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