src/run-generator/run-generator.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <unistd.h>
   4
   5 #include "alloc-util.h"
   6 #include "escape.h"
   7 #include "fd-util.h"
   8 #include "fileio.h"
   9 #include "generator.h"
  10 #include "mkdir.h"
  11 #include "proc-cmdline.h"
  12 #include "specifier.h"
  13 #include "strv.h"
  14
  15 static const char *arg_dest = NULL;
  16 static char **arg_commands = NULL;
  17 static char *arg_success_action = NULL;
  18 static char *arg_failure_action = NULL;
  19
  20 STATIC_DESTRUCTOR_REGISTER(arg_commands, strv_freep);
  21 STATIC_DESTRUCTOR_REGISTER(arg_success_action, freep);
  22 STATIC_DESTRUCTOR_REGISTER(arg_failure_action, freep);
  23
  24 static int parse(const char *key, const char *value, void *data) {
  25         int r;
  26
  27         if (proc_cmdline_key_streq(key, "systemd.run")) {
  28
  29                 if (proc_cmdline_value_missing(key, value))
  30                         return 0;
  31
  32                 r = strv_extend(&arg_commands, value);
  33                 if (r < 0)
  34                         return log_oom();
  35
  36         } else if (proc_cmdline_key_streq(key, "systemd.run_success_action")) {
  37
  38                 if (proc_cmdline_value_missing(key, value))
  39                         return 0;
  40
  41                 if (free_and_strdup(&arg_success_action, value) < 0)
  42                         return log_oom();
  43
  44         } else if (proc_cmdline_key_streq(key, "systemd.run_failure_action")) {
  45
  46                 if (proc_cmdline_value_missing(key, value))
  47                         return 0;
  48
  49                 if (free_and_strdup(&arg_failure_action, value) < 0)
  50                         return log_oom();
  51         }
  52
  53         return 0;
  54 }
  55
  56 static int generate(void) {
  57         _cleanup_fclose_ FILE *f = NULL;
  58         const char *p;
  59         char **c;
  60         int r;
  61
  62         if (strv_isempty(arg_commands) && !arg_success_action)
  63                 return 0;
  64
  65         p = strjoina(arg_dest, "/kernel-command-line.service");
  66         f = fopen(p, "wxe");
  67         if (!f)
  68                 return log_error_errno(errno, "Failed to create unit file %s: %m", p);
  69
  70         fputs("# Automatically generated by systemd-run-generator\n\n"
  71               "[Unit]\n"
  72               "Description=Command from Kernel Command Line\n"
  73               "Documentation=man:systemd-run-generator(8)\n"
  74               "SourcePath=/proc/cmdline\n", f);
  75
  76         if (!streq_ptr(arg_success_action, "none"))
  77                 fprintf(f, "SuccessAction=%s\n",
  78                         arg_success_action ?: "exit");
  79
  80         if (!streq_ptr(arg_failure_action, "none"))
  81                 fprintf(f, "FailureAction=%s\n",
  82                         arg_failure_action ?: "exit");
  83
  84         fputs("\n"
  85               "[Service]\n"
  86               "Type=oneshot\n"
  87               "StandardOutput=journal+console\n", f);
  88
  89         STRV_FOREACH(c, arg_commands) {
  90                 _cleanup_free_ char *a = NULL;
  91
  92                 a = specifier_escape(*c);
  93                 if (!a)
  94                         return log_oom();
  95
  96                 fprintf(f, "ExecStart=%s\n", a);
  97         }
  98
  99         r = fflush_and_check(f);
 100         if (r < 0)
 101                 return log_error_errno(r, "Failed to write unit file %s: %m", p);
 102
 103         /* Let's create a a target we can link "default.target" to */
 104         p = strjoina(arg_dest, "/kernel-command-line.target");
 105         r = write_string_file(
 106                         p,
 107                         "# Automatically generated by systemd-run-generator\n\n"
 108                         "[Unit]\n"
 109                         "Description=Command from Kernel Command Line\n"
 110                         "Documentation=man:systemd-run-generator(8)\n"
 111                         "SourcePath=/proc/cmdline\n"
 112                         "Requires=kernel-command-line.service\n"
 113                         "After=kernel-command-line.service\n",
 114                         WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_NOFOLLOW);
 115         if (r < 0)
 116                 return log_error_errno(r, "Failed to create unit file %s: %m", p);
 117
 118         /* And now redirect default.target to our new target */
 119         p = strjoina(arg_dest, "/default.target");
 120         if (symlink("kernel-command-line.target", p) < 0)
 121                 return log_error_errno(errno, "Failed to link unit file kernel-command-line.target → %s: %m", p);
 122
 123         return 0;
 124 }
 125
 126 static int run(const char *dest, const char *dest_early, const char *dest_late) {
 127         int r;
 128
 129         assert_se(arg_dest = dest);
 130
 131         r = proc_cmdline_parse(parse, NULL, PROC_CMDLINE_RD_STRICT|PROC_CMDLINE_STRIP_RD_PREFIX);
 132         if (r < 0)
 133                 log_warning_errno(r, "Failed to parse kernel command line, ignoring: %m");
 134
 135         return generate();
 136 }
 137
 138 DEFINE_MAIN_GENERATOR_FUNCTION(run);