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 "main-func.h"
   9 #include "mkdir.h"
  10 #include "proc-cmdline.h"
  11 #include "specifier.h"
  12 #include "strv.h"
  13
  14 static const char *arg_dest = "/tmp";
  15 static char **arg_commands = NULL;
  16 static char *arg_success_action = NULL;
  17 static char *arg_failure_action = NULL;
  18
  19 STATIC_DESTRUCTOR_REGISTER(arg_commands, strv_freep);
  20 STATIC_DESTRUCTOR_REGISTER(arg_success_action, freep);
  21 STATIC_DESTRUCTOR_REGISTER(arg_failure_action, freep);
  22
  23 static int parse(const char *key, const char *value, void *data) {
  24         int r;
  25
  26         if (proc_cmdline_key_streq(key, "systemd.run")) {
  27
  28                 if (proc_cmdline_value_missing(key, value))
  29                         return 0;
  30
  31                 r = strv_extend(&arg_commands, value);
  32                 if (r < 0)
  33                         return log_oom();
  34
  35         } else if (proc_cmdline_key_streq(key, "systemd.run_success_action")) {
  36
  37                 if (proc_cmdline_value_missing(key, value))
  38                         return 0;
  39
  40                 if (free_and_strdup(&arg_success_action, value) < 0)
  41                         return log_oom();
  42
  43         } else if (proc_cmdline_key_streq(key, "systemd.run_failure_action")) {
  44
  45                 if (proc_cmdline_value_missing(key, value))
  46                         return 0;
  47
  48                 if (free_and_strdup(&arg_failure_action, value) < 0)
  49                         return log_oom();
  50         }
  51
  52         return 0;
  53 }
  54
  55 static int generate(void) {
  56         _cleanup_fclose_ FILE *f = NULL;
  57         const char *p;
  58         char **c;
  59         int r;
  60
  61         if (strv_isempty(arg_commands) && !arg_success_action)
  62                 return 0;
  63
  64         p = strjoina(arg_dest, "/kernel-command-line.service");
  65         f = fopen(p, "wxe");
  66         if (!f)
  67                 return log_error_errno(errno, "Failed to create unit file %s: %m", p);
  68
  69         fputs("# Automatically generated by systemd-run-generator\n\n"
  70               "[Unit]\n"
  71               "Description=Command from Kernel Command Line\n"
  72               "Documentation=man:systemd-run-generator(8)\n"
  73               "SourcePath=/proc/cmdline\n", f);
  74
  75         if (!streq_ptr(arg_success_action, "none"))
  76                 fprintf(f, "SuccessAction=%s\n",
  77                         arg_success_action ?: "exit");
  78
  79         if (!streq_ptr(arg_failure_action, "none"))
  80                 fprintf(f, "FailureAction=%s\n",
  81                         arg_failure_action ?: "exit");
  82
  83         fputs("\n"
  84               "[Service]\n"
  85               "Type=oneshot\n"
  86               "StandardOutput=journal+console\n", f);
  87
  88         STRV_FOREACH(c, arg_commands) {
  89                 _cleanup_free_ char *a = NULL;
  90
  91                 a = specifier_escape(*c);
  92                 if (!a)
  93                         return log_oom();
  94
  95                 fprintf(f, "ExecStart=%s\n", a);
  96         }
  97
  98         r = fflush_and_check(f);
  99         if (r < 0)
 100                 return log_error_errno(r, "Failed to write unit file %s: %m", p);
 101
 102         /* Let's create a a target we can link "default.target" to */
 103         p = strjoina(arg_dest, "/kernel-command-line.target");
 104         r = write_string_file(
 105                         p,
 106                         "# Automatically generated by systemd-run-generator\n\n"
 107                         "[Unit]\n"
 108                         "Description=Command from Kernel Command Line\n"
 109                         "Documentation=man:systemd-run-generator(8)\n"
 110                         "SourcePath=/proc/cmdline\n"
 111                         "Requires=kernel-command-line.service\n"
 112                         "After=kernel-command-line.service\n",
 113                         WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_NOFOLLOW);
 114         if (r < 0)
 115                 return log_error_errno(r, "Failed to create unit file %s: %m", p);
 116
 117         /* And now redirect default.target to our new target */
 118         p = strjoina(arg_dest, "/default.target");
 119         if (symlink("kernel-command-line.target", p) < 0)
 120                 return log_error_errno(errno, "Failed to link unit file kernel-command-line.target → %s: %m", p);
 121
 122         return 0;
 123 }
 124
 125 static int run(int argc, char *argv[]) {
 126         int r;
 127
 128         log_setup_generator();
 129
 130         if (argc > 1 && argc != 4) {
 131                 log_error("This program takes three or no arguments.");
 132                 return -EINVAL;
 133         }
 134
 135         if (argc > 1)
 136                 arg_dest = argv[1];
 137
 138         umask(0022);
 139
 140         r = proc_cmdline_parse(parse, NULL, PROC_CMDLINE_RD_STRICT|PROC_CMDLINE_STRIP_RD_PREFIX);
 141         if (r < 0)
 142                 log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");
 143
 144         return generate();
 145 }
 146
 147 DEFINE_MAIN_FUNCTION(run);