src/run-generator/run-generator.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "alloc-util.h"
   4 #include "escape.h"
   5 #include "fd-util.h"
   6 #include "fileio.h"
   7 #include "generator.h"
   8 #include "mkdir.h"
   9 #include "proc-cmdline.h"
  10 #include "specifier.h"
  11 #include "strv.h"
  12
  13 static const char *arg_dest = NULL;
  14 static char **arg_commands = NULL;
  15 static char *arg_success_action = NULL;
  16 static char *arg_failure_action = NULL;
  17
  18 STATIC_DESTRUCTOR_REGISTER(arg_commands, strv_freep);
  19 STATIC_DESTRUCTOR_REGISTER(arg_success_action, freep);
  20 STATIC_DESTRUCTOR_REGISTER(arg_failure_action, freep);
  21
  22 static int parse(const char *key, const char *value, void *data) {
  23         int r;
  24
  25         if (proc_cmdline_key_streq(key, "systemd.run")) {
  26
  27                 if (proc_cmdline_value_missing(key, value))
  28                         return 0;
  29
  30                 r = strv_extend(&arg_commands, value);
  31                 if (r < 0)
  32                         return log_oom();
  33
  34         } else if (proc_cmdline_key_streq(key, "systemd.run_success_action")) {
  35
  36                 if (proc_cmdline_value_missing(key, value))
  37                         return 0;
  38
  39                 if (free_and_strdup(&arg_success_action, value) < 0)
  40                         return log_oom();
  41
  42         } else if (proc_cmdline_key_streq(key, "systemd.run_failure_action")) {
  43
  44                 if (proc_cmdline_value_missing(key, value))
  45                         return 0;
  46
  47                 if (free_and_strdup(&arg_failure_action, value) < 0)
  48                         return log_oom();
  49         }
  50
  51         return 0;
  52 }
  53
  54 static int generate(void) {
  55         _cleanup_fclose_ FILE *f = NULL;
  56         const char *p;
  57         char **c;
  58         int r;
  59
  60         if (strv_isempty(arg_commands) && !arg_success_action)
  61                 return 0;
  62
  63         p = strjoina(arg_dest, "/kernel-command-line.service");
  64         f = fopen(p, "wxe");
  65         if (!f)
  66                 return log_error_errno(errno, "Failed to create unit file %s: %m", p);
  67
  68         fputs("# Automatically generated by systemd-run-generator\n\n"
  69               "[Unit]\n"
  70               "Description=Command from Kernel Command Line\n"
  71               "Documentation=man:systemd-run-generator(8)\n"
  72               "SourcePath=/proc/cmdline\n", f);
  73
  74         if (!streq_ptr(arg_success_action, "none"))
  75                 fprintf(f, "SuccessAction=%s\n",
  76                         arg_success_action ?: "exit");
  77
  78         if (!streq_ptr(arg_failure_action, "none"))
  79                 fprintf(f, "FailureAction=%s\n",
  80                         arg_failure_action ?: "exit");
  81
  82         fputs("\n"
  83               "[Service]\n"
  84               "Type=oneshot\n"
  85               "StandardOutput=journal+console\n", f);
  86
  87         STRV_FOREACH(c, arg_commands) {
  88                 _cleanup_free_ char *a = NULL;
  89
  90                 a = specifier_escape(*c);
  91                 if (!a)
  92                         return log_oom();
  93
  94                 fprintf(f, "ExecStart=%s\n", a);
  95         }
  96
  97         r = fflush_and_check(f);
  98         if (r < 0)
  99                 return log_error_errno(r, "Failed to write unit file %s: %m", p);
 100
 101         /* Let's create a a target we can link "default.target" to */
 102         p = strjoina(arg_dest, "/kernel-command-line.target");
 103         r = write_string_file(
 104                         p,
 105                         "# Automatically generated by systemd-run-generator\n\n"
 106                         "[Unit]\n"
 107                         "Description=Command from Kernel Command Line\n"
 108                         "Documentation=man:systemd-run-generator(8)\n"
 109                         "SourcePath=/proc/cmdline\n"
 110                         "Requires=kernel-command-line.service\n"
 111                         "After=kernel-command-line.service\n",
 112                         WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_NOFOLLOW);
 113         if (r < 0)
 114                 return log_error_errno(r, "Failed to create unit file %s: %m", p);
 115
 116         /* And now redirect default.target to our new target */
 117         p = strjoina(arg_dest, "/default.target");
 118         if (symlink("kernel-command-line.target", p) < 0)
 119                 return log_error_errno(errno, "Failed to link unit file kernel-command-line.target → %s: %m", p);
 120
 121         return 0;
 122 }
 123
 124 static int run(const char *dest, const char *dest_early, const char *dest_late) {
 125         int r;
 126
 127         assert_se(arg_dest = dest);
 128
 129         r = proc_cmdline_parse(parse, NULL, PROC_CMDLINE_RD_STRICT|PROC_CMDLINE_STRIP_RD_PREFIX);
 130         if (r < 0)
 131                 log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");
 132
 133         return generate();
 134 }
 135
 136 DEFINE_MAIN_GENERATOR_FUNCTION(run);