src/shared/exec-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <dirent.h>
   4 #include <errno.h>
   5 #include <sys/prctl.h>
   6 #include <sys/types.h>
   7 #include <unistd.h>
   8 #include <stdio.h>
   9
  10 #include "alloc-util.h"
  11 #include "conf-files.h"
  12 #include "env-file.h"
  13 #include "env-util.h"
  14 #include "exec-util.h"
  15 #include "fd-util.h"
  16 #include "fileio.h"
  17 #include "hashmap.h"
  18 #include "macro.h"
  19 #include "process-util.h"
  20 #include "serialize.h"
  21 #include "set.h"
  22 #include "signal-util.h"
  23 #include "stat-util.h"
  24 #include "string-util.h"
  25 #include "strv.h"
  26 #include "terminal-util.h"
  27 #include "tmpfile-util.h"
  28 #include "util.h"
  29
  30 /* Put this test here for a lack of better place */
  31 assert_cc(EAGAIN == EWOULDBLOCK);
  32
  33 static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid) {
  34
  35         pid_t _pid;
  36         int r;
  37
  38         if (null_or_empty_path(path)) {
  39                 log_debug("%s is empty (a mask).", path);
  40                 return 0;
  41         }
  42
  43         r = safe_fork("(direxec)", FORK_DEATHSIG|FORK_LOG, &_pid);
  44         if (r < 0)
  45                 return r;
  46         if (r == 0) {
  47                 char *_argv[2];
  48
  49                 if (stdout_fd >= 0) {
  50                         r = rearrange_stdio(STDIN_FILENO, stdout_fd, STDERR_FILENO);
  51                         if (r < 0)
  52                                 _exit(EXIT_FAILURE);
  53                 }
  54
  55                 if (!argv) {
  56                         _argv[0] = (char*) path;
  57                         _argv[1] = NULL;
  58                         argv = _argv;
  59                 } else
  60                         argv[0] = (char*) path;
  61
  62                 execv(path, argv);
  63                 log_error_errno(errno, "Failed to execute %s: %m", path);
  64                 _exit(EXIT_FAILURE);
  65         }
  66
  67         *pid = _pid;
  68         return 1;
  69 }
  70
  71 static int do_execute(
  72                 char **directories,
  73                 usec_t timeout,
  74                 gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
  75                 void* const callback_args[_STDOUT_CONSUME_MAX],
  76                 int output_fd,
  77                 char *argv[],
  78                 char *envp[]) {
  79
  80         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
  81         _cleanup_strv_free_ char **paths = NULL;
  82         char **path, **e;
  83         int r;
  84
  85         /* We fork this all off from a child process so that we can somewhat cleanly make
  86          * use of SIGALRM to set a time limit.
  87          *
  88          * If callbacks is nonnull, execution is serial. Otherwise, we default to parallel.
