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

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