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 "main-func.h"
  10 #include "mkdir.h"
  11 #include "string-util.h"
  12 #include "util.h"
  13
  14 static const char *arg_dest = "/tmp";
  15
  16 /* So you are reading this, and might wonder: why is this implemented as a generator rather than as a plain, statically
  17  * enabled service that carries appropriate ConditionFileIsExecutable= lines? The answer is this: conditions bypass
  18  * execution of a service's binary, but they have no influence on unit dependencies. Thus, a service that is
  19  * conditioned out will still act as synchronization point in the dependency tree, and we'd rather not have that for
  20  * these two legacy scripts. */
  21
  22 static int add_symlink(const char *service, const char *where) {
  23         const char *from, *to;
  24
  25         assert(service);
  26         assert(where);
  27
  28         from = strjoina(SYSTEM_DATA_UNIT_PATH "/", service);
  29         to = strjoina(arg_dest, "/", where, ".wants/", service);
  30
  31         (void) mkdir_parents_label(to, 0755);
  32
  33         if (symlink(from, to) < 0) {
  34                 if (errno == EEXIST)
  35                         return 0;
  36
  37                 return log_error_errno(errno, "Failed to create symlink %s: %m", to);
  38         }
  39
  40         return 1;
  41 }
  42
  43 static int check_executable(const char *path) {
  44         assert(path);
  45
  46         if (access(path, X_OK) < 0) {
  47                 if (errno == ENOENT)
  48                         return log_debug_errno(errno, "%s does not exist, skipping.", path);
  49                 if (errno == EACCES)
  50                         return log_info_errno(errno, "%s is not marked executable, skipping.", path);
  51
  52                 return log_warning_errno(errno, "Couldn't determine if %s exists and is executable, skipping: %m", path);
  53         }
  54
  55         return 0;
  56 }
  57
  58 static int run(int argc, char *argv[]) {
  59         int r = 0, k = 0;
  60
  61         log_setup_generator();
  62
  63         if (argc > 1 && argc != 4)
  64                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program takes three or no arguments.");
  65
  66         if (argc > 1)
  67                 arg_dest = argv[1];
  68
  69         if (check_executable(RC_LOCAL_SCRIPT_PATH_START) >= 0) {
  70                 log_debug("Automatically adding rc-local.service.");
  71
  72                 r = add_symlink("rc-local.service", "multi-user.target");
  73         }
  74
  75         if (check_executable(RC_LOCAL_SCRIPT_PATH_STOP) >= 0) {
  76                 log_debug("Automatically adding halt-local.service.");
  77
  78                 k = add_symlink("halt-local.service", "final.target");
  79         }
  80
  81         return r < 0 ? r : k;
  82 }
  83
  84 DEFINE_MAIN_FUNCTION(run);