  89          */
  90
  91         r = conf_files_list_strv(&paths, NULL, NULL, CONF_FILES_EXECUTABLE|CONF_FILES_REGULAR|CONF_FILES_FILTER_MASKED, (const char* const*) directories);
  92         if (r < 0)
  93                 return log_error_errno(r, "Failed to enumerate executables: %m");
  94
  95         if (!callbacks) {
  96                 pids = hashmap_new(NULL);
  97                 if (!pids)
  98                         return log_oom();
  99         }
 100
 101         /* Abort execution of this process after the timout. We simply rely on SIGALRM as
 102          * default action terminating the process, and turn on alarm(). */
 103
 104         if (timeout != USEC_INFINITY)
 105                 alarm(DIV_ROUND_UP(timeout, USEC_PER_SEC));
 106
 107         STRV_FOREACH(e, envp)
 108                 if (putenv(*e) != 0)
 109                         return log_error_errno(errno, "Failed to set environment variable: %m");
 110
 111         STRV_FOREACH(path, paths) {
 112                 _cleanup_free_ char *t = NULL;
 113                 _cleanup_close_ int fd = -1;
 114                 pid_t pid;
 115
 116                 t = strdup(*path);
 117                 if (!t)
 118                         return log_oom();
 119
 120                 if (callbacks) {
 121                         fd = open_serialization_fd(basename(*path));
 122                         if (fd < 0)
 123                                 return log_error_errno(fd, "Failed to open serialization file: %m");
 124                 }
 125
 126                 r = do_spawn(t, argv, fd, &pid);
 127                 if (r <= 0)
 128                         continue;
 129
 130                 if (pids) {
 131                         r = hashmap_put(pids, PID_TO_PTR(pid), t);
 132                         if (r < 0)
 133                                 return log_oom();
 134                         t = NULL;
 135                 } else {
 136                         r = wait_for_terminate_and_check(t, pid, WAIT_LOG);
 137                         if (r < 0)
 138                                 continue;
 139
 140                         if (lseek(fd, 0, SEEK_SET) < 0)
 141                                 return log_error_errno(errno, "Failed to seek on serialization fd: %m");
 142
 143                         r = callbacks[STDOUT_GENERATE](fd, callback_args[STDOUT_GENERATE]);
 144                         fd = -1;
 145                         if (r < 0)
 146                                 return log_error_errno(r, "Failed to process output from %s: %m", *path);
 147                 }
 148         }
 149
 150         if (callbacks) {
 151                 r = callbacks[STDOUT_COLLECT](output_fd, callback_args[STDOUT_COLLECT]);
 152                 if (r < 0)
 153                         return log_error_errno(r, "Callback two failed: %m");
 154         }
 155
 156         while (!hashmap_isempty(pids)) {
 157                 _cleanup_free_ char *t = NULL;
 158                 pid_t pid;
 159
 160                 pid = PTR_TO_PID(hashmap_first_key(pids));
 161                 assert(pid > 0);
 162
 163                 t = hashmap_remove(pids, PID_TO_PTR(pid));
 164                 assert(t);
 165
 166                 (void) wait_for_terminate_and_check(t, pid, WAIT_LOG);
 167         }
 168
 169         return 0;
 170 }
 171
 172 int execute_directories(
 173                 const char* const* directories,
 174                 usec_t timeout,
 175                 gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
 176                 void* const callback_args[_STDOUT_CONSUME_MAX],
 177                 char *argv[],
 178                 char *envp[]) {
 179
 180         char **dirs = (char**) directories;
 181         _cleanup_close_ int fd = -1;
 182         char *name;
 183         int r;
 184
 185         assert(!strv_isempty(dirs));
 186
 187         name = basename(dirs[0]);
 188         assert(!isempty(name));
 189
 190         if (callbacks) {
 191                 assert(callback_args);
 192                 assert(callbacks[STDOUT_GENERATE]);
 193                 assert(callbacks[STDOUT_COLLECT]);
 194                 assert(callbacks[STDOUT_CONSUME]);
 195
 196                 fd = open_serialization_fd(name);
 197                 if (fd < 0)
 198                         return log_error_errno(fd, "Failed to open serialization file: %m");
 199         }
 200
 201         /* Executes all binaries in the directories serially or in parallel and waits for
 202          * them to finish. Optionally a timeout is applied. If a file with the same name
 203          * exists in more than one directory, the earliest one wins. */
 204
 205         r = safe_fork("(sd-executor)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG|FORK_WAIT, NULL);
 206         if (r < 0)
 207                 return r;
 208         if (r == 0) {
 209                 r = do_execute(dirs, timeout, callbacks, callback_args, fd, argv, envp);
 210                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 211         }
 212
 213         if (!callbacks)
 214                 return 0;
 215
 216         if (lseek(fd, 0, SEEK_SET) < 0)
 217                 return log_error_errno(errno, "Failed to rewind serialization fd: %m");
 218
 219         r = callbacks[STDOUT_CONSUME](fd, callback_args[STDOUT_CONSUME]);
 220         fd = -1;
 221         if (r < 0)
 222                 return log_error_errno(r, "Failed to parse returned data: %m");
 223         return 0;
 224 }
 225
 226 static int gather_environment_generate(int fd, void *arg) {
 227         char ***env = arg, **x, **y;
 228         _cleanup_fclose_ FILE *f = NULL;
 229         _cleanup_strv_free_ char **new = NULL;
 230         int r;
 231
 232         /* Read a series of VAR=value assignments from fd, use them to update the list of
 233          * variables in env. Also update the exported environment.
