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