 177                         tevent_req_set_endtime(req, ev, endtime);
 178                 }
 179
 180                 return req;
 181         }
 182
 183         /* the child */
 184         close(p1[0]);
 185         close(p2[0]);
 186         close(p3[1]);
 187         close(0);
 188         close(1);
 189         close(2);
 190
 191         /* we want to ensure that all of the network sockets we had
 192            open are closed */
 193         tevent_re_initialise(ev);
 194
 195         /* setup for logging to go to the parents debug log */
 196         dup2(p3[0], 0);
 197         dup2(p1[1], 1);
 198         dup2(p2[1], 2);
 199
 200         argv = str_list_copy(state, discard_const_p(const char *, argv0));
 201         if (!argv) {
 202                 fprintf(stderr, "Out of memory in child\n");
 203                 _exit(255);
 204         }
 205
 206         va_start(ap, argv0);
 207         while (1) {
 208                 char *arg = va_arg(ap, char *);
 209                 if (arg == NULL) break;
 210                 argv = discard_const_p(char *, str_list_add((const char **)argv, arg));
 211                 if (!argv) {
 212                         fprintf(stderr, "Out of memory in child\n");
 213                         _exit(255);
 214                 }
 215         }
 216         va_end(ap);
 217
 218         (void)execvp(state->arg0, argv);
 219         fprintf(stderr, "Failed to exec child - %s\n", strerror(errno));
 220         _exit(255);
 221         return NULL;
 222 }
 223
 224 /*
 225   handle stdout/stderr from the child
 226  */
 227 static void samba_runcmd_io_handler(struct tevent_context *ev,
 228                                     struct tevent_fd *fde,
 229                                     uint16_t flags,
 230                                     void *private_data)
 231 {
 232         struct tevent_req *req = talloc_get_type_abort(private_data,
 233                                  struct tevent_req);
 234         struct samba_runcmd_state *state = tevent_req_data(req,
 235                                            struct samba_runcmd_state);
 236         int level;
 237         char *p;
 238         int n, fd;
 239
 240         if (fde == state->fde_stdout) {
 241                 level = state->stdout_log_level;
 242                 fd = state->fd_stdout;
 243         } else if (fde == state->fde_stderr) {
 244                 level = state->stderr_log_level;
 245                 fd = state->fd_stderr;
 246         } else if (fde == state->fde_stdin) {
 247                 char c;
 248                 if (read(state->fd_stdin, &c, 1) != 1) {
 249                         /* the child has closed its stdin */
 250                         talloc_free(fde);
 251                         state->fde_stdin = NULL;
 252                         return;
 253                 }
 254         } else {
 255                 return;
 256         }
 257
 258         if (!(flags & TEVENT_FD_READ)) {
 259                 return;
 260         }
 261
 262         n = read(fd, &state->buf[state->buf_used],
 263                  sizeof(state->buf) - state->buf_used);
 264         if (n > 0) {
 265                 state->buf_used += n;
 266         } else if (n == 0) {
 267                 if (fde == state->fde_stdout) {
 268                         talloc_free(fde);
 269                         state->fde_stdout = NULL;
 270                 }
 271                 if (fde == state->fde_stderr) {
 272                         talloc_free(fde);
 273                         state->fde_stderr = NULL;
 274                 }
 275                 if (state->fde_stdout == NULL &&
 276                     state->fde_stderr == NULL) {
 277                         int status;
 278                         /* the child has closed both stdout and
 279                          * stderr, assume its dead */
 280                         pid_t pid = waitpid(state->pid, &status, 0);
 281                         if (pid != state->pid) {
 282                                 if (errno == ECHILD) {
 283                                         /* this happens when the
 284                                            parent has set SIGCHLD to
 285                                            SIG_IGN. In that case we
 286                                            can only get error
 287                                            information for the child
 288                                            via its logging. We should
 289                                            stop using SIG_IGN on
 290                                            SIGCHLD in the standard
 291                                            process model.
 292                                         */
 293                                         tevent_req_done(req);
 294                                         return;
 295                                 }
 296                                 DEBUG(0,("Error in waitpid() for child %s - %s \n",
 297                                          state->arg0, strerror(errno)));
 298                                 if (errno == 0) {
 299                                         errno = ECHILD;
 300                                 }
 301                                 tevent_req_error(req, errno);
 302                                 return;
 303                         }
 304                         status = WEXITSTATUS(status);
 305                         DEBUG(3,("Child %s exited with status %d - %s\n",
 306                                  state->arg0, status, strerror(status)));
 307                         if (status != 0) {
 308                                 tevent_req_error(req, status);
 309                                 return;
 310                         }
 311
 312                         tevent_req_done(req);
 313                         return;
 314                 }
 315                 return;
 316         }
 317
 318         while (state->buf_used > 0 &&
 319                (p = (char *)memchr(state->buf, '\n', state->buf_used)) != NULL) {
 320                 int n1 = (p - state->buf)+1;
 321                 int n2 = n1 - 1;
 322                 /* swallow \r from child processes */
 323                 if (n2 > 0 && state->buf[n2-1] == '\r') {
 324                         n2--;
 325                 }
 326                 DEBUG(level,("%s: %*.*s\n", state->arg0, n2, n2, state->buf));
 327                 memmove(state->buf, p+1, sizeof(state->buf) - n1);
 328                 state->buf_used -= n1;
 329         }
 330
 331         /* the buffer could have completely filled - unfortunately we have
 332            no choice but to dump it out straight away */
 333         if (state->buf_used == sizeof(state->buf)) {
 334                 DEBUG(level,("%s: %*.*s\n",
 335                              state->arg0, state->buf_used,
 336                              state->buf_used, state->buf));
 337                 state->buf_used = 0;
 338         }
 339 }
 340
 341 int samba_runcmd_recv(struct tevent_req *req, int *perrno)
 342 {
 343         if (tevent_req_is_unix_error(req, perrno)) {
 344                 tevent_req_received(req);
 345                 return -1;
 346         }
 347
 348         tevent_req_received(req);
 349         return 0;
 350 }