 234          *
 235          * fd is always consumed, even on error.
 236          */
 237
 238         assert(env);
 239
 240         f = fdopen(fd, "r");
 241         if (!f) {
 242                 safe_close(fd);
 243                 return -errno;
 244         }
 245
 246         r = load_env_file_pairs(f, NULL, &new);
 247         if (r < 0)
 248                 return r;
 249
 250         STRV_FOREACH_PAIR(x, y, new) {
 251                 char *p;
 252
 253                 if (!env_name_is_valid(*x)) {
 254                         log_warning("Invalid variable assignment \"%s=...\", ignoring.", *x);
 255                         continue;
 256                 }
 257
 258                 p = strjoin(*x, "=", *y);
 259                 if (!p)
 260                         return -ENOMEM;
 261
 262                 r = strv_env_replace(env, p);
 263                 if (r < 0)
 264                         return r;
 265
 266                 if (setenv(*x, *y, true) < 0)
 267                         return -errno;
 268         }
 269
 270         return r;
 271 }
 272
 273 static int gather_environment_collect(int fd, void *arg) {
 274         _cleanup_fclose_ FILE *f = NULL;
 275         char ***env = arg;
 276         int r;
 277
 278         /* Write out a series of env=cescape(VAR=value) assignments to fd. */
 279
 280         assert(env);
 281
 282         f = fdopen(fd, "w");
 283         if (!f) {
 284                 safe_close(fd);
 285                 return -errno;
 286         }
 287
 288         r = serialize_strv(f, "env", *env);
 289         if (r < 0)
 290                 return r;
 291
 292         r = fflush_and_check(f);
 293         if (r < 0)
 294                 return r;
 295
 296         return 0;
 297 }
 298
 299 static int gather_environment_consume(int fd, void *arg) {
 300         _cleanup_fclose_ FILE *f = NULL;
 301         char ***env = arg;
 302         int r = 0;
 303
 304         /* Read a series of env=cescape(VAR=value) assignments from fd into env. */
 305
 306         assert(env);
 307
 308         f = fdopen(fd, "re");
 309         if (!f) {
 310                 safe_close(fd);
 311                 return -errno;
 312         }
 313
 314         for (;;) {
 315                 _cleanup_free_ char *line = NULL;
 316                 const char *v;
 317                 int k;
 318
 319                 k = read_line(f, LONG_LINE_MAX, &line);
 320                 if (k < 0)
 321                         return k;
 322                 if (k == 0)
 323                         break;
 324
 325                 v = startswith(line, "env=");
 326                 if (!v) {
 327                         log_debug("Serialization line \"%s\" unexpectedly didn't start with \"env=\".", line);
 328                         if (r == 0)
 329                                 r = -EINVAL;
 330
 331                         continue;
 332                 }
 333
 334                 k = deserialize_environment(v, env);
 335                 if (k < 0) {
 336                         log_debug_errno(k, "Invalid serialization line \"%s\": %m", line);
 337
 338                         if (r == 0)
 339                                 r = k;
 340                 }
 341         }
 342
 343         return r;
 344 }
 345
 346 const gather_stdout_callback_t gather_environment[] = {
 347         gather_environment_generate,
 348         gather_environment_collect,
 349         gather_environment_consume,
 350 };