src/rc-local-generator/rc-local-generator.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <stdio.h>
   5 #include <unistd.h>
   6
   7 #include "generator.h"
   8 #include "log.h"
   9 #include "mkdir.h"
  10 #include "string-util.h"
  11 #include "util.h"
  12
  13 static const char *arg_dest = NULL;
  14
  15 /* So you are reading this, and might wonder: why is this implemented as a generator rather than as a plain, statically
  16  * enabled service that carries appropriate ConditionFileIsExecutable= lines? The answer is this: conditions bypass
  17  * execution of a service's binary, but they have no influence on unit dependencies. Thus, a service that is
  18  * conditioned out will still act as synchronization point in the dependency tree, and we'd rather not have that for
  19  * these two legacy scripts. */
  20
  21 static int add_symlink(const char *service, const char *where) {
  22         const char *from, *to;
  23
  24         assert(service);
  25         assert(where);
  26
  27         from = strjoina(SYSTEM_DATA_UNIT_PATH "/", service);
  28         to = strjoina(arg_dest, "/", where, ".wants/", service);
  29
  30         (void) mkdir_parents_label(to, 0755);
  31
  32         if (symlink(from, to) < 0) {
  33                 if (errno == EEXIST)
  34                         return 0;
  35
  36                 return log_error_errno(errno, "Failed to create symlink %s: %m", to);
  37         }
  38
  39         return 1;
  40 }
  41
  42 static int check_executable(const char *path) {
  43         assert(path);
  44
  45         if (access(path, X_OK) < 0) {
  46                 if (errno == ENOENT)
  47                         return log_debug_errno(errno, "%s does not exist, skipping.", path);
  48                 if (errno == EACCES)
  49                         return log_info_errno(errno, "%s is not marked executable, skipping.", path);
  50
  51                 return log_warning_errno(errno, "Couldn't determine if %s exists and is executable, skipping: %m", path);
  52         }
  53
  54         return 0;
  55 }
  56
  57 static int run(const char *dest, const char *dest_early, const char *dest_late) {
  58         int r = 0, k = 0;
  59
  60         assert_se(arg_dest = dest);
  61
  62         if (check_executable(RC_LOCAL_SCRIPT_PATH_START) >= 0) {
  63                 log_debug("Automatically adding rc-local.service.");
  64
  65                 r = add_symlink("rc-local.service", "multi-user.target");
  66         }
  67
  68         if (check_executable(RC_LOCAL_SCRIPT_PATH_STOP) >= 0) {
  69                 log_debug("Automatically adding halt-local.service.");
  70
  71                 k = add_symlink("halt-local.service", "final.target");
  72         }
  73
  74         return r < 0 ? r : k;
  75 }
  76
  77 DEFINE_MAIN_GENERATOR_FUNCTION(run);